Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Parvalbumins”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35Linked to original sources
PubMed1989

Calcium-binding protein (calbindin-D28k) and parvalbumin immunocytochemistry: localization in the rat hippocampus with specific reference to the selective vulnerability of hippocampal neurons to seizure activity.

Two neuronal calcium-binding proteins, calbindin-D28k (CaBP) and parvalbumin (PV), were localized in the normal rat hippocampus by using immunocytochemical methods to determine 1) their location and 2) whether a correlation exists between the presence of these two calcium-binding proteins and the selective vulnerability of different hippocampal neuronal populations to experimental seizure activity. CaBP-like immunoreactivity (CaBP-LI) is present in all dentate granule cells and some, but not all, CA1 and CA2 pyramidal cells. Some CA1 pyramidal cells lack CaBP-LI, and those that do are lightly stained compared to the dentate granule cells. CA3 pyramidal cells appear to contain neither CaBP- nor PV-LI, and no granule or pyramidal cells exhibit PV-LI. CaBP-LI is present in distinct populations of dentate and hippocampal interneurons but absent from others. In area dentata, CaBP-LI is present in a small number of interneurons of the molecular and granule cell layers and in a small population of presumed basket cells in or below the granule cell layer. Conversely, more presumed dentate basket cells exhibit PV-LI than CaBP-LI. In the hilus of area dentata, few cells are CaBP- or PV-immunoreactive. The hilar somatostatin/neuropeptide Y (NPY)-immunoreactive cells and hilar mossy cells, two distinct and large populations, lack CaBP- and PV-LI. In the CA3 region, CaBP-LI is present in a relatively small number of interneurons in each stratum. PV-immunoreactive interneurons in area CA3 are more numerous. In area CA1, CaBP-LI is present in many interneurons in strata radiatum and lacunosum-moleculare. Some, but relatively fewer, CaBP-positive interneurons are present in strata pyramidale and oriens. Conversely, PV-immunoreactive interneurons are numerous in strata pyramidale and oriens but rare in strata radiatum and lacunosum-moleculare. Staining with the particulate chromagen benzidine hydrochloride revealed a previously undescribed dense band of CaBP-LI in the inner dentate molecular layer, a lamina enriched with kainate-displaceable glutamate-binding sites and innervated by the apparently excitatory ipsilateral associational/commissural (IAC) pathway that originates in the CaBP-negative hilar mossy cells. Bilateral electrical stimulation of the perforant path was performed in order to destroy the hilar mossy cells and to determine if this band of CaBP-LI is normally present within the mossy cell terminals. Perforant path stimulation that destroyed hilar mossy cells throughout the dorsal portions of both hippocampi did not abolish the dense CaBP-like immunoreactivity in the inner molecular layer.

Animals↗
PubMed1990

Glutamic-acid-decarboxylase-and parvalbumin-like-immunoreactive structures in the olfactory bulb of the human adult.

This study examines the distribution and morphological characteristics of glutamic-acid-decarboxylase-like (GAD)- and parvalbumin-like (PA)-immunoreactive structures in the olfactory bulb of the human adult. GAD-immunoreactive somata occurred in the glomerular layer, the external granule cell layer, the more superficial portion of the external plexiform layer, and the internal granule cell layer. The cells were small- to medium-sized. Demonstration of lipofuscin pigment revealed the presence of unpigmented as well as pigmented neurons, thus suggesting the existence of two subpopulations of GAD-positive neurons. GAD-immunoreactive puncta and/or fibers were mainly seen in the periglomerular region and the internal granule cell layer. All other layers of the bulb, as well as the intrabulbar portion of the anterior olfactory nucleus, displayed considerably less of these puncta and/or fibers. The olfactory nerve layer remained practically clear of immunoreactive material. PA-immunoreactive somata occurred in the glomerular layer and both the external and internal granule cell layer. Only a small number of immunoreactive nerve cells were encountered within the white matter or the olfactory tract. Most PA-positive neurons displayed characteristics of short axon cells whereas a few others resembled van Gehuchten cells. All of the PA-immunoreactive neurons were devoid of lipofuscin pigment. Immunoreactive puncta and fibers were present in all layers though predominating in the periglomerular region, the olfactory nerve layer, and the internal granule cell layer. The intrabulbar portions of the anterior olfactory nucleus did not show any immunoreactive structures.

Adult↗
PubMed1990

Calcium-binding proteins, parvalbumin- and calbindin-D 28k-immunoreactive neurons in the rat spinal cord and dorsal root ganglia: a light and electron microscopic study.

The distribution of two calcium-binding proteins, parvalbumin (PV) and calbindin-D 28K (CaBP), was studied by the peroxidase-anti-peroxidase immunohistochemical method at the light and electron microscopic level in the rat spinal cord and dorsal root ganglia. The possible coexistence of these two proteins was also investigated. PV-positive neurons were revealed in all layers of the spinal cord, except lamina I, which was devoid of labelling. Most of the PV-positive cells were found in the inner layer of lamina II, lamina III, internal basilar nucleus, central gray region, and at the dorsomedial and ventromedial aspects of the lateral motor column in the ventral horn. Neuronal processes intensely stained for PV sharply delineated inner lamina II. With the electron microscope most of them appeared to be dendrites, but vesicle containing profiles were also found in a smaller number. CaBP-positive neurons appeared to be dispersed all over the spinal gray matter. The great majority of them were found in laminae I, II, IV; the central gray region; the intermediolateral nucleus; and in the ventral horn just medial to the lateral motor column. Laminae I and II were densely packed with CaBP-positive punctate profiles that proved to be dendrites and axons in the electron microscope. A portion of labelled neurons in lamina IV and on the ventromedial aspect of the lateral motor column in the ventral horn disclosed both PV- and CaBP-immunoreactivity. All of the funiculi of the spinal white matter contained a large number of fibres immunopositive for both PV and CaBP. The highest density of CaBP-positive fibres was found in the dorsolateral funiculus, which was also densely packed with PV-positive fibres. PV-positive fibres were even more numerous in the dorsal part of the dorsal funiculus. The territory of the gracile funiculus in the brachial cord and that of the pyramidal tract in its whole extent were devoid of labelled fibres. In the thoracic cord, the dorsal nucleus of Clarke received a large number of PV-positive fibres. Dorsal root ganglia displayed both PV- and CaBP-immunopositivity. The cell diameter distribution histogram of PV-positive neurons disclosed two peaks--one at 35 microns and the other at 50 microns. CaBP-positive cells in the dorsal root ganglia corresponded to subgroups of small and large neurons with mean diameters of 25 microns and 45 microns, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Proportion of parvalbumin-positive basket cells in the GABAergic innervation of pyramidal and granule cells of the rat hippocampal formation.

Recent studies have indicated that hippocampal GABAergic neurons in both the dentate gyrus and Ammon's horn contain immunoreactivity for the calcium-binding protein parvalbumin (PARV). Although the distribution of PARV-positive neurons has been previously described, detailed quantitative electron microscopic studies of the PARV-positive axon terminals in the hippocampal formation are lacking. In the present study, immunocytochemical methods were used to localize PARV-positive neurons and axon terminals to determine their similarity to GABAergic neurons. The PARV-positive cells and axon terminals are associated closely with the pyramidal and granule cell layers. In agreement with previous studies, the morphology of PARV-positive neurons is similar to that of GABAergic cells, including the basket cells of both the dentate gyrus and Ammon's horn. The PARV-positive axon terminals form exclusively symmetric synapses with somata, dendrites, dendritic spines, and axon initial segments. However, these terminals represent only a portion of the total number of terminals that form symmetric synapses. Quantitative results indicate that only 32-38% of the total number of terminals forming symmetric axosomatic synapses with principal cells of the dentate gyrus and Ammon's horn are PARV positive. Together with previous findings from light microscopic double-labeling studies, these data indicate that the PARV-positive terminals arise from a subpopulation of GABAergic hippocampal neurons. Finally, it is important to note that the terminal plexus of PARV-positive hippocampal axons overlaps at all postsynaptic sites with a plexus of PARV-negative axons.

Animals↗
PubMed1990

Localization of two calcium binding proteins, calbindin (28 kD) and parvalbumin (12 kD), in the vertebrate retina.

We used immunocytochemistry to locate two calcium binding proteins, calbindin (CaB) and parvalbumin (PV), in the retina of goldfish, frog, chick, rat, guinea pig, dog, and man. The location of CaB depended on the type of dominant photoreceptor cells in birds and mammals. In cone-dominant retinas such as those of the chick, CaB-like immunoreactivity was found in the cones, cone bipolars, and ganglion cells. Amacrine cells 5-12 microns across were also labeled. In rod-dominant retinas, such as those of the rat, guinea pig, and dog, horizontal cells, small amacrine cells (about 6 microns across), and cells in the ganglion cell layer were labeled. In the human retina, which has both cones and rods in abundance, cones, cone bipolars, ganglion cells, horizontal cells, and small and large amacrine cells were labeled. In the frog and goldfish, the level of CaB-like immunoreactivity was low. In the frog, a few cones, amacrine cells, and cells in the ganglion cell layer were labeled. No immunoreactive structures were seen in the goldfish retina. PV-like immunoreactivity was found in chicks, rats, and dogs. No such immunoreactive structures were seen in the other species. In the chick, only amacrine cells were labeled. In the rat, amacrine cells and several displaced amacrine cells were labeled. In the dog, in addition to amacrine cells and displaced amacrine cells, horizontal cells were strongly labeled. Thus, PV-like immunoreactivity was found in those elements relating to the modulation of the main pathway of the visual transmission system.

Animals↗
PubMed1990

Ontological study of calbindin-D28k-like and parvalbumin-like immunoreactivities in rat spinal cord and dorsal root ganglia.

The calcium ion plays an important role in some critical developmental events in the nervous system, such as neurulation and neurite elongation. Therefore, as the intracellular calcium-binding proteins calbindin-D28k (CaB) and parvalbumin (PV) may be expressed in these developmental events. Accordingly, the ontological expression of CaB and PV was examined immunocytochemically in the spinal cord and dorsal root ganglia (DRG) of the rat, in order to evaluate the relationship between CaB and PV expression, and other important developmental events. During the ontogenesis of the spinal cord, the CaB-like immunoreactivity was mainly observed in the cell somata. The immunoreactive cells in the ventral horn of the cervical and thoracic, lumbar, and sacral segments first appeared at embryonic day (E)-12, E-13, and E-14, respectively. However, these cells were not detected in the intermediate gray matter of the same segments at E-14, E-15, and E-16, respectively, and in the dorsal horn at E-14-E-15, E-16, and E-17, respectively. The peak of immunoreactive cells, both as to number and intensity, occurred in the perinatal period. However, from postnatal day (P)-14 on, the number and intensity of the positive cells decreased, the adult levels being reached at P-35. The PV-like immunoreactivity was mainly detected in the fibers and punctata during the ontogenesis of the spinal cord. The immunoreactive fibers first appeared on the surface of the dorsal horn in the cervical and thoracic segments at E-14, then entered the dorsal horn at E-15, and reached the intermediate gray matter and ventral horn at E-16. The first appearance of these fibers in the same areas of the lumbar and sacral segments occurred 1 day later than in the cervical and thoracic segments. During the perinatal period, the maximum content of PV-like immunoreactive fibers, together with many punctata, was seen in the gray matter. However, between P-14 and P-17, most of them lost immunoreactivity rapidly, with the exception of the medial region of the intermediate gray matter, where the PV-immunoreactive punctata remained up to the adult stage. In DRG neurons, both CaB and PV was expressed, but in different neurons. Neurons labeled with anti-CaB and anti-PV sera were first detected at E-16 and E-14, respectively. These neurons were large or medium-sized in the prenatal period.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Development of the calcium-binding protein parvalbumin and calbindin in monkey striate cortex.

The development of immunoreactivity for the calcium-binding proteins parvalbumin (PV) and calbindin-D28K (Cal) was studied in Macaca nemestrina striate cortex from fetal (F) 60 days to postnatal (P) 5 + years. We correlated changes in PV and Cal staining patterns with the well-documented developmental sequence for primate striate cortex neuron generation and maturation, synaptogenesis, and thalamocortical axon interactions in an attempt to deduce a functional role for these proteins. Our major findings is that Cal and PV have diametrically opposed developmental patterns except in layer 1. At F60 days both are present only in neurons of layer 1 and the number of labeled cell bodies and processes increases up to F125 days. Almost all Cal+ and PV+ cells in layer 1 disappear by P12 weeks. Cal is present by F113 days in pyramidal and stellate neurons, particularly layers 4-6. The numbers and staining density of cells in layers 2-6 increases up to birth and then both decline by P9-12 weeks. Supragranular layers show a second increase in Cal labeling from P20-36 weeks, and then there is a slow decline to the adult pattern which is reached by P1-2 years. Cell bodies in layers 4A, 4C alpha, and deep 4C beta are heavily Cal+ during pre- and early post-natal periods, but upper 4C beta remains unlabeled. PV is not seen until F155-162 days in layers 2-6. Large stellate and a few pyramidal cells appear first in layers 5/6 and 4C alpha, but PV+ stellate neurons are found in all layers except 4C beta by P6 weeks. Layer 4C beta contains a few PV+ cell bodies at P3 weeks, and light neuropile staining at P6 weeks, but then PV labeling rapidly increases so that by P12 weeks the density of 4C beta exceeds that of 4C alpha. Striate cortex has an adult pattern of cell number and neuropile density by P20 weeks. These developmental patterns suggest that the highest density of Cal cell body staining does not correlate with synaptogenesis, or the postnatal critical period of visually driven, binocular interactions. Rather Cal appears when lateral geniculate axons arrive in cortex, persists over the entire span of thalamocortical interactions, and disappears during the decline of cortical plasticity. The appearance of PV is highly correlated with the onset of complex visually driven activity at birth, while both the number of PV+ cell bodies and the density of PV+ neuropile reach adult levels coincident with the completion of thalamocortical connections.

Animals↗
PubMed1991

Calcium-binding protein (calbindin-D28K) and parvalbumin immunocytochemistry in the normal and epileptic human hippocampus.

The calcium-binding proteins calbindin-D28K (CaBP) and parvalbumin (PV) were localized in the "normal" and "epileptic" human hippocampus to address the possible relationship between the expression of these constitutive cytosolic calcium-binding proteins and the resistance or selective vulnerability of different hippocampal neuron populations in temporal lobe epilepsy. Compared to rodents and a baboon (Papio papio), the pattern of CaBP-like immunoreactivity (LI) in the "normal" human hippocampus is unique. CaBP-LI is present in the dentate granule cells, neurons of the "resistant zone" (area CA2), and presumed interneurons of all regions. Unlike rodent and baboon CA1 pyramidal cells, human CA1 pyramidal cells appear to be devoid of CaBP-LI. Thus, the relatively resistant dentate granule cells and CA2 pyramidal cells are the only human hippocampal principal cells that contain CaBP-LI normally. As in lower mammals, PV-LI is present exclusively in interneurons of all human hippocampal subregions. CaBP- and PV-LI were localized in hippocampi surgically removed in the treatment of intractable temporal lobe epilepsy to determine whether surviving hippocampal cells were those that express these calcium-binding proteins. Hippocampi removed from patients with tumors or arteriovenous malformations that were associated with complex partial seizures arising from this region appeared relatively normal histologically. CaBP- and PV-LI in this patient group appeared similar to that seen in autopsy controls. Conversely, "cryptogenic" epileptics, who exhibit hippocampal sclerosis as the only lesion associated with the epilepsy, exhibited a preferential survival of hippocampal cells that were CaBP- or PV-immunoreactive. In the dentate hilus, which normally contains few CaBP-LI neurons, most of the few surviving hilar neurons were CaBP-immunoreactive. Their number and darkness of staining suggests that CaBP synthesis may be increased in cells that survive. Despite an obvious decrease of PV-LI specifically in the damaged parts of the sclerotic hippocampi, PV-immunoreactive interneurons were often among the few surviving cells. Nevertheless, large expanses of the surviving granule cell layer appeared to have lost the PV-immunoreactive axosomatic fiber plexus. These results reveal a unique and striking correlation between the human hippocampal cells that normally express these calcium-binding proteins and those that survive in the sclerotic epileptic hippocampus.

Adult↗
PubMed1991

Parvalbumin- and calbindin D28k-immunoreactive neurons in the hippocampal formation of the macaque monkey.

Calcium-binding proteins calbindin D28k (CaBP) and parvalbumin (PV) were localized in neurons of the monkey hippocampal formation. CaBP immunoreactivity is present in all granule cells and in a large proportion of CA1 and CA2 pyramidal neurons, as well as in a distinct population of local circuit neurons. In the dentate gyrus, CaBP-immunoreactive nongranule cells are present in the molecular layer and in the hilar region, but they do not include the pyramidal basket cells at the hilar border. In the Ammon's horn, CaBP-positive, nonpyramidal neurons are more frequent in the CA3 area than in any other parts of the hippocampal formation. They are concentrated in the strata oriens and pyramidale of areas CA1-3, whereas only a few small neurons were found in the strata lucidum and radiatum of CA3 and in the stratum moleculare of the CA1 area. PV is exclusively present in local circuit neurons both in the dentate gyrus and in Ammon's horn. In the dentate gyrus the presumed basket cells at the hilar border exhibit PV immunoreactivity. In the hilar region and molecular layer only a relatively small number of cells are immunoreactive for PV. Most of these PV-positive cell bodies are located in the inner half of the molecular layer, with occasional horizontal cells at the hippocampal fissure. In Ammon's horn, strata oriens and pyramidale of areas CA1-3 contain a large number of PV-positive cells. There are no PV-immunoreactive cells in the strata lucidum, radiatum, or lacunosum moleculare. The CaBP- and PV-containing neurons form different subpopulations of cells in the monkey hippocampal formation. With the exception of a basket cell type in the monkey dentate gyrus, the CaBP- and PV-positive cell types were found to be remarkably similar in rodents and primates.

Animals↗
PubMed1991

Different populations of parvalbumin- and calbindin-D28k-immunoreactive neurons contain GABA and accumulate 3H-D-aspartate in the dorsal horn of the rat spinal cord.

The colocalization of parvalbumin (PV), calbindin-D28k (CaBP), GABA immunoreactivities, and the ability to accumulate 3H-D-aspartate selectively were investigated in neurons of laminae I-IV of the dorsal horn of the rat spinal cord. Following injection of 3H-D-aspartate into the basal dorsal horn (laminae IV-VI), perikarya selectively accumulating 3H-D-aspartate were detected in araldite embedded semithin sections by autoradiography, and consecutive semithin sections were treated to reveal PV, CaBP and GABA by postembedding immunocytochemistry. Perikarya accumulating 3H-D-aspartate were found exclusively in laminae I-III, and no labelled somata were found in deeper layers or in the intermediolateral column although the labelled amino acid clearly spread to these regions. More than half of the labelled cells were localized in lamina II. In this layer, 16.4% of 3H-D-aspartate-labelled perikarya were also stained for CaBP. In contrast to CaBP, PV or GABA was never detected in neurons accumulating 3H-D-aspartate. A high proportion of PV-immunoreactive perikarya were also stained for GABA in laminae II and III (70.0% and 61.2% respectively). However, the majority of CaBP-immunoreactive perikarya were GABA-negative. GABA-immunoreactivity was found in less than 2% of the total population of cells stained for CaBP in laminae I-IV. A significant proportion of the GABA-negative but PV-immunoreactive neurons also showed CaBP-immunoreactivity in laminae II and IV. These results show that out of the two calcium-binding proteins, CaBP is a characteristic protein of a small subpopulation of neurons using excitatory amino acids and PV is a characteristic protein of a subpopulation of neurons utilizing GABA as a transmitter. However, both proteins are present in additional subgroups of neurons, and neuronal populations using inhibitory or excitatory amino acid transmitters are heterogeneous with regard to their content of calcium-binding proteins in the dorsal horn of the rat spinal cord.

Animals↗
PubMed1992

The calcium binding proteins parvalbumin and calbindin-D 28K form complementary patterns in the cat superior colliculus.

Parvalbumin (PV) and calbindin-D 28K (CaBP) are calcium binding proteins involved in calcium regulation in the brain. In some regions they coexist in the same neuron, while in other regions they are found in different cell types. We have studied the distribution and morphology of PV labeled neurons in the cat superior colliculus (SC) with antibody immunocytochemistry and compared this labeling to that of CaBP. PV neurons were concentrated in a dense tier within the deep superficial gray and upper optic layers. Scattered PV neurons also were found within the deep layers of SC. By contrast, CaBP neurons were concentrated in three tiers: one within the zonal and upper superficial gray layers, a second within the deep optic and upper intermediate gray layers (IGL), and a third within the deep gray layer. The distribution of PV neurons is thus complementary to that of CaBP neurons, with the CaBP cell tiers bordering the dense tier of PV neurons. PV neurons varied in size and morphology. The average diameter of labeled cells was 20 microns, almost twice the size of CaBP neurons. The cells were predominantly round, vertical fusiform, or stellate, and included the very large neurons found scattered in the IGL. Horseradish peroxidase injections into the lateral geniculate nucleus, the lateral posterior nucleus, the opposite superior colliculus, the dorsal lateral pontine gray nucleus, and two descending pathways--the crossed predorsal bundle and the tecto-ponto-bulbar tracts--each labeled SC neurons that were also labeled by PV. A large percentage (84%) of projection neurons contained PV. This result also differs from CaBP neurons in SC, most of which are interneurons. Two antigen double-label experiments did not produce any cells that contained both PV and CaBP. The two calcium binding proteins thus reveal a unique sublaminar organization in SC that consists of alternating small cell interneuron groups and large cell projection neuron groups.

Animals↗
PubMed1992

Parvalbumin and calbindin immunocytochemistry reveal functionally distinct cell groups and vibrissa-related patterns in the trigeminal brainstem complex of the adult rat.

Immunocytochemistry for calbindin (CA) and parvalbumin (PA) was combined with retrograde tracing from the thalamus, superior colliculus (SC), and cerebellum to define the ascending projections of neurons in the rat's trigeminal (V) brainstem complex that express immunoreactivity for these calcium binding proteins. Many PA-immunoreactive neurons were observed in trigeminal nucleus principalis (PrV). Many of these cells projected to thalamus and a few sent axons to SC. In ventral PrV, PA-immunoreactive neurons were arranged in a vibrissa-related pattern. A very small number of large CA-immunoreactive neurons were observed in dorsomedial PrV. None of these cells were labeled by our tracer deposits. Small neurons in V subnucleus oralis (SpO) were also immunoreactive for PA, but none were retrogradely labeled. A small percentage of the large neurons in SpO were CA-immunoreactive; many of these were retrogradely labeled by tracer injections in the thalamus and/or SC. In V subnucleus interpolaris (SpI), many small to medium sized cells were PA-positive and they were arrayed in a vibrissae-like pattern. None of these neurons were retrogradely labeled from any of the above-listed targets, but many were retrogradely labeled by tracer injections into ipsilateral PrV. SpI also contained many large CA-immunoreactive cells. Many of these projected to the thalamus and/or SC and some were also retrogradely labeled by tracer injections into ipsilateral PrV. In V subnucleus caudalis (SpC), very dark PA-immunoreactive neurons were located in the inner part of lamina II and less often in laminae I. Lightly labeled cells were located in the magnocellular laminae and formed vibrissa-related aggregates. None of these neurons were retrogradely labeled by our tracer injections. CA-immunoreactive cells were located throughout the depth of lamina II in SpC and smaller numbers were also visible in lamina I and layers III-V. A small percentage of the CA-positive cells in lamina I and in the magnocellular layers were retrogradely labeled from the thalamus. These data indicate that PA and CA antisera identify two cell populations in whisker-related regions of the V brainstem complex and that PA cells are somatotopically patterned in PrV, SpI, and SpC. These markers also distinguish two cell groups in superficial laminae of the medullary dorsal horn.

Afferent Pathways↗
PubMed1993

Electron microscopic immunocytochemical study of the distribution of parvalbumin-containing neurons and axon terminals in the primate dentate gyrus and Ammon's horn.

Five green monkeys were examined with light and electron microscopic preparations to explore the regional differences in the distribution of parvalbumin (PV)-positive neurons and axon terminals in the primate hippocampus. PV-positive neurons were mainly found in the hilus of the dentate gyrus and the strata oriens and pyramidale of Ammon's horn. In electron microscopic preparations, the PV-positive cells displayed nuclear infoldings, intranuclear rods, a large rim of perikaryal cytoplasm with numerous organelles and both asymmetric and symmetric axosomatic synapses. One prominent PV-positive cell type in CA1 was a large multipolar neuron that resembled the large basket cells of the neocortex. Although most PV-positive dendrites were aspiny and postsynaptic to numerous axon terminals, some PV-positive dendrites in the molecular layer of the dentate gyrus displayed filipodia-like appendages with no synapses or spines that were postsynaptic to multiple axon terminals. The PV-positive dendrites in the hilus and stratum oriens were apposed at specialized junctions that resembled gap junctions. PV-positive axons were concentrated in the principal cell layers, and formed axosomatic, axodendritic, and axon initial segment synapses. In cases where these axons were observed to appose the surface of granule cells for a long length, only one axosomatic symmetric synapse per cell was found. In the hilus, PV-positive axon terminals formed synapses onto thorny excrescences of spiny cells. Both semithin sections and electron microscopic preparations indicated that more PV-positive axon terminals formed symmetric axosomatic synapses with pyramidal cells in CA2 than in CA1 and CA3. Also, CA2 displayed a unique plexus of PV-positive axon terminals in stratum lacunosum moleculare. These results indicate that the PV-positive hippocampal cells form a subset of GABAergic local circuit neurons, including the basket and chandelier cells. The ubiquitous finding of PV-positive dendrites linked by gap junctions throughout the dentate gyrus and Ammon's horn adds further data to indicate that this subset of GABAergic neurons is linked electrotonically. The synaptic organization of PV-positive neurons in the hippocampus suggests their participation in both feedback and feedforward inhibition. The PV-positive neurons in the hippocampus are only a proportion of the basket and chandelier cells, whereas virtually all of these cells in neocortex are PV-positive.

Animals↗
PubMed1993

Immunocytochemical staining of AII-amacrine cells in the rat retina with antibodies against parvalbumin.

The rod dominated rodent retina is the preferred tissue for in vitro studies of mammalian retinal physiology and pharmacology. The rod pathway through the rat retina was investigated, therefore, in order to find out whether its organization follows the mammalian "plan." AII-amacrine cells of the rat retina were injected with Lucifer Yellow to characterize the morphology of this bistratified interneuron of the rod pathway. When sections or whole mounts of the rat retina were stained with antibodies against the calcium binding protein parvalbumin (PV), two different amacrine cell types were labeled: the AII-amacrine cell and a widefield amacrine cell. They occur at a ratio of 12:1. Weak label was also observed in ganglion cells. The density of PV-labeled AII-cells decreases from approximately 7,000 cells/mm2 in upper central retina to 2,000 cells/mm2 in peripheral retina. Their cell bodies form a regular mosaic, and the dendritic arbors of three neighbouring AII-amacrine cells overlap (coverage of 3).

Animals↗
PubMed1993

Distribution, morphological features, and synaptic connections of parvalbumin- and calbindin D28k-immunoreactive neurons in the human hippocampal formation.

Calcium binding proteins calbindin D28k (CaBP) and parvalbumin (PV) are known to form distinct subpopulations of gamma-aminobutyric acid (GABA)ergic neurons in the rodent hippocampal formation. Light and electron microscopic morphology and connections of these protein-containing neurons are only partly known in the primate hippocampus. In this study, CaBP and PV were localized in neurons of the human hippocampal formation including the subicular complex (prosubiculum, subiculum, and presubiculum) in order to explore to what extent these subpopulations of hippocampal neurons differ in phylogenetically distant species. CaBP immunoreactivity was present in virtually all granule cells of the dentate gyrus and population of in a proportion of pyramidal neurons in the CA1 and CA2 regions. A distinct population of CaBP-positive local circuit neurons was found in all layers of the dentate gyrus and Ammon's horn. Most frequently they were located in the molecular layer of the dentate gyrus and the pyramidal layer of Ammon's horn. In the subicular complex pyramidal neurons were not immunoreactive for CaBP. In the prosubiculum and subiculum immunoreactive nonpyramidal neurons were equally distributed in all layers, whereas in the presubiculum they occurred mainly in the superficial layers. Electron microscopy showed typical somatic and dendritic features of the granule, pyramidal, and local circuit neurons. CaBP-positive mossy fiber terminals in the hilus of the dentate gyrus and terminals of presumed pyramidal neurons of Ammon's horn formed asymmetric synapses with dendrites and spines. CaBP-positive terminals of nonprincipal neurons formed symmetric synapses with dendrites and dendritic spines, but never with somata or axon initial segments. PV was exclusively present in local circuit neurons in both the hippocampal formation and subicular complex. Most of the PV-positive cell bodies were located among or close to the principal cell layers. However, large numbers of immunoreactive neurons were also found in the molecular layer of the dentate gyrus and in strata oriens of Ammon's horn. PV-positive cells were equally distributed in all layers of the subicular complex. Electron microscopy showed the characteristic somatic and dendritic features of local circuit neurons. PV-positive axon terminals formed exclusively symmetric synapses with somata, axon initial segments and dendritic shafts, and in a few cases with dendritic spines. The CaBP- and PV-containing neurons formed similar subpopulations in rodents, monkeys, and humans, although the human hippocampus displayed the largest variability of these immunoreactive neurons in their morphology and location. Calcium binding protein-containing neurons frequently occurred in the molecular layer of the human dentate gyrus and in the stratum lacunosum-moleculare of Ammon's horn.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1994

A study of SMI 32-stained pyramidal cells, parvalbumin-immunoreactive chandelier cells, and presumptive thalamocortical axons in the human temporal neocortex.

Immunocytochemical studies in the primate neocortex have shown that particular populations of pyramidal cells can be identified by antibody SMI 32 that recognizes a nonphosphorylated epitope of neurofilament protein, while chandelier cells (a powerful type of cortical inhibitory interneuron) and presumptive thalamocortical axons can be identified by antibodies directed against the calcium-binding protein parvalbumin (PV). We used these antibodies in correlative light and electron microscopic immunocytochemical studies to analyze certain aspects of the synaptic circuitry of human temporal neocortex. In sections cut in the tangential plane, many PV-immunoreactive chandelier cell axon terminals and apical dendrites of SMI 32-stained pyramidal cells were distributed in small clusters. Combination of immunocytochemistry for PV and SMI 32 revealed four subpopulations of pyramidal cells with regard to the immunocytochemical staining by SMI 32 and the innervation of their axon initial segments by PV-positive or -negative chandelier cell axon terminals, but there were differences in the concentration and proportion of these subpopulations by layers. Furthermore, we present electron microscopic evidence suggesting that the characteristic layer III dense band of PV-immunoreactive puncta is made up mainly of presumptive thalamocortical axon terminals. Besides, coincidence was found between the dense PV-immunoreactive band and the dendritic plexus formed by the SMI 32-stained pyramidal cells in the lower half of layer III, which leads us to think that they are probably a major target of PV-immunoreactive thalamic terminations.

Antibodies, Monoclonal↗
PubMed1994

Parvalbumin immunoreactivity in the thalamus of guinea pig: light and electron microscopic correlation with gamma-aminobutyric acid immunoreactivity.

The relationship of the calcium binding protein parvalbumin (PV) with gamma-aminobutyric acidergic (GABAergic) neurons differs within different thalamic nuclei and animal species. In this study, the distribution of PV and GABA throughout the thalamus of the guinea pig was investigated at the light microscopic level by using immunoperoxidase methods. Intense PV labelling was found in all the GABAergic neurons of the reticular nucleus and in scattered GABAergic neurons in the anteroventral nucleus, whereas GABAergic interneurons in the ventrobasal and lateral geniculate nuclei were not PV labelled. At the electron microscopic level, preembedding immunoperoxidase for PV was combined with postembedding immunogold for GABA. In the ventrobasal nucleus, four types of profiles were recognized: 1) terminals with flattened vesicles and forming symmetric synapses, which were labelled with both PV and GABA and could therefore be identified as afferents from the reticular nucleus; 2) boutons morphologically similar to presynaptic dendrites of interneurons, labelled only with GABA; 3) large terminals with round vesicles and asymmetric synapses, labelled only with PV, which contacted GABAergic presynaptic dendrites in glomerular arrangements and resembled ascending excitatory afferents; and 4) terminals unlabelled by either antiserum. In the ventrobasal nucleus of the guinea pig a double immunocytochemical labelling permits therefore the differentiation of two populations of GABAergic vesicle-containing profiles, i.e., the terminals originating from reticular nucleus (that are double labelled) and the presynaptic dendrites originating from interneurons (that are GABA-labelled only). The possibility to differentiate GABAergic inputs from the reticular nucleus and from interneurons can shed light to the functional interpretation of synaptic circuits in thalamic sensory nuclei.

Animals↗
PubMed1995

AII amacrine cell population in the rabbit retina: identification by parvalbumin immunoreactivity.

Parvalbumin (PV) is a calcium-binding protein localized to selected neurons in the nervous system, including the retina. This investigation evaluated the distribution of PV immunoreactivity in the rabbit retina using immunohistochemistry with a monoclonal antibody directed to carp PV. In the inner nuclear layer (INL), PV immunoreactivity was present in horizontal and amacrine cells. In the ganglion cell layer, PV immunostaining was confined to somata that are likely to be both displaced amacrine cells and ganglion cells. PV-immunoreactive (IR) amacrine cells were positioned in the proximal INL adjacent to the inner plexiform layer (IPL). These cells usually gave rise to a single primary process, which arborized into two distinct bands in the IPL. In sublamina a, the processes were thin and had large, irregular endings. In sublamina b, multiple processes branched from the primary process and were characterized by varicosities and spines. PV-IR amacrine cell bodies measured from 8 to 10 microns in diameter. Their density was highest in the visual streak and lowest in the periphery of the superior retina. The average number of PV-IR amacrine cells was 464,045 cells per retina (N = 3), and the average regularity index of the PV-IR cell mosaic was 3.23. PV-IR amacrine cells were further characterized by double-label immunofluorescence experiments using antibodies to PV and tyrosine hydroxylase (TH). Varicose TH-IR processes were in close apposition to many PV-IR amacrine cells and often formed "ring structures" around them. Together, these morphological, quantitative, and histochemical observations indicate that PV immunoreactivity in the INL is localized predominantly to AII amacrine cells, and therefore it is a valuable marker for the identification of this cell type.

Animals↗