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PubMed1996

Transient colocalization of parvalbumin and calbindin D28k in the postnatal cerebral cortex: evidence for a phenotypic shift in developing nonpyramidal neurons.

In the adult rat cerebral cortex the calcium-binding proteins parvalbumin and calbindin D28k are present in essentially non-overlapping populations of GABAergic interneurons. These proteins follow different developmental patterns in the cortex: calbindin D28k-immunoreactive nonpyramidal neurons are abundant until the second postnatal week and decrease markedly thereafter; it is at this time that parvalbumin immunoreactivity develops in cortical nonpyramidal neurons. To determine whether parvalbumin-immunoreactive neurons derive from calbindin D38k positive cells we used double-immunofluorescence studies for both calcium-binding proteins, together with combined immunocytochemistry for calbindin D28k and in situ hybridization for parvalbumin mRNA during postnatal development. Double-labelled cells were found in all cortical layers between P9 and P21, coinciding with the onset of parvalbumin expression. The percentage of colocalization of the two calcium-binding proteins depended on the age and layer examined. Colocalization reached a peak (80-100%) during the second postnatal week. Double-labelled neurons were rare in layer V at all ages studied. The present results indicate a phenotypic shift during the development of some cortical interneurons that halts the expression of calbindin D28k while parvalbumin expression starts. These findings agree with lineage analyses reporting that different types of nonpyramidal neuron arise from a common progenitor.

Animals↗
PubMed1984

Parvalbumin, a neuronal protein in brain cell cultures.

Dissociated brain cell cultures were derived from 14-day-old embryonic as well as from newborn mice. The cells were grown in a medium containing 10% fetal calf serum. Indirect immunofluorescence was performed using antisera directed against the Ca2+-binding protein parvalbumin (Mr 12,000). In embryonic cultures a large proportion of cells was intensely stained by antiparvalbumin . In double-labelling experiments involving the simultaneous application of antisera against parvalbumin and the neuron-specific enolase, the enolase-containing cells were also parvalbumin-positive and both antisera revealed identical intracellular staining patterns. Conversely, almost no parvalbumin- and enolase-positive cells were present in cultures derived from newborn mice. However, in these cultures many cells were immunoreactive toward the myelin basic protein, an accepted marker for oligodendrocytes. The presence of parvalbumin within the embryonic brain cell cultures was confirmed by analyses of the culture extracts (4 mM EDTA, pH 7.5) by HPLC on reverse-phase supports, two-dimensional polyacrylamide gel electrophoresis, and immunoblotting. The present study suggests that in mouse brain cell cultures, parvalbumin is localized in neurons.

Animals↗
PubMed1986

Immunochemical and immunohistochemical localization of parvalbumin in rat nervous tissues.

The contents of parvalbumin in various nervous tissues of the rat were measured by radioimmunoassay (RIA) and its cellular distribution was immunohistochemically examined by peroxidase-antiperoxidase methods. The antibody, raised in rabbits using rat skeletal muscle parvalbumin, did not cross-react with other Ca2+-binding proteins such as calmodulin or S-100 proteins. The RIA demonstrated the wide distribution of the antigen, with very high levels in the cerebellum (3,217 +/- 519 ng/mg protein). The immunohistochemical description by Celio and Heizmann [Nature 293, 300-302 (1981)] was confirmed concerning the existence of the antigen in Purkinje cells of the cerebellum; nonpyramidal neurons of the cerebral cortex; and medium-sized cells of the olfactory bulb, hippocampus, and reticular nucleus of the thalamus. In addition to these neurons, we found the parvalbumin-like immunoreactivity in the large neurons of the superior vestibular nucleus and the neurons of the medial superior olive nucleus. In the gamma-aminobutyric acid (GABA)-containing nuclei such as substantia nigra, caudatoputamen, and globus pallidus, parvalbumin-positive cells and fibers were rare. In the medial lemniscus of the midbrain which contains no GABA, parvalbumin-immunoreactive fibers were prominent. The possibility was discussed that parvalbumin exists in a specific population of neurons that differ from those containing GABA.

Animals↗
PubMedDate not supplied

Characterization of parvalbumin cDNA clones and gene expression in normal and dystrophic mice of strain 129 ReJ.

Parvalbumin is a calcium-binding protein found in fast-twitch skeletal muscles and selected cells in the brain. In several dystrophic mutants in the mouse, the parvalbumin content of skeletal muscles and brain is reduced and this deficiency appears to correlate with the inability of these mice to handle enhanced calcium uptake associated with the dystrophic process. In this study, two overlapping cDNA clones of 392 and 1268 base pairs were isolated from a mouse cDNA library in lambda gt11, characterized, and used as probes to study the involvement of the parvalbumin gene and its expression in various tissues of dystrophic mice of strain 129 ReJ. Southern blot analyses of restriction fragments of genomic DNA from normal and dystrophic mice indicate the same number and size of parvalbumin-specific gene fragments observed by other researchers, suggesting that the size of the Pva gene is the same in both normal and dystrophic mice of strain 129 ReJ. Northern blot analyses of total RNA from hind-limb muscles using cloned parvalbumin cDNA as probes revealed an abundant 800-nucleotide mRNA with lesser amounts of a 1000-nucleotide mRNA transcript in both normal and dystrophic mice of strain 129 ReJ. The amount of these mRNAs was reduced by 65-77% in dystrophic muscles preparations and was similar to the levels of beta-actin mRNA in these animals. These results suggest that parvalbumin gene expression is not down regulated in dystrophic mice of strain 129 ReJ.

Amino Acid Sequence↗
PubMed2002

Changes in the expression of parvalbumin immunoreactivity in the lumbar spinal cord of the rat following neonatal nerve injury.

Nerve injury in newborn animals results in the loss of motoneurons and dorsal root ganglion neurons and long-term changes in reflex activation of surviving motoneurons. Parvalbumin has been previously shown to be found in large-diameter primary afferent axons and interneurons in the spinal cord, and was used here to study the changes in parvalbumin-immunoreactive appositions onto identified tibialis anterior/extensor digitorum longus (TA/EDL) motoneurons, during both normal development and following neonatal nerve injury in the rat spinal cord. During normal development, there was a decrease in the number of parvalbumin-immunoreactive appositions onto TA/EDL motoneurons. Thus, at postnatal day 7 (P7), there were 72.8 +/- 17.5 (mean +/- SD) appositions per motoneuron and by P14, it had decreased to 38.8 +/- 13.2 (mean +/- SD; p > 0.05). Following neonatal nerve injury at P2, there were fewer parvalbumin-positive afferent appositions close to the TA/EDL motoneurons than normal, so that at P7, there were 53.5 +/- 17.1 (mean +/- SD), and at P14, it further decreased to 25.8 +/- 8.6 (mean +/- SD; p > 0.05). This injury-induced reduction in the number of parvalbumin-immunoreactive boutons apposing TA/EDL motoneurons may result, at least in part, from the death of dorsal root ganglion cells with the consequent loss of their central projections. The alterations in the number of parvalbumin-positive appositions close to motoneurons observed in this study may contribute to the changes in the pattern of reflex activity observed in the developing spinal cord both during normal development and following neonatal injury.

Afferent Pathways↗
PubMed2004

Gene transfer of parvalbumin improves diastolic dysfunction in senescent myocytes.

BACKGROUND: Impaired relaxation is a cardinal feature of senescent myocardial dysfunction. Recently, adenoviral gene transfer of parvalbumin, a small calcium-buffering protein found exclusively in skeletal muscle and neurons, has been shown to improve cardiomyocyte relaxation in disease models of diastolic dysfunction. The goal of this study was to investigate whether parvalbumin gene transfer could reverse diastolic dysfunction in senescent cardiomyocytes. METHODS AND RESULTS: Myocytes were isolated from senescent (26 months) and adult (6 months) F344/BN hybrid rats and were infected with Ad.Parv.GFP (where GFP is green fluorescent protein) or Ad.betagal.GFP at a multiplicity of infection of 250 for 48 hours. Uninfected senescent and adult myocytes served as controls. After stimulation at a frequency of 0.5 Hz, intracellular calcium transients and myocyte contractility were measured using dual excitation spectrofluorometry and video-edge detection system (Ionoptix). Parvalbumin significantly improved relaxation parameters in senescent myocytes: Both the rate of calcium transient decay and the rate of myocyte relengthening were dramatically increased in senescent cardiac myocytes transduced with parvalbumin compared with nontransduced and GFP-expressing controls, with no effect on myocyte shortening. CONCLUSIONS: Parvalbumin expression corrects impaired relaxation in aging myocytes. Given that abnormalities of myocyte relaxation underlie diastolic dysfunction in a large proportion of elderly patients with heart failure, gene transfer of parvalbumin may thus be a novel approach to target diastolic dysfunction in senescent myocardium.

Adenoviridae↗
PubMed2006

Morphological classification of parvalbumin-containing retinal ganglion cells in mouse: single-cell injection after immunocytochemistry.

PURPOSE: Matching the neuron's morphology with its expression of a particular protein cannot be easily achieved by immunocytochemistry alone, as many proteins are expressed too weakly. In this study, a newly developed method was adopted to match mouse retinal ganglion cell (RGC) morphology with its expression of parvalbumin. METHODS: Parvalbumin-containing ganglion cells were first identified by immunocytochemistry and then were iontophoretically injected with a lipophilic dye DiI. Then confocal microscopy was used to characterize the morphologic classification of the parvalbumin-immunoreactive (IR) ganglion cells on the basis of the dendritic field size, branching pattern, and stratification within the inner plexiform layer. RESULTS: The results indicate that at least eight different types of ganglion cells express parvalbumin in the mouse retina. They were heterogeneous in morphology: monostratified to bistratified, small-to-large dendritic field size, and sparse-to-dense dendritic arbors. CONCLUSIONS: Single-cell injection, after immunocytochemistry, provided the first means to identify the detailed functional anatomy of parvalbumin-containing RGCs in the mouse retina. The combined approach of cell morphology and the selective expression of parvalbumin will not only provide useful data for further correlation of physiological properties of the RGCs, but it will also provide a useful strategy for matching a neuron's morphology with its expression of a particular protein.

Animals↗
PubMed2005

Complementary roles of cholecystokinin- and parvalbumin-expressing GABAergic neurons in hippocampal network oscillations.

In the hippocampal CA1 area, a relatively homogenous population of pyramidal cells is accompanied by a diversity of GABAergic interneurons. Previously, we found that parvalbumin-expressing basket, axo-axonic, bistratified, and oriens-lacunosum moleculare cells, innervating different domains of pyramidal cells, have distinct firing patterns during network oscillations in vivo. A second family of interneurons, expressing cholecystokinin but not parvalbumin, is known to target the same domains of pyramidal cells as do the parvalbumin cells. To test the temporal activity of these independent and parallel GABAergic inputs, we recorded the precise spike timing of identified cholecystokinin interneurons during hippocampal network oscillations in anesthetized rats and determined their molecular expression profiles and synaptic targets. The cells were cannabinoid receptor type 1 immunopositive. Contrary to the stereotyped firing of parvalbumin interneurons, cholecystokinin-expressing basket and dendrite-innervating cells discharge, on average, with 1.7 +/- 2.0 Hz during high-frequency ripple oscillations in an episode-dependent manner. During theta oscillations, cholecystokinin-expressing interneurons fire with 8.8 +/- 3.3 Hz at a characteristic time on the ascending phase of theta waves (155 +/- 81 degrees), when place cells start firing in freely moving animals. The firing patterns of some interneurons recorded in drug-free behaving rats were similar to cholecystokinin cells in anesthetized animals. Our results demonstrate that cholecystokinin- and parvalbumin-expressing interneurons make different contributions to network oscillations and play distinct roles in different brain states. We suggest that the specific spike timing of cholecystokinin interneurons and their sensitivity to endocannabinoids might contribute to differentiate subgroups of pyramidal cells forming neuronal assemblies, whereas parvalbumin interneurons contribute to synchronizing the entire network.

Action Potentials↗
PubMed2002

In vivo labeling of parvalbumin-positive interneurons and analysis of electrical coupling in identified neurons.

GABAergic interneurons can pace the activity of principal cells and are thus critically involved in the generation of oscillatory and synchronous network activity. The specific role of various GABAergic subpopulations, however, has remained elusive. This is in part attributable to the scarcity of certain GABAergic neurons and the difficulty of identifying them in slices obtained from brain regions in which anatomical structures are not readily recognizable in the live preparation. To facilitate the functional analysis of GABAergic interneurons, we generated transgenic mice in which the enhanced green fluorescent protein (EGFP) was specifically expressed in parvalbumin-positive neurons. The high fidelity of expression obtained using bacterial artificial chromosome transgenes resulted in EGFP-labeled neurons in nearly all brain regions known to contain parvalbumin-expressing neurons. Immunocytochemical analysis showed that EGFP expression was primarily restricted to parvalbumin-positive cells. In addition to cell body labeling, EGFP expression was high enough in many neurons to enable the visualization of dendritic structures. With the help of these mice, we investigated the presence of electrical coupling between parvalbumin-positive cells in brain slices obtained from young and adult animals. In dentate gyrus basket cells, electrical coupling was found in slices from young [postnatal day 14 (P14)] and adult (P28 and P42) animals, but both strength and incidence of coupling decreased during development. However, electrical coupling between parvalbumin-positive multipolar cells in layer II/III of the neocortex remains unaltered during development. Yet another developmental profile of electrical coupling was found between layer II/III parvalbumin-positive cells and excitatory principal cells. Between these neurons, electrical coupling was found at P14 but not at P28. The results indicate that the presence and strength of electrical coupling is developmentally regulated with respect to brain area and cell type.

Action Potentials↗
PubMed1999

Localization of calcium-binding protein parvalbumin-immunoreactive neurons in mouse and hamster visual cortex.

Calcium-binding proteins are thought to play important roles in regulating intracellular calcium in the central nervous system. In the present study, we investigated the distribution and morphology of neurons containing parvalbumin in the visual cortex of mouse and hamster. The calcium-binding proteins were localized using immunocytochemistry. Parvalbumin-immunoreactive neurons were located in all layers except layer I. The highest density of parvalbumin immunoreactivity was found in layer V of both mouse and hamster. The labeled neurons varied in morphology. The majority of the parvalbumin-immunoreactive neurons both in mouse and hamster visual cortex was stellate and round, or oval with multipolar dendrites. These results indicate that the calcium-binding protein parvalbumin is contained in specific layers and in selective cell types of the mouse and hamster visual cortex. The distribution of parvalbumin in the mouse visual cortex is very similar to that of hamster.

Animals↗
PubMed1992

Calbindin and parvalbumin cells in monkey VPL thalamic nucleus: distribution, laminar cortical projections, and relations to spinothalamic terminations.

The ventral posterior lateral nucleus (VPL) of the monkey thalamus was investigated by histochemical staining for cytochrome oxidase (CO) activity and by immunocytochemical staining for the calcium-binding proteins parvalbumin and 28 kDa calbindin. Anterograde and retrograde tracing experiments were used to correlate patterns of differential distribution of CO activity and of parvalbumin and calbindin cells with the terminations of spinothalamic tract fibers and with the types of cells projecting differentially to superficial and deeper layers of primary somatosensory cortex (SI). VPL is composed of CO-rich and CO-weak compartments. Cells are generally smaller in the CO-weak compartment. Parvalbumin-immunoreactive cells and parvalbumin-immunoreactive medial lemniscal fiber terminations are confined to the CO-rich compartment. Calbindin-immunoreactive cells are found in both the CO-rich and CO-weak compartments. The CO-weak compartment, containing only calbindin cells, forms isolated zones throughout VPL and expands as a cap covering the posterior surface of the ventral posterior medial nucleus (VPM). Spinothalamic tract terminations tend to be concentrated in the CO-weak compartment, especially in the posterior cap. Other CO-weak, parvalbumin-negative, calbindin-positive nuclei, including the posterior, ventral posterior inferior, and anterior pulvinar and the small-celled matrix of VPM are also associated with concentrations of spinothalamic and caudal trigeminothalamic terminations. Parvalbumin cells are consistently larger than calbindin cells and are retrogradely labeled only after injections of tracers in middle and deep layers of SI. The smaller calbindin cells are the only cells retrogradely labeled after placement of retrograde tracers that primarily involve layer I of SI. The compartmental organization of VPL is similar to but less rigid than that previously reported in VPM. VPL and VPM relay cells projecting to different layers of SI cortex can be distinguished by differential immunoreactivity for the two calcium-binding proteins. The small-celled, CO-weak, calbindin-positive zones of VPL and VPM appear to form part of a wider system of smaller thalamic neurons unconstrained by traditional nuclear boundaries that are preferentially the targets of spinothalamic and caudal trigeminal inputs, and that may have preferential access to layer I of SI.

Animals↗
PubMed1989

Restrained least squares refinement of native (calcium) and cadmium-substituted carp parvalbumin using X-ray crystallographic data at 1.6-A resolution.

Carp parvalbumin coordinates calcium through one carbonyl oxygen atom and the oxygen-containing side chains of 5 amino acid residues, or 4 residues and a water molecule, in a helix-loop-helix structural motif. Other calcium-binding proteins, including calmodulin and troponin C, also possess this unique calcium-binding design, which is designated EF-hand or calmodulin fold. Parvalbumin has two such sites, labeled CD and EF. Each of the calcium-binding sites of refined structures of proteins belonging to this group has a 7-oxygen coordination sphere except those of the structure of parvalbumin as it was reported in 1975. This structure had been refined at 1.9 A using difference Fourier techniques on film data. The CD site appeared to be 6-coordinate and the EF site 8-coordinate. Results of NMR experiments using 113Cd-substituted parvalbumin, however, indicate that the sites are similar to one another with coordination number greater than 6. To resolve the inconsistency between crystallographic and NMR results, 1.6 A area detector data was collected for native and cadmium-substituted parvalbumin; the structures have been refined to R factors of 18.7% and 16.4%, respectively, with acceptable geometry and low errors in atomic coordinates. Differences between the parvalbumin structure described in 1975 and the present structure are addressed, including the discovery of 7-coordination for both the CD and EF sites.

Animals↗
PubMed1987

Structural organization and chromosomal assignment of the parvalbumin gene.

The structure of the rat parvalbumin gene has been elucidated from analysis of six overlapping clones isolated from a rat lambda Charon 4A genomic library. Two of the clones were mapped in detail, and all exons were localized by Southern hybridization using fragments of a full-length parvalbumin cDNA (Epstein, P., Means, A. R., and Berchtold, M. W. (1986) J. Biol. Chem. 261, 5886-5891). The rat parvalbumin transcription unit is 15.5 kilobase pairs in length and contains four introns. The first intron divides the 5'-nontranslated region, whereas the other three interrupt coding DNA. All intron/extron boundaries were sequenced as was 377 base pairs immediately 5' from the putative transcription initiation site. The promoter region contains eukaryotic regulatory homologies to the "TATA" box at -24 and "CAAT" box at -47 and -156. In addition, two doublets consisting of 11-base pair direct repeats exist in the promoter region. Parvalbumin binds two Ca2+, whereas many other members of the same superfamily bind four. Comparison of the genes that encode these proteins provides a strong confirmation of the hypothesis that parvalbumin evolved from an ancestral gene specifying a four-domain Ca2+-binding protein. The rat parvalbumin gene was also utilized to assign its human counterpart to chromosome 22 from data obtained by hybridization to DNA from a somatic cell hybrid panel. It was also used to isolate a 7.5-kilobase pair EcoRI fragment from a human chromosome 22 DNA library.

Amino Acid Sequence↗
PubMed1998

Parvalbumin, a horizontal cell-associated calcium-binding protein in retinoblastoma eyes.

PURPOSE: To search for differentiation in retinoblastoma toward horizontal cells and retinal neurons other than photoreceptor cells with antibodies to parvalbumin, a horizontal, ganglion, and amacrine cell-associated antigen. METHODS: Fifty formalin-fixed and paraffin-embedded human eyes with an intraocular retinoblastoma and two orbital recurrences were studied using the avidin-biotinylated peroxidase complex method and monoclonal antibody (mAb) PA-235 to parvalbumin. RESULTS: In the retinas of retinoblastoma eyes obtained after birth, horizontal cells at the outer border of the inner nuclear layer and their processes in the inner part of the outer plexiform layer always reacted with mAb PA-235. Immunolabeled ganglion and amacrine cells were found, respectively, in 31 (76%; 95% confidence interval [CI] 60-88) and 15 (37%; 95% (CI 22-53) of the 41 eyes with preserved retinas, whereas bipolar and photoreceptor cells were unlabeled. Undifferentiated and differentiated retinoblastoma cells in all studied specimens were negative for parvalbumin. However, immunopositive horizontal and ganglion cells engulfed by the tumor were present within 36 of the 50 retinoblastomas (72%; 95% CI 58 - 84), which often allowed the tracing of otherwise invisible remnants of former infiltrated retinas. CONCLUSIONS: Parvalbumin is a useful marker for horizontal and ganglion cells in normal and pathologic human retinas, including those entrapped within retinoblastoma. The absence of parvalbumin from tumor cells argues against differentiation similar to that seen in these parvalbumin-positive neurons and subpopulations of amacrine cells from the second trimester onward.

Antibodies, Monoclonal↗
PubMed1998

Spatiotemporal patterns of ontogenetic expression of parvalbumin in the superior colliculi of rats and rabbits.

We have examined the development of parvalbumin immunoreactivity in the superior colliculi (SC) of the perinatal and mature rats and rabbits. In mature animals, parvalbumin-expressing cells (PECs) and neuropil in the retinorecipient layers were distributed in a continuous single band extending throughout the entire extent of the colliculus, whereas those in the intermediate layers formed distinct, radially oriented patches. Parvalbumin was expressed for the first time on postconceptional day 34 (PCD 34, postnatal day 12) and PCD 42 (postnatal day 11) in the SC of rat and rabbit, respectively. During ensuing development, both the thickness of the parvalbumin-expressing band in the retinorecipient layers and the numbers of PECs in this band gradually increased, reaching adultlike values by PCD 44 and PCD 50 in the rat and rabbit, respectively. In the rat, monocular eye enucleations on PCD 23 resulted in approximately 55% reduction in the number of PECs in the retinorecipient layers of the contralateral colliculi examined on PCD 44 or PCD 50. Unilateral ablations of the entire visual cortex on PCD 23 (before the first corticotectal fibers from visual cortices reach the SC) or on PCD 28 (when about half of the corticotectal fibers have reached colliculus) resulted in, respectively, approximately 55% and approximately 25% relative reduction in the number of PECs in the retinorecipient layers of the ipsilateral colliculi examined on PCD 44 or PCD 50. We conclude that the ontogenetic expression of parvalbumin in most of PECs in the retinorecipient collicular layers is induced by the activity of the contralateral retinotectal and/or the activity of the ipsilateral corticotectal afferents.

Age Factors↗
PubMed2003

Glutamate receptor subunit 3 (GluR3) immunoreactivity delineates a subpopulation of parvalbumin-containing interneurons in the rat hippocampus.

Rasmussen's encephalitis is a childhood disease resulting in intractable seizures associated with hippocampal and neocortical inflammation. An autoantibody against the GluR3 subunit of alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptors is implicated in the pathophysiology of Rasmussen's encephalitis. AMPA receptors mediate excitatory neurotransmission in the brain and contain combinations of four subunits (GluR1-4). Although the distributions of GluR1, GluR2, and GluR4 are known in some detail, the cellular distribution of GluR3 in the mammalian brain remains to be described. We developed and characterized a GluR3-specific monoclonal antibody and quantified the cellular distribution of GluR3 in CA1 of the rat hippocampus. GluR3 immunoreactivity was detected in all pyramidal neurons and astrocytes and in most interneurons. We quantified the intensity of GluR3 immunoreactivity in interneuron subtypes defined by their calcium-binding protein content. GluR3 immunofluorescence, but not GluR1 or GluR2 immunofluorescence, was significantly elevated in somata of parvalbumin-containing interneurons compared to pyramidal somata. Strikingly, increased GluR3 immunofluorescence was not observed in calbindin- and calretinin-containing interneurons. Furthermore, 24% of parvalbumin-containing interneurons could be distinguished from surrounding neurons based on their intense GluR3 immunoreactivity. This subpopulation had significantly elevated GluR3 immunoreactivity compared to the rest of parvalbumin-containing interneurons. Electron microscopy revealed enriched GluR3 immunoreactivity in parvalbumin-containing perikarya at cytoplasmic and postsynaptic sites. Parvalbumin-containing interneurons, potent inhibitors of cortical pyramidal neurons, are vulnerable in the brains of epileptic patients. Our findings suggest that the somata of these interneurons are enriched in GluR3, which may render them vulnerable to pathological states such as epilepsy and Rasmussen's encephalitis.

Animals↗
PubMed1990

Heterogeneity of chandelier neurons in monkey neocortex: corticotropin-releasing factor- and parvalbumin-immunoreactive populations.

Chandelier neurons are a unique subclass of cortical nonpyramidal neurons. The axons of these neurons terminate in distinctive vertically arrayed cartridges that synapse on the axon initial segment of pyramidal neurons. In this study, the rapid Golgi method and immunohistochemical techniques were used to characterize the morphology, regional distribution, laminar location, and biochemical content of chandelier neurons in the prefrontal and occipital cortices of three monkey species. As in our previous studies of visual areas V1 and V2 (Lund: Journal of Comparative Neurology 257:60-92, 1987; Lund et al.: Journal of Comparative Neurology 202:19-45, 1981, 276:1-29, 1988), Golgi impregnations of areas 46 and 9 of macaque prefrontal cortex show chandelier neurons to be present in layers 2 through superficial 5. The vertical arrays of terminal boutons (axon cartridges) typical of this neuron class are also present in layers 2-6 of the prefrontal cortex, but are not found in layer 1 or the subcortical white matter. In immunohistochemical studies, a calcium-binding protein, parvalbumin, and a neuropeptide, corticotropin-releasing factor (CRF), identify rod-like structures that are morphologically similar to the axon cartridges of chandelier neurons seen in the Golgi material. In addition, both parvalbumin- and CRF-immunoreactive cartridges are located below the somata of unlabeled pyramidal neurons and appear to outline the axon initial segment of these neurons. However, we find that parvalbumin and CRF are present in only subpopulations of chandelier axon cartridges. For example, in adult primary visual cortex, parvalbumin-labeled cartridges are present in very low numbers only in layers 2-3, whereas in prefrontal and occipital association cortices these cartridges are a very prominent component of layers 2-superficial 3 and are present in much lower density in the deeper cortical layers. In contrast to these findings in adult macaque monkeys, prefrontal and occipital association cortices of infant macaque monkeys contain a very high density of parvalbumin-labeled cartridges in layer 4 and relatively few in the superficial cortical layers. Furthermore, in adult squirrel monkey prefrontal cortex, CRF-labeled cartridges are predominately present in layer 4, but these CRF-immunoreactive structures have not been observed in the homologous regions of infant or adult macaque monkeys. These findings indicate that even for neurons of such distinctive morphology and presumably constant functional role as chandelier neurons, factors such as regional and laminar location, age, and primate species are associated with differences in the biochemical content of subpopulations of these neurons.

Animals↗
PubMed1991

Subpopulations of GABAergic neurons containing parvalbumin, calbindin D28k, and cholecystokinin in the rat hippocampus.

The possible coexistence of calbindin D28k with parvalbumin and of calbindin D28k with cholecystokinin was studied in nonpyramidal cells of the rat dorsal hippocampal formation. Neighbouring Vibratome sections were immunostained either for calbindin D28k and parvalbumin or for calbindin D28k and cholecystokinin. The cells, halved during sectioning, were identified in both sections immunostained for different antigens. The coexistence of calbindin D28k and parvalbumin in the same neuron was rare throughout the hippocampal formation with the exception of stratum oriens of the CA1 region, where 9.6% of the parvalbumin-immunoreactive cells also contained calbindin D28k. In stratum radiatum of the CA3 region, calbindin D28k and cholecystokinin coexisted in 12.5% and 21.2% of the calbindin D28k and cholecystokinin-immunoreactive cells, respectively. In other regions of the hippocampal formation, the two markers coexisted in less than 5% of the cells of either type. The present results demonstrate that calbindin D28k-, parvalbumin- and cholecystokinin-containing nonpyramidal cells represent largely nonoverlapping cell populations and may thus be involved in different inhibitory circuits.

Animals↗