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Parvalbumin in most gamma-aminobutyric acid-containing neurons of the rat cerebral cortex.

gamma-Aminobutyric acid (GABA) is one of the major inhibitory neurotransmitters in the central nervous system. In the cerebral cortex, GABA-containing cells represent a subpopulation of interneurons. With semithin frozen sections, it is possible to demonstrate that most GABA neurons in the rat somatosensory cortex contain the calcium-binding protein parvalbumin and that parvalbumin is found virtually only in GABA neurons. Parvalbumin seems to influence the electrical properties and enzymatic machinery to modulate neuronal excitability and activity. The specific role of parvalbumin in GABA-containing cortical cells may be related to controlling the effectiveness of their inhibitory action.

Animals↗

An optical stopped-flow and 1H and 113Cd nuclear magnetic resonance study of the kinetics and stoichiometry of the interaction of the lanthanide Yb3+ with carp parvalbumin.

The rate constants for the dissociation of the lanthanide Yb3+ from the CD and EF calcium-binding sites of carp parvalbumin (isoelectric point, 4.25) have been measured using optical stopped-flow and 1H nuclear magnetic resonance (NMR) methods. The off-rate constants for Yb3+ are 1.5 X 10(-1) and 1.3 X 10(-3) s-1, respectively, at pH 6.6 and 23 degrees C. The relative displacement of Ca2+ from the two sites by Yb3+ was determined from the observed amplitude of the fast and slow kinetic phases. Yb3+-shifted 1H-NMR spectra of parvalbumin are presented as a function of pH, concentration, and H2O:D2O ratio to relate the NMR results to the kinetic and optical results. The displacement of Cd2+ from parvalbumin by Yb3+ was studied using 113Cd NMR. All of the results show the sequential displacement of Ca2+ from the CD and EF sites of parvalbumin by Yb3+. Some results are also presented for Tb3+ and Gd3+.

Animals↗

Ectopic parvalbumin-positive cells in the cerebellum of the adult mutant mouse 'nervous'.

The basket and stellate cells of the 'nervous' mouse cerebellum lose 50% of their presynaptic parallel fibres and more than 90% of Purkinje cells, their major postsynaptic targets, after postnatal day 23. To study the fate of these molecular layer cells we examined the cerebellum of the mutant mouse 'nervous' with antisera against the 'marker protein' parvalbumin, which exclusively tags Purkinje, basket, and stellate cells. Ten homozygous 'nervous' mice, 12-14 weeks old, and 30 control animals of several inbred strains were examined. The number of basket and stellate cells decreased in affected areas of the molecular layer. In addition, parvalbumin-positive cells were detected in the granular layer, in the white matter of the cerebellum and in the area of the cerebellar peduncles of all 'nervous' mice, but not in those of the control animals. These cells mainly occurred in areas which still displayed degenerating Purkinje cell axons. Ectopic parvalbumin-positive cells could either represent a class of interneurons, which have changed their antigenic properties, and therefore happen to stain with antisera against parvalbumin, or stratum moleculare cells which have failed to recognise their proper position during ontogenesis. Alternatively these cells could represent postdevelopmental basket cells, which have acquired the ability to migrate.

Animals↗

Immunocytochemical localization of calbindin-D28k, calbindin-D9k and parvalbumin in rat kidney.

Possible sites involved in active Ca2+ transport were traced by means of immunocytochemical detection of calcium-binding proteins (CaBP) in the mammalian kidney. Antisera were raised in rabbits against calbindin-D28k from chick kidney and calbindin-D9k from bovine intestine and parvalbumin from rabbit muscle. In the rat kidney, parvalbumin and calbindin-D9k were co-localized in the loops of Henle and distal convoluted tubule. In the collecting duct their presence was restricted to the intercalated cells. In all responsive cells parvalbumin and calbindin-D9k were present exclusively along the basolateral membrane. Calbindin-D28k was only present in the outer part of the cortex, where it was localized in the distal convoluted tubule and in the connecting tubule. In these cells calbindin-D28k was evenly distributed through the cytosol. Calbindin-D28k, unlike parvalbumin and calbindin-D9k, could not be demonstrated in the loops of Henle or collecting duct.

Animals↗

Calbindin-D9k and parvalbumin are exclusively located along basolateral membranes in rat distal nephron.

There is strong evidence that vitamin D-dependent Ca(2+)-binding proteins, i.e., calbindin-D9k and calbindin-D28k, facilitate diffusion of Ca2+ through the cytosolic compartment of renal and intestinal cells, which transport Ca2+ transcellularly. In the study presented here, parvalbumin, calbindin-D9k, and calbindin-D28k were localized precisely by immunocytochemistry in rat kidney. Antisera recognizing specifically the thick ascending loop of Henle, the connecting tubules and collecting ducts, and the intercalated cells of the collecting ducts were used to identify different cell types. In rat kidney cortex, parvalbumin and calbindin-D9k colocalized in the thick ascending loop of Henle, the distal convoluted tubule, the connecting tubule, and the intercalated cells of the collecting duct. Strikingly, in all responsive cells, parvalbumin and calbindin-D9k were exclusively present in a thin layer along the basolateral membrane. In contrast, calbindin-D28k was only present in the distal convoluted and connecting tubule, where it was evenly distributed through the cytosol. In conclusion, the exclusive localization of parvalbumin and calbindin-D9k at the basolateral membrane of immunopositive renal cells implies their involvement in the regulation of transport processes located in these membranes rather than a role as intracellular Ca2+ buffer and Ca2+ shuttle between the two opposing membranes.

Animals↗

Metal ion binding to parvalbumin. A proton NMR study.

The 1H NMR spectra of carp parvalbumin saturated with Ca2+, Cd2+, La3+ and Lu3+ were compared, using 2D 1H NMR techniques as well as conventional 1H NMR spectra. The Ca2+ and Cd2+ saturated parvalbumin (with both high affinity Ca2+-binding sites occupied) gave rise to very similar spectra. This shows that these two species have almost identical protein conformations. The 1H NMR spectrum from the Ln3+ saturated parvalbumins deviated from the other two and it was therefore concluded that Cd2+ is a better probe for Ca2+ than Ln3+ in parvalbumin and probably also for related calcium binding proteins. The addition of excess of divalent metal ions, such as Mg2+ or Ca2+, causes small changes in the chemical shift of some methyl resonances. This is presumably caused by binding of these metal ions to a third site close to the CD site which is made up of the carboxylic groups from Glu 60 and Asp 61.

Animals↗

Dopamine affects parvalbumin expression during cortical development in vitro.

This study was undertaken to determine how dopamine influences cortical development. It focused on morphogenesis of GABAergic neurons that contained the calcium-binding protein parvalbumin (PV). Organotypic slices of frontoparietal cortex were taken from neonatal rats, cultured with or without dopamine, harvested daily (4-30 d), and immunostained for parvalbumin. Expression of parvalbumin occurred in the same regional and laminar sequence as in vivo. Expression in cingulate and entorhinal preceded that in lateral frontoparietal cortices. Laminar expression progressed from layer V to VI and finally II-IV. Somal labeling preceded fiber labeling by 2 d. Dopamine accelerated PV expression. In treated slices, a dense band of PV-immunoreactive neurons appeared in layer V at 7 d in vitro (DIV), and in all layers of frontoparietal cortex at 14 DIV, whereas in control slices such labeling did not appear until 14 and 21 DIV, respectively. The laminar distribution and dendritic branching of PV-immunoreactive neurons were quantified. More labeled neurons were in the superficial layers, and their dendritic arborizations were significantly increased by dopamine. Treatment with a D1 receptor agonist had little effect, whereas a D2 agonist mimicked dopamine's effects. Likewise, the D2 but not the D1 antagonist blocked dopamine-induced changes, indicating that they were mediated primarily by D2 receptors. Parvalbumin expression was accelerated by dopaminergic reinnervation of cortical slices that were cocultured with mesencephalic slices. Coapplication of the glutamate NMDA receptor antagonist MK801 or AP5 blocked dopamine-induced increases in dendritic branching, suggesting that changes were mediated partly by interaction with glutamate to alter cortical excitability.

Aging↗

Parvalbumin in skeletal muscles of teleost (Tinca tinca L. and Misgurnus fossilis L.). Histochemical and immunohistochemical study.

Musculatures of two fish species belonging to the suborder Cyprinoidei were examined histochemically and immunohistochemically for demonstration of mATP-ase activity and parvalbumin content, respectively. The tench lateral musculature shows a typical "acid reversal" picture of mATP-ase activity--red fibres are alkali labile, acid stable and white and white fibres are alkali stable, acid labile. In the pond loach a superficial layer of musculature is composed of alkali--and acid stable red fibres. This alkaline stability of the red fibres caused the classical "acid reversal" picture impossible to obtain. For immunohistochemical reaction a monoclonal antibody specific for parvalbumin II component of the Carp muscles (Pv Carp II) was used. Immunohistochemical results gave evidence that lateral musculatures of the two species examined possessed parvalbumin II component entirely in the fast-contracting fibres--intermediate and white. This results correlate with mATP-ase activity in the tench musculature and did not correlate in the pond loach with respect to mATP-ase alkali stable red muscle fibres in the fish. We conclude that fish muscles mATP-ase activity not always correlates with parvalbumin content in the opposite to mammalian muscles where such correlation seems to be obvious.

Animals↗

[Immunolocalization of parvalbumin in two glutamatergic cell types of the guinea pig cochlea: inner hair cells and spinal ganglion neurons].

Immunoreactions to a monoclonal antibody raised against parvalbumin, a calcium-binding protein, have been detected in the inner hair cells of the organ of Corti and in the spiral ganglion neurons connected to them (type I neurons). Both cell types probably use an excitatory amino acid as a neurotransmitter (glutamate and/or aspartate). No immunoreactivity was found within the second sensory cell type (outer hair cells) nor in the olivocochlear (efferent) fibers or endings in the cochlea. In the central nervous system, parvalbumin may be involved in calcium-dependent mechanisms leading to neurotransmitter release. It could thus be hypothesized that parvalbumin also have similar implications at the level of the inner hair cell and type I neuron synapses. Additional functions could also be hypothesized for this protein in the cochlea. Within the inner hair cells, parvalbumin may be involved in the ionic regulation following potassium entry during the transduction process. Within type I neurons, by buffering sudden increases in the intracellular calcium concentration, it may allow an adaptation of the firing rate to variations in the intensity of sound stimuli.

Animals↗

Interactions of calcium binding proteins, parvalbumin and alpha-lactalbumin, with dipalmitoylphosphatidylcholine vesicles.

Interactions of Ca2+ binding proteins, pike (Esox lucius) parvalbumins pI 4.2 and 5.0, and bovine and human alpha-lactalbumins, with dipalmitoylphosphatidylcholine vesicles were studied by means of scanning microcalorimetry and intrinsic tyrosine and tryptophan fluorescence methods. The interactions of pike parvalbumins are modulated by Ca2+ and Mg2+ binding to the protein and induce some changes in the physical properties of both the proteins and liposomes. Liposomes increased thermal stability of Ca2+-loaded parvalbumin and decreased thermal stability of both Mg2+-loaded and metal-free protein. The interaction of parvalbumin with liposomes affects the phase transition from gel to liquid-crystalline state in liposomes. Ca2+-loaded alpha-lactalbumin interacts with liposomes in its native state while the metal-free protein binds to the liposomes mainly in its thermally denatured state. The results of the microcalorimetric and spectrofluorometric studies are supported by data obtained by means of gel-chromatography on Sepharose 4B. It may be suggested that these metal-modulated interactions of Ca2+-binding proteins with membranes have some functional significance.

1,2-Dipalmitoylphosphatidylcholine↗

[Absence of parvalbumins in the muscles of Lampetra fluviatilis lampreys].

Comparative data on isolation and identification of parvalbumins from muscles of the lamprey Lampetra fluviatilis and carp Cyprinus carpio are presented. No parvalbumins or some other soluble low molecular weight sarcoplasmic calcium-binding proteins were detected in the lamprey, while 4 pure fractions of parvalbumins were obtained from carp muscles. These data imply that cyclostomes do not need additional calcium regulation of the activity of fast skeletal muscles by parvalbumins.

Animals↗

Light- and electron microscopic localization of parvalbumin, calbindin D-28k and calretinin in the dorsal lateral geniculate nucleus of the rat.

The localization of parvalbumin, calbindin D-28k and calretinin have been investigated in the dorsal lateral geniculate nucleus (d lgn) of the rat at the light and electron microscopical level. Parvalbumin and calretinin positive sites are restricted to nerve fibres, whereas calbindin is present in fibres as well as in nerve cells showing morphological characteristics of interneurons. Ultrastructurally parvalbumin immunoreactivity is found in large terminals surrounded by glial lamellae containing round vesicles and making asymmetric contacts on dendrites. These morphological characteristics are typical for retinal endings of type 2a. Another kind of parvalbumin positive presynaptic terminals are seen on the surface of unstained nerve cell bodies and features symmetrical contacts. We conclude that this type represents axonal terminals of GABAergic neurons of the thalamic reticular nucleus. Calbindin positive nerve cells in the d lgn occur in the latero-dorsal part and according to morphological characteristics, belong to interneurons. Calbindin positive nerve cells receive synaptic terminals deriving from different kind of unstained presynaptic profiles. Calretinin immunoreactivity is localized in small to medium sized presynaptic endings with round vesicles, pale mitochondria and Gray-type 1 contacts on dendrites of relay- and interneurons. Some calretinin positive terminals are located in triads or in complex encapsulated regions. Therefore we identify calretinin positive terminals as the retinal inputs of type 2b. Our results demonstrate the expression of the three calcium binding proteins in morphologically, physiologically and biochemically different structures within the d lgn of the rat. The distribution differs from that found in the d lgn of the cat or monkey.

Animals↗

Novel avian thymic parvalbumin displays high degree of sequence homology to oncomodulin.

CPV3 is a novel avian parvalbumin. It displays an isoelectric point of 4.6, intermediate between that of avian thymic hormone (pI = 4.3) and the muscle parvalbumin isoform (pI = 5.2). Expression of CPV3, like that of avian thymic hormone (ATH), is restricted to the thymic stroma. However, the CPV3 content of chicken thymus tissue (120 micrograms/g tissue) is 4 times lower than that of ATH (500 micrograms/g tissue). The polymerase chain reaction (PCR) was used to gain access to the nucleotide sequence of CPV3. A 147-base pair fragment of the coding sequence, corresponding to residues 48-97, was amplified from total chicken cDNA using degenerate PCR primers. A RACE-PCR strategy was then used to extend the known sequence in both the 5' and 3' directions. The cDNA sequence thus obtained includes 671 base pairs. Primer extension analysis suggests that the cloned cDNA corresponds to a full-length transcript. Northern analysis of chicken mRNA indicates that the average CPV3 transcript is approximately 800 nucleotides in length, significantly smaller than the ATH message (approximately 1000 nucleotides). Southern analysis suggests the presence of a single CPV3 gene in the chicken genome. The translated nucleotide sequence, displaying 108 residues between the initiator and termination codons, is that of a beta-parvalbumin. The CPV3 sequence exhibits 58% identity with ATH and 52% identity with the chicken muscle isoform. Interestingly, CPV3 and the mammalian oncodevelopmental parvalbumin called oncomodulin are identical at 73 of 108 residues (68% identity). Correspondingly, flow-dialysis measurements with 45Ca2+ indicate that the Ca(2+)-binding domains are inequivalent, as in oncomodulin. The apparent dissociation constants, at pH 7.4 in 150 mM NaCl, are approximately 10 nM and 80 nM.

Amino Acid Sequence↗

Parvalbumin immunoreactivity in the telencephalic hemispheres of the tench, Tinca tinca.

The distribution of parvalbumin immunoreactivity in the telencephalic hemispheres of the tench (Tinca tinca L.) was studied using a monoclonal antibody and the avidin-biotin immunoperoxidase method. A wide distribution of immunoreactive structures was found in both dorsal and ventral areas of the telencephalic hemispheres. Normally, the parvalbumin-immunostained neurons in the dorsal area were smaller, more weakly stained, and more scattered than those in the ventral one. In the dorsal area, parvalbumin-immunoreactivity was observed in practically all divisions. The highest density of positive somata was found in the lateral nucleus. Density of stained fibres was generally low. Labelling in the ventral area appeared in the ventral and dorsal nuclei, with a high density of both immunoreactive fibres and cell bodies. Neurons were seen close to the ventricle, arranged in two groups of neurons with different sizes and morphologies. The distribution and morphological characteristics of the parvalbuminergic cells were similar to those of previously described GABAergic elements, suggesting a possible colocalization of both substances in the teleost telencephalon, as it has been observed in different telencephalic areas of land vertebrates. On the other hand, significant differences were seen between the distribution of parvalbumin in the telencephalic hemispheres of the tench in comparison with its distribution pattern in supposed homologous structures of the forebrain of amniotes.

Animals↗

Quantitative immunohistochemistry of parvalbumin expression in the rat diaphragm.

Parvalbumin is a calcium-binding protein involved in the mechanism of Ca++ exchange between sarcoplasmic reticulum and the myofibrils. This characteristic promotes a direct correlation between the amount of parvalbumin and the velocity of contraction-relaxation of skeletal muscle fibers. To quantify the expression of parvalbumin in the rat diaphragm, transverse paraffin sections of this muscle were processed immunohistochemically using antiparvalbumin monoclonal antibody. The stained sections were inspected on an image analysis device to evaluate the intensity of the immunoreaction and to make morphologic measurements of the muscle fibers. The immunoreaction intensity data allowed the division of fibers in fast- and slow-twitch types. The rat diaphragm was characterized as a fast-twitch muscle due to the presence of 59.8% of fast-twitch fibers. The fibers' lesser diameter values showed that the slow-twitch fibers had a small diameter as compared to the fast-twitch ones (P < .001). The method used suggests that immunohistochemistry for parvalbumin assisted by image analysis is a feasible technique to separate fast- and slow-twitch skeletal muscle fibers in paraffin sections and to characterize their morphologic profiles.

Animals↗

Premotor neurons for vertical eye movements in the rostral mesencephalon of monkey and human: histologic identification by parvalbumin immunostaining.

In the monkey, premotor neurons for vertical gaze are located in the mesencephalic reticular formation: the rostral interstitial nucleus of the medial longitudinal fascicle (riMLF) contains medium-lead burst neurons, and the interstitial nucleus of Cajal (iC) acts as integrator for the eye-velocity signals to eye-position signals. Both nuclei lie adjacent to each other and are similar in appearance at the transition zone in Nissl-stained sections, which makes a delineation of the functionally different nuclei difficult in human. For a neuropathologic analysis of degenerative changes in saccadic disorders of patients, the histologic identification of the riMLF and the iC is important. The aim of this study is to identify both nuclei in human by using parvalbumin as a histologic marker. First, in monkeys the premotor neurons in riMLF and iC were identified by trans-synaptic labelling after injections of tetanus toxin fragment C into vertical-pulling eye muscles. Premotor neurons were found in the riMLF mainly ipsilateral to the corresponding eye muscle motoneurons and on both sides within the iC, but here the labelled cell populations differed: the contralateral side contained more medium-sized cells compared with the mainly small-sized cell population on the ipsilateral side. Double labelling showed that almost all premotor neurons in the iC and all premotor neurons in the riMLF were parvalbumin-immunoreactive. The immunocytochemical staining of human brainstem sections revealed the riMLF as a cluster of medium-sized, elongated parvalbumin-positive cells, with a similar appearance and at a similar location as that in monkey: a wing-shaped nucleus dorsomedial to the red nucleus, rostral to the traversing tractus retroflexus, dorsally bordered by the thalamo-subthalamic paramedian artery. The adjacent iC could be distinguished easily by its more densely packed, round parvalbumin-immunoreactive neurons. The exact identification of premotor neurons of the vertical system in the normal human brain provides a reference basis for the neuropathologic analysis of vertical gaze disorders at a cellular level.

Animals↗

Parvalbumin immunoreactivity changes in the thalamic reticular nucleus during the maturation of the rat's brain.

The thalamic reticular nucleus (Rt) is a thin lamina of cells, through which thalamocortical and corticothalamic fibers pass. It is interposed between the thalamic nuclei and the internal capsule and it is composed of GABA-ergic cells with synapses that receive impulses from both kinds of fibers. Rt takes part in the negative feed-back system of controlling the information transfer from the thalamus to the cerebral cortex and it is focused in the sleep-waking cycle. The pattern of parvalbumin reactivity during maturation of Rt becomes the main aim of our study. The study was performed on 36 rats on various postnatal days (P0, P1, P2, P4, P5, P7, P10, P14, P17, P21, P30 and P90). The animals were anesthetized, transcardially perfused, cut on cryostat into 30-microns-thick frontal sections, stained immunocytochemically using standard ABC method and a mouse monoclonal antibody against parvalbumin. A small amount of round and oval, parvalbumin immunopositive cells was detected at stage PO, predominantly in the intermediate part of Rt, whereas the cells in ventral and lateral part at the same time were only slightly immunopositive. At P10 the cells in the intermediate part became more fusiform or oval because of the appearance of dendrites. At P14 we were able to observe separate, punctuated structures interpreted as the axonal endings. There were plenty of them at the time of full maturation of the intermediate portion of reticular nucleus (stage P21). At this time, the dorsal and ventral parts had their first synapses, too, but their maturation ended a week later. At P30 multipolar neurons, with round and fusiform somata were distributed relatively homogeneously throughout Rt. We compared the stage with the parvalbumin reactivity of the adult rat and found no difference in the morphological pattern of PV neurons.

Animals↗

A phosphate-acceptor protein related to parvalbumins in dogfish skeletal muscle.

A phosphate-acceptor protein was isolated from the skeletal muscle of the Pacific dogfish (Squalus acanthias) displaying properties extremely similar to those of the parvalbumins, i.e., the low-molecular-weight, soluble, Ca-binding muscle proteins found in fish and amphibians. It has the same characteristic UV spectrum, strong affinity for calcium, and immunological crossreactivity with antibodies against homogeneous dogfish parvalbumin. Although it was isolated in three states of aggregation with molecular weights of about 350,000, 75,000, and 25,000, all species dissociate in Na dodecyl sulfate into subunits of 11,000 and 13,000 molecular weight. Furthermore, whereas no phosphorylation of parvalbumins could be demonstrated under any experimental conditions, the aggregated forms could be readily phosphorylated by a cyclic AMP-independent dogfish protein kinase, but not by phosphorylase kinase. One acid-stable and base-labile phosphate group was introduced per subunit which could be rapidly released by a dogfish protein phosphatase, but only very slowly if at all by phosphorylase phosphatase. It is speculated that this "phosphate-acceptor protein" might represent a physiologically active form of the parvalbumins.

Albumins↗