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Variable in vivo regulation of rat vitamin D-dependent genes (osteopontin, Ca,Mg-adenosine triphosphatase, and 25-hydroxyvitamin D3 24-hydroxylase): implications for differing mechanisms of regulation and involvement of multiple factors.

In these studies, the regulation of renal osteopontin (OPN), intestinal calcium pump, and renal and intestinal 25-hydroxyvitamin D3 24-hydroxylase (24OHase) was compared to the regulation of calbindin by Northern blot analysis. The time course of induction of the calbindins and calcium pump messenger RNAs (mRNAs) in vitamin D-deficient rats in response to 1,25-hydroxyvitamin D3 [1,25-(OH)2D3] was similar [first induction 3 h after 1,25-(OH)2D3 (200 ng/100 g BW), reaching a maximum at 12-24 h]. However, the maximal induction of calbindin mRNA was greater (8.2 +/- 1.2-fold) than that of intestinal calcium pump mRNA (21.3 +/- 0.5-fold). 24-Hydroxylase mRNA showed a different time course of induction by 1,25-(OH)2D3. 24-Hydroxylase mRNA was undetectable in vitamin D-deficient rat intestine and kidney. In intestine, 24OHase mRNA was maximally induced early [3-6 h after 1,25-(OH)2D3] and did not accumulate long after 1,25-(OH)2D3 administration. Unlike the other vitamin D-regulated genes, OPN was uninduced by 1,25-(OH)2D3 in the kidney of D-deficient rats. However, in vitamin D-replete rats given 1,25-(OH)2D3 for 5 days, a significant induction in renal OPN was observed (6.0-fold; P < 0.01). Developmental studies indicated that renal 24OHase and intestinal calcium pump mRNAs, similar to calbindin-D9K mRNA, were induced at 3 weeks of age, the time of weaning when active intestinal calcium absorption is induced. A comparison of the effect of calcium status showed that low dietary calcium resulted in an induction of intestinal calcium pump as well as calbindin-D9K mRNA, consistent with the requirement for an increase in intestinal calcium absorption during dietary calcium restriction. We next examined gender- and age-related changes in the expression of these genes. Our results indicate that renal OPN mRNA increases markedly in males with aging (10-fold between 3-20 months; P < 0.01), whereas OPN mRNA levels are unchanged in females. In both males and females, significant increases (2.7- to 4.5-fold) in renal 24OHase mRNA were observed at 20 months compared to 3 months of age.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗

Calretinin is present in non-pyramidal cells of the rat hippocampus--II. Co-existence with other calcium binding proteins and GABA.

The possible co-existence of calretinin with other calcium binding proteins, parvalbumin and calbindin D28k, and with GABA, was studied in non-pyramidal cells of the rat dorsal hippocampal formation, using the mirror technique. The majority of the calretinin-containing neurons (83%) were found to be immunoreactive for GABA (79% in the dentate gyrus, 84% in the CA2-3, and 88% in the CA1 subfield). Most of the GABA-negative calretinin-immunoreactive neurons were located in the hilus of the dentate gyrus and in stratum lucidum of the CA3 subfield. Detailed analysis of the calretinin-immunoreactive cells of these subfields revealed that the two morphologically distinct types of calretinin neurons, i.e. the spiny and the spine-free cells, differ in their immunoreactivity for GABA. The overwhelming majority (92%) of the spine-free neurons were GABA-positive, whereas the immunoreactivity of spiny cells was ambiguous. At the sensitivity threshold of the immunocytochemical techniques used in the present study, most of the spiny cells (89%) had to be considered as GABA-negative, although the staining intensity in their cell bodies was somewhat above background level. Colchicine treatment resulted in a degeneration of calretinin-immunoreactive neurons; therefore, its effect on the GABA content of spiny neurons could not be evaluated. Nevertheless, the observations suggest that calretinin-containing neurons are heterogeneous both morphologically and neurochemically. Examination of the co-existence of calcium binding proteins revealed that none of the hippocampal cells contained both calretinin and parvalbumin in any regions of the hippocampal formation. Some overlap was detected between the calretinin- and the calbindin D28k-containing cell populations, 5.1% of the former and 6.2% of the latter were immunoreactive for both calcium binding proteins. This may be due to a small degree of cross-reactivity of the calbindin D28k antiserum with calretinin. Thus, our results demonstrate that the majority of calretinin-immunoreactive neurons are GABAergic and represent a subpopulation of non-pyramidal cells with no or only a negligible overlap with the subpopulations containing the other calcium binding proteins, parvalbumin and calbindin.

Animals↗

The total number of neurons and calcium binding protein positive neurons during aging in the cochlear nucleus of CBA/CaJ mice: a quantitative study.

The quantitative stereological method, the optical fractionator, was used for determining the total number of neurons and the total number of neurons immunostained with parvalbumin, calbindin-D28k (calbindin), and calretinin in the dorsal and posteroventral cochlear nucleus (DCN and PVCN) in CBA/CaJ (CBA) mice during aging (1-39 months old). CBA mice have only a modest sensorineural pathology late in life. An age-related decrease of the total number of neurons was demonstrated in the DCN (r=-0.54, P<0.03), while the total number of neurons in the PVCN did not show any significant age-related differences (r=0.16, P=0.57). In the DCN 5.5% of neurons were parvalbumin positive in the very old (30-39 months) mice, vs. 2.2% in the 1 month old mice. In the DCN 3% of the neurons were calbindin immunopositive in the 30-39 months mice compared to 1.9% in the 1 month old group. In the PVCN, 20% of the neurons in the very old mice were parvalbumin immunopositive, compared to 12% in the young mice. Calbindin did not show any significant age-related differences in the PVCN. The total number of calretinin immunopositive neurons both in the DCN and PVCN did not show any significant change with increasing age. In conclusion, the total neuronal number in the DCN and PVCN was age-related and region-specific. While the neuronal number in the DCN and PVCN was decreased or unchanged, respectively, the calcium binding protein positive neuronal number showed a graded increase during aging in a region-specific and protein-specific manner.

Aging↗

Expression of calcium-binding proteins in the mouse claustrum.

The present paper describes the distribution of three calcium-binding proteins (calbindin D28k, calretinin, and parvalbumin) in the mouse dorsal claustrum and endopiriform nucleus. The three calcium-binding proteins were distinctly expressed in structures of both the claustrum and the endopiriform nucleus. Calbindin was the calcium-binding protein showing the highest expression in the claustrum and the endopiriform nucleus. In contrast, calretinin-immunoreactive structures, particularly cell bodies, were very scarce in these regions. Both calbindin-immunoreactive and parvalbumin-immunoreactive neurons were more abundant in the claustrum than in the endopiriform nucleus, and more in rostral than in caudal levels. Nevertheless, calcium-binding protein immunoreactive neurons constitute a minority population of claustral neurons. The colocalization study of calbindin and parvalbumin immunoreactivities has demonstrated that both calcium-binding proteins are mostly expressed by separate claustral neurons in the mouse. On the other hand, our results on parvalbumin and calretinin immunoreactivity match a novel subdivision of the mouse claustrum mostly based on the pattern of cadherin expression [Neuroscience 106 (2001) 505]. In this sense, we propose that a specific zone of the dorsal claustrum with cell bodies that strongly express Rcad and cadherin-8 would be the selective target for parvalbumin-expressing fibers, and that they would be mostly avoided by calretinin-expressing axons.

Animals↗

Calcium binding proteins immunohistochemistry and identification of neurons in the mammalian pineal gland of the African giant rat: Cricetomys gambianus.

The presence of true neurons in the rodent pineal gland is still a matter of controversy. In this work, by using immunohistochemistry with five antibodies against calcium-binding proteins (calbindin-D28k, calretinin, calmodulin, neurocalcin and S-100 beta) and Cricetomys gambianus, a rodent belonging to Muridae family living in Africa, we were able to illustrate the presence of neurons in the pineal gland. Anti-calbindin-D28k and anti-calretinin labelled neurons belonging to two neural ganglia. One ganglion was localized in the anterior part of the gland near the pineal stalk and the other one in the posterior portion of the organ. Immunoreactive neurons are medium in size (15-20 microns) and have long thick processes running towards the stalk. Calretinin and calbindin-D28k positive neurons stained with different intensities. Thin processes were detected by anti-calretinin whereas thick processes were preferentially calbindin-D28k positive. Neurocalcin labelled a few smaller neurons and many thin processes within the ganglion. Calmodulin could not be detected immunochemically. Within the ganglia many astrocytic processes were S-100 beta positive. The afferent and the efferent pathways of the pineal ganglia remain to be elucidated.

Animals↗

Immunocytochemical localization of nitric oxide synthase-containing neurons in mouse and rabbit visual cortex and co-localization with calcium-binding proteins.

Nitric oxide (NO) occurs in various types of cells in the central nervous system. We studied the distribution and morphology of neuronal nitric oxide synthase (NOS)-containing neurons in the visual cortex of mouse and rabbit with antibody immunocytochemistry. We also compared this labeling to that of calbindin D28K, calretinin, and parvalbumin. Staining for NOS was seen both in the specific layers and in selective cell types. The densest concentration of intense anti-NOS immunoreactive (IR) neurons was found in layer VI, while the weak anti-NOS-IR neurons were found in layer II/III in both animals. The NOS-IR neurons varied in morphology. The large majority of NOS-IR neurons were round or oval cells with many dendrites coursing in all directions. Two-color immunofluorescence revealed that only 16.7% of the NOS-IR cells were double-labeled with calbindin D28K in the mouse visual cortex, while more than half (51.7%) of the NOS-IR cells were double-labeled with calretinin and 25.0% of the NOS-IR cells were double-labeled with parvalbumin in mouse. By contrast, 92.4% of the NOS-IR neurons expressed calbindin D28K while only 2.5% of the NOS-IR neurons expressed calretinin in the rabbit visual cortex. In contrast with the mouse, none of the NOS-IR cells in the rabbit visual cortex were double-labeled with parvalbumin. The results indicate that neurons in the visual cortex of both animals express NOS in specific layers and cell types, which do not correlate with the expression of calbindin D28K, calretinin or parvalbumin between the two animals.

Animals↗

Tumor necrosis factor-alpha-induced changes in insulin-producing beta-cells.

The migration of macrophages and lymphocytes that produce cytokines such as tumor necrosis factor-alpha (TNF-alpha) causes beta-cell death, leading to type 1 diabetes. Similarly, in type 2 diabetes, the adipocyte-derived cytokines including TNF-alpha are elevated in the circulation, causing inflammation and insulin resistance. Thus, the studies described in this article using TNF-alpha are relevant to furthering our understanding of the pathogenesis of diabetes mellitus. We used RINr1046-38 (RIN) insulin-producing beta-cells, which constitutively express calbindin-D(28k), to characterize the effect of TNF-alpha on apoptosis, replication, insulin release, and gene and protein expression. Western blots of TNF-alpha-treated RIN cells revealed a decrease in calbindin-D(28k). By ELISA, TNF-alpha-treated beta-cells had 47% less calbindin-D(28k) than controls. In association with the decline in calbindin-D(28k), TNF-alpha treatment of RIN cells led to a 73% greater increase in changes in intracellular calcium concentration (Delta[Ca(2+)](i)) in TNF-alpha-treated cells as compared to that in control RIN cells upon treatment with 50 mM KCl; caused a greater increase in the [Ca(2+)](i) following the addition of 5.5 microM ionomycin; increased by more than threefold the apoptotic rate, expressed as the percentage of TUNEL-positive nuclei to total nuclei; decreased the rate of cell replication by 36%; and increased and decreased selectively the expression of specific genes as determined by microarray analysis. The subcellular localizations of Bcl-2, an antiapoptotic protein, and Bax, a proapoptotic protein, within RIN cells were altered with TNF-alpha treatment such that the two were colocalized with mitochondria in the perinuclear region. We conclude that the proapoptotic action of TNF-alpha on beta-cells is manifested via decreased expression of calbindin-D(28k) and is mediated at least in part by [Ca(2+)](i).

Apoptosis↗

Differential survival patterns among midbrain dopaminergic cells of MPTP-treated monkeys and 6OHDA-lesioned rats.

We explore the patterns of survival among dopaminergic cells of the midbrain in MPTP-treated macaque monkeys and 6OHDA-lesioned Sprague-Dawley rats. For the monkeys, animals were injected intramuscularly with MPTP for 8 days consecutively and then allowed to survive for 21 days. For the rats, 6OHDA was injected into the midbrain and then allowed to survive for either 7, 28 or 84 days. Brains were processed for tyrosine hydroxylase (TH) and calbindin immunocytochemistry to label populations in the ventral and dorsal tiers of midbrain dopaminergic cells. In monkeys, while there was a decrease in the TH+ cell number in the ventral tier of MPTP-treated cases (65%), there was an overall increase (22%) in the TH+ and calbindin+ cell number in the dorsal tier. Double labelling studies indicate that approximately 50% of TH+ cells of the dorsal tier contain calbindin also. In rats, there was a decrease in TH+ cell number in the ventral tier of 6OHDA-lesioned cases (97%), and to a lesser extent, in the TH+ and calbindin+ cell number in the dorsal tier ( approximately 40%). In conclusion, we show a surprising increase in TH+ and calbindin+ cell number in the dorsal tier in response to MPTP insult; such an increase was not evident after 6OHDA insult. We suggest that the increase in antigen expression relates to the dopaminergic reinnervation of the striatum in MPTP-treated cases. We also suggest that the greater loss of dopaminergic cells in the ventral tier when compared to the dorsal tier relates to glutamate toxicity.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗

Vitamin D upregulates expression of ECaC1 mRNA in semicircular canal.

The low luminal Ca2+ concentration of mammalian endolymph in the vestibular labyrinth is required for normal balance. We found transcripts in primary cultures of semicircular canal duct (SCCD) epithelial cells from neonatal rats representing a complete transport system for transepithelial absorption of Ca2+ that is comprised of the epithelial Ca2+ channels ECaC1 (CaT2, TRPV5) and ECaC2 (CaT1, TRPV6), calbindin (calbindin-D9k, calbindin-D28k), Na+/Ca2+ exchanger (NCX1, NCX2, and NCX3), and plasma membrane Ca2+-ATPase (PMCA1, PMCA3, and PMCA4) by RT-PCR. Further, vitamin D receptor was also expressed in SCCD and it was found by quantitative RT-PCR that incubation for 24 h with 1,25-dihydroxyvitamin D3 upregulated the expression of ECaC1, calbindin-D9k, and calbindin-D28k. These observations provide evidence for the first time of an ECaC-based Ca2+ transport system in SCCD that could maintain the low Ca2+ concentration in vestibular endolymph.

Animals↗

Neurocalcin-immunopositive neurons in the rat sensory ganglia.

Distribution of neurocalcin, a calcium-binding protein having three EF hand motifs, in the rat sensory ganglia was demonstrated immunochemically and immunohistochemically. Immunoblot analysis of trigeminal, nodose and dorsal root ganglia homogenates revealed an immunoreactive band at approximately 24 kDa. Neurons labeled by the neurocalcin-antiserum represent 54%, 41% and 46% cells in the trigeminal, nodose and dorsal root ganglia, respectively. Size distribution of immunopositive cells showed a varying range. Most large cells (more than 80%) showed immunoreactivity in the trigeminal and dorsal root ganglia. A double immunofluorescent study was performed to determine the colocalization with calbindin D28k or parvalbumin, which are both calcium-binding proteins. In the trigeminal and dorsal root ganglia, almost all calbindin- or parvalbumin-immunoreactive neurons showed neurocalcin-immunoreactivity, whereas approximately 30-40% neurocalcin-immunopositive cells had calbindin- or parvalbumin-immunoreactivity. In the nodose ganglia, parvalbumin showed localization similar to other ganglia, but about half the calbindin-immunoreactive neurons had neurocalcin-immunoreactivity. These studies show that neurocalcin-immunopositive neurons are widely distributed in the sensory ganglia and most calbindin- or parvalbumin-immunoreactive neurons also contain neurocalcin. In the sensory neurons, neurocalcin may have a significant role in calcium signaling.

Animals↗

Electrotonic profile and passive propagation of synaptic potentials in three subpopulations of hippocampal CA1 interneurons.

To elucidate the role of dendritic morphology in signal transfer, the passive propagation of somatic and dendritic potentials was compared in multi-compartment models of three interneuron subpopulations in the CA1 region. Nine calbindin-, 15 calretinin- and 10 parvalbumin-containing cells were modelled incorporating the detailed geometry, the currents of the action potentials in the soma, and the AMPA, N-methyl-D-aspartate and GABA-B receptor-mediated postsynaptic currents in the dendrites. The cable properties show characteristic differences among the subpopulations. The morphotonic length of calbindin and calretinin cell dendrites is larger than of parvalbumin cells. Thus parvalbumin cells are more compact than calbindin or calretinin cells unless the ratio of their axial and membrane resistivities exceeds the ratios of the other two cell types by more than 33%. In calbindin cells, the distal parts of the extremely long dendrites that invade the alveus are virtually isolated from the soma for passively propagating signals. The synaptic potentials evoked at a given morphotonic distance from the soma show larger differences locally on the dendrites than on the soma in all subpopulations. Both the somatic and dendritic amplitude ratios are the smallest in PV cells. In calbindin cells the somatic amplitude of synaptic potentials evoked at the same morphotonic distance from the soma is similar regardless of the number of branchpoints along their path. In calretinin and parvalbumin cells, from dendrites with long primary segments synaptic potentials reach the soma with larger amplitude than from dendrites that are branching close to the soma. The dendrites with the larger impact on somatic membrane potential are usually the dendrites that enter the stratum lacunosum-moleculare. These results indicate that dendritic morphology plays a role in changing the effectiveness of synaptic potentials evoked at different dendritic locations, and in this way is likely to be an important factor in determining the integrative properties of the different neuron populations.

Animals↗

Fos induction in cortical interneurons during spontaneous wakefulness of rats in a familiar or enriched environment.

It has been repeatedly reported that Fos is spontaneously induced in several brain structures, including the cerebral cortex, during wakefulness. To ascertain whether cortical interneurons are involved in this state-dependent oscillation of gene regulation, we combined Fos immunocytochemistry with immunostaining of either parvalbumin or calbindin, known markers of cortical interneurons. Immunopositive neurons were examined in the sensorimotor and cingulate cortex. In rats perfused in basal conditions, a minor proportion (around 8%) of Fos-immunoreactive neurons in the parietal cortex were also parvalbumin- or calbindin-immunoreactive; these double immunostained cells accounted for 13% of the parvalbumin- and 34% of the calbindin-labeled neurons. Colocalization of Fos with either calcium-binding protein was instead not observed in the cingulate cortex. In rats stimulated by novel environmental cues during the period of wakefulness preceding perfusion, Fos-positive neurons increased markedly relative to unstimulated animals, and involved the majority of the calbindin- or parvalbumin-labeled cell populations (60-75% and over 95%, respectively). In the neuronal populations in which Fos was induced by exposure to the enriched environment, the proportion of calbindin- and parvalbumin-labeled cells was larger than in the unstimulated cases, and the increment was statistically significant in the cingulate cortex. The results demonstrate that Fos induction occurring in the cortex during undisturbed wakefulness in a familiar environment involves a minor proportion of interneurons. Furthermore, the findings indicate that the addition of novel environmental stimuli results in an increase of Fos-expressing neurons whose recruitment, at least in the cingulate cortex, involves a higher proportion of interneurons than of projection neurons.

Animals↗

1,25-dihydroxyvitamin D(3)-independent stimulatory effect of estrogen on the expression of ECaC1 in the kidney.

Estrogen deficiency results in a negative Ca(2+) balance and bone loss in postmenopausal women. In addition to bone, the intestine and kidney are potential sites for estrogen action and are involved in Ca(2+) handling and regulation. The epithelial Ca(2+) channel ECaC1 (or TRPV5) is the entry channel involved in active Ca(2+) transport. Ca(2+) entry is followed by cytosolic diffusion, facilitated by calbindin-D(28K) and/or calbindin-D(9k), and active extrusion across the basolateral membrane by the Na(+)/Ca(2+)-exchanger (NCX1) and plasma membrane Ca(2+)-ATPase (PMCA1b). In this transcellular Ca(2+) transport, ECaC1 probably represents the final regulatory target for hormonal control. The aim of this study was to determine whether 17beta-estradiol (17beta-E(2)) is involved in Ca(2+) reabsorption via regulation of the expression of ECaC1. The ovariectomized rat model was used to investigate the regulation of ECaC1, at the mRNA and protein levels, by 17beta-E(2) replacement therapy. Using real-time quantitative PCR and immunohistochemical analyses, this study demonstrated that 17beta-E(2) treatment at pharmacologic doses increased renal mRNA levels of ECaC1, calbindin-D(28K), NCX1, and PMCA1b and increased the protein abundance of ECaC1. Furthermore, the involvement of 1,25-dihydroxyvitamin D(3) in the effects of 17beta-E(2) was examined in 25-hydroxyvitamin D(3)-1alpha-hydroxylase-knockout mice. Renal mRNA expression of calbindin-D(9K), calbindin-D(28K), NCX1, and PMCA1b was not significantly altered after 17beta-E(2) treatment. In contrast, ECaC1 mRNA and protein levels were both significantly upregulated. Moreover, 17beta-E(2) treatment partially restored serum Ca(2+) levels, from 1.63 +/- 0.06 to 2.03 +/- 0.12 mM. In conclusion, this study suggests that 17beta-E(2) is positively involved in renal Ca(2+) reabsorption via the upregulation of ECaC1, an effect independent of 1,25-dihydroxyvitamin D(3).

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗

Cell Counts of Purkinje and Inferior Olivary Neurons in the 'Hyperspiny Purkinje Cells' Mutant Mouse.

The mutant mouse 'hyperspiny Purkinje cells' (hpc) has morphologically abnormal Purkinje cells and below normal intracerebellar calbindin-D28k, a calcium-binding protein that, in the cerebellum, is found only in the Purkinje cells. We counted the Purkinje cells on serial sections stained with thionin or labelled with anti-calbindin-D28k antibodies to investigate whether the depletion of the cerebellar content of calbindin-D28k was correlated with a reduced number of Purkinje cells. We also counted the inferior olivary neurons, as they are one of the major afferents of the Purkinje cells and also contain calbindin-D28k. The hpc mutant mice had 27% fewer cerebellar Purkinje cells and 12% fewer inferior olivary neurons than did controls. Their Purkinje cells were evenly immunostained but slightly atrophic. These data suggest that the depleted cerebellar calbindin-D28k content could be explained both by the loss of some Purkinje cells and the reduced size of the remaining ones.

Journal Article↗

Pattern of selected calcium-binding proteins in the vestibular nuclear complex of two rodent species.

The distribution of immunoreactivity to calbindin, calretinin, and parvalbumin in the vestibular nuclear complex and the adjacent nucleus prepositus hypoglossi was studied in rats and gerbils. The distribution of stained fibers was the same for both rodent species. All three calcium-binding proteins were present in vestibular afferents. However, none of the three proteins were present in all afferent fibers. Many fibers were labeled in the vestibular nerve and in fascicles of the descending vestibular nucleus, as well as ascending fibers in the superior vestibular nucleus and fibers directed to the medial vestibular nucleus. Labeled terminals were present in the medial vestibular nucleus, especially along the ventricular border, in the neuropil of the superior vestibular nucleus, and scattered in the descending and ventral portions of the lateral vestibular nucleus. Calbindin- and parvalbumin-positive terminals, but not calretinin-positive terminals, were present in the neuropil of the dorsal lateral vestibular nucleus, especially surrounding the large neuronal somas. Some of these terminals are presumably from cerebellar Purkinje cells, which were also labeled by both antibodies. The pattern of parvalbumin immunoreactivity was slightly different from that of calbindin, indicating that parvalbumin might be contained in additional fibers. Some neurons in the vestibular nuclear complex were labeled with antibodies to calretinin, but few cells were stained with either calbindin or parvalbumin antibodies. The largest group of calretinin-positive cells was a cluster of small- to medium-sized neurons located in a densely stained mesh of dendrites and terminals in the medial vestibular nucleus, adjacent to the ventricular border.

Animals↗

Neurofilament and calcium-binding proteins in the human cingulate cortex.

Functional imaging studies of the human brain have suggested the involvement of the cingulate gyrus in a wide variety of affective, cognitive, motor, and sensory functions. These studies highlighted the need for detailed anatomic analyses to delineate its many cortical fields more clearly. In the present study, neurofilament protein, and the calcium-binding proteins parvalbumin, calbindin, and calretinin were used as neurochemical markers to study the differences among areas and subareas in the distributions of particular cell types or neuropil staining patterns. The most rostral parts of the anterior cingulate cortex were marked by a lower density of neurofilament protein-containing neurons, which were virtually restricted to layers V and VI. Immunoreactive layer III neurons, in contrast, were sparse in the anterior cingulate cortex, and reached maximal densities in the posterior cingulate cortex. These neurons were more prevalent in dorsal than in ventral portions of the gyrus. Parvalbumin-immunoreactive neurons generally had the same distribution. Calbindin- and calretinin-immunoreactive nonpyramidal neurons had a more uniform distribution along the gyrus. Calbindin-immunoreactive pyramidal neurons were more abundant anteriorly than posteriorly, and a population of calretinin-immunoreactive pyramidal-like neurons in layer V was found largely in the most anterior and ventral portions of the gyrus. Neuropil labeling with parvalbumin and calbindin was most dense in layer III of the anterior cingulate cortex. In addition, parvalbumin-immunoreactive axonal cartridges were most dense in layer V of area 24a. Calretinin immunoreactivity showed less regional specificity, with the exception of areas 29 and 30. These chemoarchitectonic features may represent cellular reflections of functional specializations in distinct domains of the cingulate cortex.

Aged↗

Preferential loss of preproenkephalin versus preprotachykinin neurons from the striatum of Huntington's disease patients.

Preferential loss of basal ganglia neurons and terminals occurs in Huntington's disease (HD). Terminals of preproenkephalin medium-size spiny neurons are more vulnerable than terminals of preprotachykinin neurons, but the peptidergic neurons of origin have not yet been shown to die preferentially. We sought to determine, in the striatum, whether preproenkephalin neurons were lost to a greater extent than preprotachykinin neurons and to determine whether there were decreases in specific messenger RNA (mRNA) levels of preproenkephalin, preprotachykinin, and calbindin D28k. We found a grade-related decrease in the number of preprotachykinin- and calbindin D28k-labeled neurons per measuring field in the caudate nucleus of patients with HD. Three measures of the neuronal level of preprotachykinin mRNA were all significantly reduced (6-65% of control values) in HD caudate nucleus. No decline in calbindin D28k mRNA levels per neuron were found in HD striata compared to control striata. We found a greater loss of preproenkephalin neurons per field than preprotachyknin neurons per field in the caudate nucleus of HD brains compared to control brains. Preprotachykinin neurons are lost in HD in a grade-related manner and surviving preprotachykinin neurons are impaired in function. However, preproenkephalin neurons are lost to a greater extent than preprotachykinin neurons, which may explain preferential changes found in projection regions of the striatum. Declines in neuropeptide mRNA may be specific in HD, since calbindin D28k mRNA levels were unchanged. Alterations in the levels of expression of preproenkephalin and preprotachykinin mRNA may be direct or indirect effects of the HD mutation.

Adult↗

Parvalbumin-containing GABAergic interneurons in the rat neostriatum.

Antibodies to the intracellular calcium binding protein parvalbumin were shown to label specifically a distinct group of neostriatal GABAergic neurons. These neurons corresponded to the intensely staining subclass of neostriatal GABAergic neurons that have previously been shown to be a class of aspiny interneurons in the neostriatum. The parvalbumin neurons were aspiny neurons with varicose dendrites distributed throughout the neostriatum in a pattern identical to the intensely stained GABA neurons, and both populations of neurons showed increased numbers in the lateral part of the neostriatum. Double labeling of single neurons with both the GABA and parvalbumin antisera showed that all parvalbumin neurons were positive for GABA, but some GABA labelled neurons were not immunoreactive for parvalbumin. These parvalbumin-negative GABAergic neurons were morphologically similar to the spiny projection neurons, which are GABAergic but usually are not so heavily stained. The relationship of the GABA-containing parvalbumin neurons to the striatal mosaic organization was determined by using immunocytochemistry for another calcium binding protein, calbindin D28K, to label the matrix compartment of the striatum. The distribution of parvalbumin-positive neurons relative to the calbindin-positive matrix and calbindin-poor patches was determined by using pairs of adjacent sections stained with the calbindin and parvalbumin antisera. This analysis showed that the somata of the parvalbumin neurons were present in both patch and matrix compartments, and their axons and dendrites crossed the boundaries between compartments. A quantitative analysis of the number of neurons in each compartment revealed that the neurons showed no preferential distribution in either compartment, but instead were present according to the area occupied by that compartment.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗