Localization of chick retinal 24,000 dalton protein (visinin)-like immunoreactivity in the rat lower brain stem

Neurochemistry of the mammillary body

The mammillary body (MB) is a component of the extended hippocampal system and many studies have shown that its functions are vital for mnemonic processes. Together with other subcortical structures, such as the anterior thalamic nuclei and tegmental nuclei of Gudden, the MB plays a crucial role in the processing of spatial and working memory, as well as navigation in rats. The aim of this paper is to review the distribution of various substances in the MB of the rat, with a description of their possible physiological roles. The following groups of substances are reviewed: (1) classical neurotransmitters (glutamate and other excitatory transmitters, gamma-aminobutyric acid, acetylcholine, serotonin, and dopamine), (2) neuropeptides (enkephalins, substance P, cocaine- and amphetamine-regulated transcript, neurotensin, neuropeptide Y, somatostatin, orexins, and galanin), and (3) other substances (calcium-binding proteins and calcium sensor proteins). This detailed description of the chemical parcellation may facilitate a better understanding of the MB functions and its complex relations with other structures of the extended hippocampal system.

Purkinje-like cells of the rat cochlear nucleus: a combined functional and morphological study

Purkinje-like cells (PLCs) of the cochlear nucleus (CN) are strongly calbindin positive neurones with unknown function. In the present work functional and morphological methods have been employed to provide data about PLCs in general, and about their possible involvement in the synaptic organisation of the CN in particular. PLCs had slightly elongated soma, from which a complex dendritic arborisation extended with highly variable dimensions. On the basis of their morphology, three classes of PLCs were identified. Positively identified PLCs fired a train of action potentials on sustained depolarization. When hyperpolarizing stimuli were applied, the presence of a slowly activating, ZD7288-sensitive inward current was noted that corresponded to the h-current. PLCs received both excitatory and inhibitory synaptic inputs. Functional experiments revealed that 76% and 14% of the spontaneous inhibitory postsynaptic currents recorded from the cell bodies of the PLCs were mediated via glycinergic and GABAergic synapses, respectively. PLCs presented strong cerebellin1-like immunoreactivity, but its distribution differed from that seen in cerebellar Purkinje cells. Our results indicate that PLCs are parts of the synaptic circuitry of the CN, thus they may be actively involved in the processing and analysis of auditory information.

The brain injury biomarker VLP-1 is increased in the cerebrospinal fluid of Alzheimer disease patients

BACKGROUND

Definitive diagnosis of Alzheimer disease (AD) can be made only by histopathological examination of brain tissue, prompting the search for premortem disease biomarkers. We sought to determine if the novel brain injury biomarker, visinin-like protein 1 (VLP-1), is altered in the CSF of AD patients compared with controls, and to compare its values to the other well-studied CSF biomarkers 42-amino acid amyloid-beta peptide (Abeta(1-42)), total Tau (tTau), and hyperphosphorylated Tau (pTau).

METHODS

Using ELISA, we measured concentrations of Abeta(1-42), tTau, pTau, and VLP-1 in CSF samples from 33 AD patients and 24 controls. We compared the diagnostic performance of these biomarkers using ROC curves.

RESULTS

CSF VLP-1 concentrations were significantly higher in AD patients [median (interquartile range) 365 (166) ng/L] compared with controls [244 (142.5) ng/L]. Although the diagnostic performance of VLP-1 alone was comparable to that of Abeta, tTau, or pTau alone, the combination of the 4 biomarkers demonstrated better performance than each individually. VLP-1 concentrations were higher in AD subjects with APOE epsilon4/epsilon4 genotype [599 (240) ng/L] compared with epsilon3/epsilon4 [376 (127) ng/L] and epsilon3/epsilon3 [280 (115.5) ng/L] genotypes. Furthermore, VLP-1 values demonstrated a high degree of correlation with pTau (r = 0.809) and tTau (r = 0.635) but not Abeta(1-42) (r = -0.233). VLP-1 was the only biomarker that correlated with MMSE score (r = -0.384, P = 0.030).

CONCLUSIONS

These results suggest that neuronal injury markers such as VLP-1 may have utility as biomarkers for AD.

Subcellular localization of the inositol 1,4,5-trisphosphate receptor, P400, in the vestibular complex and dorsal cochlear nucleus of the rat

The subcellular localization of the inositol 1,4,5-trisphosphate receptor protein, P400, was studied in the vestibular complex, an area to which Purkinje cells project, as well as in neurons of the dorsal cochlear nucleus and in ectopic Purkinje cells of adult rat brain. The receptor was demonstrated by electron microscopical immunocytochemistry using the avidin-biotin peroxidase complex procedure, with the monoclonal antibody 4C11 raised against mouse cerebellar inositol 1,4,5-trisphosphate receptor protein. Immunoreactivity was found in preterminal fibres and terminal boutons in the nuclei of the vestibular complex, generally associated with the subsurface systems and stacks or fragments of smooth endoplasmic reticulum. Ectopic Purkinje cells and cartwheel cells of the dorsal cochlear nucleus also displayed immunoreactivity, but this was much less intense in the latter. The results of the present study suggest that this receptor protein, involved in the release of Ca2+, is located in sites that enable it to influence the synthesis, transport and release of neurotransmitters.

Purkinje-like cells in rat cochlear nucleus

A unique class of cells, strongly immunopositive for anti-calbindin D-28 kDa was observed in and near the cochlear nucleus of young adult, male Sprague-Dawley rats. These cells are present in small numbers which are highly variable across animals and inconstant in position. They are preferentially located in the dorsal cochlear nucleus, with occasional examples being present in the ventral cochlear nucleus, as well as in adjacent brainstem locations. They have been referred to in other studies as displaced Purkinje cells or 'Purkinje cell-like cells', and are here designated 'Purkinje-like cells' (PLCs). PLCs have relatively large cell bodies, with thick, heavily spined dendrites, and are typically situated in an immediately subpial position. The dendritic arborization extends into the interior of the nucleus, away from the pial surface, a trajectory opposite in direction to that of the cerebellar Purkinje cells. The intense immunoreactivity exhibited by PLC somata and dendrites when treated with antiserum directed against calbindin is equivalent to that of cerebellar Purkinje cells, and markedly stronger than that of most other cell populations of the cochlear nucleus. However, in tissue treated with anti-parvalbumin, which also strongly labels cerebellar Purkinje cell somata and dendrites, PLC labeling, when present, is relatively weak, limited to the cell bodies and only the base of the dendrites of PLCs, indicating non-equivalence of the two cell types. In addition, the intensity of calbindin immunostaining in the PLCs appears to be more sensitive to glutaraldehyde in any of the fixative solutions than that seen in cerebellar Purkinje cells in the same sections. Of the cell types of the cochlear nucleus, the cartwheel cells would appear to be the most similar to the PLCs on morphological and immunocytochemical grounds. However, the subpial position and average somal dimensions of the PLCs, as well as the relatively modest immunoreactivity of the cartwheel cells for calbindin, rather clearly differentiate the PLCs from this class of neurons. The results of the present study suggest that the PLCs of the cochlear nucleus, although they may arise developmentally as ectopic cerebellar Purkinje cells and maintain certain Purkinje cell characteristics, represent a distinct neuronal cell type in the adult rat cochlear nucleus, exhibiting incomplete overlap of fixation, immunocytochemical and morphological characteristics with both cartwheel cells of the cochlear nucleus and cerebellar Purkinje cells.

Immunohistochemical localization of GABA in the mammillary complex of the rat

The distribution and synaptic organization of GABAergic elements in the mammillary nuclei of rats have been examined by the immunocytochemical localization of GABA at the light and electron microscope levels. The distribution of GABA-immunoreactive fibres and terminals in the mammillary body is non-homogeneous. By light microscopy, small scattered immunoreactive terminals are observed in the pars medianus, pars posterior and ventral region of the pars medialis of the medial mammillary nucleus. Larger labelled terminals are found in the pars lateralis, the dorsal region of the pars medialis of the medial mammillary nucleus and the lateral mammillary nucleus. At the ultrastructural level, GABA-immunoreactive synaptic endings in the different subdivisions of the medial mammillary nucleus exhibit a widespread somadendritic distribution. By contrast, GABA-immunoreactive terminals within the lateral mammillary nucleus are located predominantly in the neuropil and less frequently on neuronal somata. GABA-immunoreactive synaptic endings contain pleiomorphic synaptic vesicles and have symmetrical synaptic contact zones with the somata and dendrites in the lateral and medial mammillary nuclei. After in vivo inhibition of GABA metabolism with amino-oxyacetic acid, light microscopic examination of the mammillary nuclei reveals numerous small GABA-immunoreactive cells in various subdivisions of the medial mammillary nucleus. No immunoreactive cells are observed, however, in the lateral mammillary nucleus. Electron microscopic examination demonstrates that the GABA-immunoreactive cells are astrocytes. In the labelled astrocytes, immunohistochemical reaction product is localized throughout the nucleus and cytoplasm of the cells, in thin sheet-like processes surrounding neuronal elements and in end-feet lining the basal lamina of capillaries. The results indicate that the mammillary nuclei in the rat receive a strong GABAergic innervation. Most if not all, of the GABA-immunoreactive synaptic endings in the mammillary nuclei probably arise from extrinsic inhibitory sources. The possible sources of the GABA-immunoreactive input to the mammillary complex are discussed.

Calretinin and calbindin-D28k in rat brain: patterns of partial co-localization

Calretinin and calbindin-D28k are homologous calcium-binding proteins, each present in a variety of neurons in the brain. Their distributions in the rat brain have been compared at the cellular level to determine whether they tend to occur in the same or in different cells, and to determine whether calbindin-positive cells show any common features once crossreaction with calretinin has been eliminated. The results show great heterogeneity. Most cells which contain one of the proteins do not contain the other, but many cells do contain both; even in the ventral cochlear nucleus, where there is abundant calretinin and most calbindin-like immunoreactivity is due to crossreaction, a few cells contain both proteins. In the substantia nigra and ventral tegmental area, many cells are double-positive but some only contain one or the other protein. Only the triangular septal nucleus is uniformly positive for both proteins. Cells which look like local-circuit neurons in many forebrain areas (cortex, hippocampus, olfactory bulb, anterior olfactory nucleus) are exclusively positive for either calretinin or calbindin, in spite of their similar morphology. In the more heterogeneous parts of the brain (including hypothalamus central gray and substantia gelatinosa), there are mixtures of calretinin-positive, calbindin-positive, and double-positive cells. In comparison with previous data on the chick, some aspects of the distributions are conserved, but double-positive cells are more frequent in the rat. The degree of heterogeneity observed, even within comparatively well-defined neuronal populations, makes it difficult to infer in what neuronal properties these proteins could be involved.

Calbindin-D28K (CaBP28k)-like Immunoreactivity in Ascending Projections

This study concerns the involvement of calbindin-D28K (CaBP28k)-containing neurons in the efferent projections of both the trigeminal nucleus caudalis and the dorsal vagal complex (nucleus of the solitary tract and area postrema) in rats. Recent evidence has shown that these projections are particularly important for the processing of visceroception and/or nociception at central levels. The trigeminal nucleus caudalis has dense projections to both the nucleus of the solitary tract and the parabrachial area; the dorsal vagal complex is intimately connected to the parabrachial area. CaBP28k is a calcium-binding protein the function of which could be a determining factor in controlling the excitability of cells by acting on intrinsic calcium metabolism. CaBP28k content of projections was ascertained using a double labelling approach that combined the retrograde transport of a protein - gold complex to identify projection cells and immunocytochemistry to identify CaBP28k-positive cells. The trigeminal nucleus caudalis is rich in both CaBP28k-immunoreactive cells and cells projecting to the parabrachial area or the nucleus of the solitary tract. Cells containing both the protein and the retrograde tracer, however, were mostly restricted to the superficial layers (laminae I and outer II) and to their rostral extensions, the dorsal paramarginal and paratrigeminal nuclei. These trigeminal subdivisions are targets for nociceptive, visceroceptive and thermal inputs of peripheral origins. The dorsal vagal complex is rich in CaBP28k. Dense populations of immunoreactive cells are observed in the ventrolateral part of the area postrema and all of the three main subdivisions of the nucleus of the solitary tract (rostral gustatory, ventrolateral respiratory and medial cardiovascular subregions). The subnucleus commissuralis, subnucleus centralis and dorsal subnuclei are particularly densely stained. The subnucleus centralis, which is involved in regulating food and water intake, does not project to the parabrachial area. The area postrema, subnucleus commissuralis and dorsal subnuclei, which are implicated in cardiovascular and/or ingestive behaviours, have dense projections to the parabrachial area, many of which contain CaBP28k. The present results demonstrate that CaBP28k-containing cells form a major part of the solitary and trigeminal projection systems, including subregions that are involved in visceroception and/or nociception processing. The location of solitary nucleus projection cells overlaps those of some neuropeptidergic projecting populations, suggesting colocalization. Consequently, certain neuropeptidergic actions may be CaBP28k-dependent.

Calretinin in rat brain: an immunohistochemical study

Calretinin is a calcium-binding protein related to calbindin-D28k; both are present in different though overlapping sets of neurons in brains of birds and mammals. We describe in detail the pattern of calretinin immunoreactivity in the rat brain. As in chick brain, calretinin immunoreactivity is abundant in various sensory pathways (particularly certain cells and fibres of the cochlear nuclei and olfactory bulb), in the heterogeneous parts of the brainstem and in parts of the hypothalamus. Many primary sensory fibres are strongly positive. Major groups of calretinin-positive neurons also include the thalamic reticular nucleus, triangular septal nucleus, lateral mammillary nucleus and substantia nigra pars compacta. Many other calretinin-positive cells are recognizable as local inhibitory neurons. Calretinin is absent from all but a few cells in the cerebral cortex, and is never found in motor neurons. There are also some distinctive positive structures whose identity is uncertain, notably irregular "shells" of cells and fibres around the thalamus and in the amygdala and an unnamed cell type in the vestibulocerebellum.

Two calcium-binding proteins mark many chick sensory neurons

The first immunohistochemical results with a new neuronal calcium-binding protein, calretinin, are presented. Calretinin is related to the 28,000 mol. wt calcium-binding protein, calbindin, and a survey of the chick brain by in situ hybridization has identified the brain nuclei that expressed the genes for the two proteins [Rogers J.H., J. Cell Biol. 105, 1343 (1987)]. Now, antisera have been raised against calretinin fusion proteins in order to visualize individual neurons. The antisera have been used in an immunohistochemical survey of calretinin and calbindin in the chick sensory nuclei and ganglia, where these two proteins are found to be particularly prevalent. In the central nervous system, they are seen in many secondary sensory neurons and local circuit neurons, the two proteins being almost always in separate cells. However, in ganglion cells of the spinal nerves, inner ear, and retina, they are often expressed together. Their distribution in the brain is generally different from that of a third calcium-binding protein, parvalbumin. These proteins may modulate many important calcium-dependent processes in neurons, and probably have multiple functions.

Immunoreactivity for calretinin and other calcium-binding proteins in cerebellum

Two calcium-binding proteins, calbindin and parvalbumin, have been reported to be abundant in Purkinje cells and other cell types in the cerebellum. Immunoreactivity for a related protein, calretinin, is now reported in cerebellum of chick and rat. In the chick, antibodies against calretinin stain mossy fibres throughout, and climbing fibres in a distinct group of folia. They also stain several cell types in the molecular layer. As there is no detectable calretinin mRNA in the cerebellar cortex, this cellular staining may be due to cross-reaction with an unknown antigen. In the rat, antibodies against calretinin stain the Lugaro cells, and some granule cells in lobe X; they also give weak staining of all the granule cells in the other lobes. Thus almost all the neuronal cell types in the cerebellum show immunoreactivity for at least one of the calcium-binding proteins in one or both species.

Neurotensin-containing projections from the retrosplenial cortex to the anterior ventral thalamic nucleus in the rat

The neurotensin-containing projections from the retrosplenial cortex to the anterior ventral thalamus were demonstrated by electrolytic lesion studies and fluorescent retrograde tracing combined with immunocytochemistry. Three-to-five-day-old rats were used, because the immunoreactivity of neurotensin fibers in anterior ventral thalamus was the highest at this age. When neurotensin-containing neurons located in layer VI of the retrosplenial cortex were unilaterally destroyed by applying an electrolytic current to the retrosplenial area, the neurotensin fibers in the ipsilateral anterior ventral thalamus decreased dramatically. Unilateral injection of a fluorescent retrograde tracer, Fast Blue, into the anterior ventral thalamus, labeled neurons in the ipsilateral retrosplenial cortex, and many of these cells also had neurotensin-like immunoreactivity. These results suggested that a major origin of the neurotensin fibers in the anterior ventral thalamus was in the ipsilateral retrosplenial granular cortex.

Localization of calbindin D28 mRNA in rat tissues by in situ hybridization

We investigated, by in situ hybridization histochemistry, the cellular localization of the mRNA encoding a vitamin D-dependent calcium-binding protein (calbindin D28) in rat brain and peripheral organs. Using a [35S]cRNA probe under high stringency conditions, specific mRNA was found in tissues well known for their calbindin D28 content, e.g. renal distal tubules, cerebellar Purkinje cells and dentate gyrus granule cells. Tissue devoid of this protein, such as liver, also lacked specific mRNA. In situ hybridization histochemistry allows the precise identification of cells expressing calbindin D28 and offers a new approach to study its regulation and possible role, e.g. in neuronal function.

Immunohistochemical cross-reactivity and electrophoretic comigration between calbindin D-27 kDa and visinin

Calbindin D-27 kDa (previously named vitamin D-CaBP or cholecalcin) and visinin present similitude both for their purification procedure and histochemical localization. We systematically compared by histochemistry calbindin and visinin immunoreactive structures in chick and pigeon retina, in rat cerebellum and kidney and in pigeon cerebellum. The calbindin and visinin immunoreactive structures were identical except in the retina. Preabsorption of anti-visinin with purified chick or rat calbindin suppresses the labelling in every organ studied except in the photoreceptor layer of pigeon and chick retina. Such a persistence of labelling was explained by Western blotting analysis of chick-retina soluble proteins showing a pattern of 7 different proteins recognized by anti-visinin even though only one protein was recognized in rat kidney and cerebellum. Anti-visinin is thus a polyclonal antibody reacting with more than one antigen of the chick retina, one of those antigens being calbindin. Calbindin is the single antigen recognized by anti-visinin in the other tested organs. In conclusion, we present evidence that visinin is a calbindin.

Mammillothalamic enkephalinergic pathway in the rat: an immunocytochemical analysis

We studied the afferent sources of Leu-enkephalin (ENK) -like immunoreactive (ENKI) fibers in the anteroventral thalamic nucleus (AV) of the rat using experimental immunohistochemistry. These fibers were markedly fewer on the operated side after the destruction of the medial mammillary nucleus pars medialis where a number of ENKI cells were observed. This strongly suggests that these ENKI cells project ipsilaterally to the AV. ENKI fibers seemed to reach the AV via the mammillothalamic tract.

Ontogeny of visinin-like immunoreactive structures in the rat cerebellum and vestibular nuclei: an immunohistochemical analysis

The ontogeny of visinin-like immunoreactive (visinin-IR) structures in the cerebellum and vestibular nuclei of the rat brain was examined by indirect immunofluorescence. Visinin-IR structures are localized exclusively in the Purkinje cell system in these areas. Immunoreactive Purkinje cells first appear at gestational day 18, increasing in number with age. The axons appear at gestational day 19 and develop markedly until reaching the adult level at postnatal day 4. However, immunoreactive dendrites do not reach the adult pattern until postnatal day 21. In the cerebellar and vestibular nuclei, immunoreactive fibers first appeared at gestational day 18 and increased in number there with age, reaching the adult level at postnatal day 4.

Localization of chick retinal visinin-like immunoreactivity in the rat forebrain and diencephalon

The present study is an examination, using an indirect immunofluorescence method, of the distribution of visinin, a 24,000 dalton peptide, in the rat forebrain and diencephalon. Immunoreactive structures were localized in the neuronal elements showing an uneven distribution. Immunoreactive neurons were found in the olfactory bulb, anterior olfactory nucleus, cerebral cortex, amygdaloid complex, ventral portion of the nucleus caudatus putamen, septal area, nucleus accumbens, nucleus paratenialis, nucleus rhomboideus, nucleus reuniens, nucleus paraventricularis hypothalami, nucleus supraopticus, nucleus anterior hypothalami, preoptic area, hypothalamic periventricular nucleus, nucleus mammillaris medialis, medial habenular nucleus, zona incerta, nucleus lateralis thalami, nucleus tractus optici and gyrus dentatus. Immunoreactive fibers were observed in the above areas, particularly near the labelled cells, forming fiber plexuses of varying density. In addition, dense plexuses were also seen in the globus pallidus, anteroventral nucleus of the thalamus, substantia nigra and hippocampus. In the former three structures, no labelled cells were present and in the latter, a few scattered neurons were found, indicating that these fibers originate from extrinsic sources.