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We studied changes in the expression of growth-associated protein 43 (GAP43), glial fibrillary acidic protein (GFAP), and calcium-binding proteins (calbindin [Cb] and parvalbumin [Pv]) in the dorsal lateral geniculate nucleus (dLGN) of four capuchin monkeys with laser-induced retinal lesions. The lesions were generated with the aid of a neodymium-YAG dual-frequency laser with shots of different intensity and at different survival time in each animal. The expression of these proteins in the layers of the dLGN was evaluated by performing histodensitometry of coronal sections throughout the nucleus. High-power laser shots administered at the border of the optic disc (OD)-injured fibers resulted in large scotomas. These lesions produced a devastating effect on fibers in this passage, resulting in large deafferentation of the dLGN. The time course of plasticity expressed in this nucleus varied with the degree of the retinal lesion. Topographically, corresponding portions of the dLGN were inferred by the extent of the ocular dominance column revealed by cytochrome oxidase histochemistry in flattened preparations of V1. In the region representing the retinal lesion, the expression of GFAP, GAP43, Pv, and Cb increased and decreased in the corresponding dLGN layers shortly after lesion induction and returned to their original values with different time courses. Synaptogenesis (indicated by GAP43 expression) appeared to be increased in all layers, while "cleansing" of the glial-damaged region (indicated by GFAP expression) was markedly greater in the parvocellular layers, followed by the magnocellular layers. Schematic drawings of optic discs laser lesions and of series of coronal sections of the dLGN, in three monkeys, depicting the areas of the nucleus deafferented by the lesions., (© 2022 Wiley Periodicals LLC.)

Parkinson's disease is characterized by a selective loss of dopaminergic neurons in the nigrostriatal pathway. However, not all dopaminergic neurons degenerate in this disease, and calcium has been suspected of playing a role in this differential vulnerability. An overexpression of the calcium-dependent protease calpain II has recently been reported in the parkinsonian substantia nigra, suggesting that a rise in intracellular calcium concentrations may be involved in the mechanism leading to cell death. The proteasic activity of calpain is regulated by an endogenous inhibitory protein called calpastatin. Because little is known about the distribution of calpastatin in the primate brain, we first analyzed immunohistochemically the calpastatin expression in normal human and monkey brain. A ubiquitous distribution of calpastatin immunostaining was observed in both cases, but its expression was variable from one region to another. In the basal ganglia, staining was intense in the striatum, in the pallidal complex, and in some nuclei of the thalamus. The cerebellum was stained intensely, particularly in the granular and Purkinje cell layers. A dense, heterogeneous staining was observed in the hippocampal formation, mostly in the pyramidal and granular layers. The distribution of staining was similar in the different cerebral cortices studied, and it was most intense in layer V. In the brainstem, staining was particularly prominent in the substantia nigra pars reticulata and compacta, the central gray substance, the superior colliculus, and the cuneiform nucleus, and staining was moderate in the tegmenti pedonculopontinus nucleus and the griseum pontis. In the second part of the study, the authors compared calpastatin expression in the mesencephalon between patients with Parkinson's disease and control subjects. Sequential double staining revealed that some dopaminergic neurons coexpress calpastatin, the proportion of double-stained neurons ranging between 52% and 76% among the different dopaminergic cell groups. Quantitative analysis of the number of calpastatin-stained neurons evidenced a loss of both calpastatin-positive and calpastatin-negative neurons in the substantia nigra of patients with Parkinson's disease. These data suggest that calpain II overexpression in Parkinson's disease is not compensated for by a concomitant increase in calpastatin expression., (Copyright 2000 Wiley-Liss, Inc.)

The present study analyzed the relationships of glycine (GLY)-immunoreactive (-IR) and unlabeled profiles in the primate spinal cord. Light microscopic analysis demonstrated GLY-IR profiles in laminae III-VII, with fewer labeled profiles in laminae I, II, VIII, IX and X. The dorsal part of the lateral funiculus and the dorsal funiculus contained few labeled axons, in contrast to all other areas of white matter, which were heavily labeled. At the electron microscopic level, GLY-IR terminals in monkeys contained mainly round, with occasional pleomorphic, clear vesicles; however, F-type GLY-IR terminals synapsing on motoneurons contained pleomorphic vesicles. This seems to be an important species difference because vesicles in GLY-IR terminals in rat and cat are predominantly oval or elliptical. GLY-IR terminals synapsed on unlabeled as well as GLY-IR cell bodies and dendrites. This is morphological evidence that GLY may be both an inhibitor (GLY-IR terminals synapse on and presumably inhibit non-GLY cell bodies and dendrites) and a disinhibitor (GLY-IR terminals synapse on and presumably inhibit other GLY elements) of spinal activity. Also noteworthy was the conspicuous absence of axoaxonic interactions involving GLY-IR terminals. A related finding was that GLY profiles were always postsynaptic, never presynaptic, to glomerular primary afferent terminals. The functional implications would seem to be that primary afferent input can activate the spinal GLY system but that there is little GLY presynaptic control of afferent input in monkeys. This is in contrast to rats and cats, in which axoaxonic interactions involving GLY-IR terminals have been observed and where it is common to find GLY-IR terminals presynaptic to glomerular primary afferent terminals.

The calcium-binding protein calretinin is present in an intrinsic GABAergic and an extrinsic non-GABAergic system in the rat and monkey hippocampal formation. Important species differences have been noted in hippocampal cell types immunostained for calretinin and the termination pattern of calretinin containing hypothalamic afferents in the hippocampus. In the present study, calretinin-containing neurons were visualized using immunocytochemistry in the human hippocampal formation of individuals which showed no significant neuropathological alterations. Calretinin-immunoreactivity was present exclusively in non-granule cells of the dentate gyrus and in non-pyramidal cells of Ammon's horn. Calretinin-positive neurons were found most frequently in the hilus of the fascia dentata and in strata radiatum and lacunosum-moleculare of CA1, whereas neurons in CA2 and CA3 were rarely immunostained. The majority of calretinin-immunoreactive neurons were small, bipolar or fusiform neurons. The dendritic trees of the calretinin-positive neurons were, for the most part, parallel to the dendrites of the principal cells. In the hilus, however, we observed cells with dendrites restricted to the hilar area. These dendrites were parallel to the granule cell layer. In the stratum lacunosum-moleculare, neurons with dendrites oriented parallel to the hippocampal fissure were frequently detected. In general, dendrites were smooth or sparsely spiny, displaying small conventional spines. The axons usually emerged from the proximal dendrite and could be followed over long distances. Axons were thin, had small varicosities and displayed only few collaterals which branched relatively far away from the cell body. Distinct bands of darkly stained calretinin-positive fibers occupied the innermost portion of the dentate molecular layer and the pyramidal cell layer of CA2. This distribution of calretinin-immunoreactive structures in the human hippocampus is similar to that observed in other primates but differs from that described in lower mammals, i.e., the rat. Our findings suggest that primates may share a common hippocampal calretinin-containing system, presumably both the intrinsic GABAergic and the extrinsic hypothalamic non-GABAergic components.

The localization of the N-methyl-D-aspartate receptor subunit NR2A was studied, by using light microscopic immunocytochemistry, in the retina of adult rat, rabbit, cat, and monkey. Strong, punctate immunolabeling was observed in the inner plexiform layer indicating a synaptic localization of the NR2A subunit. The punctate labeling was concentrated in two bands corresponding to the on- and off-sublaminae of the inner plexiform layer. The punctate character of immunofluorescence suggested a synaptic localization of the receptor. This was confirmed by electron microscopy of immunostained adult rat retina. The staining was localized postsynaptic to cone bipolar cells, and only one of the two postsynaptic elements of the dyad was labeled. Staining was not observed at extrasynaptic plasma membranes. In situ hybridization of adult rat retina showed expression of the NR2A subunit in virtually all ganglion cells and displaced amacrine cells in the ganglion cell layer and in a subset of amacrine cells in the inner nuclear layer. The postnatal developmental expression of the NR2A subunit was studied in rat retina by light microscopic immunocytochemistry. Punctate immunolabeling appeared prior to eye opening, and the developmental profile of NR2A could be compatible with a role in development of circuitry in the inner plexiform layer.

The spinal cord terminations of two electrophysiologically identified single C-fibers (one identified as a C-nociceptor) were intra-axonally labeled with horseradish peroxidase and analyzed with both light and electron microscopy. Serial section ultrastructural analysis and postembedding immunocytochemical techniques for calcitonin gene-related peptide (CGRP), substance P (SP), and GABA were used to study the synaptology, and neuropeptide content. All C-terminal synapses were in laminae I and II. The terminals sampled (n = 73) from these two C-fibers rarely established glomerular synaptic complexes, but rather, simple terminals, usually measuring 1-4 microns in length and 1-3 microns in diameter. They most often established 1 or 2 (range 1 to 5) quite large asymmetric axodendritic synaptic contacts. Postsynaptic structures included dendritic spines and shafts with and without vesicles. C-terminals were filled with small round synaptic vesicles (45-60 nm) and also contained variable numbers of large dense-core vesicles (LDCVs, 80-110 nm). LDCVs inside identified C-terminals frequently displayed CGRP immunoreactivity. We were unable to detect SP immunoreactivity inside our sample of C-fiber LDCVs. C-terminals were never found postsynaptic to other profiles. Thus, the C-fiber terminals sampled in this study have simple synaptology, do not receive presynaptic control and contain CGRP immunoreactivity. They differ greatly from the terminals of A delta nociceptors studied previously by our group that had glomerular endings, often received presynaptic input and did not contain CGRP immunoreactivity. This suggests the existence of different processing mechanisms, at the level of the first synapse, for nociceptive inputs arriving to lamina I and II through different types of primary afferents.

The inferior olive is divided into several subnuclei that receive specific sensory information. The caudal dorsal cap of the medial accessory subdivision of the inferior olive receives horizontal optokinetic information from the nucleus of the optic tract. The immediately subjacent beta-nucleus receives vertical vestibular information mediated by a GABAergic pathway originating from the ipsilateral descending and medial vestibular nuclei. None of the transmitters to the dorsal cap have been identified. Using choline acetyltransferase (ChAT) immunohistochemistry, we have identified a cholinergic pathway that terminates exclusively in the dorsal cap of rats and monkeys. No other division of the inferior olive received a significant cholinergic innervation. In the rabbit, immunostaining for ChAT reveals a weaker and more diffuse cholinergic innervation of both the dorsal cap and the subjacent beta-nucleus. In rats and rabbits we injected iontophoretically the orthograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L) into the medial and descending vestibular nuclei (MVN, DVN) as well as the nucleus prepositus hypoglossi (NPH) in order to trace the possible origin of the cholinergic projection. PHA-L injections into the NPH and medial aspect of the MVN labeled terminals within the contralateral dorsal cap. PHA-L injections in the central and lateral aspects of the MVN as well as the DVN labeled the ipsilateral beta-nucleus. Pressure injections of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) in the caudal dorsal cap of the rabbit inferior olive demonstrated a predominantly contralateral projection to the dorsal cap from the lateral aspect of the NPH. However, pressure injections of HRP into the caudal dorsal cap combined with ChAT immunohistochemistry in the rabbit demonstrated that most of the neurons of the NPH that projected to the dorsal cap were not cholinergic, and that most of the ChAT-positive neurons within the NPH occupied a more ventral location than the neurons within the NPH that were retrogradely labeled from the HRP injection into the contralateral dorsal cap. In the rat, we made lesions in the MVN, DVN and NPH by injection of ibotenic acid (0.3-0.5 microliter), in an attempt to deplete the dorsal cap of the inferior olive of its cholinergic input. Lesions confined to the NPH and medial aspect of the MVN of the rat caused a loss of ChAT staining in the contralateral dorsal cap. Lesions placed more laterally within the MVN or DVN failed to deplete ChAT-positive terminals in the contralateral or ipsilateral dorsal caps. The dorsal cap of the rat and monkey receives a discrete cholinergic projection.(ABSTRACT TRUNCATED AT 400 WORDS)

A neurotrophic activity of adult monkey and bovine interphotoreceptor matrix (IPM) was examined by using cultured human Y79 retinoblastoma cells as a model system. The cells were stimulated for 7 days in suspension culture with soluble IPM components and then attached to poly-D-lysine substratum. IPMs from both species induced greater than 80% neuronal differentiation of Y79 cell aggregates after 11 days of attachment as adjudged morphologically by the extension of lengthy, neurite-like processes. Immunocytochemical studies indicate that differentiated Y79 cells had an increased level of expression of neuron-specific enolase and a concomitant decreased expression of glial fibrillary acidic protein. This neurotrophic activity cannot be ascribed to nerve growth factor, platelet-derived growth factor, fibroblast growth factor, epidermal growth factor, or transforming growth factor beta. Although the nature of the factor and its cellular source have yet to be characterized, it may be related to a recently described neurotrophic protein secreted by human fetal retinal pigment epithelial cells in culture. Our findings provide evidence supporting the neuroblastic potential of the Y79 cell line and indicate that the IPM contains a potent neurotrophic activity. Such factors may be important to normal differentiation and maintenance of function of the neural retina.

The utilization of dopamine in the adult human retina was examined by using high-affinity uptake, localization, synthesis, and release as neurotransmitter-specific physiological probes. Autoradiographic and histochemical studies have shown that dopamine-accumulating and dopamine-containing cells of the human retina belong to a population of neurons whose somata are located in the proximal regional of the inner nuclear layer. Some of these are amacrine cells which are pre- and postsynaptic to other amacrine cells exclusively in the inner plexiform layer. However, evidence is presented which indicates the existence of interplexiform dopaminergic neurons which send processes to both plexiform layers of the retina. These neurons contain a high concentration of dopamine, take up 3H-dopamine by a hig-affinity mechanism, and release endogenous or accumulated dopamine by a Ca2+-dependent mechanism upon depolarization with high extracellular K+. An endogeneous level of about 20 pmoles dopamine per mg protein was measured in freshly isolated retina using high-pressure liquid chromatography with electrochemical detection. These results demonstrate that mechanisms for dopaminergic neurotransmission are present in the human retina.

Estrogen is concentrated within cellular nuclei in discrete regions of the monkey brain 30 and 60 minutes following intravenous injection of [3H] estradiol. Chromatographic data is provided to suggest that most of the localized estrogen is in the form of estradiol with lesser amounts of estrone and estriol. Three "major" areas of estrogen accumulation include: (1) preopticostrial accumulation: n. preopticus medialis--n. interstitialis striae terminalis, (2) basal hypothalamic accumulation: n. infundibularis--n. ventromedialis--n. premammillaris ventralis, and (3) the amygdaloid accumulation. Several "minor" areas of estrogen accumulation include the tuberculum olfactorium, insulae Calleja, n. triangularis septi, a. hypothalamica anterior, n. anterior hypothalami, n. paraventricularis, n. supraopticus, n. periventricularis and the substantia grisea centralis. The neocortex, rhombencephalon and spinal cord are essentially unlabeled. The major areas of accumulation are similar in several other mammalian and avian species while these, and some minor areas of accumulation, have been shown in neuroanatomical studies to be interconnected by several pathways, especially the stria terminalis. Lesion, implant, stimulation, recording and morphometric studies, in several species, support the concept that this arrangement provides a neuroanatomical substrate which would allow the integration of the various facets of the neuroendocrine reproductive response.