Localization of the KCC4 potassium-chloride cotransporter in the nervous system

Potassium-chloride cotransporters (KCCs) collectively play a crucial role in the function and development of both the peripheral and central nervous systems. KCC4 is perhaps the least abundant KCC in the adult mammalian brain, where its localization is unknown. In the embryonic brain, KCC4 mRNA is found in the periventricular zone, cranial nerves and choroid plexus [Eur J Neurosci 16 (2002) 2358]. To investigate the distribution of KCC4 protein in the nervous system we developed a rabbit polyclonal antibody directed against a short N-terminal peptide. Western blot analysis of brain microsomal protein using purified antibody revealed the presence of a band at approximately 145 kDa, consistent with the size of a glycosylated K-Cl cotransporter. Western blot analysis of brain, spinal cord and peripheral nerves revealed high expression levels in peripheral nerves and spinal cord, with low levels in whole brain. Within the brain, the cerebral cortex, hippocampus, and cerebellum revealed minimal KCC4 expression, whereas midbrain and brainstem demonstrated higher levels. In the adult mouse brain, KCC4 staining was observed on the apical membrane of choroid plexus epithelial cells as well as in cranial nerves. All other brain structures, e.g. cortex, hippocampus, cerebellum showed no KCC4 immunoreactivity, suggesting very low or absent expression of the cotransporter in these regions. Co-staining of KCC4 with anti-MAP2, GFAP and CNPase revealed that KCC4 is expressed in peripheral neurons. Thus, KCC4 is expressed on the apical membrane of the choroid plexus, where it likely participates to K(+) reabsorption. KCC4 is also expressed in peripheral neurons, where its function remains to be determined.     

Distribution of gephyrin in the human brain: an immunohistochemical analysis

Gephyrin is an ubiquitously expressed protein that, in the central nervous system, generates a protein scaffold to anchor inhibitory neurotransmitter receptors in the postsynaptic membrane. It was first identified as a protein component of the glycine receptor complex. Recent studies have demonstrated that gephyrin is colocalized with several subtypes of GABA(A) receptors and is part of postsynaptic GABA(A) receptor clusters. Here, we describe a study of the regional and cellular distribution of gephyrin in the human brain, determined by immunohistochemical localisation at the light and confocal laser scanning microscopic levels. At the regional level, gephyrin immunoreactivity was observed in most of the major brain regions examined. The most intense staining was in the cerebral cortex, hippocampus and caudate-putamen, in various brainstem nuclei with more moderate levels in the thalamus and cerebellum. At the cellular level gephyrin immunoreactivity was present on the plasma membranes of the soma and dendrites of pyramidal neurons throughout the various cortical regions examined. In the hippocampus, intense staining was observed on the granule cells of the dentate gyrus, and neurons of the CA1 and CA3 regions showed intense punctate gephyrin staining on their apical dendrites and cell bodies. Gephyrin immunoreactivity was also observed on neurons in the thalamus, globus pallidus and substantia nigra. In the putamen intense labelling of the striosomes was observed; most of the medium-sized neurons in the caudate-putamen were weakly labelled and many large neurons of the striatum were conspicuously stained. Many of the brainstem nuclei, notably the dorsal motor nucleus of the vagus, hypoglossal nucleus, trigeminal nucleus and inferior olive were all labelled with gephyrin. The spinal cord also showed high levels of gephyrin immunoreactivity. Our results demonstrate that the anchoring protein gephyrin is ubiquitously present in the human brain. We therefore suggest that gephyrin may have a central organizer role in assembling and stabilizing inhibitory postsynaptic membranes in human brain and is similar in function to those observed in the rodent brain. These findings contribute towards elucidating the role of gephyrin in the human brain.     

Immunohistochemical localization of protein-O-carboxylmethyltransferase in rat brain neurons

The distribution of the enzyme protein-O-carboxylmethyltransferase (EC 2.1.1.24) has been investigated in the rat brain using both immunohistochemical and biochemical techniques. The enzyme, which carboxylmethylates free aspartic and glutamic acid residues of protein substrates, was localized in neurons, but not other cell types throughout the brain. The highest immunoreactivity was detected throughout the cortex, followed by the hippocampus, the corpus striatum, the thalamus and the amygdala. Immunoreactive cells were detected in other brain regions but were not as prominent as those regions listed above. The distribution of immunoreactivity in the hippocampus was most striking, with considerable labelling of the pyramidal and granule cells in all regions. Numerous pyramidal cells were labelled in the cerebral cortex, with some ascending processes exhibiting immunoreactivity. The corpus striatum was uniformly labelled, suggesting that the enzyme was not localized to any specific neurotransmitter system. The antisera employed in this study was generated against purified bovine brain protein-O-carboxylmethyltransferase and Western immunoblot analysis showed cross reactivity against both rat brain and human erythrocyte forms of the enzyme. Enzyme activity and methyl acceptor protein capacity were examined in 1.5 mm coronal sections of rat brain. The regions with highest enzyme activities were found in cross-sections containing cortex and corpus striatum or cortex and hippocampus. The lowest enzyme activities were noted in slices of brainstem and cerebellum, areas exhibiting low amounts of immunoreactive protein-O-carboxylmethyltransferase. Methyl acceptor protein capacity was highest in slices of cortex and corpus striatum, cortex and hippocampus and was lowest in slices of brainstem and cerebellum. These results demonstrate that protein-O-carboxylmethyltransferase has an unique neuronal pattern of distribution in the rodent central nervous system, and suggest that the carboxylmethylation of proteins may be of functional significance in these neurons.     

Kv3.1和Kv3.2钾离子通道蛋白在大鼠神经系统的分布

本研究用免疫组织化学方法观察了Kv3.1和Kv3.2钾离子通道蛋白在大鼠神经系统的分布状况。结果显示,两种蛋白在神经系统内具有区域性的分布特点。Kv3.1免疫阳性神经元主要见于大脑皮层、海马锥体细胞层、纹状体、丘脑网状核、下丘脑、腹侧耳蜗核、桥核等脑区;Kv3.2阳性神经元主要分布于大脑皮层深层、海马始层、Calleja岛、外侧丘系腹侧核、背侧耳蜗核、小脑皮层Purkinje细胞层、前庭核等处。Kv3.1和Kv3.2阳性胞体在某些脑区如大脑皮层、海马、耳蜗核、外侧丘系核等处呈现"互补"性的分布特点。另外,在一些脑区还观察到了Kv3.1和Kv3.2免疫阳性纤维和终末。:Kv3.1和Kv3.2在神经系统内广泛的分布,提示它们可能参与了多种生理功能。     

Distribution of the high-affinity choline transporter in the central nervous system of the rat

In cholinergic nerve terminals, Na(+)- and Cl(-)-dependent, hemicholinium-3-sensitive, high-affinity choline uptake is thought to be the rate-limiting step in acetylcholine synthesis. The high-affinity choline transporter cDNA responsible for the activity was recently cloned. Here we report production of a highly specific antibody to the high-affinity choline transporter and distribution of the protein in the CNS of the rat. The antibody stained almost all known cholinergic neurons and their terminal fields. High-affinity choline transporter-immunoreactive cell bodies were demonstrated in the olfactory tubercle, basal forebrain complex, striatum, mesopontine complex, medial habenula, cranial nerve motor nuclei, and ventral horn and intermediate zone of the spinal cord. Noticeably, high densities of high-affinity choline transporter-positive axonal fibers and puncta were encountered in many brain regions such as cerebral cortex, hippocampus, amygdala, striatum, several thalamic nuclei, and brainstem. Transection of the hypoglossal nerve resulted in a loss of high-affinity choline transporter immunoreactivity in neurons within the ipsilateral hypoglossal motor nucleus, which paralleled a loss of immunoreactivity to choline acetyltransferase. The antibody also stained brain sections from human and mouse, suggesting cross-reactivity.These results confirm that the high-affinity choline transporter is uniquely expressed in cholinergic neurons and is efficiently transported to axon terminals. The antibody will be useful to investigate possible changes in cholinergic cell bodies and axon terminals in human and rodents under various pathological conditions.     

Effects of hypoxia on expression of transforming growth factor-beta1 and its receptors I and II in the amoeboid microglial cells and murine BV-2 cells

Transforming growth factor-beta1 (TGF-beta1) is widely recognized as a prototype of multifunctional growth factors and master switches in the regulation of key events of development, disease and repair. It is localized in neurons, astrocytes and brain macrophages in altered conditions but its localization in the amoeboid microglial cells (AMC), a nascent brain macrophage in the developing brain has remained unexplored. Here we report expression of TGF-beta1 and its receptors namely, transforming growth factor-beta receptor I (TbetaRI) and transforming growth factor-beta receptor II (TbetaRII) in AMC and BV-2 cells induced by hypoxia. Firstly, increase in TGF-beta1 mRNA expression and TGF-beta1 release was observed in the corpus callosum in postnatal rats subjected to a single hypoxic exposure. RT-PCR and Western blot analysis revealed a concomitant upregulation of TbetaRI and TbetaRII mRNA and protein. Secondly, immunofluorescence labeling showed that the preponderant AMC in the corpus callosum were immunoreactive for TGF-beta1 and its receptors. In rats subjected to hypoxia, immunoexpression of TGF-beta1 and both receptors was markedly enhanced. In longer surviving rats, the AMC transformed into ramified microglia but retained in them the immunoreactivity. In BV-2 cells exposed to hypoxia, TGF-beta1 mRNA expression and release of TGF-beta1 into the medium were significantly increased. It is noteworthy that expression of TbetaRI and TbetaRII mRNA and protein in hypoxic BV-2 cells was reduced indicating a differential response of AMC and BV-2 cells to hypoxia. Notwithstanding, it is unequivocal that AMC in the developing brain express and release TGF-beta1 into the ambient environment. We suggest that this may be a mechanism to help autoregulate microglial activation in adverse conditions via its receptors.     

In Memoriam Rita Levi-Montalcini (1909–2012)

Abstract

The localization of acidic fibroblast growth factor (aFGF) in the male mouse brain was studied with biochemical and immunocytochemical techniques. Using two peptide-based aFGF antisera directed against independent epitopes, Western gel analysis of dissected brain demonstrated significant levels of aFGF immunoreactivity in the pons-medulla, hypothalamus and cerebellum. The cortex contained much less immunoreactivity. Consistent with the biochemical data, immunocytochemical analysis with the same two antisera demonstrated that aFGF immunoreactivity is localized in neuronal cell bodies in these regions. Numerous immunoreactive neurons were observed in the reticular formation of the pons and medulla, as well as in several other brainstem nuclei and areas. Immunoreactive neurons were also present in the lateral and medial hypothalamus, and some thalamic, subthalamic and epithalamic nuclei. In the basal ganglia, immunoreactive neurons were present in the amygdala and septum. Few intensely stained immunoreactive neurons were observed in the striatum, pallidum and neocortex. Limbic cortices contained more numerous immunoreactive neurons than neocortex. These results support the concept that aFGF is present in the brain, where it is heterogeneously distributed in neuronal cell bodies in regions involved in sensory, extrapyramidal motor, limbic and autonomic functions. The results are consistent with various neurotrophic, autogenic, and neuromodulatory functions associated with aFGF in the mammalian central nervous system.     

Transforming growth factor-beta1 induces transforming growth factor-beta1 and transforming growth factor-beta receptor messenger RNAs and reduces complement C1qB messenger RNA in rat brain microglia

Transforming growth factor-beta1 is a multifunctional peptide with increased expression during Alzheimer's disease and other neurodegenerative conditions which involve inflammatory mechanisms. We examined the autoregulation of transforming growth factor-beta1 and transforming growth factor-beta receptors and the effects of transforming growth factor-beta1 on complement C1q in brains of adult Fischer 344 male rats and in primary glial cultures. Perforant path transection by entorhinal cortex lesioning was used as a model for the hippocampal deafferentation of Alzheimer's disease. In the hippocampus ipsilateral to the lesion, transforming growth factor-beta1 peptide was increased >100-fold; the messenger RNAs encoding transforming growth factor-beta1, transforming growth factor-beta type I and type II receptors were also increased, but to a smaller degree. In this acute lesion paradigm, microglia are the main cell type containing transforming growth factor-beta1, transforming growth factor-beta type I and II receptor messenger RNAs, shown by immunocytochemistry in combination with in situ hybridization. Autoregulation of the transforming growth factor-beta1 system was examined by intraventricular infusion of transforming growth factor-beta1 peptide, which increased hippocampal transforming growth factor-beta1 messenger RNA levels in a dose-dependent fashion. Similarly, transforming growth factor-beta1 increased levels of transforming growth factor-beta1 messenger RNA and transforming growth factor-beta type II receptor messenger RNA (IC(50), 5pM) and increased release of transforming growth factor-beta1 peptide from primary microglia cultures. Interactions of transforming growth factor-beta1 with complement system gene expression are also indicated, because transforming growth factor-beta1 decreased C1qB messenger RNA in the cortex and hippocampus, after intraventricular infusion, and in cultured glia. These indications of autocrine regulation of transforming growth factor-beta1 in the rodent brain support a major role of microglia in neural activities of transforming growth factor-beta1 and give a new link between transforming growth factor-beta1 and the complement system. The auto-induction of the transforming growth factor-beta1 system has implications for transgenic mice that overexpress transforming growth factor-beta1 in brain cells and for its potential role in amyloidogenesis.     

NGF在成年猴脑的分布

为了解NGF在成年猴脑的分布,采用免疫组化SP法对成年猴脑多个冠状位切片进行免疫组化反应。结果证明,NGF阳性反应神经元主要分布于大脑皮质Ⅲ、V层,小脑Purkinje细胞,海马,齿状回,纹状体,脑干网状结构等处。此外,在黑质、舌下神经核、迷走神经背核、前庭神经核、三叉神经核、疑核、下橄榄核也出现NGF阳性反应。在大脑和脑干还观察到NGF阳性胶质细胞。本实验结果表明,在成年猴脑的多个脑区有NGF表达,提示NGF可能涉及猴脑某些神经元及胶质细胞的生理过程。     

Localization of neuroglobin protein in the mouse brain

Neuroglobin is a recently discovered vertebrate oxygen-binding respiratory protein. In situ hybridization data demonstrated that neuroglobin-mRNA is widely expressed in neuronal cells of the central and peripheral nervous systems as well as in endocrine cells. The present study was conducted to investigate the presence of neuroglobin protein in neurons of the mouse brain. A polyclonal antibody directed against a synthetic peptide of neuroglobin was raised in rabbits and affinity-purified. The specificity of the antibody was demonstrated by ELISA and preabsorption tests. We report here for the first time that neuroglobin is expressed on the protein level in many brain sites including cerebral cortical regions, subcortical structures such as thalamus and hypothalamus, nuclei of cranial nerves in the brainstem and cerebellum. Thus, the widespread distribution of neuroglobin protein is in good agreement with its mRNA localization. Regionally differing intensities of immunostaining suggest different levels of neuroglobin protein expression, in line with the idea that brain regions show variation in their tolerance towards hypoxic conditions.     

神经激肽B受体在小鼠中枢神经系统内的定位分布

目的　研究神经激肽B受体 (NK3)在小鼠中枢神经系统内的定位分布。　方法　免疫组织化学染色。　结果　在小鼠中枢神经系统的绝大部分区域 ,NK3受体样免疫反应产物位于胞体和树突上 ,少部分区域位于神经毡 (neuropil)内。大量NK3受体样免疫反应神经元出现于前嗅核、伏隔核、隔区、腹侧苍白球、苍白球、尾壳核、终纹床核、下丘脑前区、下丘脑结节区、下丘脑外侧区、穹隆周区、视上核、弓状核、乳头体、黑质、腹侧被盖区、红核后区、上丘和下丘、导水管周围灰质、孤束核、及延髓和脊髓背角浅层。大脑皮质的浅层、梨状皮质、背侧海马、杏仁核、脑干网状结构等核团内也含有一定数量的阳性神经元。在丘脑的中线核团和板内核、腹侧海马和脚间核等处 ,NK3受体免疫反应产物主要位于神经毡内。　结论　NK3受体广泛分布于小鼠中枢神经系统内 ,提示它可能具有重要的生理功能     

Topographical gradient in expression of R2D5 antigen in superior olivary nuclei and hippocampal dentate gyrus of the cat.

An immunohistochemical analysis of the cat central nervous system revealed that a monoclonal antibody which recognizes a soluble cytosolic protein, R2D5, bound two regions in a prominent spatial gradient. In the medial and lateral superior olivary nuclei of the brainstem, R2D5 immunoreactivity appeared as a gradient across a population of topographically ordered principal neurons. The spatial gradient corresponded to the tonotopic organization in the superior olivary nuclei: i.e., R2D5 immunoreactivity tended to occur more frequently and intensely in low-frequency neurons than in high-frequency neurons. Granule cells in the hippocampal dentate gyrus also had a pronounced spatial gradient in R2D5 immunoreactivity expression, and this gradient corresponded to the septotemporal axis of the hippocampus. Granule cells of the temporal (ventral) portions of the hippocampus were labeled intensely with R2D5 antibody, while those located in progressively more septal (dorsal) portions had gradually less immunoreactivity. These results suggest that in both the superior olivary nuclei and the hippocampal dentate gyrus, neurons differ in intrinsic properties by their position along specific axes. They suggest also that the hippocampus has an intrinsic functional organization related to the spatial gradient along its septotemporal axis.     

Localization and modulation of calcitonin gene-related peptide-receptor component protein-immunoreactive cells in the rat central and peripheral nervous systems

Calcitonin gene-related peptide (CGRP) is widely distributed in the central and peripheral nervous system. Its highly diverse biological activities are mediated via the G protein-coupled receptor that uniquely requires two accessory proteins for optimal function. CGRP receptor component protein (RCP) is a coupling protein necessary for CGRP-receptor signaling. In this study, we established the anatomical distribution of RCP in the rat central and peripheral nervous system and its relationship to CGRP immunoreactivity. RCP-immunoreactive (IR) perikarya are widely and selectively distributed in the cerebral cortex, septal nuclei, hippocampus, various hypothalamic nuclei, amygdala, nucleus colliculus, periaqueductal gray, parabrachial nuclei, locus coeruleus, cochlear nuclei, dorsal raphe nuclei, the solitary tractus nucleus and gracile nucleus, cerebellar cortex, various brainstem motor nuclei, the spinal dorsal and ventral horns. A sub-population of neurons in the dorsal root ganglia (DRG) and trigeminal ganglia were strongly RCP-IR. Overall, the localization of RCP-IR closely matched with that of CGRP-IR. We also determined whether RCP in DRG and dorsal horn neurons can be modulated by CGRP receptor blockade and pain-related pathological stimuli. The intrathecal injection of the antagonist CGRP(8-37) markedly increased RCP expression in the lumbar DRG and spinal dorsal horn. Carrageenan-induced plantar inflammation produced a dramatic bilateral increase in RCP expression in the dorsal horn while a partial sciatic nerve ligation reduced RCP expression in the ipsilateral superficial dorsal horn. Our data suggest that the distribution of RCP immunoreactivity is closely matched with CGRP immunoreactivity in most of central and peripheral nervous systems. The co-localization of RCP and CGRP in motoneurons and primary sensory neurons suggests that CGRP has an autocrine or paracrine effect on these neurons. Moreover, our data also suggest that RCP expression in DRG and spinal cord can be modulated during CGRP receptor blockade, inflammation or neuropathic pain and this CGRP receptor-associated protein is dynamically regulated.     

Transforming growth factor-beta, but not ciliary neurotrophic factor, inhibits DNA synthesis of adrenal medullary cells in vitro

Transforming growth factor-betas are members of a superfamily of multifunctional cytokines regulating cell growth and differentiation. Their functions in neural and endocrine cells are not well understood. We show here that transforming growth factor-betas are synthesized, stored and released by the neuroendocrine chromaffin cells, which also express the transforming growth factor-beta receptor type II. In contrast to the developmentally related sympathetic neurons, chromaffin cells continue to proliferate throughout postnatal life. Using 5-bromo-2'-deoxyuridine pulse labeling and tyrosine hydroxylase immunocytochemistry as a marker for young postnatal rat chromaffin cells, we show that treatment with fibroblast growth factor-2 (1 nM) and insulin-like growth factor-II (10 nM) increased the fraction of 5-bromo-2'-deoxyuridine-labeled nuclei from 1% to about 40% of the cells in the absence of serum. In the presence of fibroblast growth factor-2 and insulin-like growth factor-II, transforming growth factor-beta1 (0.08 nM) reduced 5-bromo-2'-deoxyuridine labeling by about 50%, without interfering with chromaffin cell survival or death. Doses lower and higher than 0.08 nM were less effective. Similar effects were seen with transforming growth factor-beta3. In contrast to transforming growth factor-beta, ciliary neurotrophic factor, which inhibits proliferation of sympathetic progenitor cells, was not effective on rat chromaffin cells from postnatal day 6. Glucocorticoids also suppress DNA synthesis in fibroblast growth factor-2/insulin-like growth factor-II-treated chromaffin cells. This effect was not mediated by chromaffin cell-derived transforming growth factor-beta, as shown by addition of neutralizing antibodies. We conclude that one function of adrenal medullary transforming growth factor-beta may be to act as a negative regulator of chromaffin cell division.     

A novel member to the family of perineuronal antigens associated with subpopulatios of central neurons in the rat

Summary We reported earlier that monoclonal antibodies (MAbs) 473 and 376 gave perineuronal staining of different subsets of central neurons, and that both immunoreactivities were labile to treatment with chondroitinase ABC. On the other hand, MAb 1B5, the immunoreactivity to which is uncovered by chondroitinase ABC, stained a neuronal subset that included neurons positive to MAbs 473 and 376 (Fujita et al. 1989). We now report a new antibody, MAb 374, that stained perimeter of neurons of a subset different from those stained by MAbs 473, 376 and 1B5. In the rat central nervous system MAb 374-positive cells were found in the neocortex, thalamic reticular nucleus, hippocampus, cerebellar cortex and nuclei, and in the brain stem. MAb 374-immunoreactive neuropil was found in the medial habenular, arcuate, dorsal endopiriform nuclei, and the two plexiform layers of the retina. The immunoreactivity was not affected by treatment with chondroitinase ABC. Immunoblot experiments using a rat brain homogenate revealed a specific band at a position corresponding to a molecular weight of 600 kD.     

Immunocytochemical evidence for the involvement of glycine in sensory centers of the rat brain.

Glycine-like immunoreactivity was localized to a number of sites in the rat brain which are involved in processing sensory information. In the auditory and vestibular systems, glycine immunoreactivity was seen in dorsal and ventral cochlear nuclei, superior olive, trapezoid body, medial and lateral vestibular nuclei, and inferior colliculus. Staining in the visual system was seen in retina, dorsal lateral geniculate nucleus, and superior colliculus. The olfactory system exhibited staining in the olfactory bulb and accessory olfactory formation. Somatosensory centers with glycine immunoreactivity included the dorsal column nuclei, spinal trigeminal nucleus, principal sensory nucleus of V, reticular formation, and periaqueductal gray. Glycine-immunoreactive neurons were also seen in cerebellar cortex, deep cerebellar nuclei, hippocampus, cerebral cortex, and striatum. The distribution of staining indicates that glycine plays a major role in sensory centers with actions at both strychnine-sensitive and strychnine-insensitive receptors.     

Molecular cloning of rat trkC and distribution of cells expressing messenger RNAs for members of the trk family in the rat central nervous system.

Tyrosine protein kinases trk, trkB and trkC are signal-transducing receptors for the neurotrophins nerve growth factor, brain-derived nerve growth factor, neurotrophin-3 and neurotrophin-4. Here we report on the isolation of cDNA fragments encoding a part of rat trk and trkB proteins, respectively, and characterization of a full-length cDNA clone encoding rat trkC. Cells expressing mRNAs for the different members of the trk family were identified in the rat central nervous system by in situ hybridization using oligonucleotide probes designed from the isolated cDNA sequences and complementary to mRNA sequences coding for the extracellular region of the receptors. The expression of trk mRNA was found to be restricted to neurons of the basal forebrain, caudate-putamen with features of cholinergic cells and to magnocellular neurons of several brainstem nuclei. In contrast, cells expressing trkB and trkC mRNAs were widely distributed in the brain. Areas expressing high levels of trkB or trkC mRNAs included olfactory formations, neocortex, hippocampus, thalamic and hypothalamic nuclei, brainstem nuclei, cerebellum and spinal cord motoneurons. A similar distribution for trkB and trkC mRNAs was shown in most areas but each probe specific for these mRNAs also provided distinct labeling patterns in different subregions, layers and cells. Comparison between our data and previous analyses of cells expressing mRNAs for neurotrophins and the low-affinity nerve growth factor receptor suggests that different modes of action and different combinations of receptors mediate biological responses to neurotrophins in the adult rat brain.     

The localization and distribution of high affinity beta-nerve growth factor binding sites in the central nervous system of the adult rat. A light microscopic autoradiographic study using [125I]beta-nerve growth factor

Although beta-nerve growth factor is primarily known for its trophic role in the peripheral nervous system, recent reports have also revealed an inductive effect of beta-nerve growth factor on the cholinergic metabolism of the forebrain. To learn more about the significance and location of beta-nerve growth factor action in the central nervous system, the distribution of [125I]beta-nerve growth factor binding sites was studied by using the method of in situ receptor autoradiography and compared with the distribution of acetylcholinesterase, a sensitive enzyme marker of cholinergic neurons. The autoradiographic studies demonstrated strong, specific and saturable [125I]beta-nerve growth factor binding to several neuronal groupings in the forebrain and brainstem. beta-Nerve growth factor binding sites and strong acetylcholinesterase reactivity were jointly distributed in the forebrain on the medial septal nucleus, the diagonal band of Broca, the magnocellular basal nucleus and in the striatum. In the brainstem, beta-nerve growth factor binding sites were located on a number of neuronal groups in the reticular formation, the dorsolateral lemniscus and the cochlear nuclei. In contrast to the forebrain, less correlation was found with the distribution of acetylcholinesterase; no beta-nerve growth factor receptor expression was recorded on the cholinergic motor nuclei of the brainstem, while specific [125I]beta-nerve growth factor labeling could be located on the non-cholinergic cochlear nuclei. The present autoradiographic studies reveal a variety of tentatively beta-nerve growth factor receptor-positive neurons in the central nervous system. While strong correlation between the cholinergic metabolism and the presence of specific beta-nerve growth factor binding is demonstrated in the forebrain, this observation could not be extended to the brainstem, indicating the chemical diversity of central beta-nerve growth factor receptor-positive neurons.