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PubMed1982

Acute subcortical lesions modify cortical muscarinic receptors in human brain.

Post-mortem determinations of muscarinic cholinergic receptor parameters by means of binding procedures were carried out in human brains. In patients who died from internal capsule stroke a significant increase in cortical (Brodmann area 8) muscarinic receptor density was present when compared to non-neurological controls. No significant changes were detected in cortical choline acetyltransferase. Subcortical structures such as thalamus and caudate nucleus seemed to undergo opposite effects. It is suggested that acute interruption of fibers ascending to the cortex from subcortical areas can alter muscarinic receptor properties in the cerebral cortex.

Aged↗
PubMed1988

Immunohistochemical localization of cytochrome P-450 in the rat brain.

Immunohistochemical localization of cytochrome P-450 in the brains of normal untreated male rats has been demonstrated with polyclonal antibodies raised against hepatic P-450C. These antibodies recognize P-450C and D, two closely related forms of P-450. We have identified P-450C,D immunoreactivity (P-450C,D-i) within both neurons and glial cells. Neuronal cell bodies showing P-450C,D-i were present in several forebrain areas, including the olfactory bulb, the caudate nucleus, the cingulate, the frontal and the entorhinal cortex, the hippocampus and the thalamus. In the brainstem, P-450C,D-i neurons were detected in the substantia nigra, the nucleus locus coeruleus, raphe nucleus, reticular formation and the trigeminal nerve nucleus and the dorsal motor nucleus of the vagus. Glial cells containing P-450C,D-i were situated within myelinated fiber tracts in the forebrain (e.g. the corpus callosum, the internal capsule) and the brainstem (e.g. the superior cerebellar peduncle, the medial longitudinal fasciculus). Some, but not all, of the P-450C,D-i glial cells also stained with an antibody against glial fibrillary acidic protein. The present findings represent the first immunohistochemical demonstration of cytochrome P-450 in the brain and suggest that cytochrome P-450C,D is constitutive in neurons and glial cells of most brain regions throughout the rat neuraxis.

Animals↗
PubMed1988

An N-methyl-D-aspartate receptor mediated excitatory postsynaptic potential evoked in subthalamic neurons in an in vitro slice preparation of the rat.

Subthalamic (STH) neurons with slow EPSPs mediated by an N-methyl-D-aspartate (NMDA) receptor were studied in rat brain slice preparation. When STH neurons were intracellularly recorded with KCl-filled electrodes, stimulation of the internal capsule (IC) evoked a short duration depolarization followed by a slow excitatory postsynaptic potential (EPSP) lasting 100-200 ms. The amplitude of the slow EPSP was increased when the neuron was hyperpolarized by a low intensity current injection but was blocked when it was hyperpolarized with strong current. The slow EPSP was reversibly suppressed by application of 30-50 microM DL-2-amino-5-phosphonovareric acid (APV). STH neurons also were recorded, with potassium methylsulfate filled electrodes, in the slice preparation obtained from rats that received chronic knife cuts of the IC at the level of the entopeduncular nucleus. Stimulation of the IC immediately rostral to the STH evoked a fast EPSP followed by a slow EPSP, and IPSPs were largely eliminated in this preparation. The slow EPSP was augmented in MG-free medium and suppressed by 50 microM APV. These results suggest that NMDA receptor mediating slow EPSPs may regulate activities of STH neurons.

2-Amino-5-phosphonovalerate↗
PubMed1992

Localization of interleukin 6 mRNA and interleukin 6 receptor mRNA in rat brain.

The cytokine interleukin 6 (IL6) has several effects on the central nervous system in addition to the well established regulation of the acute phase inflammatory response. Therefore, the distribution of IL6- and IL6 receptor mRNA in the rat brain has been investigated by in situ hybridization using [35S]-labeled oligonucleotides. The messages of both genes were found in the CA1-CA4 regions as well as in the dentate gyrus of the hippocampus, in the habenulae, the dorsomedial and the ventromedial hypothalamus, in the internal capsule, the optic tract and in the piriform cortex. These data indicate both neuronal and glial localization of IL6 and IL6 receptor and their involvement in an autocrine or paracrine action of the cytokine in centrally regulated functions including neuroendocrine control.

Animals↗
PubMed1984

Thalamic relay nucleus stimulation for relief of intractable pain. Clinical results and beta-endorphin immunoreactivity in the cerebrospinal fluid.

Deep brain stimulation (thalamic relay nucleus, periaqueductal gray and internal capsule) was applied to various cases of intractable pain, and the resulting degree of pain reduction and alteration in beta-endorphin immunoreactivity in the cerebrospinal fluid (CSF) were compared. The following results were obtained. (1) The studies on intractable pain revealed that the levels of beta-endorphin immunoreactivity in the CSF were lower than those in the control group. (2) Thalamic relay nucleus stimulation proved effective not only for deafferentiation pain, but also for somatogenic pain. No relationship was, however, noted between pain reduction and the rate of increase of beta-endorphin immunoreactivity in the CSF. (3) The incidence of stimulation tolerance following prolonged stimulation of the thalamic relay nucleus can be reduced to a minimum by administration of L-DOPA. It is concluded that the increase in beta-endorphin in the CSF is not the direct and major cause of pain reduction during treatment by thalamic relay nucleus stimulation. It may be assumed that neuronal facilitation on the monoaminergic descending pain inhibitory system plays a role in reducing pain.

Adult↗
PubMed1988

Disappearance of phantom pain after focal brain infarction.

A patient with hemiplegia and hemihypoesthesia is presented in whom preexisting phantom limb pain disappeared with the appearance of a stroke localized by CT scan to the posterior internal capsule. Differentiation between the cutaneous sensation and the sensation of phantom limb pain that appeared later seems to support the assumed existence of a polysynaptic sensory pathway that conveys the sensations of deafferentation.

Aged↗
PubMed1988

Stimulation-produced analgesia (SPA) from brain-stem and diencephalic sites in the rat: relationships between analgesia, aversion, seizures and catalepsy.

Electrical stimulation of dorsal and dorsolateral periaqueductal gray (PAG) and internal capsule (IC) sites in the rat elicited tail flick and formalin test stimulation-produced analgesia (SPA). SPA from PAG sites was associated with aversion. SPA from IC sites was associated with aversion, generalized seizures and catalepsy. Ventrobasal nucleus of thalamus (VB) stimulation did not elicit analgesia or aversion but did induce behavior characteristic of limbic seizures. A sub-anesthetic dose of sodium pentobarbital (20 mg/kg) suppressed IC stimulation-produced generalized seizures and catalepsy, and attenuated, but did not eliminate, tail flick test analgesia. These data suggest that SPA from IC sites in the rat is partially confounded with reduced responsivity. The hypothesis that SPA associated with aversion may represent a form of stress-induced analgesia is discussed.

Analgesia↗
PubMed1982

Cortical afferents of the nucleus accumbens in the cat, studied with anterograde and retrograde transport techniques.

The cortical afferentation of the nucleus accumbens in the cat was studied with the aid of retrograde tracing techniques. Retrograde experiments were carried out with horseradish peroxidase or one of the fluorescent tracers Bisbenzimid, Nuclear Yellow and Fast Blue. In the anterograde experiments [3H]leucine and [35S]methionine were used as tracers. Following injections in the nucleus accumbens, retrogradely-labelled cells were found in the medial frontal cortex, the anterior olfactory nucleus, the posterior part of the insular cortex, the endopiriform nucleus, the amygdalo-hippocampal area, the entorhinal and perirhinal cortices and the subiculum of the hippocampal formation. In the medial frontal cortex most of the labelled cells were found in layers III and V of the prelimbic area (area 32 of Brodmann), but retrogradely-filled neurons were also present in the infralimbic area and in the caudoventral part of the lateral bank of the proreal gyrus. Retrogradely-labelled cells in the entorhinal and perirhinal cortices were located in the deep cellular layers. Following large injections in the nucleus accumbens, retrograde labelling in the subiculum extended from the most dorsal, septal pole to the most ventral, temporal pole. Injections of anterograde tracers were placed in the frontal cortex, the entorhinal and perirhinal cortices and the hippocampal formation. The prelimbic area was found to project via the internal capsule to mainly the rostral half of the nucleus accumbens, whereas in the caudal half of the nucleus only a lateral region receives frontal cortical fibres. Following injections in the infralimbic area only fibres passing through the nucleus accumbens were labelled. Afferents from the entorhinal and perirhinal cortices reach the nucleus accumbens by way of the external capsule and terminate mainly in a ventral zone of the nucleus accumbens. Afferents from the entorhinal area are distributed to the entire accumbens, whereas the termination field of the perirhinal afferents is largely restricted to the lateral part of the nucleus accumbens. Both the frontal cortex and the entorhinal and perirhinal cortices appear to project also to the nucleus caudatus and the tuberculum olfactorium. These cortical areas also project to the contralateral striatum. Both anterograde and retrograde tracing experiments demonstrated a topographical relationship between the subiculum and the nucleus accumbens. The ventral pole of the subiculum projects via the fornix to the medial part of the caudal half of the nucleus accumbens and to a small dorsomedial area in its rostral half. Successively more dorsal portions in the subiculum project to successively more ventrolateral parts in the rostral nucleus accumbens. The projection from the hippocampus was found to extend also to the tuberculum olfactorium. The results of the present study do not provide unambiguous criteria for the delimitation of the nucleus accumbens in the cat.

Animals↗
PubMed1982

Morphological and physiological properties of neostriatal neurons: an intracellular horseradish peroxidase study in the rat.

The physiological and morphological (light and electron microscopic) properties of four categories of neostriatal neurons (two types of medium spiny cells and two types of aspiny cells) were analyzed using the technique of intracellular recording and intracellular labeling with horseradish peroxidase. All of the neurons in this study had excitatory responses following stimulation of the cortex and substantia nigra except for the large aspiny neuron for which only substantia nigra inputs were tested. Morphologically, these neurons differed with respect to the size and shape of their somata, density and distribution of dendritic spines and distribution of their axons and axon collaterals. Ultrastructurally, observed somatic differences included the quantity and distribution of organelles and conformation of the nuclear envelope. The axons of one type of medium spiny neuron and the large aspiny neuron were myelinated. Unmyelinated axon collaterals arose from the axons of both types of medium spiny neurons and formed synapses on the dendritic shafts and possibly with the necks of spines of other neostriatal neurons. The parent axons of the most common type of medium spiny neurons were followed to the globus pallidus and, in some cases, to the internal capsule.

Animals↗
PubMed1985

Bilateral corticosubthalamic nucleus projections: an electrophysiological study in rats with chronic cerebral lesions.

The present study sought to determine the distribution of the cortical areas giving rise to the corticosubthalamic nucleus projections, using extracellular stimulating and recording techniques in rats with and without chronic lesions. In acute rats, cortical stimulation induced a powerful excitation in 87% of the subthalamic nucleus cells recorded. This response was obtained from stimulation over a large extent of the cortex since nearly all the ipsilateral cortex and the rostral two-thirds of the contralateral side was found to influence the activity of the subthalamic nucleus neurones. An excitatory response quite similar to that induced by cortical stimulation was recorded in the subthalamic nucleus after striatal or internal capsule stimulations. Therefore in order to eliminate the possibility of recording a polysynaptic excitation, similar experiments were performed in rats bearing various chronic lesions. With either ipsilateral or contralateral cortical stimulations, there was no major consequence of these lesions on the type or characteristics of the response recorded or on the percentage of responding cells. The cortical origin of the excitation of the subthalamic neurones was further supported by the results of experiments performed in chronically decorticated rats. It is concluded that (1) the subthalamic nucleus receives an excitatory cortical input, (2) this control comes from ipsilateral and contralateral cortical areas and (3) it only involves direct corticosubthalamic nucleus fibres. The subthalamic nucleus is, together with the striatum, the only basal ganglia nucleus known to receive afferents from extensive regions of the cortex. By its two main afferents (cortex and external segment of the pallidum), the subthalamic nucleus is in a position to compare direct cortical informations with cortical informations processed at the striatopallidal complex level.

Animals↗
PubMed1986

Projections from the hypothalamus and its adjacent areas to the posterior pituitary in the rat.

Cholera toxin conjugated horseradish peroxidase was injected into the posterior pituitary and its afferents traced in 21 albino rats. The neuronal processes as well as the perikarya were elaborately displayed. The principal and retrochiasmatic supraoptic nuclei and the magnocellular paraventricular subnuclei were densely labelled. The accessory cell groups or nuclei labelled included: the medial preoptic and anterior hypothalamic areas, the anterior and posterior fornical nuclei, the lateral hypothalamic area, the nucleus circularis and nucleus of the forebrain bundle and hitherto unknown or not fully appreciated retrochiasmatic area, the dorsal accessory groups in an area between the stria medullaris and fornix, on the one hand, and the stria terminalis and internal capsule, on the other, and a well developed subependymalperiventricular zone. The medial preoptic nucleus, subfornical organ and organ vasculosum laminae terminalis were also weakly stained. Dendrites of the magnocellular paraventricular nucleus have been said by some to be largely confined to the subnuclei in which they lie. Immunohistochemical studies have proved that they extended beyond their nuclear confinement. The present study has found much wider extension of their dendritic fields. In fact, dendrites of the magnocellular neurosecretory cells in general were long and had a certain degree of directional bias. Several sites projecting to the posterior pituitary were closely related to the cerebrospinal fluid. Namely, the subependymal neuronal plexuses along the third ventricle and beneath the interventricular foramen, and the subpial dendritic plexuses of the supraoptic and retrochiasmatic supraoptic nuclei. Neurons were seen to squeeze in-between the ependymal cells, bringing themselves very close to the cerebrospinal fluid. No direct cerebrospinal fluid-contacting elements, either cell bodies or processes, however, could be ascertained. It is proposed that these plexuses may monitor changes in the cerebrospinal fluid. Besides the principal neurohypophysial tract the posterior pituitary was found in the present study to receive its afferents via two accessory fasciculi, one coursing in the medial forebrain bundle and the other running along the lateral wall of the infundibular recess subependymally.

Afferent Pathways↗
PubMed1987

Immunohistochemical localization of cytochrome P-450 in rat brain.

The presence of cytochrome P-450 in rat brain was studied by immunohistochemistry, using antibodies to cytochrome P-450 purified from livers of phenobarbital- or 3-methylcholanthrene-treated rats. Immunoreactive nerves were observed only in brain sections incubated with immunoglobulin-G to 3-methylcholanthrene-induced cytochrome P-450. This immunoreactivity was abolished by preabsorption of the antibody with highly purified rat liver cytochrome P-450c, the major cytochrome P-450 isozyme induced by 3-methylcholanthrene, but was not affected by other cytochrome P-450 isozymes induced by phenobarbital, isosafrole or pregnenolone-16 alpha-carbonitrile. The most abundant concentration of nerve fibers with cytochrome P-450 immunoreactivity was observed in the globus pallidus. Immunoreactive fibers were also observed in the caudate putamen, amygdala, septum, ventromedial nucleus of the hypothalamus, medial forebrain bundle, ansa lenticularis, and ventromedial portion of the internal capsule and crus cerebri. Cell bodies with cytochrome P-450 immunoreactivity were observed in the caudate putamen and in the perifornical area of the hypothalamus. The cytochrome P-450 immunoreactive fibers in the globus pallidus and caudate putamen do not appear to emanate from cell bodies in the substantia nigra, since there was no reduction in the density of these fibers after unilateral stereotaxic electrolytic destruction of the substantia nigra (zona compacta and reticulata). Our data suggest that these striatal nerve processes are derived from cell bodies within the caudate putamen itself. The present results indicate that rat brain contains a form of cytochrome P-450 with antigenic relatedness to the hepatic 3-methylcholanthrene-inducible cytochrome P-450c.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

The pre- and postnatal development of the dopaminergic cell groups in the ventral mesencephalon and the dopaminergic innervation of the striatum of the rat.

In the adult rat the striatum is a compartmentalized structure, which is reflected in the inhomogeneous distribution of dopamine. As a first step to test the hypothesis that dopamine plays an organizational role in the development of the striatum, the ontogeny of the dopaminergic system was studied in detail with immunocytochemical methods employing antibodies against dopamine. Rat embryos, fetuses, pups and adults were perfusion-fixed with glutaraldehyde on all prenatal days from E11 onward, postnatally on P2, P4, P6, P7, P8, P13, P14, P20, P21, and in adult age. On E13 the first dopaminergic cells are detected in the ventral prosencephalon. On E14 two dopaminergic cell groups are present in the ventral mesencephalon, and fibres of these cells reach the ventrolateral part of the ganglionic eminence. In the next two days both the cell groups and their projections rapidly increase in size. On E17 the afferent dopaminergic fibres to the striatum become aligned and form huge bundles that are closely associated with the fascicles of the internal capsule. Rostrally, the development of the striatal dopaminergic innervation shows a clear ventrolateral to dorsomedial gradient, whereas more caudally the dopaminergic fibres innervate the striatum from a ventromedial position. The lateral parts of the otherwise compact mesencephalic cell groups consist of loosely arranged cells. From E17 onward these cells become arranged into a dorsal and a ventral group. Just before birth, on E21, the primordia of the dopaminergic cell groups in the substantia nigra pars compacta and pars reticulata can be observed. On E19 several centres with extensive fibre ramifications along the dorsolateral margin of the caudate putamen represent the first signs of the inhomogeneous distribution of dopaminergic fibres in the dorsal striatum seen during the next two weeks. In the following pre- and postnatal days these so-called dopaminergic "patches" also appear more medially. By the third postnatal week most of the patches are no longer detectable, and only the most dorsolaterally located ones, i.e. in the region where they first were detected on E19, remain visible through to the adult stage. Prenatally, no varicosities can be observed in the dopaminergic fibres. The first varicosities appear after birth. Their number increase rapidly during the first and second postnatal weeks and reaches near adult levels on P20. The development of the striatal dopaminergic innervation, and that of the "patches" in particular, is discussed in relation to the development of the mesencephalic dopaminergic cell groups.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1989

Connectivity of striatal grafts implanted into the ibotenic acid-lesioned striatum--II. Cortical afferents.

Grafts of fetal striatal tissue, implanted into the ibotenic acid-lesioned caudate-putamen in adult recipient rats, have previously been shown to receive extensive afferent inputs from various subcortical areas in the host. In the present study, the formation of graft afferents from the host neocortex has been analysed, 3-12 months after transplantation, by means of the anterograde axonal tracer Phaseolus vulgaris leucoagglutinin, iontophoretically injected at multiple sites into the host frontal cortex, in combination with intra-transplant injections of the fluorescent retrograde tracer, Fluoro-Gold. From the cortical injection sites, fibres labelled with Phaseolus vulgaris leucoagglutinin could be traced through the corpus callosum, along the myelinated fascicles of the internal capsule, into the host caudate-putamen. The labelled axons passed in large numbers across the host-graft border zone to form a rich terminal plexus that covered large parts of the grafted tissue, in close association with the grafted neurons. The labelled corticostriatal terminal network was dense, particularly in the peripheral portions of the grafts, although it did not reach the density seen in the spared portions of the host caudate-putamen. Injections of Fluoro-Gold into the depth of the striatal grafts labelled large numbers of neurons in the frontoparietal cortical regions. Consistent with previous findings, labelled neurons were also found, ipsilateral to the graft, in the intralaminar nuclear complex of the thalamus, basolateral amygdala, substantia nigra and dorsal raphe. The host neocortical neurons labelled by Fluoro-Gold injections into the graft had the same laminar and regional distribution as the neurons labelled from the homotopic area of the intact striatum, indicating that the cortical afferents to the graft were derived from those corticostriatal neurons which projected to the area of the ibotenic acid-lesioned caudate-putamen into which the graft had been placed. The number of Fluoro-Gold-labelled cortical neurons ipsilateral to the graft reached in the best cases about 1/3 of the number labelled by identical Fluoro-Gold injections into the intact caudate-putamen. Labelled neurons occurred, with a similar distribution, also in the contralateral frontoparietal cortex, but they were considerably fewer in number. The results demonstrate that fetal striatal tissue, implanted into the previously neuron-depleted adult caudate-putamen, receives innervations from all normal principal cortical and subcortical striatal afferent systems, thus pointing to a remarkable capacity of the implanted fetal striatal neurons to become anatomically integrated into the lesioned host striatal circuitry.

Animals↗
PubMed1989

Connectivity of striatal grafts implanted into the ibotenic acid-lesioned striatum--III. Efferent projecting graft neurons and their relation to host afferents within the grafts.

Efferent projections of intrastriatally implanted striatal neurons have been studied using a combination of anterograde and retrograde axonal tracers. Adult rats subjected to a unilateral ibotenic acid lesion of the head of the caudate putamen received cell suspension grafts obtained from 14 15-day-old striatal primordia. Three and a half to 20 months after transplantation the rats received either intratransplant injections of the anterograde axonal tracer Phaseolus vulgaris leucoagglutinin or injections of fluorescent retrograde tracers. Fluoro-Gold and rhodamine-labelled latex beads, into the host globus pallidus and substantia nigra. Injections of Phaseolus vulgaris leucoagglutinin located entirely within the grafts labelled axons that ramified extensively within the tissue itself, as well as axons that extended caudally, across the graft host border, along the myelinated fascicles of the internal capsule to arborize in the medial parts of the host globus pallidus. A few axons also reached the entopeduncular nucleus. Injections of Fluoro-Gold into the host globus pallidus labelled large numbers of graft neurons, which had a prominent patchy distribution and were most abundant in the caudal portions of the grafts. Clear retrograde labelling was also seen after injection of Fluoro-Gold or rhodamine beads into the host substantia nigra, although the number of labelled graft neurons was 30-50 times lower than that seen after pallidal injections. Combined injections of Fluoro-Gold into the pallidus and rhodamine beads into the nigra showed that the vast majority of cells labelled from the nigra were also labelled by Fluoro-Gold from the pallidus. In some of the grafted and Fluoro-Gold-injected animals, the fetal donor tissue had been labelled with [3H]thymidine prior to transplantation. Many examples of neurons labelled with both [3H]thymidine and Fluoro-Gold were found after tracer injections into the host globus pallidus, and double-labelled neurons were identified also after Fluoro-Gold injections into the host substantia nigra. In several animals retrograde tracing was combined with labelling of host dopaminergic afferents (by tyrosine hydroxylase immunohistochemistry) and cortical afferents (by injections of Phaseolus vulgaris leucoagglutinin into the host frontal cortex). Comparison of adjacent sections revealed a striking overlap between the patches of Fluoro-Gold-labelled graft neurons (labelled from the host pallidum) and the dense patches of tyrosine hydroxylase-positive terminals. In addition, many of the Fluoro-Gold-labelled cell patches received a high density of cortical afferents labelled by Phaseolus vulgaris leucoagglutinin.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Altered glial fibrillary acidic protein immunoreactivity in rat brain following chronic hypoxia.

Glial fibrillary acidic immunoreactivity in brain was examined in normal animals and in rats subjected to chronic hypoxia. Animals were exposed to a chronic normobaric adaptive hypoxia with decreasing amounts of oxygen (finally 6%) for a period of 59 and 114 days, respectively. In paraffin-embedded sections the glial fibrillary acidic protein immunoreactivity in normal and hypoxic animals was examined at three coronal levels. A mild glial fibrillary acidic protein immunoreactivity in the perivascular glial layer, external glial limitans membrane and periventricular astrocytes, as well as in some areas of hippocampus and cerebellum, was noted in normal animals. Chronic hypoxia for 114 days resulted in a marked increase of glial fibrillary acidic protein immunoreactivity in dentate gyrus of hippocampus, Bergmann glia of the cerebellum, internal capsule and pyramidal tract. On the other hand, the glial fibrillary acidic protein activity following 59 days hypoxic exposure was almost the same as controls. These results show that systemic deep chronic hypoxia (depending on the intensity and the duration) activates the endogenous expression of glial fibrillary acidic protein in astrocytes of specific brain regions. The probable significance of this finding is discussed.

Animals↗
PubMed1991

Localization and characterization of endothelin receptor binding sites in the rat brain visualized by in vitro autoradiography.

Endothelin binding sites in rat brain were mapped by quantitative in vitro autoradiography employing [125I]endothelin-1 as radioligand. [125I]Endothelin-1 bound with high affinity and specificity to rat cerebellar sections and was potently displaced by unlabelled endothelins (endothelin-1 greater than endothelin-2 = endothelin-3) and sarafotoxin 6B. The highest densities of endothelin binding sites were found in the cerebellum (especially Purkinje cell layer), choroid plexus and median eminence. High densities were found in the supraoptic and paraventricular hypothalamic nuclei, anterior hypothalamic area, ventromedial hypothalamic nucleus, mammillary nuclei and glomerular layer of olfactory bulb. Moderate densities were found in many thalamic nuclei, the pretectal region, interpeduncular nucleus, suprachiasmatic nucleus, raphe nuclei, tegmental nuclei, olfactory ventricle, red nucleus, subthalamic nucleus, central gray, reticular nuclei, vestibular nuclei, oculomotor and trochlear nuclei, hypoglossal nucleus, motor trigeminal nucleus, nucleus of the trapezoid body and lateral cerebellar nucleus. Low but detectable densities of endothelin binding sites were found in medial geniculate nucleus, fields of Ammon's horn, caudate-putamen, globus pallidus, entopeduncular nucleus, substantia nigra, anterior commissure, internal capsule, anterior pituitary, median preoptic nucleus, septohypothalamic nucleus, superior colliculus and area postrema. These patterns were completely abolished by 1 microM unlabelled endothelin-1, -2 and -3 and sarafotoxin S6B. Brain endothelin binding sites show high affinity for endothelin-1, -2 and -3 and sarafotoxin 6B with highest affinity for endothelin-1. Endothelin binding sites show a non-vascular pattern of distribution in the brain, suggesting that the peptide may have widespread functions as a modulator of neuronal function.

Animals↗
PubMed1992

Cholinergic neurons in the rat central nervous system demonstrated by in situ hybridization of choline acetyltransferase mRNA.

Digoxigenin-labeled RNA probes and in situ hybridization histochemistry were used to examine choline acetyltransferase gene expression in the rat central nervous system. Hybridization signal was present only in brain sections processed with the antisense riboprobe. The sense probe did not yield labeling, further validating the specificity of tissue reactivity. Telencephalic neurons containing the mRNA for the cholinergic synthetic enzyme were found in the caudate-putamen nucleus, nucleus accumbens, olfactory tubercule, islands of Calleja complex, medial septal nucleus, vertical and horizontal limbs of the diagonal band, substantia innominata, nucleus basalis, and nucleus of the ansa lenticularis. Some somata evincing hybridization signal were observed in the anterior amygdalar area, and an occasional such cell was seen in the basolateral and central amygdalar nuclei. Neurons in the cerebral cortex, hippocampus, and primary olfactory structures did not demonstrate hybridocytochemically detectable amounts of choline acetyltransferase mRNA. Thalamic cells were devoid of reactivity, with the exception of several neurons located primarily in the ventral two-thirds of the medial habenula. A few somata labeled with riboprobe were found in the lateral hypothalamus, caudal extension of the internal capsule, and zona incerta. Neurons in the pedunculopontine and laterodorsal tegmental nuclei were moderately reactive, whereas cells of the parabigeminal nucleus exhibited a very weak hybridization signal. No somata in the brainstem raphe nuclei, including raphe obscurus and raphe magnus, were observed to bind riboprobe. In contrast, motor neurons of the cranial nerve nuclei demonstrated relatively large amounts of choline acetyltransferase mRNA. Putative cholinergic somata in the ventral horns and intermediolateral cell columns of the spinal cord were also labeled with riboprobe, as were a few cells around the central canal. We conclude that hybridocytochemistry with digoxigenin-labeled riboprobes confirms the existence of cholinergic neurons (i.e. those that synthesize and use acetylcholine as a neurotransmitter) in most of the neural regions deduced to contain them on the basis of previous histochemical and immunocytochemical data. Notable exceptions are the cerebral cortex and hippocampus, which do not possess neurons expressing detectable levels of choline acetyltransferase mRNA.

Animals↗