GABAA and GABAB receptor site distribution in the rat central nervous system

An autoradiographic procedure has been used to determine the quantitative distributions of gamma-aminobutyric acid (GABAA and GABAB) receptor subtypes in rat brain. Although the concentrations of both receptor binding sites were similar in some brain regions GABAA sites generally outnumbered GABAB sites. The highest concentration of GABAA sites were detected in the frontal cortex, the granule cell layer of the cerebellum, the olfactory bulb and the thalamic medial geniculate. The highest concentration of GABAB sites occurred in the molecular layer of the cerebellum, the interpeduncular nucleus, frontal cortex, anterior olfactory nucleus and thalamic nuclei. In addition the globus pallidus, temporal cortex, lateral posterior thalamus, superior colliculus, pontine nucleus, raphe magnus, spinal trigeminal tract and substantia gelatinosa contained significantly more GABAB sites than GABAA sites. The physiological and pharmacological significance of this heterogeneity has yet to be determined.     

Evidence of a collicular input to the dorsal lateral geniculate nucleus in rabbits — electrophysiology

Summary In anesthetized and paralyzed rabbits, unit responses of lateral geniculate nucleus (LGN) cells to focal electrical stimulation of the superior colliculus were studied. Geniculate responses to collicular stimulation (SCS) were compared with responses to optic nerve shock (ONS). A weak correlation coefficient suggested that collicular stimulation did not fire geniculate cells through collateral activation. Further differentiation between collicular and retinofugal inputs to LGN was made possible by repetitive stimulation. Geniculate cells which responded to collicular stimulation were relay cells as they were antidromically invaded from the visual cortex. This ruled out recordings from the ventral geniculate, since this area does not project to the visual cortex. A direct colliculo-geniculate pathway was revealed by antidromic activation of collicular cells by stimulation of the dorsal LGN. Finally, triggering flashes by collicular firing resulted in a marked modification of the geniculate test response. The results suggest that the superior colliculus sends fibers to the LGN and is capable of modulating the retino-cortical neuronal message at the level of the LGN.     

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.     

Type 1 metalloproteinase is selectively expressed in adult rat brain and can be rapidly up-regulated by kainate

The expression of metalloproteinase MMP-1 was traced in frontal sections of the rat brain in normal conditions and 4 h after an intraperitoneal injection of kainate. In the olfactory lobe, immunoreactivity was normally detected in the lateral olfactory tract. Kainate treatment led to the appearance of additional immunoreactivity in the neuropilar tracts. In the hippocampal part of brain, immunoreactive neurons were found exclusively after the kainate treatment in several hypothalamic and amygdalar nuclei, and in the restricted cortex areas (clusters of neurons in layers 3–4 of cortex, and a stripe of cells in layer 6). In the area between the hippocampus and cerebellum, MMP-1-like immunoreactivity was normally present in the entorhinal cortex, in the lateral periaqueductal gray, and in the pontine nucleus. After kainate treatment, the immunoreactive neurons were also found in the medial entorhinal cortex and in the dorsal raphe nucleus. In the brain stem, the immunoreactive cells were normally found in six nuclei. After kainate treatment, additional immunoreactivity appeared in the inferior olive neurons and in tracts supplying the cerebellar cortex. Thus, MMP-1 is present in several brain areas in normal conditions at a detectable level, and its expression increases after kainate-induced seizures.     

Effects of eye-enucleation on substance P-immunoreactive fibers of some retinorecipient nuclei of the rat in relation to their origin from the superior colliculus.

We have previously shown that retinal deafferentation causes a decrease in immunoreactive dendrites of substance P-positive neurons of the superficial superior colliculus of the rat. Since some retinorecipient thalamic and pretectal nuclei are putative targets for substance P-containing cells of the superior colliculus, the present study attempted to ascertain whether substance P-immunoreactive fibers in these nuclei are also affected by retinal denervation. We found that unilateral eye removal produced a progressive increase in fibrous substance P immunoreactivity in the nucleus of the optic tract, lateral posterior nucleus, and lateral geniculate nucleus of the side contralateral to the enucleation. On the other hand, unilateral lesions to the superficial layers of the superior colliculus produced a dramatic reduction in substance P immunoreactivity in the ipsilateral nucleus of the optic tract, lateral posterior nucleus, and dorsal and ventral lateral geniculate nuclei. In bilaterally enucleated animals, unilateral lesion to the superior colliculus produced, as expected, loss of immunoreactive fibers only in the lateral posterior nucleus and the retinorecipient nuclei ipsilateral to the lesion. These results suggest that transneuronal changes in the distribution of substance P in collicular neurons observed after enucleation could be reflected in their projections to the other primary visual centers and to the lateral posterior nucleus.     

大鼠束缚后脑内Fos蛋白的表达

目的探讨大鼠束缚后对大鼠脑内Fos蛋白表达的影响。方法将大鼠束缚于小的塑料桶内1、3或6h,于解束后30min处死,脑组织进行Fos蛋白免疫组织化学染色。结果Fos阳性神经元表达于1．前脑：扣带回、新皮质(尤其是第3和5层)、外侧隔核、杏仁中央核;2．间脑：下丘脑视前区、下丘脑外侧区、视上核、室旁核、第三脑室室周区、弓状核、丘脑室旁核、外侧膝状体、内侧膝状体;3．脑干：中脑的上丘视性层、中脑导水管周围灰质、下丘的皮质部;脑桥的臂旁外侧核、蓝斑、A5区;延髓的耳蜗核、延髓内脏带(MVZ)等处。Fos表达的时问规律是束缚1h最高,3h次之,6h最少。结论大鼠被束缚后全脑多处核团的神经元发生不同程度的Fos反应,随着束缚时间的延长,动物产生适应性,Fos表达减少。     

Patterns of expression of brain-derived neurotrophic factor and tyrosine kinase B mRNAs and distribution and ultrastructural localization of their proteins in the visual pathway of the adult rat

We have examined the cellular and subcellular distribution and the patterns of expression of brain-derived neurotrophic factor (BDNF), and of its high affinity receptor, tyrosine kinase B (TrkB), in retinorecipient regions of the brain, including the superior colliculus, the lateral geniculate nucleus and the olivary pretectal nucleus. In the retinorecipient layers of the superior colliculus, BDNF protein and mRNA were present in the cell bodies of a subpopulation of neurons, and BDNF protein was present in the neuropil as punctate or fiber-like structures. In the lateral geniculate nucleus, however, BDNF mRNA was not detected, and BDNF protein was restricted to punctate and fiber-like structures in the neuropil, especially in the most superficial part of the dorsal lateral geniculate nucleus, just below the optic tract. At the ultrastructural level, BDNF protein was localized predominantly to axon terminals containing round synaptic vesicles and pale mitochondria with irregular cristae, which made asymmetric (Gray type I) synaptic specializations (R-boutons). Enucleation of one eye was followed by loss of BDNF immunoreactivity and disappearance of BDNF-positive R-boutons in the contralateral visual centers, confirming the retinal origin of at least most of these terminals. TrkB was present in postsynaptic densities apposed to immunoreactive R-boutons in the superior colliculus and lateral geniculate nucleus, and was also associated with axonal and dendritic microtubules. These findings suggest that BDNF is synthesized by a subpopulation of retinal ganglion cells and axonally transported to visual centers where this neurotrophin is assumed to play important roles in visual system maintenance and/or in modulating the excitatory retinal input to neurons in these centers.     

Colocalization of parvalbumin, calretinin and calbindin D-28k in human cortical and subcortical visual structures

Several studies have demonstrated that three calcium-binding proteins parvalbumin (PV), calbindin D-28k (CB) and calretinin (CR) mark distinct subsets of cortical interneurons. This study demonstrates, in cortical and subcortical visual structures, the coexistence of two calcium-binding proteins in some neuronal subpopulations. The human visual cortex (VC), lateral geniculate nucleus (LGN), lateral inferior pulvinar (LIP) and superior colliculus (SC) were examined by a double-labelling immunocytochemical technique. The VC showed mostly separate populations of PV, CB and CR immunoreactive (-ir) interneurons, but also small populations of double-stained PV+CR and CR+CB neurons, while PV+CB neurons were less frequent. An average of 2.5% of the immunoreactive neurons were double-stained for PV+CR and 7.1% for CR+CB in area 17, while this percentage was slightly higher in association area 18 (3.3 and 7.4%, respectively). In the LGN and LIP, double-stained neurons were scarce, but in the fibre capsule of these nuclei, as well as in the optic radiation (OR) and white matter underlying area 17, both double-stained PV+CR or CR+CB and separate populations of PV-ir, CB-ir and CR-ir neurons and fibres were observed. Unlike the thalamic regions, the SC showed some double-stained PV+CR and CR+CB neurons, scattered both in the superficial and deep layers. These findings are discussed in the light of similar observations recently reported from other regions of the human brain.     

Golgi-Kopsch silver study of the brain of a patient with untreated phenylketonuria, seizures, and cortical blindness.

This report describes the morphological changes observed in the brain of an untreated 27-year-old man with phenylketonuria, cortical blindness, and seizures. Golgi-Kopsch silver, cresyl violet, and hematoxylin and eosin stains were used to study cell structure and organization of the cerebellum, the lateral geniculate nuclei, the visual cortex, frontal cortex, and hippocampus. Extensive neuronal losses occurred in the right lateral geniculate nucleus (LGN), the visual cortex, and hippocampus. The left LGN, cerebellum, and frontal cortex retained neuronal components; there was a reduction in the number of dendritic processes on the Purkinje cells of the PKU subject. The loss of neurons in the LGN and occipital cortex is related to the blindness and the neuronal loss in the hippocampus is related to seizure activity.     

Some topographical connections of the striate cortex with subcortical structures in Macaca fascicularis

Summary Subcortical connections of the striate cortex with the superior colliculus (SC), the lateral pulvinar (Pl), the inferior pulvinar (Pi) and the dorsal lateral geniculate nucleus (LG) were studied in the macaque monkey, Macaca fascicularis, following cortical injections of tritiated proline and/or horseradish peroxidase. All four structures were shown to receive topographically organized projections from the striate cortex. The exposed surface of the striate cortex was found to be connected to the rostral part of the SC and the caudal part of the LG. Injections of the exposed striate cortex close to its rostral border resulted in label in adjoining parts of the Pl and Pi. The ventral half and dorsal half of the calcarine fissure were connected with the medial and lateral parts of the SC, the ventrolateral and dorsomedial portions of the Pl and Pi and the lateral and medial parts of the LG, respectively. Injections located at the lateral posterior extreme of the calcarine fissure resulted in label at the optic disc representation in the LG. The horseradish peroxidase material demonstrated that LG neurons in all laminae and interlaminar zones project to the striate cortex.Abbreviations BIC brachium of the inferior colliculus - BSC brachium of the superior colliculus - C cerebellum - CG central grey - i interlaminar zone(s) of the dorsal lateral geniculate nucleus - IC inferior colliculus - ICc central nucleus of the inferior colliculus - LG dorsal lateral geniculate nucleus - m magnocellular layer(s) of the dorsal lateral geniculate nucleus - MG medial geniculate body - p parvocellular layer(s) of the dorsal lateral geniculate nucleus - P pulvinar complex - Pi inferior pulvinar - PG pregeniculate nucleus - Pl lateral pulvinar - Pm medial pulvinar - s superficial layer(s) of the dorsal lateral geniculate nucleus - SC superior colliculus - sgs stratum griseum superficiale of the superior colliculus - R reticular nucleus of the thalamus - VP ventroposterior group - 17 Area 17 Supported by NEI Grants EY-07007 (J. Graham) and EY-02686 (J.H. Kaas)     

Distribution of vasoactive intestinal polypeptide in the rat and mouse brain.

The distribution of cell bodies and nerve fibers that combine with antisera to vasoactive intestinal polypeptide (VIP) was studied by immunohistochemistry in combination with radioimmunoassay in the brain of rat and mouse. The highest concentrations (60pmol/g wet wt) of immuno-reactive VIP were found in the cerebral cortex and in certain limbic structures, whereas the concentrations in the basal ganglia, thalamus, lower brain stem, cerebellum and spinal cord were low (<15pmol/g). VIP-immunoreactive cell bodies were found mainly in the cerebral cortex and the limbic system, with the great majority of them in neo- and allocortical areas. In the neocortex the VIP-containing cell bodies were found in layers II-V in all areas. The cells were fusiform or stellate shaped, resembling intracortical and corticocortical association neurones. In the pyriform and entorhinal cortex the cell bodies were located mainly in layer II. In the hippocampal complex VIP-containing cell bodies occurred in both the subiculum, areas CA1 and CA3 and the dentate gyrus. Most of the cells had the appearance of interneurones, some of them probably being identical with basket cells. Of subcortical areas, the amygdala had the largest number of VIP-containing cell bodies; they were numerous in all amygdaloid nuclei except in the central nucleus. Non-cortical areas where there were cell bodies containing VIP included the anterior olfactory nuclei, the bed nucleus of stria terminalis, lateral septum, suprachiasmatic nucleus, superior colliculus, and the mesencephalic periaqueductal gray.VIP-immunoreactive fibres had a distribution which on the whole paralleled that of the cell bodies, suggesting that many of the VIP-containing cells project locally. VIP-containing fibres were numerous in the following areas: the entire neocortex, the pyrifom cortex, the entorhinal cortex, the hippocampal complex, the amygdala (the central nucleus in particular), the anterior olfactory nuclei, the nucleus accumbens, ventral pallidum, bed nucleus of stria terminalis, suprachiasmatic nucleus, medial preoptic nucleus, median eminence, lateral geniculate body, pretectum, superior colliculus, periaqueductal gray, and the lateral parabrachial nucleus. Only few, scattered fibres were seen in other parts of the brain stem, in the striatum, thalamus and spinal cord. The cerebellum was devoid of VIP-containing fibres. VIP-containing neurones seem to form predominantly local projections. In addition, some VIP-containing neurones probably also form long projections, such as descending and transcallosal projections from the cortical cells, and projections from the amygdala to preoptic, hypothalamic and basal forebrain areas.The characteristic telencephalic distribution of the neurones that contain VIP suggests a role for this peptide in cortical and limbic functions.     

Central connections of the olfactory bulb in the american opossum (didelphys virginiana): A light microscopic degeneration study

Destructive lesions were made in the right olfactory bulb of 16 adult opossums. Following postoperative survival periods of 4 to 31 days, the animals were sacrificed and perfused with 10% Formalin. Frozen sections of the brain were cut in either the coronal, horizontal, or sagittal plane and processed by the Fink-Heimer II method. Degenerating axons of olfactory bulb neurons were traced caudally in the ipsilateral lateral olfactory tract (LOT). Small lesions revealed a topographic representation of the olfactory bulb within the LOT. The dorsal, lateral, and ventral parts of the bulb were, respectively, represented in the dorsal, intermediate, and ventral parts of the LOT. Terminal degeneration was observed in the superficial half of the molecular layer ipsilaterally in the following structures: anterior olfactory nucleus, anterior hippocampal rudiment, olfactory tubercle, piriform cortex, ventrolateral frontal neocortex, lateral entorhinal cortex, nucleus of the LOT, and the lateral aspect of the cortical amygdaloid nucleus. No degeneration was observed in the anterior limb of the anterior commissure. Dorsal and lateral parts of the olfactory bulb projected to the anterolateral aspect of the olfactory tubercle, whereas the ventral part projected heavily to the entire tubercle. There was no evidence of topographic projections to other olfactory structures. The observations of the present investigation indicated that the olfactory bulb projections in the opossum, a primitive mammal, are essentially comparable with those of placental mammals.     

猫外侧膝状体神经元HRP示踪结合Calbindin的免疫组织化学研究

目的 HRP示踪结合Calbindin双标猫外侧膝状体核(LGN)至视皮质的中继神经元.方法 在猫视皮质的17区多点微量注射30%HRP,逆行标记LGN至视皮质的中继神经元,先以金标抗HRP-抗孵育切片,用免疫金银法将HRP颗粒转化黑色银颗粒.然后用ABC法作Calbindin(CB)的免疫组化,试图双标记LGN的中继神经元.结果 HRP标记细胞与CB免疫阳性细胞清晰可辨,HRP标记细胞内为银染黑色颗粒,而CB免疫阳性细胞为染色均匀的棕色.猫LGN的A、A_1和C板层均有CB免疫阳性神经元的分布;HRP标记细胞分布于A和A_1板层.LGN内未见HRP和CB的双标记神经元.结论 LGN内含CB神经元可能不参与视觉信息的传导,而是与局部视觉信息的整合有关.     

Atrial natriuretic polypeptide: topographical distribution in the rat brain by radioimmunoassay and immunohistochemistry

The widespread distribution of neurons containing alpha-atrial natriuretic polypeptide-like immunoreactivity in the rat brain was demonstrated using radioimmunoassay and immunohistochemistry in conjunction with specific antisera. The highest concentrations of alpha-atrial natriuretic polypeptide-like immunoreactivity were in the hypothalamus and septum, with low but still appreciable concentrations in the mesencephalon, cerebral cortex, olfactory bulb and thalamus by radioimmunoassay. Immunohistochemical studies clearly showed that the perikarya of immunoreactive neurons are most prevalent in the ventral part of the lateral septal nucleus, periventricular preoptic nucleus, bed nucleus of the stria terminalis, periventricular and dorsal parts of the paraventricular hypothalamic nucleus, ventromedial nucleus, dorsomedial nucleus, arcuate nucleus, median mamillary nucleus, supramamillary nucleus, zona incerta, medial habenular nucleus and the periaqueductal grey matter. Scattered neurons were seen in the cingulate cortex, endopiriform nucleus, lateral hypothalamic area, and pretectal and dorsal thalamic areas. In addition to the areas mentioned above, high concentrations of immunoreactive varicose fibers were seen in the glomerular layer of the olfactory bulb, external layer of the median eminence, central to paramedian parts of the interpeduncular nucleus and the paraventricular hypothalamic nucleus. The globus pallidus, medial and central amygdaloid nuclei, dorsal raphe, dorsal parabrachial nucleus, locus coeruleus, vagal dorsal motor nucleus, solitary nucleus and some circumventricular organs, including the subfornical organ and organum vasculosum laminae terminalis, contained considerable numbers of immunoreactive varicose fibers. In dehydrated rats and homozygous Brattleboro rats, the pattern of alpha-atrial natriuretic polypeptide-immunoreactive neurons and varicose fibers was qualitatively similar to that seen in normal conditioned rats. This study gives an atlas of the distribution of the alpha-atrial natriuretic polypeptide-containing neuronal system in the rat brain and provides the groundwork for studying the influence of this new peptide on various brain functions.     

Golgi-Kopsch silver study of the brain of a patient with untreated phenylketonuria,seizures, and cortical blindness

This report describes the morphological changes observed in the brain of an untreated 27-year-old man with phenylketonuria, cortical blindness, and seizures. Golgi–Kopsch silver, cresyl violet, and hematoxylin and eosin stains were used to study cell structure and organization of the cerebellum, the lateral geniculate nuclei, the visual cortex, frontal cortex, and hippocampus. Extensive neuronal losses occurred in the right lateral geniculate nucleus (LGN), the visual cortex, and hippocampus. The left LGN, cerebellum, and frontal cortex retained neuronal components; there was a reduction in the number of dendritic processes on the Purkinje cells of the PKU subject. The loss of neurons in the LGN and occipital cortex is related to the blindness and the neuronal loss in the hippocampus is related to seizure activity. © Wiley-Liss, Inc.     

Time of origin of neurons of the rat superior colliculus in relation to other components of the visual and visuomotor pathways

Summary Groups of pregnant rats were injected with two successive daily doses of ³H-thymidine from gestational day 12 and 13 (E12+E13) until the day before parturition (E21+22) in order to label all the multiplying precursors of neurons. At 60 days of age the proportion of neurons generated (or no longer labelled) on specific days was determined in the separate layers of the superior colliculus. Neurogenesis begins with the production of a few large multipolar neurons in layers V and IV on day E12; the bulk (87%) of these cells are generated on day E13. This early-produced band of large neurons, the intermediate magnocellular zone, divides the superior colliculus into two cytogenetically distinct regions. In both the deep and the superficial superior colliculus neuron production is relatively protracted. In the deep superior colliculus neuron production peaks on day E15 in layer VII, on day E15 and E16 in layer VI, and on day E16 (the large neurons excluded) in layer V, indicating an inside-out sequence. In the superficial superior colliculus peak production time of layer III cells is on day E15 and of layer IV cells on day E16; peak production time of both layer I and II is on day E16 but in the latter region neuron production is more prolonged and ends on day El8. One interpretation of these results is that the two pairs of superficial layers are produced in an outside-in sequence. These three cytogenetic subdivisions of the superior colliculus may be correlated with its structural-functional parcellation into an efferent spinotectal, a deep somatomotor and a superficial visual component.A comparison of neurogenesis in different components of the visuomotor and visual pathways of the rat indicates that the motor neurons of the extraocular muscles, the abducens, trochlear and oculomotor nuclei, and neurons of the nucleus of Darkschewitsch are produced first. Next in line are source neurons of efferents to the bulb and the spinal cord: those of the Edinger-Westphal nucleus and the intermediate magnocellular zone of the superior colliculus. These are followed by the relay neurons of the dorsal nucleus of the lateral geniculate body. The neurons of the superficial superior colliculus and of the visual cortex implicated in visual sensori-motor integrations are produced last.Abbreviations A aqueduct - ap stratum album profundum (layer VII) - bi brachium of the inferior colliculus - c caudal - CGd central gray, pars dorsalis - CGl central gray, pars lateralis - CGv central gray, pars ventralis - dm deep magnocellular zone - EW Edinger-Westphal nucleus - gi stratum griseum intermediale (layer IV) - gp stratum griseum profundum (layer VI) - gs stratum griseum superficiale (layer II) - IC inferior colliculus - im intermediate magnocellular zone - LGd lateral geniculate nucleus, pars dorsalis - ll lateral lemniscus - lm stratum lemnisci (layer V) - MG medial geniculate nucleus - ND nucleus of Darkschewitsch - NO nucleus of the optic tract - op stratum opticum (layer III) - ot optic tract - r rostral - SC superior colliculus - vIII third ventricle - ZO stratum zonale (layer I) - III oculomotor nucleus - IV trochlear nucleus - Vm mesencephalic nucleus of the trigeminal - VI abducens nucleus     

Fatty acid amide hydrolase is located preferentially in large neurons in the rat central nervous system as revealed by immunohistochemistry

The distribution in the rat brain of fatty acid amide hydrolase (FAAH) an enzyme that catalyzes the hydrolysis of the endogenous cannabinoid anandamide was studied by immunohistochemistry. An immunopurified, polyclonal antibody to the C terminal region of FAAH was used in these studies. The large principal neurons, such as pyramidal cells in the cerebral cortex, the pyramidal cells the hippocampus, Purkinje cells in the cerebellar cortex and the mitral cells in the olfactory bulb, showed the strongest FAAH immunoreactivity. These FAAH-containing principal neurons except the mitral cells in the olfactory bulb are in close proximity with cannabinoid CB1 receptors as revealed by our previous immunohistochemical study. Moderately or lightly stained FAAH-containing neurons were also found in the amygdala, the basal ganglia, the deep cerebellar nuclei, the ventral posterior nuclei of the thalamus, the optic layer and the intermediate white layer of the superior colliculus and the red nucleus in the midbrain, and motor neurons of the spinal cord. These data demonstrate that FAAH is heterogeneously distributed and this distribution exhibits considerable, although not complete, overlap with the distribution of cannabinoid CB1 receptors in rat brain.     

Numerical estimation of gamma-aminobutyric acid (GABA)-containing neurons in three thalamic nuclei of the cat: direct GABA immunocytochemistry

The percentage of neurons that are immunoreactive for the inhibitory neurotransmitter, gamma-aminobutyric acid (GABA) was determined within: (1) the lateral geniculate nucleus (LGN), (2) the ventrobasal complex (VB) and (3) the antero-ventral nucleus (AV) of the thalamus in the cat. An antiserum to GABA was used to stain GABA-containing perikarya in 1.0 micrometer thick Araldite-embedded sections. Immunostained somata in all three nuclei were invariably smaller than the immuno-negative nerve cells. 27% of all neurons in the LGN, 33% in the VB and 25% in the AV were immunoreactive for GABA.     

Inputs from the olfactory bulb and olfactory cortex to the entorhinal cortex in the cat

Summary The spatial organization and laminar distribution of projections from the olfactory bulb and the anterior (PPCa) and posterior (PPCp) divisions of the prepiriform cortex to the entorhinal cortex were studied with anterograde (³H-leucine) and retrograde (WGA-HRP) tracing techniques. After ³H-leucine injections into the olfactory bulb transported labeling was seen over the lateral entorhinal area, except its most medial part, and over the rostral part of the medial entorhinal area. The labeling covers exclusively layer Ia. The lateral and medial entorhinal areas are also reached by fibers from the prepiriform cortex. The projection to the medial entorhinal area has not been described previously. Following injections of ³H-leucine into the PPCa transported labeling is present over the entire expanse of the entorhinal cortex and is located over layer Ib with the greatest density in its superficial part. Injections of ³H-leucine into the PPCp give rise to transported labeling over much of the entorhinal cortex. No labeling was found over the most medial parts of the medial subdivision (VMEA) of the lateral entorhinal area and the medial entorhinal area. Labeling occupies layer Ib, especially its middle part, and layers II and III. Both PPCa and PPCp appear to project most heavily to the dorsal (DLEA) and ventral (VLEA) subdivisions of the lateral entorhinal area. From the retrograde experiments it can be inferred that cells of layers II and III of the PPCa project predominantly to the DLEA, whereas those of the PPCp project predominantly to the VLEA. The MEA receives its heaviest projection from layer II of both PPCa and PPCp. In control experiments with ³H-leucine injections into the endopiriform nucleus it was found that this nucleus projects to the entire expanse of the entorhinal cortex. The fibers distribute to all layers with the exception of layer Ia.Abbreviations AI agranular insular cortex - AL lateral nucleus of the amygdala - BL basolateral nucleus of the amygdala - BM basomedial nucleus of the amygdala - C claustrum - CoA cortical nucleus of the amygdala - DLEA dorsal division of the lateral entorhinal cortex - END endopiriform nucleus - H hippocampus - I granular insular cortex - lot lateral olfactory tractus - MCL mitral cell layer of the olfactory bulb - MEA medial entorhinal area - OB olfactory bulb - PPCa anterior part of the prepiriform nucleus - PPCp posterior part of the prepiriform nucleus - VLEA ventral division of the lateral entorhinal cortex - VMEA ventromedial division of the lateral entorhinal cortex - 35 area 35 of the perirhinal cortex - 36 area 36 of the perirhinal cortex     

Autoradiographic localization of muscarinic cholinergic receptors in visual areas of cat brain: variations in sensitivity of N-[3H]methylscopolamine binding sites to carbachol and pirenzepine

The distribution of muscarinic acetylcholine receptors (MChRs) was studied in visual areas of cat brain using in vitro quantitative autoradiography with 1 nM N-[3H]methylscopolamine ([3H]NMS) as a radioligand. The highest density of [3H]NMS binding was observed in lamina A of the lateral geniculate nucleus (LGN) and in layer II/III of the visual cortex. The lowest binding was seen in the stratum griseum intermediale of the superior colliculus (SC). The comparison of inhibition of [3H]NMS binding by 100 microM carbachol and 300 nM pirenzepine showed that the SC and LGN contain predominantly M2 sites. M1 sites constitute the main population of MChRs in the cortical areas studied.