Topography of choline acetyltransferase-containing neurons in the forebrain of the rat

Atlas of cholinergic neurons in the forebrain and upper brainstem of the macaque based on monoclonal choline acetyltransferase immunohistochemistry and acetylcholinesterase histochemistry

Choline acetyltransferase immunohistochemistry was used to map the cholinergic cell bodies in the forebrain and upper brainstem of the macaque brain. Neurons with choline acetyltransferase-like immunoreactivity were seen in the striatal complex, in the septal area, in the diagonal band region, in the substantia innominata, in the medial habenula, in the pontomecencephalic tegmentum and in the oculomotor and trochlear nuclei. The ventral striatum contained a higher density of cholinergic cell bodies than the dorsal striatum. All of the structures that contained the choline acetyltransferase positive neurons also had acetylcholinesterase-rich neurons. Choline acetyltransferase positive neurons were not encountered in the cortex. Some perikarya in the midline, intralaminar, reticular and limbic thalamic nuclei as well as in the hypothalamus were rich in acetylcholinesterase but did not give a positive choline acetyltransferase reaction. A similar dissociation was observed in the substantia nigra, the raphe nuclei and the nucleus locus coeruleus where acetylcholinesterase-rich neurons appeared to lack perikaryal choline acetyltransferase activity.

Immunocytochemical studies of GABAergic neurons in rat basal ganglia and their relations to other neuronal systems

GABAergic neurons were localized in the rat basal ganglia by glutamate decarboxylase (GAD) immunohistochemistry. In the striatum (caudato-putamen, accumbens nucleus) a medium density of GAD-positive terminals was observed; a small number of medium-to-large size neurons and the vast majority of medium-size neurons were GAD immunoreactive. In addition, opioid peptide-like immunoreactivity was colocalized in a subclass of GAD-positive medium-size striatal neurons. The pallido-nigral system (GP, VP, EP, SNR) displayed a high density of GAD-positive axon terminals which synapsed upon dendrites and nerve cell bodies. The majority of pallido-nigral neurons also were GAD-immunoreactive. In contrast, the substantia nigra pars compacta and the subthalamic nucleus contained only few GAD-immunoreactive neurons.

Cortical cholinergic projections from the basal forebrain of the rat, with special reference to the prefrontal cortex innervation

The topographic organization of cells containing choline-acetyltransferase (CAT) and located within the magnocellular nuclei of the basal forebrain was studied by correlating maximum CAT decrease in one or another cortical region with a given localization of the cell lesions. Lesions were made by using ibotenic acid. Lesions affecting the ventral pallidum decreased CAT activity in the antero-medial prefrontal cortex and lesions of the internal and ventral borders of the pallidum decreased CAT activity in sensori-motor and parieto-temporal cortices. None of these lesions produced a decrease of CAT activity in the hippocampus. These results suggest that it is possible to show the presence of a specific cholinergic projection from the basal forebrain to the medial-associative prefrontal cortex of the rat.

Cortical projections of the nucleus of the diagonal band of Broca and of the substantia innominata in the rat: an anatomical study using the anterograde transport of a conjugate of wheat germ agglutinin and horseradish peroxidase

The projections of the nucleus of the diagonal band of Broca and of the substantia innominata to the cerebral cortex were studied in the rat, using the anterograde transport of wheat germ agglutinin conjugated with horseradish peroxidase. Following diagonal band injections, fibers were observed ascending in the septum and reaching the cingulate cortex. They had a rostrocaudal, horizontal direction, mostly in layer VI and could be followed over long distances on sagittal sections. The fibers gave off collaterals which were seen ascending in the cerebral cortex and reaching more superficial layers. Following substantia innominata injections, fibers were observed to take two routes: the first one identical to the one described above and a second through the caudate-putamen reaching the temporo-insular cortex. Terminal fields had a more diffuse distribution following substantia innominata than following diagonal band injections. No clear laminar pattern of termination was observed. However the density of terminals was higher in layers IV, V and VI than in layers I, II and III. Since the conjugate used is not taken up by fibers of passage, this pattern of connection is believed to reflect the organization of the projection of the nucleus of the diagonal band and of the substantia innominata to the cerebral cortex.

Specific retrograde transport of nerve growth factor (NGF) from neocortex to nucleus basalis in the rat

[125I]labeled NGF injected in very small quantities into the frontal or dorsal anterior occipital cortex of adult rats, was specifically taken up and transported retrogradely to large, presumably cholinergic neurons in the nucleus basalis region (lateral preoptic nucleus, anterior lateral hypothalamic nucleus, substantia innominata, ventral globus pallidus and internal capsule), as revealed by light microscopic autoradiography. Cells projecting to the injection site in the frontal cortex were localized ipsilaterally in the more caudal parts of the nucleus basalis region, whereas cells projecting to the dorsal anterior occipital cortex could be found throughout the entire extent of the nucleus basalis and also in the vertical and horizontal limb of the nucleus of the diagonal band of Broca. Other nuclei known to project to the cortex (locus coeruleus, substantia nigra, nucleus raphe, thalamus) were consistently found to be unlabeled. In contrast to [125I]NGF, injection of [125I]cytochrome C failed to label any cell bodies in the basal forebrain nuclei by retrograde transport. This high selectivity for uptake and retrograde transport of NGF indicates the presence of membrane receptors for NGF or a closely related molecule on these cholinergic neurons of the basal forebrain innervating the cerebral cortex.

Evidence that thalamic efferent neurones are non-cholinergic: a study in the rat with special reference to the thalamostriatal pathway

Controversy surrounds the question as to whether some fibres of the thalamostriatal projection, are cholinergic. The present experiments show that lesions of the parafascicular-intralaminar thalamus produced no reductions in choline acetyltransferase (ChAT) activities in any area of microdissected rat caudate-putamen complex or dorsolateral frontal cortex. We conclude that thalamostriatal projections are entirely non-cholinergic. Furthermore, lesions of the mediodorsal or periventricular thalamus resulted in no change in ChAT activities in their terminal projection areas (medio-/orbitofrontal cortices and nucleus accumbens, respectively). The probability that all thalamic outputs are non-cholinergic is discussed.

Concurrent visualization of choline acetyltransferase-like immunoreactivity and retrograde transport of neocortically injected markers in basal forebrain neurons of cat and rat

Magnocellular neurons in the basal forebrain of rats and cats were retrogradely labeled with Fast Blue or horseradish peroxidase injected into the neocortex. Using antisera against choline acetyltransferase (ChAT) a direct double-labeling technique was carried out and it was demonstrated that retrogradely transported markers and ChAT-like immunoreactivity occur within the same neurons. These findings strongly support the cholinergic nature of basal forebrain projection to the neocortex.

Recovery of neocortical choline acetyltransferase activity following ibotenic acid injection into the nucleus basalis of Meynert in rats

The present experiment was designed to investigate the depletion and possible recovery of neocortical choline acetyltransferase (ChAT) levels following damage to the basal forebrain cholinergic (Ch) system in rats. A unilateral injection of ibotenic acid was made into the left nucleus basalis of Meynert (nbM). Seven days after the injection, neocortical ChAT levels had decreased 60%. After 3 months it had returned to normal. Thus this system shows extensive plasticity and recovery of function with time.

Organization of cerebral cortical afferent systems in the rat. II. Magnocellular basal nucleus

The organization of the magnocellular basal nucleus (MBN) projection to cerebral cortex in the rat has been studied by using cytoarchitectonic, immunohistochemical, and retrograde and anterograde transport methods. The distribution of retrogradely labeled basal forebrain neurons after cortical injections of wheat germ agglutinin-horseradish peroxidase conjugate was essentially identical to that of neurons staining immunohistochemically for choline acetyltransferase. These large (20-30 micrometers perikaryon diameter) multipolar neurons were found scattered through a number of basal forebrain cell groups: medial septal nucleus, nucleus of the diagonal band of Broca, magnocellular preoptic nucleus, substantia innominata, and globus pallidus. This peculiar distribution mimics the locations of pathways by which descending cortical fibers enter the diencephalon. Each cortical area was innervated by a characteristic subset of MBN neurons, always located in close association with descending cortical fibers. In many instances anterogradely labeled descending cortical fibers appeared to ramify into diffuse terminal fields among MBN neurons which were retrogradely labeled by the same cortical injection. Double label experiments using retrograde transport of fluorescent dyes confirmed that MBN neurons innervate restricted cortical fields. Anterograde autoradiographic transport studies after injections of 3H-amino acids into MBN revealed that MBN axons reach cerebral cortex primarily via two pathways: (1) The medial pathway, arising from the medial septal nucleus, nucleus of the diagonal band, and medial substantia innominata and globus pallidus MBN neurons, curves dorsally rostral to the diagonal band nucleus, up to the genu of the corpus callosum. Most of the fibers either directly enter medial frontal cortex or turn back over the genu of the corpus callosum into the superficial medial cingulate bundle. Many of these fibers enter anterior cigulate or retrosplenial cortex, but some can be traced back to the splenium of the corpus callosum, where a few enter visual cortex but most turn ventrally and sweep into the hippocampal formation. Here they are joined by other fibers which, at the genu of the corpus callosum, remain ventrally located and run caudally through the dorsal fornix into the hippocampus. (2) The lateral pathway arises in part from medial septal, diagonal band, and magnocellular preoptic neurons whose axons sweep laterally through the substantia innominata to innervate primarily piriform, perirhinal, and endorhinal cortex. Some of these fibers may also enter the hippocampal formation from the entorhinal cortex via the ventral subiculum.(ABSTRACT TRUNCATED AT 400 WORDS)

Distribution of acetylcholinesterase-containing neurons in the basal forebrain and upper brainstem of the squirrel monkey (Saimiri sciureus)

The topographical distribution of neurons containing acetylcholinesterase (AChE, EC 3.1.1.7) in the basal forebrain and upper brainstem of the squirrel monkey (Saimiri sciureus) was studied by means of Butcher's pharmacohistochemical technique which involves staining for AChE at various times after the systemic administration of the AChE inhibitor di-isopropylphosphorofluoridate (DFP). Only those neurons whose AChE staining was as intense as that of known cholinergic neurons present in the same material (e.g., neurons of cranial nerve nuclei) were examined and mapped. Three major collections of such strongly-stained AChE neurons were disclosed in squirrel monkey brain: one located in the striatum, the other lying along the ventralmost aspects of the basal forebrain, and a third one present within the midbrain-pontine tegmentum. The striatal AChE neurons vary in shape from fusiform with 2 thick processes to polygonal with 4-5 thinner processes. They are uniformly scattered throughout the caudate nucleus and putamen and represent only a small proportion of the total striatal cell population (4-6 cells/mm2). They most likely correspond to the aspiny type II cells described in Golgi material of monkey striatum. Similar neurons occur also in ventral striatal areas comprising nucleus accumbens septi and the deep polymorph layer of the olfactory tubercle. The second major AChE neuronal population is composed of the magnocellular neurons that form a somewhat continuous chain of neuronal aggregates extending rostrocaudally from the septal region to the caudal pole of the lentiform nucleus. It includes the neurons of the medial septal nucleus, the nucleus of the diagonal band of Broca and the nucleus basalis of Meynert, all displaying strikingly similar morphological and histochemical characteristics. The AChE neuronal population of nucleus basalis encroaches markedly upon the lateral hypothalamus laterally and the globus pallidus dorsally. The third important AChE cell collection occurs within the pedunculopontine nucleus area in upper brainstem. In that constellation, the AChE neurons are clustered in 2 continuous cell groups: one located dorsolaterally, the other lying ventromedially to the brachium conjunctivum. The thick processes of these neurons form impressive AChE neuronal networks that surround and pervade the brachium conjunctivum over long distances. This cell group, which is one of the most highly AChE reactive structures of the entire brain in the squirrel monkey, may provide a major cholinergic input to various basal ganglia structures, particularly the substantia nigra.

Immunocytochemical identification of cholinergic neurons in the monkey central nervous system using monoclonal antibodies against choline acetyltransferase

A monoclonal antibody directed against rat brain choline acetyltransferase (ChAT) was used to stain cholinergic nerve cells within the brain and spinal cord of macaques. ChAT immunoreactivity was seen in motor neurons of the brainstem and spinal cord, in large neurons of the striatum, and in large neurons in the basal forebrain (medial septum--diagonal band--nucleus basalis complex); each of these groups of neurons is believed to be cholinergic. The ability to visualize cholinergic neurons in the nervous system of primates provides a new approach to the study of cholinergic systems in health and disease.

Acetylcholine excites identified septo-hippocampal neurons in the rat

Neurons of the medial septum-nucleus of the diagonal band of Broca (vertical limb) area were identified as septo-hippocampal neurons by antidromic electrical activation in anesthetized rats. A large majority of these presumably cholinergic neurons could be excited by the iontophoretic application of acetylcholine or cholinergic agonists such as carbachol. The acetylcholine-induced excitations were readily antagonized by atropine. These results suggest that cholinergic neurons can be excited by their own transmitter, i.e. acetylcholine.

Retrograde changes in cholinergic neurons in the basal forebrain of the rat following cortical damage

The effects of unilateral cortical damage on immunohistochemically identified cholinergic neurons of the basal nucleus have been examined in the rat. In the first 2 weeks after operation, the cells were swollen and their nuclei became eccentric, these changes being closely similar to those seen in the cholinergic oculomotor nuclei of the same animals following removal of the extraocular muscles. During the third week these acute changes were replaced by shrinkage of the cholinergic cell bodies and their dendrites. At longer survival times the appearance of the neurons did not alter, and all the cholinergic cells persisted in their shrunken form after 120 days, the longest survival time examined.

Autoradiographic labeling of the cholinergic habenulo-interpeduncular projection

The transmitter-specific autoradiographic method has been used to retrogradely trace the habenulo-interpeduncular cholinergic projection. [3H]Choline injection in the interpeduncular nucleus resulted in remarkable labeling of the fasciculus retroflexus and in very strong accumulation of silver grains in the medial habenula. Brainstem nuclei sending non-cholinergic projections to the interpeduncular nucleus were not labeled. The present findings strongly support the notion of a cholinergic medial habenula-interpeduncular nucleus projection in agreement with recent immunohistochemical evidence, but in contrast to previous immunocytochemical and pharmacohistochemical results.

Synaptic activation of phasic bursting in rat supraoptic nucleus neurones recorded in hypothalamic slices

Using slices of rat hypothalamus (400-500 micron thick), intracellular and extracellular recordings were made of activity from eight-eight neurones in the supraoptic nucleus (s.o.n.). Electrical stimulation with single stimuli dorsolateral to s.o.n. was excitatory to fifty-nine phasically firing cells (67% of total, 95% of phasic cells). In intracellularly recorded cells, such stimulation reliably evoked excitatory post-synaptic potentials which often gave rise to action potentials. Trains of stimuli reliably triggered bursts of action potentials which continued after stimulation had ceased. Stimulation more dorsal or more lateral to the critical region or in the optic tract adjacent to the s.o.n. did not evoke responses. Stimulation dorsomedial to the nucleus produced only direct, probably antidromic, activation of s.o.n. neurones. Application of acetylcholine (ACh) by microperifusion in the s.o.n. region mimicked the effect of electrical stimulation by evoking prolonged discharge in eight of eight tested phasically firing s.o.n. neurones. Non-phasic, continuously firing neurones were either inhibited or unaffected by electrical stimulation in the critical region. The discharge pattern of unaffected cells (six cells) was not modified by locally applied ACh, although they were excited by local application of sodium glutamate. The excitatory, synaptically mediated, responses to stimulation in the dorso-lateral region were blocked reversibly by the nicotinic blockers, d-tubocurarine chloride and hexamethonium bromide (in seven of seven cells tested), but were unaffected by the muscarinic blocker, atropine, even at high concentrations (two of two cells tested). Thus, this activation appears to be mediated by nicotinic receptors. In separate experiments with the position of stimulating and recording electrodes reversed, s.o.n. stimulation was effective in antidromically activating one cell of sixty-eight recorded extracellularly in the dorsolateral region. Some slowly firing s.o.n. neurones (less than 4 Hz) were inhibited by electrical stimulation in the same area in which phasically active cells were excited. In these cases, stimulation produced large summating i.p.s.p.s. and/or inhibition of ongoing activity for the duration of the stimulus train. These results support evidence from earlier studies that the cholinergic input to s.o.n. neurones originates from cells in its close proximity, and suggests this input to be via a monosynaptic pathway.

Ultrastructural observations of the cholinergic neuron in the rat striatum as identified by acetylcholinesterase pharmacohistochemistry

In order to examine the ultrastructural features of the cholinergic neuron in the striatum (caudatoputamen) of the rat, cytochemistry for acetylcholinesterase was conducted 2-12 h after intramuscular injection of the irreversible acetylcholinesterase inhibitor diisopropylphosphorofluoridate. Light microscopic examination of Epon sections reacted from acetylcholinesterase showed that only large-sized cells in the striatum (25-35 microns in the long axis) were stained intensely. In the case of longer survival periods (10-12 h), some lightly stained cells (medium-sized) were seen dispersed amongst the large acetylcholinesterase-rich cells. Electron microscopic observations were made on ultrathin sections of selected large acetylcholinesterase-rich neurons that were first studied by light microscopy. The nucleus of these cells has an eccentric position and possesses several indentations of the nuclear envelope. The cytoplasm contains abundant organelles, many exhibiting features unique to this cell type. Many stacks of granular endoplasmic reticulum, arranged in a parallel manner and forming typical Nissl bodies, were observed in the periphery of the perikarya, and many distinct golgi complexes were seen in the perinuclear zone. At all post-diisopropylphosphorofluoridate survival times, heavy deposits of acetylcholinesterase reaction product were found within the perikarya of this cell type, for the most part within the cisternae of the granular endoplasmic reticulum. At the longer post-diisopropylphosphorofluoridate survival times, reaction product within the cytoplasm was very dense and appeared to have reached a maximum level. At these times reaction product also appeared in the secondary and tertiary dendritic branches of the large-sized neurons. Of the other cell types in the striatum, two types of medium-sized cells displayed a light deposit of reaction product in their perikarya, but this was observed only at longer recovery times (8-12 h). The majority of cells in the striatum lacked reaction particles. Throughout the early post-diisopropylphosphorofluoridate period, the recovery of enzyme activity in the neuropil was moderate compared to that seen within cell bodies. These findings indicate that the large-sized neuron is the only striatal structure that shows rapid regeneration of acetylcholinesterase activity during the early recovery phase after diisopropylphosphorofluoridate administration. Previous studies have indicated that this type of neuron represents the cholinergic interneuron of the striatum. (ABSTRACT TRUNCATED AT 400 WORDS)

A comparison of the distribution of central cholinergic neurons as demonstrated by acetylcholinesterase pharmacohistochemistry and choline acetyltransferase immunohistochemistry

The topographical distribution of cholinergic cell bodies has been studied in the rat brain and spinal cord by choline acetyltransferase (ChAT)-immunohistochemistry and acetylcholinesterase (AChE)-pharmacohistochemistry using diisopropylfluorophosphate (DFP). The ChAT-containing cells and the cells that stained intensely for AChE 4-8 hr after DFP were mapped in detail on an atlas of the forebrain (telencephalon, diencephalon) hindbrain (mesencephalon, rhombencephalon) and cervical cord (C2, C6). Striking similarities were observed between ChAT-positive cells and neuronal soma that stained intensely for AChE both in terms of cytoarchitectural characteristics, and with respect to the distribution of the labelled cells in many areas of the central nervous system (CNS). In the forebrain these areas include the caudatoputamen, nucleus accumbens, medial septum, nucleus of the diagonal band, magnocellular preoptic nucleus and nucleus basalis magnocellularis. In contrast, a marked discrepancy was observed in the hypothalamus and ventral thalamus where there were many neurons that stained intensely for AChE, but where there was an absence of ChAT-positive cells. No cholinergic perikarya were detected in the cerebral cortex, hippocampus, amygdala and dorsal diencephalon by either histochemical procedure. In the hindbrain, all the motoneurons constituting the well-established cranial nerve nuclei (III-VII, IX-XII) contained ChAT and exhibited intense staining for AChE. Further, a close correspondence was observed in the distribution of labeled neurons obtained by the two histochemical procedures in the midbrain and pontine tegmentum, including the laterodorsal tegmental nucleus, some areas in the caudal pontine and bulbar reticular formation, and the central gray of the closed medulla oblongata. On the other hand, AChE-intense cells were found in the nucleus raphe magnus, ventral part of gigantocellular reticular nucleus, and flocculus of the cerebellum, where ChAT-positive cells were rarely observed. According to both techniques, no positive cells were seen in the cerebellar nuclei, the pontine nuclei, or the nucleus reticularis tegmenti pontis. Large ventral horn motoneurons and, occasionally, cells in the intermediomedial zone of the cervical cord displayed ChAT-immunoreactivity and intense AChE staining. On the other hand, AChE-intense cells were detected in the dorsal portion of the lateral funiculus, but immunoreactive cells were not found in any portion of the spinal cord white matter.(ABSTRACT TRUNCATED AT 400 WORDS)

Central cholinergic pathways in the rat: an overview based on an alternative nomenclature (Ch1-Ch6)

Monoclonal antibodies to choline acetyltransferase and a histochemical method for the concurrent demonstration of acetylcholinesterase and horseradish peroxidase were used to investigate the organization of ascending cholinergic pathways in the central nervous system of the rat. The cortical mantle, the amygdaloid complex, the hippocampal formation, the olfactory bulb and the thalamic nuclei receive their cholinergic innervation principally, from cholinergic projection neurons of the basal forebrain and upper brainstem. On the basis of connectivity patterns, we subdivided these cholinergic neurons into six major sectors. The Ch1 and Ch2 sectors are contained within the medial septal nucleus and the vertical limb nucleus of the diagonal band, respectively. They provide the major cholinergic projections of the hippocampus. The Ch3 sector is contained mostly within the lateral portion of the horizontal limb nucleus of the diagonal band and provides the major cholinergic innervation to the olfactory bulb. The Ch4 sector includes cholinergic neurons in the nucleus basalis, and also within parts of the diagonal band nuclei. Neurons of the Ch4 sector provide the major cholinergic innervation of the cortical mantle and the amygdala. The Ch5-Ch6 sectors are contained mostly within the pedunculopontine nucleus of the pontomesencephalic reticular formation (Ch5) and within the laterodorsal tegmental gray of the periventricular area (Ch6). These sectors provide the major cholinergic innervation of the thalamus. The Ch5-Ch6 neurons also provide a minor component of the corticopetal cholinergic innervation. These central cholinergic pathways have been implicated in a variety of behaviors and especially in memory function. It appears that the age-related changes of memory function as well as some of the behavioral disturbances seen in the dementia of Alzheimer's Disease may be related to pathological alterations along central cholinergic pathways.

Mapping of cholinergic neurons associated with rat supraoptic nucleus: combined immunocytochemical and histochemical identification

Recent electrophysiological experiments have suggested that electrical stimulation of an area dorsolateral to the rat supraoptic nucleus (SON) activates a cholinergic pathway to the vasopressin neurons of the SON. As no detailed information is available concerning the distribution and projections of the cholinergic neurons in this area, we have sought to provide this using a combination of choline acetyltransferase (ChAT) immunocytochemistry and acetylcholinesterase (AChE) histochemistry. In some cases, these techniques were applied to the same neurons. Almost all neurons just outside of the SON that showed ChAT-like immunoreactivity also stained densely for AChE. These cells were distributed in a region dorsolateral to the SON. Light, punctate AChE staining around SON neurons was observed predominantly in the more ventral and posterior parts of the nucleus and were suggestive of synaptic terminals. Cholinergic fibres were found to enter the SON mainly from a lateral direction, turning in an anterior or posterior direction inside the nucleus. These results support the conclusion of earlier studies that the major cholinergic input to the SON arises in its immediate vicinity. We hypothesize that these ChAT/AChE-positive neurons are those responsible for cholinergically mediated, osmotically-stimulated release of vasopressin.

Cholinergic projections from the basal forebrain to the frontal cortex: a combined fluorescent tracer and immunohistochemical analysis in the rat

Cholinergic projections from the basal forebrain to some regions of the frontal cortex were studied by infusing propidium iodide (PI), a fluorescent tracer, into areas 6 and 10 and microscopically assessing the cellular co-localization of PI and immunohistochemically demonstrated choline-O-acetyltransferase (ChAT). The same brain sections were additionally processed for acetylcholinesterase (AChE, pharmacohistochemical regimen) and Nissl material (cresyl violet stain). Basal forebrain neurons projecting to the frontal cortex were found primarily in nucleus basalis, but others were located in association with the substantia innominata/lateral preoptic area, magnocellular preoptic area, and ansa lenticularis. These projection neurons were large (greater than 25 micrometers in maximum soma extent), demonstrated ChAT-like immunoreactivity, stained intensely for AChE following systemic administration of bis-(1-methylethyl)phosphorofluoridate, and were highly chromophilic.

Neurones localized with antibodies against choline acetyltransferase in the enteric nervous system

This is the first report of the histochemical localization of peripheral neurones with antibodies raised against choline acetyltransferase. The antiserum was raised in a rat against the enzyme purified from porcine brain. An indirect immunohistochemical technique was used to localize nerve cell bodies and nerve fibres in the stomach, small intestine and colon of the guinea-pig and the mouse small intestine. Reactive nerve cell bodies were found in both the myenteric and submucous ganglia. Varicose nerve fibres were in the ganglia, in the circular smooth muscle and in the mucosa of the small intestine.

Cholinergic neurons in the rat cerebral cortex demonstrated by immunohistochemical localization of choline acetyltransferase

The presence of cholinergic neurons in rat cerebral cortex was demonstrated by immunohistochemical localization of choline acetyltransferase, the enzyme synthesizing the neurotransmitter acetylcholine. The stained neurons were found throughout the entire cortex and were present in layers II--VI. Two morphological distinct classes of cholinergic neurons have been identified and compared with those neurons containing acetylcholinesterase.

Direct reciprocal connections between the bed nucleus of the stria terminalis and dorsomedial medulla oblongata: evidence from immunohistochemical detection of tracer proteins

Connections between the bed nucleus of the stria terminalis and the dorsomedial medulla oblongata have been examined by immunohistochemical detection of the tracer proteins horseradish peroxidase (HRP) or wheat germ agglutinin (WGA). Two sets of four rats received 0.2 or 0.4 microliter of either tracer injected into the dorsomedial medulla oblongata, were fixed by perfusion 48 hours later, and were processed for immunohistochemical detection of the tracers. Rats receiving HRP showed only a few single neurons retrogradely labelled in the ipsilateral bed nucleus, and some anterogradely labelled fibers. Rats receiving WGA showed a large number of retrogradely labelled neurons in the ipsilateral bed nucleus. Labelled neurons were most concentrated in a group in the central, dorsal, and lateral aspects of the nucleus at the level of the anterior commissure and just caudal to this. Just ventral to this group was a dense cluster of anterogradely labelled fibers. The retrogradely labelled neurons ranged from 12 to 20 microns in size and were multipolar. These findings indicate that there are direct reciprocal connections between the bed nucleus of the stria terminalis and the autonomic centers of the dorsomedial medulla oblongata and strengthen the concept that this nucleus is involved in forebrain integration of autonomic functions.