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J C Lauterborn

Publications and source records attributed to J C Lauterborn.

At least 19 recordsLinked to original sources
PubMed2000

Positive modulation of AMPA receptors increases neurotrophin expression by hippocampal and cortical neurons.

This study investigated whether positive modulators of AMPA-type glutamate receptors influence neurotrophin expression by forebrain neurons. Treatments with the ampakine CX614 markedly and reversibly increased brain-derived neurotrophic factor (BDNF) mRNA and protein levels in cultured rat entorhinal/hippocampal slices. Acute effects of CX614 were dose dependent over the range in which the drug increased synchronous neuronal discharges; threshold concentrations for acute responses had large effects on mRNA content when applied for 3 d. Comparable results were obtained with a second, structurally distinct ampakine CX546. Ampakine-induced upregulation was broadly suppressed by AMPA, but not NMDA, receptor antagonists and by reducing transmitter release. Antagonism of L-type voltage-sensitive calcium channels blocked induction in entorhinal cortex but not hippocampus. Prolonged infusions of suprathreshold ampakine concentrations produced peak BDNF mRNA levels at 12 hr and a return to baseline levels by 48 hr. In contrast, BDNF protein remained elevated throughout a 48 hr incubation with the drug. Nerve growth factor mRNA levels also were increased by ampakines but with a much more rapid return to control levels during chronic administration. Finally, intraperitoneal injections of CX546 increased hippocampal BDNF mRNA levels in aged rats and middle-aged mice. The present results provide evidence of regional differences in mechanisms via which activity regulates neurotrophin expression. Moreover, these data establish that changes in synaptic potency produce sufficient network level physiological effects for inducing neurotrophin genes, indicate that the response becomes refractory during prolonged ampakine exposure, and raise the possibility of using positive AMPA modulators to regulate neurotrophin levels in aged brain.

Aging↗
PubMed1999

Subpopulations of striatal interneurons can be distinguished on the basis of neurotrophic factor expression.

Substantial evidence supports a role for trophic activities in the function and survival of fully mature striatal neurons, but little is known regarding trophic factor expression in adult striatum. In situ hybridization was used to identify the distribution and the neurotransmitter phenotypes (i.e., cholinergic and gamma-aminobutyric acid [GABA]-ergic) of cells expressing acidic fibroblast growth factor (aFGF), glial cell line-derived neurotrophic factor (GDNF), or nerve growth factor (NGF) mRNA in adult rat striatum. Each trophic factor mRNA was localized to large, sparsely scattered striatal cells that corresponded to interneurons. Double-labeling studies demonstrated that NGF mRNA was expressed by GABAergic and never by cholinergic cells, whereas aFGF and GDNF mRNAs were expressed by both cell types. Approximately 75% of aFGF+ and GDNF+ cells in dorsal striatum and 46% of aFGF+ and 61% of GDNF+ cells in ventral striatum were cholinergic. Conversely, about 32% of aFGF+ and 24% of GDNF+ cells in dorsal striatum and 55% of aFGF+ and 27% of GDNF+ cells in ventral striatum were GABAergic. A portion of aFGF+ and NGF+ cells was of the parvalbumin GABAergic subtype. The colocalization of trophic factor expression was also examined. Of aFGF+ cells, 20% and 41% were NGF+ and 67% and 83% were GDNF+ in dorsal and ventral striata, respectively. These findings demonstrate that aFGF, GDNF, and NGF are synthesized by discrete but overlapping populations of striatal interneurons. The expression of these survival factors may contribute to the resistance of striatal interneurons to various insults including excitotoxicity.

Animals↗
PubMed1998

Transcript-specific effects of adrenalectomy on seizure-induced BDNF expression in rat hippocampus.

Activity-induced brain-derived neurotrophic factor (BDNF) expression is negatively modulated by circulating adrenal steroids. The rat BDNF gene gives rise to four major transcript forms that each contain a unique 5' exon (I-IV) and a common 3' exon (V) that codes for BDNF protein. Exon-specific in situ hybridization was used to determine if adrenalectomy has differential effects on basal and activity-induced BDNF transcript expression in hippocampus. Adrenalectomy alone had only modest effects on BDNF mRNA levels with slight increases in exon III-containing mRNA with 7-10-day survival and in exon II-containing mRNA with 30-days survival. In the dentate gyrus granule cells, adrenalectomy markedly potentiated increases in exon I and II cRNA labeling, but not increases in exon III and IV cRNA labeling, elicited by one hippocampal afterdischarge. Similarly, for the granule cells and CA1 pyramidal cells, hilus lesion (HL)-induced recurrent limbic seizures elicited greater increases in exon I and II cRNA hybridization in adrenalectomized (ADX) as compared to adrenal-intact rats. In this paradigm, adrenalectomy modestly potentiated the increase in exon III-containing mRNA in CA1 but had no effect on exon IV-containing mRNA content. These results demonstrate that the negative effects of adrenal hormones on activity-induced BDNF expression are by far the greatest for transcripts containing exons I and II. Together with evidence for region-specific transcript expression, these results suggest that the effects of stress on adaptive changes in BDNF signalling will be greatest for neurons that predominantly express transcripts I and II.

Adrenal Cortex Hormones↗
PubMed1998

Lysosomal dysfunction reduces brain-derived neurotrophic factor expression.

Brain-derived neurotrophic factor (BDNF) expression in hippocampus and cortex is considerably reduced in Alzheimer's disease. The present study tested if lysosomal disturbances, a concomitant of brain aging, impair basal and/or induced expression of BDNF. Cultured hippocampal slices were incubated with N- CBZ-L-phenylalanyl-L-alanine-diazomethylketone (ZPAD), an inhibitor of cathepsins B and L, for 6 days and processed for in situ hybridization using radiolabeled cRNA probes against BDNF mRNA. Multiple densitometric readings were collected from each of the three principal hippocampal subdivisions. Within-slice averages were substantially lower in the ZPAD-treated group compared to controls. Treatment with the inhibitor did not change average neuron diameter or packing density. Intense stimulation of glutamate receptors with kainate for 30 min (followed by a 90-min recovery period) caused a nearly threefold increase in BDNF mRNA concentrations in the dentate gyrus while having only marginal effects in the other subdivisions. Slice averages of ZPAD-exposed cultures treated with kainate were lower than those of controls exposed to the excitotoxin; however, on a percentage basis, the kainate-induced increase in the dentate gyrus was comparable for the two groups (175 +/- 31 vs 179 +/- 39%). Kainate for 1 h (with a 5-h recovery) affected BDNF mRNA in a manner similar to that found with shorter infusions, i.e., induction in stratum granulosum but not elsewhere, lower overall slice averages with ZPAD treatment, and no evidence that ZPAD blocked the percentage increase in the dentate gyrus. These results provide evidence that lysosomal dysfunction occurring during brain aging could disrupt ongoing BDNF production without substantially impairing the neurotrophin response to intense physiological activity. The first observation suggests a plausible aging sequence leading to pathology while the second may be of interest with regard to possible therapeutics.

Aging↗
PubMed1998

Neonatal treatment with 192 IgG-saporin produces long-term forebrain cholinergic deficits and reduces dendritic branching and spine density of neocortical pyramidal neurons.

The role of basal forebrain-derived cholinergic afferents in the development of neocortex was studied in postnatal rats. Newborn rat pups received intraventricular injections of 192 IgG-saporin. Following survival periods ranging from 2 days to 6 months, the brains were processed to document the cholinergic lesion and to examine morphological consequences. Immunocytochemistry for choline acetyltransferase (ChAT) and in situ hybridization for ChAT mRNA demonstrate a loss of approximately 75% of the cholinergic neurons in the medial septum and nucleus of the diagonal band of Broca in the basal forebrain. In situ hybridization for glutamic acid decarboxylase mRNA reveals no loss of basal forebrain GABAergic neurons. Acetylcholinesterase histochemistry demonstrates a marked reduction of the cholinergic axons in neocortex. Cholinergic axons are reduced throughout the cortical layers; this reduction is more marked in medial than in lateral cortical areas. The thickness of neocortex is reduced by approximately 10%. Retrograde labeling of layer V cortico-collicular pyramidal cells reveals a reduction in cell body size and also a reduction in numbers of branches of apical dendrites. Spine densities on apical dendrites are reduced by approximately 20-25% in 192 IgG-saporin-treated cases; no change was detected in number of spines on basal dendrites. These results indicate a developmental or maintenance role for cholinergic afferents to cerebral cortical neurons.

Acetylcholinesterase↗
PubMed1998

Anterograde transport of neurotrophin proteins in the CNS--a reassessment of the neurotrophic hypothesis.

The basic tenets of the neurotrophic hypothesis are that i) limiting quantities of a given factor are produced in specific target tissues; ii) responsive neurons projecting to these targets compete for the limiting amounts of the factor; iii) the factor is bound within the target by selective receptors on afferent terminals, internalized, and retrogradely transported to the neuronal cell body where it provides signals affecting neuronal survival and differentiation. Although originally formulated on the basis of evidence for NGF's actions on peripheral sensory and sympathetic neurons, the neurotrophic hypothesis appeared to be upheld for CNS neuronal systems as well, where NGF was found to function primarily as a target-derived trophic factor for basal forebrain cholinergic neurons. With the discovery of additional neurotrophins sharing considerable structural homology with NGF, the question arose of whether the neurotrophic hypothesis held true for all members of this protein family. Recent investigations into the localization and function of neurotrophins other than NGF, particularly BDNF and NT-3, have provided evidence indicating that these molecules may not act in a manner consistent with the neurotrophic hypothesis, as originally postulated. Numerous studies in the peripheral and central nervous systems have now demonstrated that BDNF (and NT-3) may be preferentially trafficked anterogradely along axonal processes and stored within pre-synaptic terminals. Other studies have suggested that these factors may be released in an activity-dependent, rather than constitutive, manner and can act in autocrine or paracrine fashions to subserve an assortment of biological functions including anterograde effects on cell survival and differentiation, as well as more novel roles in synaptic transmission. These recent findings strongly suggest that, while the various neurotrophin proteins may be grouped into a single family based upon their structural homology, they should be considered as a heterogeneous group of trophic factors based upon function and mode of action.

Animals↗
PubMed1997

Distribution of brain-derived neurotrophic factor (BDNF) protein and mRNA in the normal adult rat CNS: evidence for anterograde axonal transport.

A sensitive immunohistochemical technique was used, along with highly specific affinity-purified antibodies to brain-derived neurotrophic factor (BDNF), to generate a detailed mapping of BDNF immunoreactivity (BDNF-ir) throughout the adult rat CNS. A parallel analysis of sites of BDNF synthesis was performed with in situ hybridization techniques using a cRNA probe to the exon encoding mature rat BDNF protein. These combined data revealed (1) groups of cell bodies containing diffuse BDNF-ir throughout the CNS that were strongly correlated with fields of cells containing BDNF mRNA; (2) varying degrees of BDNF-ir outside of cell bodies, in what appeared to be fibers and/or terminals; and (3) many regions containing extremely heavy BDNF-immunoreactive fiber/terminal labeling that lacked BDNF mRNA (e.g., medial habenula, central nucleus of the amygdala, bed nucleus of stria terminalis, lateral septum, and spinal cord). The latter observation suggested that in these regions BDNF was derived from anterograde axonal transport by afferent systems. In the two cases in which this hypothesis was tested by the elimination of select afferents, BDNF immunostaining was completely eliminated. These data, along with the observation that BDNF-ir was rarely found within dendrites or fibers en passage, suggest that BDNF protein produced in adult CNS neurons is polarized primarily along axonal processes and is preferentially stored in terminals within the innervation target.

Animals↗
PubMed1996

Differential effects of protein synthesis inhibition on the activity-dependent expression of BDNF transcripts: evidence for immediate-early gene responses from specific promoters.

In the adult rat forebrain, brain-derived neurotrophic factor (BDNF) expression is very rapidly induced by neuronal activity, suggesting that this might occur without intervening protein synthesis. The rat BDNF gene has four differentially regulated promoter regions; each gives rise to an mRNA containing a unique 5' exon (I-IV) and a common 3' exon (V) that codes for mature BDNF protein. The present study used exon-specific in situ hybridization and both in vivo and in vitro preparations to determine whether activity induces BDNF as an "immediate-early gene" (IEG) from specific promoter regions and to compare the regulation of BDNF and nerve growth factor (NGF). In cultured hippocampal slices, kainic acid markedly increased pan-BDNF (exon V) and NGF mRNA content; cycloheximide attenuated the effect of kainic acid on both. In vivo stimulation of a paroxysmal afterdischarge increased both pan-BDNF and NGF mRNA levels in the dentate gyrus granule cells; pretreatment with anisomycin modestly attenuated the paroxysmal afterdischarge-induced increase of both transcripts. To determine whether partial drug effects on BDNF expression reflect the differential regulation of transcript species, levels of mRNAs containing exons I-IV were evaluated. A single afterdischarge increased exon I-IV-containing mRNA levels; anisomycin significantly attenuated the increase in exon I- and II-containing mRNAs but had no effect on the increase in exon III- and IV-containing mRNAs. These data show that for mature forebrain neurons, activity induces the expression of BDNF exon III- and IV-containing transcripts as IEG responses.

Animals↗
PubMed1996

Acidic fibroblast growth factor mRNA is expressed by basal forebrain and striatal cholinergic neurons.

Evidence for the importance of the basal forebrain cholinergic system in the maintenance of cognitive function has stimulated efforts to identify trophic mechanisms that protect this cell population from atrophy and dysfunction associated with aging and disease. Acidic fibroblast growth factor (aFGF) has been reported to support cholinergic neuronal survival and has been localized in basal forebrain with the use of immunohistochemical techniques. Although these data indicate that aFGF is present in regions containing cholinergic cell bodies, the actual site of synthesis of this factor has yet to be determined. In the present study, in situ hybridization techniques were used to evaluate the distribution and possible colocalization of mRNAs for aFGF and the cholinergic neuron marker choline acetyltransferase (ChAT) in basal forebrain and striatum. In single-labeling preparations, aFGF mRNA-containing neurons were found to be codistributed with ChAT mRNA+ cells throughout all fields of basal forebrain, including the medial septum/diagonal band complex and striatum. By using a double-labeling (colormetric and isotopic) technique, high levels of colocalization (over 85%) of aFGF and ChAT mRNAs were observed in the medial septum, the diagonal bands of Broca, the magnocellular preoptic area, and the nucleus basalis of Meynert. The degree of colocalization was lower in the striatum, with 64% of the cholinergic cells in the caudate and 33% in the ventral striatum and olfactory tubercle labeled by the aFGF cRNA. These data demonstrate substantial regionally specific patterns of colocalization and support the hypothesis that, via an autocrine mechanism, aFGF provides local trophic support for cholinergic neurons in the basal forebrain and the striatum.

Animals↗
PubMed1995

NGF mRNA is expressed by GABAergic but not cholinergic neurons in rat basal forebrain.

Nerve growth factor (NGF) supports the survival and biosynthetic activities of basal forebrain cholinergic neurons and is expressed by neurons within lateral aspects of this system including the horizontal limb of the diagonal bands and magnocellular preoptic areas. In the present study, colormetric and isotopic in situ hybridization techniques were combined to identify the neurotransmitter phenotype of the NGF-producing cells in these two areas. Adult rat forebrain tissue was processed for the colocalization of mRNA for NGF with mRNA for either choline acetyltransferase, a cholinergic cell marker, or glutamic acid decarboxylase, a GABAergic cell marker. In both regions, many neurons were single-labeled for choline acetyltransferase mRNA, but cells containing both choline acetyltransferase and NGF mRNA were not detected. In these fields, virtually all NGF mRNA-positive neurons contained glutamic acid decarboxylase mRNA. The double-labeled cells comprised a subpopulation of GABAergic neurons; numerous cells labeled with glutamic acid decarboxylase cRNA alone were codistributed with the double-labeled neurons. These data demonstrate that in basal forebrain GABAergic neurons are the principal source of locally produced NGF.

Acetylcholine↗
PubMed1995

Expression of agrin mRNA is altered following seizures in adult rat brain.

Agrin mRNA is broadly distributed throughout the adult rat brain, consistent with its proposed role in synaptogenesis and the organization of synaptic proteins in the central nervous system. The present study examined the effect of neuronal activity on agrin mRNA expression in adult rat forebrain using the hilus lesion paradigm for seizure induction and in situ hybridization and polymerase chain reaction techniques for quantification and characterization of agrin mRNA content. Seizures induced rapid, prolonged, and region-specific changes in agrin mRNA expression with the most prominent alterations occurring in hippocampal and cortical neurons. However, there were no detectable perturbations in the relative abundance of alternatively spliced agrin transcripts in affected brain regions. Activity-dependent changes in agrin expression suggest a role for this protein in modifications of synaptic structure associated with functional synaptic plasticity.

Agrin↗
PubMed1995

A subpopulation of striatal gabaergic neurons expresses the epidermal growth factor receptor.

Epidermal growth factor and transforming growth factor alpha are mitogenic polypeptides that act at the epidermal growth factor receptor, a protein tyrosine kinase.10,16,18,24 Studies have shown that epidermal growth factor and transforming growth factor alpha support the survival and promote the differentiation of central nervous system neurons in vitro.13,21,33 Messenger RNAs for both transforming growth factor alpha and the epidermal growth factor receptor have been identified in the adult and developing mammalian central nervous system, particularly within the neostriatum of young animals.11,15,27,28,30 However, the cell types that synthesize these messenger RNAs in striatum are not well understood. The present study investigates the hypothesis that epidermal growth factor receptor and transforming growth factor alpha are synthesized by striatal GABAergic neurons using double-labeling in situ hybridization in the rat. Most neurons within the neostriatum that intensely expressed messenger RNA for the 67,000 mol. wt isoform of glutamate decarboxylase also expressed messenger RNA for the epidermal growth factor receptor. Scattered striatal cells with neuronal morphology were immunoreactive for epidermal growth factor receptor protein, indicating that epidermal growth factor receptor messenger RNA expressed by striatal neurons is translated. Striatal neurons that expressed high levels of the 67,000 mol. wt isoform of glutamate decarboxylate messenger RNA did not appear to express transforming growth factor alpha messenger RNA. The present study indicates that epidermal growth factor receptor is synthesized by a subpopulation of GABAergic striatal neurons, supporting the hypothesis that transforming growth factor alpha and epidermal growth factor act directly upon neurons to produce their neurotrophic effects. These neurons may be GABAergic interneurons, which have been shown to be relatively resistant to degeneration in Huntington's disease and excitotoxic models of this disease.6,1,9

Animals↗
PubMed1994

Seizure-induced increases in NGF mRNA exhibit different time courses across forebrain regions and are biphasic in hippocampus.

In the present study, in situ hybridization and S1 nuclease protection analyses were used to evaluate the temporal and spatial parameters of changes in nerve growth factor (NGF) mRNA expression in rat forebrain following hilus lesion-induced recurrent limbic seizures. Seizure-induced increases in NGF mRNA levels were widespread with differences in the temporal parameters of change between brain areas. There were two distinct increases in NGF cRNA hybridization in dentate gyrus stratum granulosum. Hybridization was increased several-fold by 6 h after a seizure-producing hilus lesion (HL), declined to below control values by 12 h post-HL, and then increased again by 24 h post-HL, or 12 h after the termination of seizures. This biphasic increase was corroborated by S1 nuclease protection analysis. In entorhinal cortex, cingulate cortex and neocortex NGF cRNA hybridization was markedly increased first in layers II/III by 6-12 h post-HL and progressed to layers V/VI by 24 h post-HL. Striking increases in NGF mRNA were detected in the majority of amygdaloid nuclei beginning with the cortical nuclei by 12 h postlesion and extending into the more deeply placed nuclei by 24 h postlesion. Labeling was increased in sparsely distributed neurons in the caudate putamen, ventral pallidum, and tenia tecta at 24 h post-HL. In all areas, hybridization declined to control values by 48-96 h post-HL. NGF expression was not changed in some forebrain regions which normally contain NGF mRNA including the diagonal bands of Broca and select thalamic nuclei. These data demonstrate that seizures stimulate NGF expression in many different types of neurons. Moreover, regional differences in the time courses of induction suggest that distinct regulatory mechanisms subserve activity-dependent changes in NGF mRNA expression in different neuronal populations.

Animals↗
PubMed1994

Cellular localization of NGF and NT-3 mRNAs in postnatal rat forebrain.

The presence of transiently elevated levels of mRNA for nerve growth factor (NGF) and neurotrophin-3 (NT-3) in postnatal development of several brain areas suggests that these factors may be expressed by a greater number of cell types in the immature than in the adult brain. To evaluate this possibility, in situ hybridization was used to determine the cellular localization of NGF mRNA and NT-3 mRNA in hippocampus, cingulate cortex, posterolateral neocortex, thalamus, and cerebellum of postnatal rat. In areas expressing both neurotrophins (i.e., hippocampus, cingulate cortex, and anteroventral thalamus), NT-3 mRNA was detected at earlier ages than NGF mRNA. Patterns of hybridization in hippocampus and cerebellum indicate that NT-3 is expressed by neurons soon after leaving the mitotic cycle whereas NGF expression is a feature of more mature neurons. The exception to this pattern was NGF expression in the lateral geniculate nuclei which was present by Postnatal Day 1 and retained in the adult. Both neurotrophins were transiently expressed in several brain areas. The loss of expression with age was most striking in thalamus with transient expression of NT-3 mRNA by the majority of dorsal thalamic relay nuclei and of NGF mRNA by fewer nuclei including the posterior, anteroventral, ventrolateral, and ventromedial nuclei. NT-3 expression also was transient in caudal cingulate/retrosplenial cortex, hippocampal CA3 stratum pyramidale, and the granule cells of archicerebellum. In early postnatal cingulate and retrosplenial cortices there were reciprocal rostrocaudal gradients of NGF and NT-3 expression. These results suggest both distinct and overlapping functions for NT-3 and NGF in early developmental processes including involvement of NT-3 in cerebellar development and of NGF in the development and maintenance of visual afferents to thalamus. Patterns of neurotrophin expression in medial limbic cortex may establish trophic gradients which influence the topography of thalamic innervation.

Aging↗
PubMed1994

Localization and alternative splicing of agrin mRNA in adult rat brain: transcripts encoding isoforms that aggregate acetylcholine receptors are not restricted to cholinergic regions.

Agrin is a protein implicated in the formation and maintenance of the neuromuscular junction. In addition to motor neurons, agrin mRNA has been detected in the brains of embryonic rat and chick and adult marine ray, suggesting that this molecule may also be involved in the formation of synapses between neurons. As a step toward understanding agrin's role in the CNS, we utilized Northern blot and in situ hybridization techniques to analyze the regional distribution and cellular localization of agrin mRNA in the spinal cord and brain of adult rats. The results of these studies indicate that the agrin mRNA is expressed predominantly by neurons broadly distributed throughout the adult CNS. Moreover, expression of agrin mRNA is not restricted to cholinergic structures or regions of the brain receiving cholinergic input. Recently, RNA isolated from rat embryonic spinal cord was shown to contain four alternatively spliced agrin mRNAs, referred to as agrin0, agrin8, agrin11, and agrin19, each of which encodes agrin proteins that are active in acetylcholine receptor aggregating assays (Ferns et al., 1992). Using the polymerase chain reaction we demonstrate that all four of these agrin transcripts are expressed within the adult CNS. Agrin0, agrin8, and agrin19 were present in all regions analyzed. In contrast, agrin11 was detected only in forebrain. Results of these studies indicate that both the level of expression and pattern of alternative splicing of agrin mRNA are differentially regulated in the brain. The broad and predominantly neuronal distribution of agrin mRNA in the adult brain suggests that, in addition to its role at the neuromuscular junction, agrin may play a role in formation and maintenance of synapses between neurons in the CNS.

Agrin↗
PubMed1993

Nerve growth factor mRNA is expressed by GABAergic neurons in rat hippocampus.

Isotopic and colorimetric in situ hybridization techniques were combined to determine if nerve growth factor (NGF) mRNA is colocalized with mRNA for the GABA biosynthetic enzyme glutamic acid decarboxylase (GAD) in adult rat hippocampus. Quantification of neurons labeled with both 35S-labeled GAD67 mRNA and digoxigenin-labeled NGF cRNA determined that of the NGF cRNA-labeled neurons, 97% within regions CA3-CA1, and 88% within the hilus, were also labeled with GAD67 cRNA. Overall, 47% of the total population of GAD67 cRNA labeled cells were NGF cRNA positive. The greater portion of stratum granulosum was lightly labeled by the NGF cRNA alone. The results indicate that, excepting stratum granulosum, NGF is predominantly synthesized by GABAergic neurons in rat hippocampus.

Animals↗
PubMed1993

In situ hybridization localization of choline acetyltransferase mRNA in adult rat brain and spinal cord.

The cellular distribution of choline acetyltransferase (ChAT) mRNA within the adult rat central nervous system was evaluated using in situ hybridization. In forebrain, hybridization of a 35S-labeled rat ChAT cRNA densely labeled neurons in the well-characterized basal forebrain cholinergic system including the medial septal nucleus, diagonal bands of Broca, nucleus basalis of Meynert and substantia innominata, as well as in the striatum, ventral pallidum, and olfactory tubercle. A small number of lightly labeled neurons were distributed throughout neocortex, primarily in superficial layers. No cellular labeling was detected in hippocampus. In the diencephalon, dense hybridization labeled neurons in the ventral aspect of the medial habenular nucleus whereas cells in the lateral hypothalamic area and supramammillary region were more lightly labeled. Hybridization was most dense in neurons of the motor and autonomic cranial nerve nuclei including the oculomotor, Edinger-Westphal, and trochlear nuclei of the midbrain, the abducens, superior salivatory, trigeminal, facial and accessory facial nuclei of the pons, and the hypoglossal, vagus, and solitary nuclei and nucleus ambiguous of the medulla. In addition, numerous cells in the pedunculopontine and laterodorsal tegmental nuclei, the ventral nucleus of the lateral lemniscus, the medial and lateral divisions of the parabrachial nucleus, and the medial and lateral superior olive were labeled. Occasional labeled neurons were distributed in the giantocellular, intermediate, and parvocellular reticular nuclei, and the raphe magnus nucleus. In the medulla, light to moderately densely labeled cells were scattered in the nucleus of Probst's bundle, the medial vestibular nucleus, the lateral reticular nucleus, and the raphe obscurus nucleus. In spinal cord, the cRNA densely labeled motor neurons of the ventral horn, and cells in the intermediolateral column, surrounding the central canal, and in the spinal accessory nucleus. These results are in good agreement with reports of the immunohistochemical localization of ChAT and provide further evidence that cholinergic neurons are present within neocortex but not hippocampus.

Animals↗