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D B Rye

Publications and source records attributed to D B Rye.

At least 37 records · Page 2Linked to original sources
PubMed1997

Serotonergic dorsal raphe nucleus projections to the cholinergic and noncholinergic neurons of the pedunculopontine tegmental region: a light and electron microscopic anterograde tracing and immunohistochemical study.

The serotonergic dorsal raphe nucleus is considered an important modulator of state-dependent neural activity via projections to cholinergic neurons of the pedunculopontine tegmental nucleus (PPT). Light and electron microscopic analysis of anterogradely transported biotinylated dextran, combined with choline acetyltransferase (ChAT) immunohistochemistry, were employed to describe the synaptic organization of mesopontine projections from the dorsal raphe to the PPT. In a separate set of experiments, we utilized immunohistochemistry for the serotonin transporter (SERT), combined with ChAT immunohistochemistry at the light and electron microscopic levels, to determine whether PPT neurons receive serotonergic innervation. The results of these studies indicate that: (1) anterogradely labeled and SERT-immunoreactive axons and presumptive boutons invest the PPT at the light microscopic level; (2) at the ultrastructural level, dorsal raphe terminals in the PPT pars compacta synapse mainly with dendrites and axosomatic contacts were not observed; (3) approximately 12% of dorsal raphe terminals synapse with ChAT-immunoreactive dendrites; and (4) at least 2-4% of the total synaptic input to ChAT-immunoreactive dendrites is of dorsal raphe and/or serotonergic origin. This serotonergic dorsal raphe innervation may modulate cholinergic PPT neurons during alterations in behavioral state. The role of these projections in the initiation of rapid eye movement (REM) sleep and the ponto-geniculo-occipital waves that precede and accompany REM sleep is discussed.

Acetylcholine↗
PubMed1997

Immunochemical analysis of dopamine transporter protein in Parkinson's disease.

The plasma membrane dopamine transporter (DAT) is considered to be a reliable marker of presynaptic dopaminergic terminal loss. Previous in vivo imaging and postmortem binding studies have detected a loss in striatal DAT binding in Parkinson's diseased (PD) brain; however, these techniques have poor spatial resolution and may suffer from nonspecific binding of some ligands. In this study, we use novel highly specific monoclonal antibodies to distinct epitopes of human DAT to quantify and localize the protein. Western blot analysis revealed marked reductions in DAT immunoreactivity in putamen, caudate, and nucleus accumbens of PD brain compared with control cases, and the reductions were significantly correlated to disease duration. Immunohistochemistry revealed DAT-immunoreactive fibers and puncta that were dense throughout the striatum of control brains but that were drastically reduced in putamen of PD brains. Caudate from PD brains showed a significant degree of sparing along the border of the ventricle, and the nucleus accumbens was relatively preserved. An unexpected finding was that discrete islands of DAT immunoreactivity were preserved within the matrix of PD putamen. Thus, immunological analysis of DAT protein provides novel and sensitive means for localizing and quantifying DAT protein in PD and other neurological disorders involving dopaminergic systems.

Aged↗
PubMed1997

Presenilin-1 protein expression in familial and sporadic Alzheimer's disease.

Mutations of the presenilin PS1 and PS2 genes are closely linked to aggressive forms of early-onset (< 60 years) familial Alzheimer's disease. A highly specific monoclonal antibody was developed to identify and characterize the native PS1 protein. Western blot analyses revealed a predominant 32-kd immunoreactive polypeptide in a variety of samples, including PC12 cells transfected with human PS1 complementary DNA, brain biopsy specimens from demented patients, and postmortem samples of frontal neocortex from early-onset familial Alzheimer's disease cases (PS1 and PS2), late-onset sporadic Alzheimer's disease cases, and cases of other degenerative disorders. This truncated polypeptide contains the N-terminus of PS1 and appeared unchanged across cases. In 2 early-onset cases linked to missense mutations in the PS1 gene, a PS1 immunoreactive protein (approximately 49 kd) accumulated in the frontal cortex. This protein was similar in size to full-length PS1 protein present in transfected cells overexpressing PS1 complementary DNA, and in lymphocytes from an affected individual with a deletion of exon 9 of the PS1 gene, suggesting that mutations of the PS1 gene peturb the endoproteolytic processing of the protein. Immunohistochemical studies of control brains revealed that PS1 is expressed primarily in neurons, with the protein localized in the soma and dendritic processes. In contrast, PS1 showed striking localization to the neuropathology in early-onset familial Alzheimer's disease and sporadic Alzheimers' disease cases. PS1 immunoreactivity was present in the neuritic component of senile plaques as well as in neurofibrillary tangles. Localization of PS1 immunoreactivity in familial and sporadic Alzheimer's disease suggests that genetically heterogeneous forms of the disease share a common pathophysiology involving PS1 protein.

Adult↗
PubMed1997

Contributions of the pedunculopontine region to normal and altered REM sleep.

The pedunculopontine (PPN) region of the upper brainstem is recognized as a critical modulator of activated behavioral states such as wakefulness and rapid eye movement (REM) sleep. The expression of REM sleep-related physiology (e.g. thalamocortical arousal, ponto-geniculate-occipital (PGO) waves, and atonia) depends upon a subpopulation of PPN neurons that release acetylcholine (ACh) to act upon muscarinic receptors (mAChRs). Serotonin's potent hyperpolarization of cholinergic PPN neurons is central to present working models of REM sleep control. A growing body of experimental evidence and clinical experience suggests that the responsiveness of the PPN region, and thereby modulation of REM sleep, involves closely adjacent glutamatergic neurons and alternate afferent neurotransmitters. Although many of these afferents are yet to be defined, dopamine-sensitive GABAergic pathways exiting the main output nuclei of the basal ganglia and adjacent forebrain nuclei appear to be the most conspicuous and the most likely to be clinically relevant. These GABAergic pathways are ideally sited to modulate the physiologic hallmarks of REM sleep differentially (e.g. atonia versus cortical activation), because each originates from a functionally unique forebrain circuit and terminates in a unique pattern upon brain stem neurons with unique membrane characteristics. Evidence is reviewed that changes in the quality, timing, and quantity of REM sleep that characterize narcolepsy, REM sleep behavior disorder, and neurodegenerative and affective disorders (depression and schizophrenia) reflect 1) changes in responsiveness of cells in the PPN region governed by these afferents; 2) increase or decrease in PPN cell number; or 3) mAChRs mediating increased responsiveness to ACh derived from the PPN. Auditory evoked potentials and acoustic startle responses provide means independent from recording sleep to assess pathophysiologies affecting the PPN and its connections and thereby complement investigations of their role in affecting daytime functions (e.g. arousal and attention).

Acetylcholine↗
PubMed1995

Disruptive nocturnal behavior in Parkinson's disease and Alzheimer's disease.

Disruptive nocturnal behavior, often referred to as sundowning, is a commonly encountered clinical problem in most forms of dementia. This study compared disruptive nocturnal behavior in patients with Alzheimer's disease (AD) and Parkinson's disease (PD). Questionnaire data were collected from 60 AD and 48 PD caregivers. Respondents were asked to record the typical time of day when any of seven disruptive behaviors were evidenced in their patients, if at all. Two scores were computed: (1) a sundowning score (number of nocturnal disruptive behaviors, range 0-7), and (2) a total score (number of disruptive behaviors without regard to time, range 0-7). Results indicated PD patients were more likely than AD patients to exhibit disruptive nocturnal behavior. The dose, timing, or number of years on antiparkinsonian medication were not related to nocturnal disruptive behavior within the PD patient group. These findings raise the possibility that sundowning in PD patients may be a manifestation of dopaminergic depletion within the basal ganglia or other abnormalities involving the cholinergic, serotoninergic and/or noradrenergic systems in the brainstem.

Aged↗
PubMed1995

Identification and characterization of antidepressant-sensitive serotonin transporter proteins using site-specific antibodies.

Serotonin (5HT) transporters (SERTs) are responsible for clearance of synaptic and plasma 5HT and are molecular targets for multiple therapeutic and addictive compounds. Recently brain and peripheral SERT cDNAs have been cloned and characterized functionally in transfected cells. Antipeptide (S365) and anti-fusion protein (CT-2) antibodies, directed at epitopes poorly conserved among other Na+/Cl- cotransporters, have been prepared to facilitate the identification and characterization of SERT proteins in native and transfected cells. Immunoprecipitations and immunoblots of rat/human SERT-transfected HeLa cells reveal specific SERT-immunoreactive glycoproteins absent from extracts of vector-transfected cells and absent when incubations were conducted using peptide- or fusion protein-absorbed antibody. In SDS-PAGE of membranes prepared from rat midbrain and cortex, SERTs migrate as single 76 kDa polypeptides with a relative abundance consistent with the known distribution of 5HT neurons and axonal projections. SERT-immunoreactive proteins are also detectable in platelet and pulmonary membranes, sites of peripheral 5HT uptake, but not in liver. Our studies also indicate that brain and platelet SERTs are formed from identical polypeptides differing significantly in their extent of N-linked glycosylation. Immunocytochemistry performed on rat brain sections with CT-2 antibody revealed SERT expression associated with brainstem raphe nuclei in a pattern virtually identical to that obtained by labeling adjacent sections with 5HT antisera. SERT-immunoreactive fibers were found to be widely distributed throughout the rodent brain, with highest density in forebrain regions known to receive a dense serotonergic innervation. In a similar manner, CT-2 antibody also detects endogenous expression of human SERT proteins, providing an opportunity for future studies on the modulation of transporter protein expression in neurologic and psychiatric disorders.

Animals↗
PubMed1993

Localization of D1 and D2 dopamine receptors in brain with subtype-specific antibodies.

Five or more dopamine receptor genes are expressed in brain. However, the pharmacological similarities of the encoded D1-D5 receptors have hindered studies of the localization and functions of the subtypes. To better understand the roles of the individual receptors, antibodies were raised against recombinant D1 and D2 proteins and were shown to bind to the receptor subtypes specifically in Western blot and immunoprecipitation studies. Each antibody reacted selectively with the respective receptor protein expressed both in cells transfected with the cDNAs and in brain. By immunocytochemistry, D1 and D2 had similar regional distributions in rat, monkey, and human brain, with the most intense staining in striatum, olfactory bulb, and substantia nigra. Within each region, however, the precise distributions of each subtype were distinct and often complementary. D1 and D2 were differentially enriched in striatal patch and matrix compartments, in selective layers of the olfactory bulb, and in either substantia nigra pars compacta or reticulata. Electron microscopy demonstrated that D1 and D2 also had highly selective subcellular distributions. In the rat neostriatum, the majority of D1 and D2 immunoreactivity was localized in postsynaptic sites in subsets of spiny dendrites and spine heads in rat neostriatum. Presynaptic D1 and D2 receptors were also observed, indicating both subtypes may regulate neurotransmitter release. D1 was also present in axon terminals in the substantia nigra. These results provide a morphological substrate for understanding the pre- and postsynaptic functions of the genetically defined D1 and D2 receptors in discrete neuronal circuits in mammalian brain.

Antibody Specificity↗
PubMed1993

Differences in the retinohypothalamic tract in albino Lewis versus brown Norway rat strains.

Differences in sleep-wake patterns in response to light-dark stimulation have been observed between albino Lewis and pigmented Brown Norway strains of rats, which may be associated with albinism. Since several anatomical differences have been demonstrated in the visual pathways of albino and pigmented mammals, the present study was undertaken to determine whether additional differences in visual pathways of these rat strains exist that might account for their behavioral differences. Using anterograde tracing techniques and image analysis, we have investigated the retinal projections of Lewis and Brown Norway rats. Our results demonstrate that the distribution of retinal terminals in the hypothalamic suprachiasmatic nucleus extends over a greater area in Lewis compared to Brown Norway rats. This zone of termination corresponds to a cytoarchitectonically definable ventrolateral subdivision of the suprachiasmatic nucleus (SCN), which is also greater in Lewis than in Brown Norway rats. These results may have implications for behaviors related to the SCN.

Albinism↗
PubMed1993

The distribution of Alz-50 immunoreactivity in the normal human brain.

Alz-50 is a monoclonal antibody that recognizes normal tau proteins as well as phosphorylated tau proteins that are associated with paired helical filaments in Alzheimer's disease. To establish an accurate baseline for future pathological studies, we examined the distribution of Alz-50 immunoreactivity in normal human brain from infancy to senescence. We found extensive staining patterns of somata and axonal profiles in the striatum, amygdala, hypothalamus, brainstem and spinal cord in all normals at all ages. Similar normal staining patterns were seen in the brains of patients who had suffered trauma, tumors, cerebral infarcts, grade 1 periventricular hemorrhages, and in those who had suffered from amyotrophic lateral sclerosis, Parkinson's disease, multi-systems atrophy and Shy-Drager syndrome. An absence of cell body staining and only minimal axonal staining was noted in the same brains with immunocytochemistry using PHF-1, a monoclonal antibody generated against paired helical filament proteins from Alzheimer brains. The characteristic staining pattern of Alz-50 in normal brains is substantially more extensive than has previously been recognized. This pattern, which presumably describes a specific class of tau proteins, must be distinguished from the pathological staining observed in neurodegenerative diseases.

Aging↗
PubMed1992

Afferent projections to the cholinergic pedunculopontine tegmental nucleus and adjacent midbrain extrapyramidal area in the albino rat. I. Retrograde tracing studies.

The afferent connections of the pedunculopontine tegmental nucleus (PPT) and the adjacent midbrain extrapyramidal area (MEA) were examined by retrograde tracing with wheat germ agglutinin-conjugated horseradish peroxidase (WGA-HRP). Major afferents to the PPT originate in the periaqueductal gray, central tegmental field, lateral hypothalamic area, dorsal raphe nucleus, superior colliculus, and pontine and medullary reticular fields. Other putative inputs originate in the paraventricular and preoptic hypothalamic nuclei, the zona incerta, nucleus of the solitary tract, central superior raphe nucleus, substantia innominata, posterior hypothalamic area, and thalamic parafascicular nucleus. The major afferent to the medially adjacent MEA originates in the lateral habenula, while other putative afferents include the perifornical and lateral hypothalamic area, periaqueductal gray, superior colliculus, pontine reticular formation, and dorsal raphe nucleus. MEA inputs from basal ganglia nuclei include moderate projections from the substantia nigra pars reticulata, entopeduncular nucleus, and a small projection from the globus pallidus, but not the subthalamic nucleus. Dense anterograde labeling was observed in the substantia nigra pars compacta, entopeduncular nucleus, subthalamic nucleus, globus pallidus, and caudate-putamen only following WGA-HRP injections involving the MEA. The results of this study demonstrate that the PPT and MEA share many potential afferents. Remarkable differences were found that support distinguishing between these two nuclei in future studies regarding the functional organization of the midbrain and pons. The results, for example, confirm our previous observations that the largely reciprocal connections between the midbrain and basal ganglia distinguish the MEA from the PPT. Afferents from the lateral habenula and contralateral superior colliculus represent extensions of more traditional basal ganglion circuitry which further delineate the MEA from the PPT. The results are discussed with respect to the important role of the midbrain and pons in behavioral state control and locomotor mechanisms.

Afferent Pathways↗
PubMed1991

Cortical asymmetry of REM sleep EEG following unilateral pontine hemorrhage.

A 24-year-old woman with a left pontine hematoma showed marked asymmetry in the EEG of REM sleep, suggesting that a unilateral pontine lesion is sufficient to disrupt normal REM sleep EEG in the ipsilateral hemisphere. Other REM sleep characteristics (rapid eye movements, muscle atonia) were unaffected by this lesion.

Adult↗
PubMed1988

Cholinergic vs. noncholinergic efferents from the mesopontine tegmentum to the extrapyramidal motor system nuclei.

Previous studies have suggested that the pedunculopontine tegmental nucleus (PPTn) is reciprocally connected with extrapyramidal motor system nuclei (EPMS) whereas other studies have implicated the PPTn in behavioral state control phenomena such as sleep-wakefulness cycles. Many of these studies define the nonprimate PPTn as an area of mesopontine tegmentum which is labeled from injections of anterograde tracers into the basal ganglia. Recently, we have defined the rat PPTn as a large-celled, cholinergic nucleus. The rat PPTn is cytologically distinct from a group of smaller, noncholinergic neurons that are medially adjacent to the PPTn. This noncholinergic group is further distinguished from the PPTn by its afferent input from the globus pallidus, entopeduncular nucleus, and substantia nigra. We refer to the latter area as the midbrain extrapyramidal area (MEA). Using combined choline acetyltransferase immunohistochemistry of the PPTn and WGA-HRP retrograde tracing from the EPMS, we investigated the efferent connections of the MEA and PPTn to the EPMS in the rat. The noncholinergic MEA, rather than the PPTn, is the major source of tegmental innervation to the globus pallidus, caudate-putamen, subthalamic nucleus, entopeduncular nucleus, substantia nigra, and motor cortex. In contrast, the cholinergic PPTn is the major source of tegmental innervation to the ventrolateral thalamic nucleus. This finding is in contradistinction to thalamic projections from the surrounding reticular formation, which are identified only after WGA-HRP injections into "nonspecific" thalamic nuclei. This body of evidence suggests that the noncholinergic MEA represents an additional component of the EPMS and may correspond to the "mesencephalic locomotor region." The cholinergic PPTn may play a role in more global thalamic functions such as the "reticular activating system" rather than a primary role in motor function.

Animals↗
PubMed1988

Medullary and spinal efferents of the pedunculopontine tegmental nucleus and adjacent mesopontine tegmentum in the rat.

The medullary and spinal efferents of the pedunculopontine tegmental nucleus and adjacent mesopontine tegmentum were investigated by employing (1) the anterograde autoradiographic methodology and (2) the retrograde transport of HRP and/or WGA-HRP in combination with choline acetyltransferase immunohistochemistry. The anterograde experiments identified five descending pathways from the mesopontine tegmentum: (1) Probst's tract, which descends in the dorsolateral reticular formation in close relation to the nucleus of the solitary tract; (2) a ventrolateral branch of Probst's tract that extends ventrolaterally alongside the spinal trigeminal nucleus; (3) a ventromedial branch of Probst's tract that extends ventromedially through the gigantocellular field of the medulla; (4) the medial reticulospinal tract, which descends in parallel with the medial longitudinal fasciculus and turns ventrolaterally along the dorsal surface of the inferior olive to enter the ventrolateral funiculus of the spinal cord; and (5) a crossed ventromedial pathway, which descends in a ventral paramedian position through the magnocellular field of the medulla. The origins of these pathways reflected a rough lateral-to-medial topography of mesopontine tegmental cell groups. The parabrachial nucleus, situated furthest laterally, for example, projected primarily through Probst's tract and its ventrolateral branch. The pedunculopontine tegmental nucleus, midbrain extrapyramidal area, and the subceruleal region, situated more medially, projected descending axons largely through the ventromedial branch of Probst's tract. The pontine tegmental field, situated furthest medially and ventromedially, was the largest contributor to the medial reticulospinal tract. The retrograde transport experiments confirmed these general organizational features. The combination of retrograde transport with choline acetyltransferase immunohistochemistry established that the cholinergic pedunculopontine tegmental nucleus contributes a large portion to the mesopontine tegmental innervation of the medullary reticular formation. A much smaller number of cholinergic pedunculopontine neurons project as far as the spinal cord. Spinal projections from the mesopontine tegmentum originate largely from non-cholinergic neurons of the midbrain extrapyramidal area, subceruleal region, Kölliker-Fuse division of the parabrachial nucleus, and pontine tegmental field.

Animals↗
PubMed1987

The origins of cholinergic and other subcortical afferents to the thalamus in the rat.

The origins of the cholinergic and other afferents of several thalamic nuclei were investigated in the rat by using the retrograde transport of wheat germ agglutinin conjugated-horseradish peroxidase in combination with the immunohistochemical localization of choline acetyltransferase immunoreactivity. Small injections placed into the reticular, ventral, laterodorsal, lateroposterior, posterior, mediodorsal, geniculate, and intralaminar nuclei resulted in several distinct patterns of retrograde labelling. As expected, the appropriate specific sensory and motor-related subcortical structures were retrogradely labelled after injections into the principal thalamic nuclei. In addition, other basal forebrain and brainstem structures were also labelled, with their distribution dependent on the site of injection. A large percentage of these latter projections was cholinergic. In the brainstem, the cholinergic pedunculopontine tegmental nucleus was retrogradely labelled after all thalamic injections, suggesting that it provides a widespread innervation to the thalamus. Neurons of the cholinergic laterodorsal tegmental nucleus were retrogradely labelled after injections into the anterior, laterodorsal, central medial, and mediodorsal nuclei, suggesting that it provides a projection to limbic components of the thalamus. Significant basal forebrain labelling occurred only with injections into the reticular and mediodorsal nuclei. Only injections into the reticular nucleus resulted in retrograde labelling of the cholinergic neurons in the nucleus basalis of Meynert. The results provide evidence for an organized system of thalamic afferents arising from cholinergic and noncholinergic structures in the brainstem and basal forebrain. The brainstem structures, especially the cholinergic pedunculopontine tegmental nucleus, appear to project directly to principal thalamic nuclei, thereby providing a possible anatomical substrate for mediating the well-known facilitory effects of brainstem stimulation upon thalamocortical transmission.

Acetylcholine↗
PubMed1987

Pedunculopontine tegmental nucleus of the rat: cytoarchitecture, cytochemistry, and some extrapyramidal connections of the mesopontine tegmentum.

The pedunculopontine tegmental nucleus (PPTn) was originally defined on cytoarchitectonic grounds in humans. We have employed cytoarchitectonic, cytochemical, and connectional criteria to define a homologous cell group in the rat. A detailed cytoarchitectonic delineation of the mesopontine tegmentum, including the PPTn, was performed employing tissue stained for Nissl substance. Choline acetyltransferase (ChAT) immunostained tissue was then analyzed in order to investigate the relationship of cholinergic perikarya, dendritic arborizations, and axonal trajectories within this cytoarchitectonic scheme. To confirm some of our cytoarchitectonic delineations, the relationships between neuronal elements staining for ChAT and tyrosine hydroxylase were investigated on tissue stained immunohistochemically for the simultaneous demonstration of these two enzymes. The PPTn consists of large, multipolar neurons, all of which stain immunohistochemically for ChAT. It is present within cross-sections that also include the A-6 through A-9 catecholamine cell groups and is traversed by catecholaminergic axons within the dorsal tegmental bundle and central tegmental tract. The dendrites of PPTn neurons respect several nuclear boundaries and are oriented perpendicularly to several well-defined fiber tracts. Cholinergic axons ascend from the mesopontine tegmentum through the dorsal tegmental bundle and a more lateral dorsal ascending pathway. A portion of the latter terminates within the lateral geniculate nucleus. It has been widely believed that the PPTn is reciprocally connected with several extrapyramidal structures, including the globus pallidus and substantia nigra pars reticulata. Therefore, the relationships of pallidotegmental and nigrotegmental pathways to the PPTn were investigated employing the anterograde autoradiographic methodology. The reciprocity of tegmental connections with the substantia nigra and entopeduncular nucleus was investigated employing combined WGA-HRP injections and ChAT immunohistochemistry. The pallido- and nigrotegmental terminal fields did not coincide with the PPTn, but, rather, were located just medial and dorsomedial to it (the midbrain extrapyramidal area). The midbrain extrapyramidal area, but not the PPTn, was reciprocally connected with the substantia nigra and entopeduncular nucleus. We discuss these results in light of other cytoarchitectonic, cytochemical, connectional, and physiologic studies of the functional anatomy of the mesopontine tegmentum.

Animals↗
PubMed1986

Substance P-containing terminals in synaptic contact with cholinergic neurons in the neostriatum and basal forebrain: a double immunocytochemical study in the rat.

Antibodies against substance P and choline acetyltransferase (ChAT) have been used in a sequential double-immunocytochemical ultrastructural study of the rat forebrain. The peroxidase-anti-peroxidase procedure was used for both antigens, however, two different substrates for the peroxidase reactions were used. The substance P-immunoreactive sites were first localized using 3,3'-diaminobenzidine as the substrate, then the ChAT-immunoreactive sites were localized using benzidine dihydrochloride. The reaction product formed by the two substrates was distinguishable in both the light and electron microscopes. Using this procedure, the cell bodies and proximal dendrites of identified cholinergic neurons in the neostriatum were found to receive symmetrical synaptic input from substance P-immunoreactive boutons. A similar pattern of substance P-immunoreactive synaptic input was observed onto magnocellular basal forebrain cholinergic neurons in the ventral pallidum and ventromedial globus pallidus. In both the striatum and basal forebrain substance P-immunoreactive boutons were also seen in contact with structures that did not display ChAT immunoreactivity.

Animals↗
PubMed1986

Colocalization of atriopeptin-like immunoreactivity with choline acetyltransferase- and substance P-like immunoreactivity in the pedunculopontine and laterodorsal tegmental nuclei in the rat.

Atriopeptin, the atrial natriuretic peptide, is a circulating hormone that plays an important role in the regulation of fluid and electrolyte balance. Immunohistochemical studies have shown that large, multipolar atriopeptin-like immunoreactive (APir) neurons are present in areas of the midbrain corresponding to the large neurons of the pedunculopontine tegmental (PPT) and lateral dorsal tegmental (TLD) nuclei, all of which can be stained immunohistochemically for choline acetyltransferase-like immunoreactivity (ChATir). A subpopulation of these cholinergic PPT and TLD neurons are also known to contain substance P-like immunoreactivity (SPir). Using an immunofluorescent technique that allows simultaneous localization of two antigens, we have studied the relationship between APir, SPir and ChATir in the pontine tegmentum of the rat. We have found that the large multipolar APir neurons of the pontine tegmentum are identical to the ChATir neurons of the PT and TLD nuclei and a subpopulation of the APir neurons in PPT and TLD neurons are also SPir.

Animals↗