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At least 19 recordsLinked to original sources
PubMed1982

In vivo release of serotonin in two raphe nuclei (raphe dorsalis and magnus) of the cat.

The release of 3H-serotonin (3H-5-HT) endogenously synthesized from 3H-tryptophan was estimated in both dorsalis and magnus (MRN) raphe nuclei of anaesthetized "encéphale isolé" cats, by using push-pull cannulae. Resting steady state in the release of 3H-5-HT was observed 30 min after the beginning of superfusion with L-3H-tryptophan. The amounts of 3H-5-HT released in the DRN and the MRN are much greater than those measured simultaneously in the caudate nucleus. A marked increase either in the 5-HT release was seen in the presence of fluoxetine, a potent reuptake blocker of 5-HT, or during local depolarization with potassium chloride. The spontaneous release was diminished by removing Ca++ and by adding cobalt to the medium. Tetrodotoxin (TTX) decreased the 5-HT release in the DRN and, based on previously established, blocked the stimulating effect of batrachotoxin. According to the pharmacological characteristics of the monoamine dendritic release determined for dopamine in the substantia nigra [17], our results suggest that 5-HT release processes in the DRN correspond to a release from nerve endings, not from dendrites. The purpose of this study was to determine if the 5-HT released in the DRN is released from either axon terminals or dendrites. Morphological studies performed on the DRN do not consistently demonstrate the high density of serotoninergic varicosities in the DRN. In addition, two types of 5-HT axonal varicosities, characterized by their synaptic or non-synaptic junctions, are present in the brain. The concept that the quantities of 5-HT released could vary from one type compared to the other is discussed.

Animals↗
PubMed1991

Immunohistochemical evidence for the coexistence of substance P, thyrotropin-releasing hormone, GABA, methionine-enkephalin, and leucin-enkephalin in the serotonergic neurons of the caudal raphe nuclei: a dual labeling in the rat.

By means of dual immunohistochemical labeling on the same brain section examined with a light microscope, the present study reports the presence with serotonin (5-hydroxytryptamine; 5-HT) of gamma-aminobutyric acid (GABA), substance P (SP), thyrotropin-releasing hormone (TRH), leucin-enkephalin (LEU-enk), or methionine-enkephalin (MET-enk), within the same neuron in the nuclei raphe magnus, raphe obscurus, and raphe pallidus of the rat. On the one hand, peptides or GABA are detected with specific rabbit antibodies by indirect peroxidase labeling using peroxidase-conjugated Fab fragments, and on the other, 5-HT is detected with a rabbit antibody against the BSA-serotonin conjugate by radio-immunocytochemistry using [125I]-labeled protein A. The possible coexistence of TRH and SP in these neurons is also investigated by using peroxidase labeling and radio-immunocytochemical detection, respectively. In the whole caudal raphe nuclei the proportion of each coexisting peptide with 5-HT appears in decreasing order as: TRH greater than SP greater than MET-enk # LEU-enk greater than GABA. In all instances the level of coexistence differs considerably in B1-B2 vs. B3 cell groups. No SP/TRH dually labeled cells have ever been found in any of the serotonergic nuclei of the caudal raphe. Given the evidence that these raphe nuclei project possibly to the spinal cord, these data constitute an anatomical substrate for the several distinct physiological functions presumably subserved by 5-HT in the cord, namely the modulation of nociception, motor, and autonomic functions.

Animals↗
PubMed1996

p-Chlorophenylalanine-induced alteration of somatodendritic levels of tryptophan hydroxylase within the rat mesencephalic raphe nuclei.

Tryptophan hydroxylase distribution was examined across the nuclei raphe dorsalis, medianus, and pontis of the adult rat, under basal conditions and 2 days after a single injection of p-chlorophenylalanine, an irreversible tryptophan hydroxylase inhibitor. Tryptophan hydroxylase-expressing cells were numbered in transverse sections processed for immunohistochemistry, and the area of tryptophan hydroxylase distribution was delineated in adjacent sections transferred onto nitrocellulose and processed for immunoautoradiography. Two distinct areas were visualized: an inner zone, corresponding to the area displaying tryptophan hydroxylase-immunoreactive cells (so-called somatic area), and an outer zone, here called perisomatic, devoid of perikarya yet rich in tryptophan hydroxylase-positive neuropil in the histological sections. After treatment with p-chlorophenylalanine, a significant decrease in the number of tryptophan hydroxylase-immunoreactive cells could be observed only in the rostral raphe dorsalis, particularly within its ventromedian and dorsomedian subdivisions. In all raphe nuclei, the topological reconstruction of the somatic area was not modified. Based on the densitometric measurements in the immunoautoradiographs, however, a dramatic decrease in the content, concentration, and volume of expression of tryptophan hydroxylase could be documented in the three raphe nuclei. Detailed analysis of these results led to the conclusion that (a) tryptophan hydroxylase expression is differentially regulated in different serotoninergic cell body subpopulations of the raphe, some of which are more sensitive to p-chlorophenylalanine, and (b) distribution of tryptophan hydroxylase protein is modified also in the somatodendritic area in all raphe nuclei.

Analysis of Variance↗
PubMed1988

Immunocytochemical analysis of noradrenaline, substance P and enkephalin axonal contacts on serotonin neurons in the caudal raphe nuclei of the cat.

The present study investigates the anatomical basis for interactions between serotonin immunoreactive neurons in nuclei raphe magnus and pallidus, and either noradrenaline, substance P (SP) or enkephalin immunoreactive axonal varicosities. Using a double-label immunocytochemical method, we found that each of these neurochemicals could be localized to axons which contacted serotonin immunoreactive neurons. The frequency and location of these inputs differed in nuclei raphe magnus and pallidus. SP immunoreactive varicosities formed the greatest number of contacts. These findings suggest that serotonin-containing neurons in the caudal raphe nuclei receive input from multiple putative neurotransmitters.

Animals↗
PubMed1981

Ontogeny of medullary raphe nuclei in the rabbit brain stem: a Golgi study.

Nuclei raphe obscurus, pallidus, and magnus, found in the midline and paramedian regions of the medulla, were examined in rabbits between day 22 of gestation and adulthood. At day 22 of gestation (total gestation period of 32 days), the neurons were small with sparsely branched processes. Between day 26 of gestation and 6 days of age, the dendrites expanded, increased the number and length of their branches, and developed abundant spines. During this period, the cell bodies grew in size. From postnatal day 6 to adulthood, a mature pattern of dendritic branching was achieved, and the number of spines on the dendrites was reduced. Nuclei raphe obscurus, pallidus and magnus each possessed cells with unique morphological appearances early in ontogeny, but showed a similar pattern of enhanced dendritic branching with numerous spines through early neonatal development, followed by a reduction in the number and size of the spines. Despite the morphological heterogeneity of the medullary raphe nuclei, their general pattern of dendritic development is similar, suggesting that afferent connections to these nuclei may be formed during cellular maturation by a process similar to that described for the reticular formation and other central neurons.

Aging↗
PubMed1986

[Neuroendocrine mechanisms of participation of the raphe nuclei in the development of hypertensive reactions in emotional stress].

The experiments on cats and rabbits have studied electroencephalographic, endocrine and blood pressure responses to stress (5-hour immobilization with electrical foot shock) before and after coagulation of the midbrain nuclei raphe. Blood pressure and adrenal responses in advanced (4-hour) stress were elevated in intact animals, the responses attenuating after coagulation of the nuclei raphe. Background bioelectrical activity of the midbrain reticular formation and hypothalamus was found to be activated in the operated animals. Stress was followed by the reduction in bioelectrical changes of the above subcortical structures with the parallel development of "burst" activity in the dorsal hippocamp.

Animals↗
PubMed1979

Neuronal-vascular relationships in the raphe nuclei, locus coeruleus, and substantia nigra in primates.

A fluorescence histochemical and electron microscopic study of the monoaminergic cell groups in the squirrel monkey and Rhesus monkey brains has revealed the direct apposition of blood vessels to perikarya and dendrites of monoaminergic neurons. Capillaries and small arterioles or venules, ranging from 8-50 microns in diameter, showed perikarya and dendrites abutting the basement membrane without evidence of glial interposition. This neuronal-vascular relationship was present in 20% to 30% of the small vessels in the serotonergic nuclei raphe dorsalis and centralis superior and in the noradrenergic locus coeruleus. Such contacts were clearly present but observed less frequently in the dopaminergic substantia nigra pars compacta and in the serotonergic nuclei raphe obscurus, pallidus, magnus, and pontis. We postulate that monoamine-containing neurons apposed to blood vessels in certain regions of the brain may be influenced directly by hormones or other substances in blood.

Animals↗
PubMed1985

Changes of serotonin and dopamine metabolism in various forebrain areas of rats injected with morphine either systemically or in the raphe nuclei dorsalis and medianus.

The regional brain metabolism of serotonin (5-HT) and dopamine (DA) was studied in rats injected with morphine either systemically or in the nuclei raphe medianus (MR) or dorsalis (DR). A subcutaneous injection of 10 mg/kg morphine significantly raised the levels of 5-hydroxyindoleacetic acid (5-HIAA) in the diencephalon, striatum, nucleus accumbens and cortex with no effect in the hippocampus. Similar changes in 5-HT metabolism were found in animals injected with 5 micrograms/0.5 microliter in the DR whereas morphine injected in the MR raised 5-HIAA levels only in the nucleus accumbens. A subcutaneous or direct injection of morphine in the DR significantly raised the levels of homovanillic acid (HVA) and dihydroxyphenylacetic acid (DOPAC) in the striatum and nucleus accumbens, but injection in the MR was ineffective. All the effects of morphine were blocked by naloxone, injected either intraperitoneally (1 mg/kg) or directly in the raphe nuclei (2 micrograms/0.5 microliter). Pretreatment with parachlorophenylalanine, an inhibitor of serotonin synthesis, significantly reduced the effect of morphine injected in the DR on dopamine metabolism in the striatum and nucleus accumbens. The data suggest that a major mechanism by which morphine increases 5-HT metabolism in the rat forebrain is activation of 5-HT cells in the nucleus raphe dorsalis, and this action may contribute to the increased DA metabolism found in the animal injected with morphine in this brain area.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1987

Interrelationships between the heart and central nervous system: localization of neuro-transmitters and imaging of their associated nuclei, including the raphe nuclei & the locus coeruleus, as well as the imaging of the heart and its representation areas in slices of the human central nervous system using the "Bi-Digital O-Ring Test" imaging method.

Using microscopic slides of specific tissues from the human body or pure substances including neuro-transmitters such as serotonin, dopamine, norepinephrine, etc., as reference control substances in the Bi-Digital O-Ring Test Molecular Identification Method, the author was able to localize and image normal and abnormal internal organs, and to localize and trace the distribution of neurotransmitters in the different parts of the central nervous system. Using microscopic slides of different parts of the heart, we were able to image the outline of the heart as well as the SA node, AV node, tricuspid valve, mitral valve, aortic valve, pulmonary valve, coronary arteries, and aorta and its branches, including the vertebral arteries, without using any bulky or expensive imaging instruments. Using serotonin as a reference control substance on the different parts of the central nervous system, it was possible to demonstrate the 6 well-known raphe nuclei and the locus coeruleus (which contains serotonin & norepinephrine), as well as the distribution of serotonin in the cerebrum and the cerebellum, all of which closely resembled previously published well-known neuroanatomical structures and distributions of neurotransmitters. As an extension of this work, possible representations of different internal organs on the central nervous system were examined using microscopic slides of different internal organs as reference control substances. The results indicated that the entire heart is represented primarily in the medulla oblongata, and that the SA node and the upper half of the left atrium are represented in the caudal end of the pons; the right side of the heart (i.e. R-atrium, AV node, tricuspid valve, R-ventricle) is represented on the right side of the medulla oblongata, and the left side of the heart (i.e. lower half of the L-atrium, mitral valve, L-ventricle) is represented on the left side of the medulla oblongata, and the upper half of the left atrium is represented in the caudal end of the left side of the pons. The bottoms of the ventricles are located near the spinal cord. Furthermore, the right and the left sides of the heart are represented in specific areas of each side of the right and left hemispheres of the cerebral cortex, and there are connecting pathways between the representation areas of identical parts of the heart, through the corpus callosum and other neuro-pathways.

Central Nervous System↗
PubMed1986

Further evidence for excitatory amino acid transmission in the lateral habenular projection to the rostral raphe nuclei: lesion-induced decrease of high affinity glutamate uptake.

In previous autoradiographic studies we reported selective retrograde D-[3H]aspartate labelling of lateral habenular afferents to the nuclei raphe dorsalis (NRD) and centralis superior (RCS). This study reports biochemical support, lesion-induced decrease of high affinity glutamate uptake, for excitatory amino acid transmission in the habenulo-raphe connection. Rats received bilateral electrolytic lesions in the lateral habenular nuclei and survived 9-10 days. Brainstems were sectioned on a Vibratome, and NRD and RCS tissue microdissected. Glutamate uptake in sham-operated rats was in the NRD 23.6 +/- 2.3 nmol/g prot. (mean +/- S.E.M.) ([3H]glutamate 10(-7) M, 3 min, 25 degrees C) and in the RCS 14.6 +/- 1.0 nmol/g. Habenular lesions reduced glutamate uptake in the NRD by 20.7 +/- 2.0% (P less than 0.001) and in the RCS by 10.7 +/- 4.3% (P less than 0.05).

Amino Acids↗
PubMed1984

Differential pulse voltammetric determination of 5-hydroxyindoles in four raphe nuclei of chronic freely moving rats simultaneously recorded by polygraphic technique: physiological changes with vigilance states.

Nuclei raphe dorsalis ( RDN ), centralis (RCN), pontis (RPN) and magnus ( RMN ) were separately studied using differential pulse voltammetry ( DPV ) in chronic freely moving rats during the recording of their sleep-waking cycle by polygraphic technique. In each of these nuclei the height of the electrochemical signal appearing at +300 mV (peak 3) was maximum during waking (W), lower during slow-wave sleep (SWS) and minimum during paradoxical sleep (PS). Some pharmacological treatments indicated that in each of these nuclei the peak 3 represents the oxidation of the 5-hydroxyindoles. DPV measurements performed during specific behavioral states (eating, grooming, washing, drinking) called active waking (AW) or manipulations (handling, tail-pinch) demonstrated that this technique enables detection of changes occurring in animals under physiological conditions.

Animals↗
PubMed1979

The raphe nuclei of the rabbit brain stem.

The raphe nuclei of the rabbit brain stem were found in the midline and adjacent reticular formation of the medulla, pons, and mesencephalon. Nuclei raphe obscurus, pallidus, and magnus were located in the medulla. Nucleus raphe pontis and the caudal portion of nuclei raphe dorsalis and centralis superior were present in the pons. The rostral portion of nuclei raphe dorsalis and centralis superior, and nuclei linearis caudalis and intermedius were present in the msencephalon. Wings of neurons extended from the midline clusters of raphe neurons into the adjacent reticular formation. These wings of neurons contained serotonergic perikarya which were cytoarchitecturally indistinguishable from the midline neurons. A detailed localization of these nuclei is presented in atlas form. These raphe nuclei contained heterogeneous populations of neurons which varied in the size, shape and density of the cell bodies. In addition, the dendritic branching, specific orientation of dendrites, and appearance of spines were distinct for each of the raphe nuclei. Individual raphe nuclei often contained several subpopulations of neurons characterized by unique spatial configuration and orientation. The main morphological similarities of the raphe nuclei are location in or adjacent to the midline, the presence of serotonergic cell bodies in all raphe nuclei except the linear nuclei, and heterogeneous cell populations.

Afferent Pathways↗
PubMed1986

Serotonin turnover in discrete hypothalamic nuclei and mesencephalic raphe nuclei of young and adult spontaneously hypertensive rats.

Serotonin levels and turnover were analyzed in discrete forebrain and mesencephalic nuclei of young (4-week-old) and adult (14-week-old) spontaneously hypertensive rats and age-matched normotensive control Wistar Kyoto rats. Most changes observed were age-dependent, and occurred only in young, early hypertensive rats. Both serotonin levels and the accumulation rate of 5-hydroxy-tryptophan after L-amino acid decarboxylase inhibition were higher in the nuclei periventricularis and paraventricularis of the hypothalamus of young hypertensive rats than in controls. In addition, 4-week-old spontaneously hypertensive rats showed higher 5-hydroxytryptophan accumulation rates in the nuclei supraopticus and dorsomedialis of the hypothalamus than controls. The only difference in serotonin metabolism found in adult hypertensive rats was high serotonin concentration in the median eminence of the hypertensive animals. Our results suggest the presence of anatomically specific, age-dependent alterations in serotonin metabolism, localized to selected hypothalamic nuclei in young hypertensive rats. These data support a role for the hypothalamic serotonin in the development of the spontaneous (genetic) hypertension in the rat.

5-Hydroxytryptophan↗
PubMedDate not supplied

[Neuropeptides in the raphe nuclei: an immunocytochemical study].

INTRODUCTION: The raphe nuclei are involved in numerous mechanisms, included the antinociceptives. In the raphe nuclei of the cat, the distribution of neuropeptides is not very studied. Aim. To know the distribution of peptidergic fibers and cell bodies in the raphe nuclei of the cat. We studied a total of fifteen neuropeptides. MATERIAL AND METHODS: We used four control cats (without colchicine) and six with colchicine (administered into the Sylvian aqueduct). We used an indirect immunocytochemical technique. The histologic controls carried out confirm the specificity of the primary and secondary antibodies used. RESULTS: We observed in the fibers and/or the cell bodies located in the dorsal raphe nucleus a total of 14 neuropeptides, 12 in the raphe pallidus, 11 in the medial raphe, 10 in the raphe magnus, 8 in the raphe pontis and 7 in the raphe obscurus. We observed immunoreactive cell bodies in the raphe pallidus (with neurokinin A/leucine enkephalin), in the medial raphe (beta endorphin/alpha neo endorphin), in the raphe magnus (leucine enkephalin) and in the dorsal raphe (beta endorphin/alpha neo endorphin/methionine enkephalin Arg6 Gly7 Leu8/leucine enkephalin/neurokinin A/neurotensin). CONCLUSIONS: 1. There are differences on the distribution of the peptidergic fibers/cell bodies observed in the raphe nuclei of the rat, the cat and the man; 2. The raphe nuclei could receive peptidergic afferences containing dynorphin A, galanin, neuropeptide Y, somatostatin ; 3. The cell bodies located in the medial raphe and containing beta endorphin or alpha neo endorphin could be projecting neurons; 4. There is a great functional complexity in the raphe nuclei due to the great number of neuropeptides observed in them; 5. The neuropeptides could interact between them, and 6. The neuropeptides located in the raphe nuclei could be involved in the control of the nociceptive information.

Afferent Pathways↗
PubMed1985

[Preliminary observations on the distribution of serotoninergic and cerebellar-projecting neurons of the raphe nuclei of the brain stem].

Cerebellar projection from raphe nuclei were investigated in rabbit by using retrograde transport of HRP and serotonergic mapping by direct fluorescence. A close topographical correlation between the HRP labeled cells and the serotonergic neurons has been observed. The current study has demonstrated the presence of paramedian and lateral cells whose cytoarchitecture is identical with midline cells of many raphe nuclei. All of the raphe nuclei except the linear nuclei, contained serotonergic perikarya. The midline and paramedian portions of the nuclei raphe obscurus, pallidus, magnus, and nucleus raphe dorsalis contained principally serotonergic neurons; the lateral portions of the medullary raphe nuclei and the nuclei raphe pontis and centralis superior contained a significant number of non-fluorescent cells. In these regions, fluorescent sections often revealed the size, shape, and orientation of the perikarya and dendrites; further verification of cytoarchitectural characteristics of these neurons depended heavily upon these clues.

Animals↗
PubMed2000

Involvement of the caudal raphe nuclei in the feeding behavior of rats.

Involvement of the caudal raphe nuclei (raphe pallidus, RPa; raphe magnus, RMg, and raphe obscurus, ROb) in feeding behavior of adult rats was studied by measuring c-Fos protein expression, in animals submitted to the "meal-feeding" model of food restriction in which the rats were fed ad libitum only from 7:00 to 9:00 h, for 15 days. The experimental groups submitted to chronic fasting, named 'search for food' (SF), 'ingestion of food' (IF) and 'satiety of food' (SaF) were scheduled after a previous study in which the body weight and the general and feeding behaviors were evaluated by daily monitoring. Acute, 48-h fasting (AF) was used as control. In the chronic group, the animals presented a 16% reduction in body weight in the first week, followed by a continuous, slow rise in weight over the subsequent days. Entrainment of the sleep-wake cycle to the schedule of food presentation was also observed. The RPa was the most Fos immunopositive nucleus in the chronic fasting group, followed by the RMg. The ANOVA and Tukey test (P<0.05) confirmed these results. The IF group was significantly different from the other three groups, as also was the number of labeled cells in the RPa in SF and IF groups. Nevertheless, no significant difference was observed between RMg and RPa, or RMg and ROb in the SaF and AF. However, it is interesting to observe that the groups in which the animals were more active, searching for or ingesting food, presented a larger number of labeled cells. These results suggest a different involvement of the caudal raphe nuclei in the somatic and autonomic events of feeding behavior, corroborating the functions reported for them earlier.

Animals↗
PubMed1977

The cerebellar projection from the raphe nuclei in the cat as studied with the method of retrograde transport of horseradish peroxidase.

Following injections of horseradish peroxidase (HRP) in the cerebellar cortex and nuclei of the cat, the distribution of labeled cells in the raphe nuclei was mapped. The findings confirm those made previously in studies of retrograde cell degeneration following cerebellar ablations (Brodal et al., 1960a), and in addition reveal new details in the projection of the raphe nuclei onto the cerebellar cortex and nuclei. All the raphe nuclei except nucleus linearis intermedius and nucleus linearis rostralis project onto the cerebellar cortex. The nuclei raphe obscurus and pontis contribute the greatest number of afferents to the cerebellum. With the exception of lobule VI which probably is the recipient of a weak projection, all parts of the cerebellar cortex receive afferents from the raphe nuclei. The heaviest projection is to the vermis of lobules VIIA and X, and to crus II. The afferents to the cerebellar nuclei are few in number (Tables 2-6). The observations indicate that each raphe neuron probably projects to more than one terminal site in the cerebellum. The findings are discussed with reference to other efferent and afferent studies of the raphe nuclei. All these studies indicate that the raphe nuclei have widespread efferent and afferent connections, making them capable to participate in a variety of regulatory functions.

Animals↗