Distribution and quantitative characterization of NADPH-diaphorase-reactive neurons in analgesic zones of the rat midbrain

The distribution of nitric oxide synthase (nicotinamide adenine dinucleotide phosphate diaphorase, NADPH-d)-containing neurons in the rat midbrain was studied. We found that NADPH-d-reactive neurons were predominantly concentrated in the dorsolateral part of the periaqueductal gray (PAG) and the dorsal raphe nucleus, which are implicated in the control of nociceptive transmission. Such neurons were also present in the supraoculomotor cap and laterodorsal tegmental nuclei. In the dorsolateral part ofPAG, the moderately stained small fusiform cells were revealed. In the dorsal raphe nucleus and laterodorsal tegmental nuclei, the densely stained multipolar or oval cells of larger size dominanted. The NADPH-d-reactive cells were not found in the ventrolateral part of central gray, which is considered the main source of antinociceptive descending influences. Quantitative analysis of histochemically revealed neurons showed that their number is somewhat higher in the caudal parts of dorsolateral central gray and considerably higher in the rostral regions of some dorsal raphe subnuclei. This peculiarity was expressed in significant accumulation of the NADPH-d-reactive neurons at the midbrain levels from Fr –7.6 to –8.0. The possible involvement of the NO-synthase-containing class of neurons in the functional organization of analgesic zones and formation ofPAG antinociceptive output signals is discussed.Neirofiziologiya/Neurophysiology, Vol. 28, No. 1, pp. 36–46, January–February, 1996.     

Cholinergic and catecholaminergic neurons relay striatal information to the optic tectum in amphibians.

In the amphibians Rana perezi and Xenopus laevis, the involvement of cholinergic and catecholaminergic neurons in the relay of basal ganglia inputs to the tectum was investigated. Tract-tracing experiments, in which anterograde tracers were applied to the basal ganglia and retrograde tracers to the optic tectum, were combined with immunohistochemistry for choline acetyltransferase and tyrosine hydroxylase. The results of these experiments suggest that dopaminergic neurons of the suprachiasmatic nucleus and pretectal region, noradrenergic cells of the locus coeruleus and the cholinergic neurons of the pedunculopontine and laterodorsal tegmental nuclei mediate at least part of the basal ganglia input to the tectum in anurans.     

电损毁大鼠杏仁中央核对脑桥臂旁核味觉神经元的影响

应用细胞外记录的电生理学方法,在乌拉坦麻醉的大鼠观察了电损毁双侧杏仁中央核前后脑桥臂旁核味觉神经元对四种基本味觉刺激(即氯化钠、盐酸、奎宁和蔗糖)反应的变化。根据对味觉刺激的优势反应,29个记录的味觉神经元中,有14个NaCl优势、9个HCl优势、3个QH2SO4优势和3个蔗糖优势反应神经元。损毁杏仁中央核明显增强臂旁核味觉神经元对盐酸和硫酸奎宁的反应(P＜0．01)。氯化钠优势、盐酸优势和奎宁优势反应神经元对盐酸和硫酸奎宁的反应在电损毁杏仁中央核后也明显增强。在破坏杏仁中央核后,臂旁核味觉神经元对氯化钠和硫酸奎宁苦味的分辨能力降低。以上结果提示,杏仁中央核在大鼠脑桥水平的味觉编码中发挥重要作用,它可能是通过参与对味觉的影响来调节机体的摄食行为。     

The thalamic paraventricular nucleus relays information from the suprachiasmatic nucleus to the amygdala: A combined anterograde and retrograde tracing study in the rat at the light and electron microscopic levels

The relationship between efferents of the hypothalamic suprachiasmatic nucleus (SCN) and neurons of the thalamic paraventricular nucleus (PVT) projecting to the amygdala was investigated in the rat using tract tracing in light and electron microscopy. Biotinylated dextran amine was used to label anterogradely SCN efferents. These fibers were found to reach the thalamic midline, terminating in PVT, through three pathways: anterodorsally through the preoptic region, dorsally through the periventricular hypothalamus, and through the contralateral medial hypothalamic and preoptic areas after crossing the midline in the optic chiasm. Preterminal and terminal-like elements labeled from the SCN were distributed throughout the rostrocaudal extent of PVT, with an anteroposterior gradient of density. Labeled terminal elements were densest in the dorsal portion of PVT beneath the ependymal lining and some of them entered the ependyma. Anterograde tracing of SCN fibers was combined with injections of retrograde tracers in the amygdala. Numerous retrogradely labeled cell bodies were seen throughout PVT, with a prevalence in its anterodorsal portion. Overlap was detected between puncta labeled from the SCN and retrogradely labeled neurons, especially in the anterodorsal sector of PVT, where numerous puncta were in close apposition to thalamo-amygdaloid cells. Electron microscopy revealed that boutons labeled from the SCN established synaptic contacts with dendritic profiles of PVT neurons labeled from the amygdala. The findings demonstrate that information processed in the biological clock is conveyed to the amygdala through PVT, indicating that this nucleus plays a role in the transfer of circadian timing information to the limbic system.     

Peptide immunoreactive neurons in the amygdala and the bed nucleus of the stria terminalis project to the midbrain central gray in the rat.

The central nucleus of the amygdala, bed nucleus of the stria terminalis, and central gray are important components of the neural circuitry responsible for autonomic and behavioral responses to threatening or stressful stimuli. Neurons of the amygdala and bed nucleus of the stria terminalis that project to the midbrain central gray were tested for the presence of peptide immunoreactivity. To accomplish this aim, a combined immunohistochemical and retrograde tracing technique was used. Maximal retrograde labeling was observed in the amygdala and bed nucleus of the stria terminalis after injections of retrograde tracer into the caudal ventrolateral midbrain central gray. The majority of the retrogradely labeled neurons in the amygdala were located in the medial central nucleus, although many neurons were also observed in the lateral subdivision of the central nucleus. Most of the retrogradely labeled neurons in the BST were located in the ventral and posterior lateral subdivisions, although cells were also observed in most other subdivisions. Retrogradely labeled neurotensin, corticotropin releasing factor (CRF), and somatostatin neurons were mainly observed in the lateral central nucleus and the dorsal lateral BST. Retrogradely labeled substance P-immunoreactive cells were found in the medial central nucleus and the posterior and ventral lateral BST. Enkephalin-immunoreactive retrogradely labeled cells were not observed in the amygdala or bed nucleus of the stria terminalis. A few cells in the hypothalamus (paraventricular and lateral hypothalamic nuclei) that project to the central gray also contained CRF and neurotensin immunoreactivity. The results suggest the amygdala and the bed nucleus of the stria terminalis are a major forebrain source of CRF, neurotensin, somatostatin, and substance P terminals in the midbrain central gray.     

Somatostatinergic projections from the central nucleus of the amygdala to the vagal nuclei

In the rat, somatostatin immunoreactivity was identified in neurons of the central nucleus of the amygdala that were retrogradely labeled by injection of fluorescent dyes into the nucleus tractus solitarius and dorsal motor nucleus of the vagus nerve. The double-labeled neurons are located in the medial subdivision of the central nucleus and appear to comprise less than one fifth of the descending pathway. These results suggest that somatostatin may act as a neurotransmitter in a pathway which mediates cardiovascular and other autonomic responses to fear-producing and other emotional stimuli.     

Regulation of nucleus accumbens dopamine release by the dorsal raphe nucleus in the rat

The effects of microinfusingl-glutamate, serotonin (5-HT), (±)-8-hydroxy-2-(di-N-propylamino) tetralin (8-OH DPAT; a 5-HT_1A agonist), and muscimol (a GABA_A agonist) into the dorsal raphe nucleus on the extracellular levels of 5-HT, dopamine (DA) and their metabolites in the nucleus accumbens were studied in unanesthetized, freely moving, adult male Wistar rats, using the technique of microdialysis coupled with small-bore HPLC. Administration of 0.75 gl-glutamate produced a 25–50% increase (P<0.05) in the extracellular levels of both 5-HT and DA. On the other hand, infusion of 8-OH DPAT and, to a lesser extent, 5-HT produced a significant (P<0.05) decrease in the extracellular levels of both 5-HT and DA. Muscimol (0.25 or 0.50 g) had little effect on the extracellular concentrations of 5-HT or DA following its administration. In general, the extracellular levels of the major metabolites of 5-HT and DA in the nucleus accumbens were not altered by microinfusion of any of the agents. The data indicate that (a) the 5-HT neurons projecting to the nucleus accumbens from the dorsal raphe nucleus can be activated by excitatory amino acid receptors and inhibited by stimulation of 5-HT_1A autoreceptors, and (b) the dorsal raphe nucleus 5-HT neuronal system may regulate the ventral tegmental area DA projection to the nucleus accumbens.Special issue dedicated to Dr. Morris H. Aprison     

The efferent connections of the lateral septal nucleus in the guinea pig: projections to the diencephalon and brainstem

Summary The anterograde Phaseolus vulgaris-leucoagglutinin (PHA-L) tracing technique was used to determine the distribution of efferent fibers originating in the lateral septal nucleus of the guinea pig. For complementary detection of the chemical identity of the target neurons, double-labeling immunocytochemistry was performed with antibodies to PHA-L and to vasopressin, oxytocin, vasoactive intestinal polypeptide, serotonin or dopamine -hydroxylase, respectively. The hypothalamus received the majority of the PHA-L-stained septofugal fibers. Here, a specific topography was observed. (1) The medial and lateral preoptic area, (2) the anterior, lateral, dorsal, posterior hypothalamic and retrochiasmatic area, (3) the supraoptic, paraventricular, suprachiasmatic, dorsomedial, caudal ventromedial and arcuate nuclei, and (4) the tuberomammillary, medial and lateral supramammillary, dorsal and ventral premammillary nuclei always contained PHA-L-labeled fibers. The rostral portion of the ventromedial nucleus and the medial and lateral mammillary nucleus only occasionally showed weak terminal labeling. In other diencephalic areas, termination of PHA-L-labeled fibers was observed in the epithalamus and the nuclei of the midline region of the thalamus. In the mesencephalon, terminal varicosities occurred in the ventral tegmental area, interfascicular and interpeduncular nucleus, and periaqueductal gray. In addition, the dorsal and medial raphe nuclei of the metencephalon, together with the locus coeruleus and the dorsal tegmental nucleus, received lateral septal efferents.     

Afferent projections to the locus coeruleus nucleus in the cat. Study by the horseradish peroxidase technic]

Using a retrograde tracer technique with horseradish peroxidase, we have revealed some afferent projections to the locus coeruleus complex from the contralateral pontine tegmentum, raphe nuclei, substantia nigra, nucleus of the solitory tract, dorsal motor nucleus of the vagus and other regions of the ponto-bulbar reticular formation as well as from hypothalamic and preoptic areas.     

Pattern of afferents to the lateral septum in the guinea pig

Summary The septal region represents an important telencephalic center integrating neuronal activity of cortical areas with autonomous processes. To support the functional analysis of this brain area in the guinea pig, the afferent connections to the lateral septal nucleus were investigated by the use of iontophoretically applied horseradish peroxidase (HRP). Retrogradely labeled perikarya were located in telencephalic, diencephalic, mesencephalic and metencephalic sites. The subnuclei of the lateral septum (pars dorsalis, intermedia, ventralis, posterior) receive afferents from the (i) medial septal nucleus, diagonal band of Broca (pars horizontalis and pars ventralis), and the principal nucleus of the stria terminalis, the hippocampus, and amygdala (nucleus medialis); (ii) the medial habenular nucleus, and the para- (peri-) ventricular, parataenial and reuniens nuclei of the thalamus; the anterior, lateral and posterior hypothalamic areas in particular, the medial and lateral preoptic, suprachiasmatic, periventricular, paraventricular, arcuate, premammillary, and supramammillary nuclei; (iii) the periaquaeductal grey, ventral tegmental area, nucleus interfascicularis, nucleus reticularis linearis, central linear nucleus, interpeduncular nucleus; (iv) dorsal and medial raphe complex, and locus coeruleus. Each subnucleus of the lateral septum displays an individual, differing pattern of afferents from the above-described regions. Based on a double-labeling method, the vasopressinergic and serotonergic afferents to the lateral septum were found to originate in the nucleus paraventricularis hypothalami and the raphe nuclei, respectively.Abbreviations ARC arcuate nucleus - BNST bed nucleus of the stria terminalis - CL central linear nucleus - DBBh diagonal band of Broca (pars horizontalis) - DBBv diagonal band of Broca (pars ventralis) - DR dorsal raphe nucleus - HC hippocampus - IF interfascicular nucleus - IP interpeduncular nucleus - LC locus coeruleus - LDT laterodorsal tegmental nucleus - LHA lateral hypothalamic area - LPO lateral preoptic area - LSN lateral septal nucleus - MA medial amygdaloid nucleus - MH medial habenular nucleus - MPO medial preoptic region - MR medial raphe nucleus - MSN medial septal nucleus - PAG periaquaeductal grey - PEN periventricular nucleus - PHA posterior hypothalamic area - PMd premammillary region (pars dorsalis) - PMv premammillary region (pars ventralis) - PT parataenial nucleus - PVN paraventricular hypothalamic nucleus - PVT paraventricular thalamic nucleus - RE nucl. reuniens - RL nucl. reticularis linearis - SCN suprachiasmatic nucleus - SMl supramammillary region (pars lateralis) - SMm supramammillary region (pars medialis) - SUB subiculum - TS triangular septal nucleus - VTA ventral tegmental area - ac anterior commissure - bc brachium conjunctivum - bp brachium pontis - cc corpus callosum - fr fasciculus retroflexus - fx fornix - ml medial lemniscus - mlf fasciculus longitudinalis medialis - mp mammillary peduncle - mt mammillary tract - oc optic chiasm - on optic nerve - pc posterior commissure - pt pyramidal tract - sm stria medullaris - st stria terminalis - vhc ventral hippocampal commissure Supported by the Deutsche Forschungsgemeinschaft (Nu 36/2-1)     

Neuropeptide Y innervation of amygdaloid and hypothalamic neurons that project to the dorsal vagal complex in rat

The anatomic relationship between neuropeptide Y (NPY)-immunoreactive terminals and forebrain areas in the rat that contain neurons that project to the dorsal vagal complex (DVC) was examined. To accomplish this, the combined retrograde fluorescent tracer and immunofluorescent technique was used. Neurons projecting to the DVC within the parvocellular divisions of the paraventricular nucleus of the hypothalamus were the most heavily innervated of the regions studied. A relatively high density of NPY-immunoreactive terminals innervated regions of the arcuate, dorsomedial and lateral hypothalamic areas that contained DVC efferent cells. Neurons that projected to the DVC within the medial division of the central nucleus of the amygdala and the lateral part of the bed nucleus of the stria terminalis were also innervated by NPY immunoreactive terminals. The results suggest an important role for NPY terminals in the modulation of neurons within the amygdala and hypothalamus that directly influence visceral-autonomic functions of the dorsal vagal complex. The source and possible function of NPY within these regions is discussed.     

Anatomical relationship between neuropeptide-containing fibers and efferent vagal neurons projecting to the rat corpus.

Injections of the retrograde tracers into the posterior surface of the stomach at the greater curvature resulted in labelling of the right half of the dorsal motor nucleus of the vagus. Whereas injections into the anterior and posterior surfaces of the corpus resulted in bilateral labelling in the medulla. Immunocytochemical staining of the labelled sections using antisera to substance P was confined to a dense network of fibers within the dorsal motor nucleus of the vagus and the nucleus tractus solitarius with no cell bodies being detected. Calcitonin gene-related peptide-immunoreactivity was detected in nerve fibers in the nucleus tractus solitarius and cell bodies of the hypoglossal nucleus. Finally, neuropeptide Y-immunoreactivity was confined to nerve fibers within the vagal complex. Of the neurons labelled by the retrograde tracers injected into the corpus all were in close spatial contact with fibers containing substance P-immunoreactivity. A smaller number were associated with neuropeptide Y-containing fibers with a few adjacent to calcitonin gene-related peptide-immunoreactive fibers. These results indicate that substance P and neuropeptide Y may directly regulate efferent neurons controlling gastric motility and acid secretion. Calcitonin gene-related peptide, however, is unlikely to directly modulate the cell bodies of the neurons in the dorsal motor nucleus but may modulate the dendrites from these neurons in the nucleus tractus solitarius.     

Role of dorsal raphe nucleus serotonin 5-HT1A receptor in the regulation of REM sleep

Cholinergic neurons in the laterodorsal (LDT) and the pedunculopontine (PPT) tegmental nuclei act to promote REM sleep (REMS). The predominantly glutamatergic neurons of the REMS-induction region of the medial pontine reticular formation are in turn activated by cholinergic cells, which results in the occurrence of tonic and phasic components of REMS. All these neurons are inhibited by serotonergic (5-HT), noradrenergic, and presumably histaminergic (H2 receptor) and dopaminergic (D2 and D3 receptor) cells. 5-Hydroxytryptamine-containing neurons in the dorsal raphe nucleus (DRN) virtually cease firing when an animal starts REMS, consequently decreasing the release of 5-HT during this state. The activation of GABA(A) receptors is apparently responsible for this phenomenon. Systemic administration of the selective 5-HT1A receptor agonist 8-OHDPAT induces dose-dependent effects; i.e. low doses increase slow wave sleep and reduce waking, whereas large doses increase waking and reduce slow wave sleep and REM sleep. Direct injection of 8-OHDPAT or flesinoxan, another 5-HT1A agonist into the DRN, or microdialysis perfusion of 8-OHDPAT into the DRN significantly increases REMS. On the other hand, infusion of 8-OHDPAT into the LDT selectively inhibits REMS, as does direct administration into the DRN of the 5-HT1A receptor antagonists pindolol or WAY 100635. Thus, presently available evidence indicates that selective activation of the somatodendritic 5-HT1A receptor in the DRN induces an increase of REMS. On the other hand, activation of the postsynaptic 5-HT1A receptor at the level of the PPT/LDT nuclei decreases REMS occurrence.     

Afferent connections in the ventromedial hypothalamus of rats demonstrated by retrograde transport of horseradish peroxidase

Projections into rat ventromedial hypothalamus were studied with retrograde transport of horseradish peroxidase (HRP). Following injection of HRP into ventromedial hypothalamus, labeled neurons were found in cortical and medial amygdaloid nuclei, ipsilateral mediodorsalis thalamus (MD), dorsal raphe nucleus, and contralateral sensorimotor cortex. Futhermore, labeled axons that connect directly amygdala with hypothalamus (DAH) also were found.     

胃肠道伤害性刺激诱导中缝背核触液神经元Fos表达

本文以ＣＢ－ＨＲＰ逆行追踪和原癌基因ｃ－ｆｏｓ表达技术相结合,观察胃肠道伤害性刺激后中缝背核触液神经元Ｆｏｓ的表达。在中缝背核发现三种标记神经元,包括ＣＢ－ＨＲＰ逆行标记神经元（３０８）、Ｆｏｓ阳性神经元（４２）和ＣＢ－ＨＲＰ／Ｆｏｓ双重标记神经元（５）。本研究提示中缝背核含有一些具有双重功能的神经元,它们既在脑－脑脊液神经体液回路中传递信息,又在胃肠道伤害性刺激的中枢传递和功能调控中起一定的作用     

Sources of cortical,hypothalamic and spinal serotonergic projections: Topical organization in the dorsal raphe nucleus

A study was made of retrograde axon transport of luminescent stains (primulin, fluoro-gold, fast blue, and nuclear yellow) from the spinal cord, the frontal cortex and lateral hypothalamus to various neuron groups of the periventricular gray matter of the midbrain and the dorsal tegmentum of the pons Varolii. Two large groups of serotonergic neurons are localized in the dorsomedial area of the dorsal raphe nucleus where projections to the thoracic segments of the spinal cord originate. Some of these neurons form divergent axon collaterals to the frontal cortex. Our data indicate that the antinociceptive effect of stimulating the "purely analgesic zone" of the midbrain periventricular gray matter may be due to direct involvement of the dorsal raphe nucleus in the descending control of impulsation induced by nociceptive stimulation at the spinal cord level. The neurotransmitter and neuromodulator role of separate cortical and hypothalamic projections of serotonin-containing neurons in the dorsal raphe nucleus is discussed.A. M. Gorky Medical Institute, Donetsk. A. A. Bogomolets Institute of Physiology, Ukrainian Academy of Sciences, Kiev. Translated from Neirofiziologiya, Vol. 24, No. 1, pp. 87–96, January–February, 1992.     

Estradiol acts in the medial preoptic area, arcuate nucleus, and dorsal raphe nucleus to reduce food intake in ovariectomized rats

Estradiol (E2) exerts an inhibitory effect on food intake in a variety of species. While compelling evidence indicates that central, rather than peripheral, estrogen receptors (ERs) mediate this effect, the exact brain regions involved have yet to be conclusively identified. In order to identify brain regions that are sufficient for E2's anorectic effect, food intake was monitored for 48 h following acute, unilateral, microinfusions of vehicle and two doses (0.25 and 2.5 μg) of a water-soluble form of E2 in multiple brain regions within the hypothalamus and midbrain of ovariectomized rats. Dose-related decreases in 24-h food intake were observed following E2 administration in the medial preoptic area (MPOA), arcuate nucleus (ARC), and dorsal raphe nucleus (DRN). Within the former two brain areas, the larger dose of E2 also decreased 4-h food intake. Food intake was not influenced, however, by similar E2 administration in the paraventricular nucleus, lateral hypothalamus, or ventromedial nucleus. These data suggest that E2-responsive neurons within the MPOA, ARC, and DRN participate in the estrogenic control of food intake and provide specific brain areas for future investigations of the cellular mechanism underlying estradiol's anorexigenic effect.     

Corticotropin-releasing hormone-like immunoreactivity in the brain of the snake Bothrops jararaca

The distribution of corticotropin-releasing hormone in the brain of the snake Bothrops jararaca was studied immunohistochemically. Immunoreactive neurons were detected in telencephalic, diencephalic and mesencephalic areas such as dorsal cortex, subfornical organ, paraventricular nucleus, recessus infundibular nucleus, nucleus of the oculomotor nerve and nucleus of the trigeminal nerve. Immunoreactive fibres ran along the hypothalamo-hypophysial tract to end in the outer layer of the median eminence and the neural lobe of the hypophysis. In general, immunoreactive fibres occurred in the same places of immunoreactive neurons. In addition, immunoreactive fibres were observed in the septum, amygdala, lamina terminalis, supraoptic nucleus, nucleus of the paraventricular organ, ventromedial hypothalamic nucleus and interpeduncular nucleus. These results indicate that, as for other vertebrates, corticotropin-releasing hormone in B. jararaca brain, besides being a releasing hormone, may also act as a central neurotransmitter and/or neuromodulator.     

Neuropeptide FF2 receptor distribution in the human brain. An immunohistochemical study

Human neuropeptide FF2 (hFF2) receptor has been postulated to mediate central autonomic regulation by virtue of its ability to bind with high affinity to many amidated neuropeptides. In the present immunohistochemical study, we identified hFF2 positive neurons in the forebrain and medulla oblongata of individuals, who died suddenly of mechanical trauma or hypothermia. Morphologically, these neurons demonstrated features identified with both projection neurons and interneurons. In the forebrain, the highest density of hFF2 expressing neurons was observed in the anterior amygdaloid area and dorsomedial hypothalamic nucleus, especially in its caudal part. A lesser density of hFF2 neurons was identified in the ventromedial hypothalamic nucleus, lateral and posterior hypothalamic areas whereas few cells were visualized in the paraventricular hypothalamic nucleus, perifornical nucleus, horizontal limb of the diagonal band, ventral division of the bed nucleus of the stria terminalis, nucleus basalis of Meynert and ventral tegmental area. In the medulla, significant numbers of hFF2 neurons were observed in the dorsal motor nucleus of vagus and to a lesser extent in the area of catecholaminergic cell groups, A1/C1. These data provide first immunohistochemical evidence of hFF2 localization in the human brain, which is consistent with that reported for tissue distribution of FF2 mRNA and FF2 binding sites within the brain of a variety of mammalian species. The distribution of hFF2 may help in identifying the role of amidated neuropeptides in the human brain within the context of central autonomic and neuroendocrine regulation.