Somatostatin-immunoreactive nerve cell bodies and fibers in the medulla oblongata et spinalis.

Complete serial sectioning of the medulla oblongata in monkey, cat, guinea pig, and japanese dancing mouse and incubation for somatostatin-immunoreaction was carried out. Numerous regions of the medulla oblongata such as the nucleus reticularis gigantocellularis, nucleus cuneatus et gracillis, nucleus raphe magnus, nucleus tractus solitarius, nucleus vestibularis, and parts of the oliva contain dense networks of somatostatin-immunoreactive nerve fibers. Cell bodies were seen in the nucleus reticularis medullae oblongatae. In the spinal cord the sections from each segment were analyzed, showing the highest concentrations of somatostatinergic fibers in the substantia gelantinosa of the columna dorsalis. Cell bodies were seen in the zona intermedia centralis, especially in the upper cervical segments. Many positive fibers were also seen in the entire zona intermedia and the columna ventralis. Especially prominent was the immunoreactivity in the zona intermediolateralis of the thoracic segments and the columna ventralis of the lower lumbar and sacral segments.     

Distribution of reticulospinal neurons in the chicken by retrograde transport of WGA-HRP

To determine the distribution of reticulospinal (RS) neurons in the chicken, WGA-HRP was injected into the cervical or lumbosacral enlargement either unilaterally or bilaterally. The brainstem reticular nuclei sent largely descending fibers to both the spinal enlargements. The mesencephalon (medial and lateral mesencephalic reticular formation) and the rostral pons (nucleus reticularis [n.r.] pontis oralis) project mainly to the cervical enlargement. RS neurons were mainly distributed from the pontomedullary junction to the rostral medulla including n. r. pontis caudalis and pars gigantocellularis, n. r. gigantocellularis, n. r. parvocellularis, n. r. paragigantocellularis, and n. r. subtrigeminalis. It is suggested that the majority of these neurons send axons at least as far as the lumbosacral enlargement. In the lower medulla, RS neurons were distributed in the dorsal and ventral parts of the central nucleus of the medulla.     

Distribution of 5-HT (serotonin) immunoreactivity in the central nervous system of the inshore hagfish,Eptatretus burgeri

Summary Immunohistochemical techniques were used to study the distribution of serotonin in the central nervous system of the hagfish,Eptatretus burgeri, in order to produce a detailed map of serotonin-containing structures. In the hypothalamus, many serotonin-containing neurons contacted the cerebrospinal fluid. Most of the serotonin-containing cell bodies were located in the raphe region, where they were compactly distributed at the level of the nucleus motorius tegmenti pars anterior but more diffusely distributed at the level of the nucleus motorius tegmenti pars posterior. Serotonin-containing cell bodies and varicose fibers were widely distributed throughout the brain and upper spinal cord segments, but the distribution density was not even. On the basis of its abundance, serotonin can be judged to have an important function in the control of the hagfish central nervous system. From a phylogenetic point of view, serotonin-containing neurons in the raphe region appear to be a common property of all classes of vertebrates studied except the lampreys, whereas serotonin-containing cerebrospinal fluid-contacting neurons may be considered to be a primitive condition in all nonmammalian vertebrates.     

Substance P-immunoreactive neurons in the brainstem of the cat related to cardiovascular centers

Summary The distribution of substance P-immunoreactivity (SP-IR) in the brainstem and spinal cord of normal and colchicine-pretreated cats was analysed using the peroxidase-antiperoxidase (PAP) technique. Numerous SP-IR fibers are present in the nucleus solitarius, nucleus dorsalis nervi vagi and nucleus spinalis nervi trigemini, various parts of the formatio reticularis, substantia grisea centralis mesencephali, locus coeruleus and nucleus parabrachialis. SP-IR perikarya occur in the substantiae gelatinosa and intermedia of the spinal cord, the nucleus spinalis nervi trigemini-pars caudalis, the nucleus dorsalis nervi vagi, and the nucleus solitarius, as well as in the adjacent formatio reticularis and the medullary nuclei of the raphe. In addition, SP-IR cell bodies are located in the nuclei raphe magnus and incertus, ventral and dorsal to the nucleus tegmentalis dorsalis (Gudden), nucleus raphe dorsalis, substantia grisea centralis mensencephali, locus coeruleus, nucleus parabrachialis and colliculus superior.The results indicate that SP-IR neurons may be involved in the regulation of cardiovascular functions both at the central and peripheral level. A peripheral afferent portion seems to terminate in the nucleus solitarius and an efferent part is postulated to originate from the nucleus dorsalis nervi vagi and from the area of the nuclei retroambiguus, ambiguus and retrofacialis.     

Selective Labeling of [3H]2-Deoxy-d-Glucose in the Snake Trigeminal System: Basal and Infrared-Stimulated Conditions

[³H]2-Deoxy-d-glucose (2-DG) and high-resolution autoradiography were employed to investigate labeling patterns of the trigeminal and infrared sensory system in acrotaline snake, the pit viper (Trimeresurus flavoviridis). Following intracardiac injection of 9.25 MBq [³H]2-DG, neurons in the nucleus of the lateral descending trigeminal tract (LTTD), nucleus reticularis caloris (RC), nucleus trigemini mesencephalicus, nucleus trigemini motorius, and trigeminal ganglia were labeled in various degrees after the pit organ had been removed (basal condition). This revealed that a higher rate of glucose utilization occurred in these nuclei than in the common sensory trigeminal nuclei, which lacked labeling entirely. When a pit was stimulated periodically with an infrared stimulus for 45 min, the difference in percentage of labeled cells was ipsilaterally increased by 12.84% in large cells of the LITD and by 7.55% in the RC, as compared with the contralateral, basal-condition side. These slight changes indicate a small increase of glucose consumption during infrared reception. On the other hand, the small cells in the LTTD showed labeling that did not change with stimulation, suggesting that 2-DG uptake in inhibitory interneurons is relatively constant.     

Noradrenergic and adrenergic systems in the brain of the urodele amphibian,Pleurodeles waltlii,as revealed by immunohistochemical methods

The distribution of noradrenaline and adrenaline in the brain of the urodele amphibian Pleurodeles waltlii has been studied with antibodies raised against noradrenaline and the enzymes dopamine--hydroxylase and phenylethanolamine-N-methyltransferase. Noradrenaline-containing cell bodies were found in the anterior preoptic area, the hypothalamic nucleus of the periventricular organ, the locus coeruleus and in the solitary tract/area postrema complex at the level of the obex. Noradrenergic fibers are widely distributed throughout the brain innervating particularly the ventrolateral forebrain, the medial amygdala, the lateral part of the posterior tubercle, the parabrachial region and the ventrolateral rhombencephalic tegmentum. Putative adrenergic cell bodies were found immediately rostral to the obex, ventral to the solitary tract. Whereas the cell bodies and their dendrites were Golgi-like stained, axons were more difficult to trace. Nevertheless, some weakly immunoreactive fibers could be traced to the basal forebrain. A comparison of these results with data previously obtained in anurans reveals not only several general features, but also some remarkable species differences.Abbreviations Acc Nucleus accumbens - AP area postrema - Apl amygdala, pars lateralis - Apm amygdala, pars medialis - ca commissura anterior - Cb cerebellum - cc central canal - Dp dorsal pallium - epl external plexiform layer - gl glomerular layer of the olfactory bulb - H ganglion habenulae - igl internal granular layer - Ip nucleus interpeduncularis - Lc locus coeruleus - Ll lateral line lobe - Lp lateral pallium - Ls lateral septum - ml mitral cell layer - Mp medial pallium - Ms medial septum - nPT nucleus pretectalis - NPv nucleus of the periventricular organ - nV nervus trigeminus - oc optic chiasm - Poa preoptic area - Ri nucleus reticularis inferior - SC nucleus suprachiasmaticus - sol solitary tract - Str striatum - thd thalamus dorsalis - thv thalamus ventralis - To tectum opticum - TP tuberculum posterius - V ventricle - VH ventral hypothalamic nucleus - III nucleus nervi oculomotorii - IXm nucleus motorius nervi glossopharyngei - Xm nucleus motorius nervi vagi     

Neuropeptide Y mRNA and peptide in the night-migratory redheaded bunting brain

This study investigated the distribution of neuropeptide Y (NPY) in the brain of the night-migratory redheaded bunting (Emberiza bruniceps). We first cloned the 275-bp NPY gene in buntings, with ≥95 % homology with known sequences from other birds. The deduced peptide sequence contained all conserved 36 amino acids chain of the mature NPY peptide, but lacked 6 amino acids that form the NPY signal peptide. Using digosigenin-labeled riboprobe prepared from the cloned sequence, the brain cells that synthesize NPY were identified by in-situ hybridization. The NPY peptide containing cell bodies and terminals (fibers) were localized by immunocytochemistry. NPY mRNA and peptide were widespread throughout the bunting brain. This included predominant pallial and sub-pallial areas (cortex piriformis, cortex prepiriformis, hyperpallium apicale, hippocampus, globus pallidus) and thalamic and hypothalamic nuclei (organum vasculosum laminae terminalis, nucleus (n.) dorsolateralis anterior thalami, n. rotundus, n. infundibularis) including the median eminence and hind brain (n. pretectalis, n. opticus basalis, n. reticularis pontis caudalis pars gigantocellularis). The important structures with only NPY-immunoreactive fibers included the olfactory bulb, medial and lateral septal areas, medial preoptic nucleus, medial suprachiasmatic nucleus, paraventricular nucleus, ventromedial hypothalamic nucleus, optic tectum, and ventro-lateral geniculate nucleus. These results demonstrate that NPY is possibly involved in the regulation of several physiological functions (e.g. daily timing feeding, and reproduction) in the migratory bunting.     

Immunohistochemical localization of neuropeptide Y-like substance in the brain and hypophysis of the brown hagfish,Paramyxine atami

The distribution of neuropeptide Y-like immunoreactivity in the brain and hypophysis of the brown hagfish, Paramyxine atami, was examined by use of the peroxidase-antiperoxidase method. Immunoreactive cells were found in two areas of the brain, the nucleus hypothalamicus of the diencephalon and the ventrolateral area of the caudal tegmentum, at the level of the nucleus motorius V–VII. The labeled cells of the nucleus hypothalamicus were loosely grouped and recognized as bipolar neurons. Immunolabeled fibers were widely distributed in the brain, showing the highest density in the diencephalon. They were sparse, or absent, in the olfactory bulb, habenula, primordium hippocampi, neurohypophysis, corpus interpedunculare, and dorsolateral area of the medulla oblongata. The fibers appeared to project exclusively from the ventral hypothalamus to various other portions of the brain: the anterolateral areas of the telencephalon via the basal hypothalamus, the pars dorsalis thalami, the dorsocaudal region of the mesencephalon, and the ventromedial portions of the tegmentum and anterior medulla oblongata. These findings suggest that, in the brown hagfish, NPY-like substance is involved in neuroregulation of various cerebral areas, but it may be of little significance in the control of pituitary function.     

Immunohistochemical Localization of C-RFamide, a FMRF-related Peptide, in the Brain of the Goldfish, Carassius auratus

Carassius RFamide (C-RFa) is a novel peptide found in the brain of the Japanese crucian carp. It has been demonstrated that mRNA of C-RFa is present in the telencephalon, optic tectum, medulla oblongata, and proximal half of the eyeball in abundance. Immunohistochemical methods were employed to elucidate the distribution of the peptide in the brain of the goldfish (Carassius auratus) in detail. C-RFaimmunoreactive perikarya were observed in the olfactory bulb, the area ventralis telencephali pars dorsalis and lateralis, nucleus preopticus, nucleus preopticus periventricularis, nucleus lateralis tuberis pars posterioris, nucleus posterioris periventricularis, nucleus ventromedialis thalami, nucleus posterioris thalami, nucleus anterior tuberis, the oculomotor nucleus, nucleus reticularis superior and inferior, facial lobe, and vagal lobe. C-RFa immunoreactive fibers and nerve endings were present in the olfactory bulb, olfactory tract, area dorsalis telencephali pars centralis and medialis, area ventralis telencephali, midbrain tegmentum, diencephalon, medulla oblongata and pituitary. However, in the optic tectum the immunopositive perikarya and fibers were less abundant. Based on these results, some possible functions of C-RFa in the nervous system were discussed.     

Distribution of NT-IR perikarya in the brain of the guinea pig with special reference to cardiovascular centers in the medulla oblongata

Summary The occurrence and distribution of neurotensin-immunoreactive (NT-IR) perikarya was studied in the central nervous system of the guinea pig using a newly raised antibody (KN 1). Numerous NT-IR perikarya were found in the nuclei amygdaloidei, nuclei septi interventriculare, hypothalamus, nucleus parafascicularis thalami, substantia grisea centralis mesencephali, ventral medulla oblongata, nucleus solitarius and spinal cord. The distribution of NT-IR perikarya was similar to that previously described in the rat and monkey. In the gyrus cinguli, hippocampus and nucleus olfactorius, though, no NT-IR neurons were detected in this investigation. Additional immunoreactive perikarya, however, were observed in areas of the ventral medulla oblongata, namely in the nucleus paragigantocellularis, nucleus retrofacialis and nucleus raphe obscurus.The relevance of the NT-IR perikarya within the ventral medulla oblongata is discussed with respect to other neuropeptides, which are found in this area, and to cardiovascular regulation.Abbreviations abl nucleus amygdaloideus basalis lateralis - abm nucleus amygdaloideus basalis medialis - acc nucleus amygdaloideus centralis - aco nucleus amygdaloideus corticalis - ahp area posterior hypothalami - ala nucleus amygdaloideus lateralis anterior - alp nucleus amygdaloideus lateralis posterior - ame nucleus amygdaloideus medialis - atv area tegmentalis ventralis - bst nucleus proprius striae terminalis - CA commissura anterior - CC corpus callosum - cgld corpus geniculatum laterale dorsale - cglv corpus geniculatum laterale ventrale - cgm corpus geniculatum mediale - CHO chiasma opticum - CI capsula interna - co nucleus commissuralis - cod nucleus cochlearis dorsalis - cp nucleus caudatus/Putamen - cs colliculus superior - cu nucleus cuneatus - dmh nucleus dorsomedialis hypothalami - DP decussatio pyramidum - em eminentia mediana - ent cortex entorhinalis - epi epiphysis - FLM fasciculus longitudinalis medialis - fm nucleus paraventricularis hypothalami pars filiformis - FX fornix - gd gyrus dentatus - gp globus pallidus - gr nucleus gracilis - hl nucleus habenulae lateralis - hm nucleus habenulae medialis - hpe hippocampus - ift nucleus infratrigeminalis - io oliva inferior - ip nucleus interpeduncularis - LM lemniscus medialis - MT tractus mamillo-thalamicus - na nucleus arcuatus - nls nucleus lateralis septi - nms nucleus medialis septi - npca nucleus proprius commissurae anterioris - ns nucleus solitarius - n III nucleus nervi oculomotorii - nt V nucleus tractus spinalis nervi trigemini - ntm nucleus mesencephalicus nervi trigemini - osc organum subcommissurale - P tractus cortico-spinalis - PC pedunculus cerebri - PCI pedunculus cerebellaris inferior - pir cortex piriformis - pol area praeoptica lateralis - pom area praeoptica medialis - prt area praetectalis - pt nucleus parataenialis - pvh nucleus paraventricularis hypothalami - pvt nucleus paraventricularis thalami - r nucleus ruber - re nucleus reuniens - rgi nucleus reticularis gigantocellularis - rl nucleus reticularis lateralis - rm nucleus raphe magnus - ro nucleus raphe obscurus - rp nucleus raphe pallidus - rpc nucleus reticularis parvocellularis - rpgc nucleus reticularis paragigantocellularis - sch nucleus suprachiasmaticus - SM stria medullaris thalami - snc substantia nigra compacta - snl substantia nigra lateralis - snr substantia nigra reticularis - ST stria terminalis - tad nucleus anterior dorsalis thalami - tam nucleus anterior medialis thalami - tav nucleus anterior ventralis thalami - tbl nucleus tuberolateralis - tc nucleus centralis thalami - tl nucleus lateralis thalami - tmd nucleus medialis dorsalis thalami - TO tractus opticus - TOL tractus olfactorium lateralis - tpo nucleus posterior thalami - tr nucleus reticularis thalami - trs nucleus triangularis septi - TS tractus solitarius - TS V tractus spinalis nervi trigemini - tvl nucleus ventrolateralis thalami - vmh nucleus ventromedialis hypothalami - vh ventral horn, Columna anterior - zi zona incerta Supported by the Deutsche Forschungsgesellschaft (DFG) SFB 90, Carvas     

Somatostatin-immunoreactive fiber projections into the brain stem and the spinal cord of the rat

Summary By use of the PAP-immunohistochemical staining technique with serial sections, somatostatin-immunoreactive fiber projections into the brain stem and the spinal cord are described. These projections originate in the periventricular somatostatin-immunoreactive perikarya of the hypothalamus and form three main pathways: (1) along the stria medullaris thalami and the fasciculus retroflexus into the interpeduncular nucleus; (2) along the medial forebrain bundle into the mammillary body; and (3) via the periventricular gray and the bundle of Schütz into the midbrain tegmentum. Densely arranged immunoreactive fibers and/or basket-like fiber terminals are observed within the following afferent systems: somatic afferent systems (nucleus spinalis nervi trigemini, substantia gelatinosa dorsalis of the entire spinal cord), and visceral afferent systems (nucleus solitarius, regio intermediolateralis and substantia gelatinosa of the sacral spinal cord). These projections form terminals around the perikarya of the second afferent neuron. Perikarya of the third afferent neuron are influenced by somatostatin-immunoreactive projections into the auditory system (nucleus dorsalis lemnisci lateralis, nucleus corporis trapezoidei). Furthermore, a somatostatin-immunoreactive fiber projection is found in the ventral part of the medial accessory olivary nucleus, in nuclei of the limbic system (nucleus habenularis medialis, nuclei supramamillaris and mamillaris lateralis) and in the formatio reticularis (nucleus Darkschewitsch, nuclei tegmenti lateralis and centralis, nucleus parabrachialis lateralis, as well as individual perikarya of the reticular formation). Targets of these projections are interneurons within interlocking neuronal chains.Supported by the Deutsche Forschungsgemeinschaft (Grant Nr. Kr 569/3) and Stiftung Volkswagenwerk     

Evolution of the reticular formation

The reticular formation of mammals contains numerous nuclei which can be recognized by their projection patterns, cytoarchitectonics, and neuropeptide/neurotransmitter content. We have identified reticular nuclei in representatives from numerous reptilian groups and ascertained presence or absence of these reticular nuclei in an attempt to use neuronal occurrence as a tool to determine phylogenetic relationships. Recently these studies have been extended to two elasmobranchs, a galeomorph shark and a ray. In this report, we concentrate on three medullary spinal projecting reticular nuclei, reticularis gigantocellularis, reticularis magnocellularis, and reticularis paragigantocellularis. We found that all three nuclei were present in rats, lizards, and elasmobranchs, but one nucleus was absent in crocodilians, and two nuclei were absent in turtles. Thus brain organization may give us clues to phylogenetic relationships. Moreover, these three reticular nuclei exhibited remarkably similar cellular morphology in mammals, reptiles, and elasmobranchs.     

Central projections of the lagena (the third otolith endorgan of the inner ear) in the pigeon

Central projections of the lagena were studied in the pigeon using transport of biotinylated dextran amine (BDA) that was locally applied to the lagenar epithelium through the opened cochlear canal. Descending (dorsocaudal part) and superior (middle part) vestibular nuclei were the main rhombencephalon structures with the maximum density of labeled fibers and terminals. Lesser numbers of labeled fibers were observed in the ventral part of the lateral vestibular nucleus and also in the medial vestibular nucleus; single labeled fibers were found in the cochlear nuclei. In the cases where BDA diffused not only in the lagena but also on the basilar papilla after application of the marker to the cochlear canal, considerable numbers of labeled fibers were observed in the cochlear nuclei; apart from this, the pattern of distribution of labeled fibers in the vestibular nuclei did not differ in general from that described above (in the case of a sufficiently local application of BDA only to the lagena). Efferent lagenar neurons were localized ventrally with respect to the vestibular nuclei, in particular in the nucl. reticularis pontis caudalis. Neirofiziologiya/Neurophysiology, Vol. 40, No. 3, pp. 199–210, May–June, 2008.     

Distribution of parvalbumin-immunoreactivity in the rat thalamus using a monoclonal antibody

1. The distribution of parvalbumin cell bodies and fibers in the thalamus of the rat was studied using a monoclonal antibody and the avidin-biotin-peroxidase method. The densest clusters of immunoreactive perikarya were observed in the nuclei ventralis posterior, reticularis, ventralis anterior and zona incerta, whereas the nuclei habenularis lateralis, lateralis posterior, lateralis, centralis lateralis and ventralis lateralis had the lowest density. In the nucleus geniculatum laterale ventralis, the density of parvalbumin cell bodies was intermediate. In all these thalamic nuclei, small, round or fusiform immunoreactive cells with short immunolabeled dendritic processes were observed. 2. The densest network of immunoreactive fibers was observed in the nuclei geniculatum laterale ventralis, reticularis and zona incerta. The nuclei geniculatum laterale dorsalis, ventralis posterior, medialis ventralis, ventralis anterior, anterior ventralis, anterior dorsalis and rhomboidens contained a moderate number of parvalbumin fibers, whereas the nuclei lateralis posterior, habenularis lateralis, parataenialis, centrum medianum, lateralis, centralis lateralis, ventralis lateralis, medialis dorsalis, anterior medialis, ventralis medialis and lateralis anterior had the lowest density of immunoreactive fibers. In addition, a large number of immunoreactive fibers was found in the lemniscus medialis and a scarce number in the stria medullaris. 3. No immunoreactive structure was observed in the nuclei habenularis medialis, paraventricularis, reuniens and geniculatum mediale. 4. Thus, perikarya and fibers containing parvalbumin are widely distributed throughout the thalamus of the rat, suggesting that parvalbumin might play a role, directly or indirectly, in limbic, visual and somatosensory mechanisms.     

The distribution of corticotropin releasing factor-like immunoreactive neurons in rat brain

Using the indirect immunofluorescent technique, corticotropin releasing factor (CRF)-like immunoreactive nerve fibers and cell bodies were observed to be widely distributed in rat brain. A detailed stereotaxic atlas of CRF-like immunoreactive neurons was prepared. Large numbers of CRF-containing perikarya were observed in the nucleus paraventricularis, with scattered cells in the following nuclei: accumbens, interstitialis stria terminalis, preopticus medialis, supraopticus, periventricularis hypothalami, amygdaloideus centralis, dorsomedialis, substantia grisea centralis, parabrachialis dorsalis and ventralis, tegmenti dorsalis lateralis, vestibularis medialis, tractus solitarius and reticularis lateralis. The most intense staining of CRF-containing fibers was observed in the external lamina of the median eminence. Moderate numbers of CRF-like fibers were observed in the following nuclei: lateralis and medialis septi, tractus diagonalis, interstitialis stria terminalis, preopticus medialis, supraopticus, periventricularis thalami and hypothalami, paraventricularis, anterior ventralis and medialis thalami, rhomboideus, amygdaloideus centralis, habenulae lateralis, dorsomedialis, ventromedialis, substantia grisea centralis, cuneiformis, parabrachialis dorsalis and ventralis, tegmenti dorsalis lateralis, cerebellum, vestibularis medialis, reticularis lateralis, substantia gelatinosa trigemini and lamina I and II of the dorsal horn of the spinal cord. The present findings suggest that a CRF-like peptide may be involved in a neurotransmitter or neuromodulator role, as well as a hypophysiotropic role.     

Electrophysiological Study of Supraspinal Input and Spinal Output of Cat's Subnucleus Reticularis Dorsalis (SRD) Neurons

This work addressed the study of subnucleus reticularis dorsalis (SRD) neurons in relation to their supraspinal input and the spinal terminating sites of their descending axons. SRD extracellular unitary recordings from anesthetized cats aimed to specifically test, 1) the rostrocaudal segmental level reached by axons of spinally projecting (SPr) neurons collateralizing or not to or through the ipsilateral nucleus reticularis gigantocellularis (NRGc), 2) whether SPr fibers bifurcate to the thalamus, and 3) the effects exerted on SRD cells by electrically stimulating the locus coeruleus, the periaqueductal grey, the nucleus raphe magnus, and the mesencephalic locomotor region. From a total of 191 SPr fibers tested to cervical 2 (Ce2), thoracic 5 (Th5) and lumbar5 (Lu5) stimulation, 81 ended between Ce2 and Th5 with 39 of them branching to or through the NRGc; 21/49 terminating between Th5 and Lu5 collateralized to or through the same nucleus, as did 34/61 reaching Lu5. The mean antidromic conduction velocity of SPr fibers slowed in the more proximal segments and increased with terminating distance along the cord. None of the 110 axons tested sent collaterals to the thalamus; instead thalamic stimulation induced long-latency polysynaptic responses in most cells but also short-latency, presumed monosynaptic, in 7.9% of the tested neurons (18/227). Antidromic and orthodromic spikes were elicited from the locus coeruleus and nucleus raphe magnus, but exclusively orthodromic responses were observed following stimulation of the periaqueductal gray or mesencephalic locomotor region. The results suggest that information from pain-and-motor-related supraspinal structures converge on SRD cells that through SPr axons having conduction velocities tuned to their length may affect rostral and caudal spinal cord neurons at fixed delays, both directly and in parallel through different descending systems. The SRD will thus play a dual functional role by simultaneously regulating dorsal horn ascending noxious information and pain-related motor responses.     

Cloning of corticotropin-releasing hormone (CRH) precursor cDNA and immunohistochemical detection of CRH peptide in the brain of the Japanese eel,paying special attention to gonadotropin-releasing hormone

The stress-related corticotropin-releasing hormone (CRH) was first identified by isolation of its cDNA from the brain of the Japanese eel Anguilla japonica. CRH cDNA encodes a signal peptide, a cryptic peptide and CRH (41 amino acids). The sequence homology to mammalian CRH is high. Next, the distribution of CRH-immunoreactive (ir) cell bodies and fibers in the brain and pituitary were examined by immunohistochemistry. CRH-ir cell bodies were detected in several brain regions, e.g., nucleus preopticus pars magnocellularis, nucleus preopticus pars gigantocellularis and formatio reticularis superius. In the brain, CRH-ir fibers were distributed not only in the hypothalamus but also in various regions. Some CRH-ir fibers projected to adrenocorticotropic hormone (ACTH) cells in the rostral pars distalis of the pituitary and also the α-melanocyte-stimulating hormone (α-MSH) cells in the pars intermedia of the pituitary. Finally, the neuroanatomical relationship between the CRH neurons and gonadotropin-releasing hormone (GnRH) neurons was examined by dual-label immunohistochemistry. CRH-ir fibers were found to be in close contact with GnRH-ir cell bodies in the hypothalamus and in the midbrain tegmentum and GnRH-ir fibers were in close contact with CRH-ir cell bodies in the nucleus preopticus pars magnocellularis. These results suggest that CRH has some physiological functions other than the stimulation of ACTH and α-MSH secretion and that reciprocal connections may exist between the CRH neurons and GnRH neurons in the brain of the Japanese eel.     

Behavioural and cardiovascular responses to electrical stimulation of the medulla oblongata of the cat

Effects of stimulation of the nucleus tractus solitarii, the dorsal motor nucleus of the vagus, the nucleus reticularis paramedianus, and the nucleus cuneatus were studied in free-moving cats. Stimulation of the medullary nuclei that are known to be involved in the central nervous control of cardiovascular functions might activate preprogrammed motor responses such as licking and sniffing, and induce complex behavioural response patterns such as sleep or flight reaction. Moreover, both lever-pressing for rewarding brain stimulation, and eating in food deprived cats might be modulated by these stimulations. In a shuttle box the cats showed no tendency toward shuttling during stimulation, except the stimulation of the nucleus reticularis paramedianus which produced aversion. The cardiovascular and respiratory effects varied parallel with the behavioural responses. It is concluded that the medullary nuclei related to visceral functions are capable of affecting somatomotor behaviour either directly on the motor system, or by inducing complex response patterns in which somatomotor and visceral responses are integrated.     

Basal ganglia influences on the cerebellum of the cat

The changes in firing rate of intracerebellar nuclear neurons following electrical stimulation of the contralateral basal ganglia were investigated in adult cats, in which antidromic activation of cortico-pontine and/or cortico-olivar fibers arising in the area 6 had been excluded by chronic ablation of the motor cortex. Activation of putamen and caudate nucleus induced discharge changes in a low percentage (below 12.5%) of both medial and lateral cerebellar nuclei neurons, while stimulation of globus pallidus and especially of entopeduncular nucleus modified the spontaneous discharge of a greater percent of cells (up to 29%), mainly in the most lateral cerebellar portions. The basal ganglia-induced effects were abolished upon section of the brachium pontis but not of the restiform body. Latency values of the responses, which were predominantly excitatory in nature, suggest the involvement of structures interposed between basal ganglia and precerebellar systems. We postulated that impulses issued by the basal ganglia could reach the cerebellum through a pathway that involves the pedunculopontine nucleus and the nucleus reticularis tegmenti pontis.     

Localization of cholinergic neurons in the cat lower brain stem

The localization of cholinergic neurons in the cat lower brain stem was determined immunocytochemically with a monoclonal antibody against choline acetyltransferase (ChAT), the acetylcholine synthesizing enzyme. ChAT-positive neurons were observed in four major cell groups: cranial nerve motor and special visceromotor neurons: parasympathetic preganglionic visceromotor neurons; neurons located in the ponto-mesencephalic tegmentum including area X (or pedunculopontine tegmental nucleus), nucleus laterodorsalis tegmenti (Ldt) of Castaldi, and peri-locus coeruleus alpha (peri-alpha); and neurons located in nucleus reticularis magnocellularis (Mc) and adjacent nucleus reticularis gigantocellularis (Gc) of the medulla.