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Eric W Roubos

Publications and source records attributed to Eric W Roubos.

At least 19 recordsLinked to original sources
PubMed2007

Neuropeptide Y activates urocortin 1 neurons in the nonpreganglionic Edinger-Westphal nucleus.

Central regulatory pathways promoting stress adaptation utilize various neurotransmitters/neuropeptides, such as urocortin 1 (Ucn1) and neuropeptide Y (NPY). Ucn1 is abundantly expressed in the nonpreganglionic Edinger-Westphal nucleus (npEW), where it is codistributed with NPY-immunoreactive (ir) terminals. A special role for both neuropeptides has been postulated in stress adaptation. Using double-labeling immunohistochemistry, we observed close appositions between NPY-ir terminals and neurons immunoreactive for Ucn1 in the rat, as well as in the human npEW. Therefore, we hypothesized that NPY might control the activity of Ucn1-positive neurons in the npEW. To test this hypothesis, NPY was injected into the lateral cerebral ventricle of rats, resulting in a strong activation of npEW Ucn1 neurons as revealed by Fos immunohistochemistry. Ucn1 mRNA was also upregulated in the npEW 2 hours after the injection of NPY. In a search for the type of NPY receptor that mediates this NPY-induced recruitment of npEW-Ucn1 cells, we found that the great majority of Ucn1 cells exhibited NPY Y5 receptor immunoreactivity, and only a few of the Ucn1 cells coexpressed the Y1 receptor. We concluded that NPY, via NPY Y5 and to a lesser extent via the Y1 receptors, exerts a stimulatory action on Ucn1 cells in the npEW. Further studies are currently in progress to elucidate the significance of this NPY-Ucn1 interaction in the npEW.

Adaptation, Psychological↗
PubMed2006

Monitoring neurotransmitter release using surface-enhanced Raman spectroscopy.

Surface-enhanced Raman spectroscopy (SERS) is a promising tool to monitor neurotransmitter release at the single-cell level: it is a sensitive technique that provides structural information of the released compounds and spatial information about their release sites. In this study we demonstrate that depolarization-evoked catecholamine secretion by rat phaeochromocytoma (PC12) cells can be spatially resolved by SERS using silver colloids. A suitable SERS substrate was created by adding silver colloids to the cell culture medium. Nomarski-DIC microscopy combined with reflection confocal laser scanning microscopy showed that the colloids were primarily present on top of the cell membrane. The SERS spectra were successfully corrected for the contribution of cell constituents. Dopamine and noradrenaline were localized by examining the correlation coefficient between spectra and reference catecholamine spectra. Potential improvements of the temporal resolution of the technique are discussed.

Animals↗
PubMed2006

NMDA-NR1 and AMPA-GluR4 receptor subunit immunoreactivities in the absence epileptic WAG/Rij rat.

From an age of 2-3 months onwards, the WAG/Rij rat, a genetic model for absence epilepsy, develops spike-wave discharges (SWD). SWD start in the peri-oral somatosensory cortex (POsc), whereas the rostral reticular thalamic nucleus (rRTN) contributes to synchronizing the thalamo-cortical oscillations. We hypothesize that N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoazolepropionic acid (AMPA) receptors in the POsc and rRTN are involved in, respectively, the initiation and synchronization of SWD activity. As a first step to test this hypothesis, 3 months old non-epileptic and 6 months old absence epileptic WAG/Rij rats were compared with age-matched non-epileptic ACI control rats. The presence of NMDA and AMPA receptors was assessed by quantifying immunostaining for the NMDA-NR1 subunit and the AMPA-GluR4 subunit, respectively. In the POsc, WAG/Rij rats of both ages showed less NMDA-NR1 (-14.7%) and AMPA-GluR4 (-8.7%) subunit staining than ACI rats. From 3 to 6 months, AMPA-GluR4 subunit staining more strongly increased in the rRTN of WAG/Rij rats than of ACI rats. Further studies should support our assumption that in the POsc of the WAG/Rij rat, SWD start as a result of reduced NMDA- and AMPA-mediated glutamatergic stimulation, and that AMPA-GluR4 containing neurons in the rRTN of this rat strain contribute to synchronization of thalamic and cortical neurons.

Aging↗
PubMed2006

Distribution and expression of CRF receptor 1 and 2 mRNAs in the CRF over-expressing mouse brain.

Corticotropin-releasing factor (CRF) acts through CRF 1 and CRF 2 receptors (CRF1, CRF2). To test the hypothesis that CRF controls the expression of these receptors in a brain site- and receptor-type specific manner, we studied CRF1 mRNA and CRF2 mRNA expressions in mice with central CRF over-expression (CRF-OE) and using in situ hybridization. CRF1 and CRF2 mRNAs appear to be differentially distributed across the brain. The brain structures expressing the receptors are the same in wild-type (WT) and in CRF-OE mice. We therefore conclude that chronically elevated CRF does not induce or inhibit expression of these receptors in structures that normally do not or do, respectively, show these receptors. However, from counting cell body profiles positive for CRF1 and CRF2 mRNAs, clear differences appear in receptor expression between CRF-OE and WT mice, in a brain-structure-specific fashion. Whereas some structures do not differ, CRF-OE mice exhibit remarkably lower numbers of CRF1 mRNA-positive profiles in the subthalamic nucleus (-38.6%), globus pallidus (-31.5%), dorsal part of the lateral septum (-23.5%), substantia nigra (-22,8%), primary somatosensory cortex (-18.9%) and principal sensory nucleus V (-18.4%). Furthermore, a higher number of CRF2 mRNA-positive profiles are observed in the dorsal raphe nucleus (+32.2%). These data strongly indicate that central CRF over-expression in the mouse brain is associated with down-regulation of CRF1 mRNA and up-regulation of CRF2 mRNA in a brain-structure-specific way. On the basis of these results and the fact that CRF-OE mice reveal a number of physiological and autonomic symptoms that may be related to chronic stress, we suggest that CRF1 in the basal nuclei may be involved in disturbed information processing and that CRF2 in the dorsal raphe nucleus may play a role in mediating stress-induced release of serotonin by CRF.

Animals↗
PubMed2005

Receptors for neuropeptide Y, gamma-aminobutyric acid and dopamine differentially regulate Ca2+ currents in Xenopus melanotrope cells via the G(i) protein beta/gamma-subunit.

Secretion of alpha-melanophore-stimulating hormone (alphaMSH) from pituitary melanotrope cells of the amphibian Xenopus laevis is under inhibitory synaptic control by three neurotransmitters produced by the suprachiasmatic nucleus: gamma-aminobutyric acid (GABA), neuropeptide Y (NPY) and dopamine (DA). These inhibitory effects occur through G(i)-protein-coupled receptors (G(i)PCR), and differ in strength: GABA(B)-receptor-induced inhibition is the weakest, whereas DA (via a D2-receptor) and NPY (via a Y1-receptor) strongly inhibit, with NPY having a long-lasting effect. Previously it was shown that DA inhibits two (R- and N-type channel) of the four voltage-operated Ca2+ channels in the melanotrope, and that only part of this inhibition is mediated by beta/gamma-subunits of the G(i) protein. We here demonstrate that also the Y1- and GABA(B)-receptor inhibit only part of the total Ca2+ current (I(Ca)), with fast activation and inactivation kinetics. However, GABA(B)-mediated inhibition is weaker than the inhibitions induced via Y1- and D2-receptors (-21 versus -27% and -30%, respectively). Using a depolarizing pre-pulse protocol it was demonstrated that GABA(B)-induced inhibition of I(Ca) most likely depends on Gbeta/gamma-subunit activation whereas Y1- and D2- induced inhibitions are only partially mediated by Gbeta/gamma-subunits. No differences were found between the Y1- and D2-induced inhibitions. These results imply that activation of different G(i)PCR inhibits the I(Ca) through different mechanisms, a phenomenon that may underlie the different potencies of the suprachiasmatic neurotransmitters to inhibit alphaMSH secretion.

Animals↗
PubMed2005

alpha-Melanophore-stimulating hormone (alpha-MSH) antagonizes interleukin-1beta-induced hyperalgesia and Fos expression in the paraventricular and arcuate nucleus of the rat.

It is known that intracerebroventricular (ICV) administration of a low dose of interleukin-1beta (IL-1beta) induces hyperalgesia and that this effect can be inhibited by alpha-melanophore-stimulating hormone (alpha-MSH). To identify the part of the brain that is affected by hyperalgesia-induced IL-1beta and the possible site of alpha-MSH inhibition, we have examined Fos expression in the rat brain in response to ICV microinjection of alpha-MSH and/or IL-1beta. Following injection of 10 pg IL-1beta, hyperalgesia was induced and Fos became expressed in the paraventricular nucleus (PVN) of the hypothalamus and in the arcuate nucleus (ARC), which contains alpha-MSH-producing neurons. IL-1beta injection did not induce Fos expression in the pars intermedia of the pituitary gland, which contains endocrine melanotrope cells that release alpha-MSH into the systemic circulation. ICV co-injection of IL-1beta with 30 ng alpha-MSH fully inhibited both hyperalgesia and Fos expression in the PVN and the ARC. We conclude that PVN neurons are activated by hyperalgesic IL-1beta and propose that this effect is abolished by alpha-MSH possibly released from the ARC but not from the pituitary gland.

Animals↗
PubMed2005

Chronic ether stress-induced response of urocortin 1 neurons in the Edinger-Westphal nucleus in the mouse.

Urocortin 1 (Ucn1) neurons, most abundantly expressed in the Edinger-Westphal nucleus (E-WN), respond to various acute challenges. In a recent study, we found that acute ether stress resulted in the strongest activation of E-WN Ucn1 cells, as revealed by immunohistochemistry for Fos (often used as a marker for neuronal activation). Although the acute stress responsiveness of E-WN Ucn1 neurons has been widely studied, the activation pattern of Fos in these neurons in response to repeated challenges has not yet been investigated. Therefore, we quantitatively studied Fos activation in E-WN neurons and measured Ucn1 mRNA levels in E-WN neurons after acute and chronic ether stress in mice. Acute stress resulted in a robust Fos response and an increase in Ucn1 mRNA as compared to non-stressed mice. In the chronic stress paradigm, Fos expression was unchanged, whereas after 2 and 3 weeks of daily ether exposure Ucn1 mRNA expression had strongly declined in the E-WN. Fos and Ucn1 mRNA were co-expressed in E-WN neurons in both acutely and chronically stressed animals. This paper is the first to demonstrate that Ucn1 mRNA-expressing neurons in the E-WN show a non-habituating Fos response to a chronic homotypic ether challenge that also resulted in a reliable down-regulation of E-WN Ucn1 mRNA levels vs. acutely stressed animals. Based on these results, we propose that the E-WN-Ucn1 system represents a novel stress adaptation pathway, which may play an important role in coping with chronic challenges.

Analysis of Variance↗
PubMed2005

Evidence that urocortin I acts as a neurohormone to stimulate alpha MSH release in the toad Xenopus laevis.

We have raised the hypothesis that in the South African clawed toad Xenopus laevis, urocortin 1 (UCN1), a member of the corticotropin-releasing factor (CRF) peptide family, functions not only within the brain as a neurotransmitter/neuromodulator but also as a neurohormone, promoting the release of alpha-melanophore-stimulating hormone (alphaMSH) from the neuroendocrine melanotrope cells in the intermediate lobe of the pituitary gland. This hypothesis has been investigated by (1) assessing the distribution of UCN1 and CRF by light immunocytochemistry, (2) determining the subcellular presence of UCN1 in the neural lobe of the pituitary gland by immuno-electron microscopy applying high-pressure freezing and cryosubstitution, and (3) testing the effect of UCN1 on MSH release from toad melanotrope cells using in vitro superfusion. In the X. laevis brain, the main site of UCN1-positive somata was found to be the Edinger-Westphal nucleus. UCN1 immunoreactivity (ir) also occurs in the nucleus posteroventralis tegmenti, central gray, nucleus reticularis medius, nucleus motorius nervi facialis, and nucleus motorius nervi vagi. UCN1 occurs together with CRF in the nucleus motorius nervi trigemini, and in the magnocellular nucleus, which send a UCN1- and CRF-containing fiber tract to the median eminence. Strong UCN1-ir and CRF-ir were found in the external zone of the median eminence. From the internal zone of the median eminence, UCN1-ir fibers, but few CRF-ir fibers, were found to project to the pituitary neural lobe, where they form numerous neurohemal axon terminals. Ultrastructurally, two types of terminal containing UCN1-ir secretory granules were distinguished: type A contains large, moderately electron-dense, round secretory granules and type B is filled with smaller, strongly electron-dense, ellipsoid secretory granules. In vitro superfusion studies showed that UCN1 stimulated the release of alphaMSH from melanotrope cells in a dose-dependent manner. Our results support the hypothesis that in X. laevis, UCN1 released from neurohemal axon terminals in the pituitary neural lobe functions as a stimulatory neurohormone for alphaMSH release from melanotrope cells of the pituitary intermediate lobe.

Animals↗
PubMed2005

Dopamine D2-receptor activation differentially inhibits N- and R-type Ca2+ channels in Xenopus melanotrope cells.

Dopamine inhibits pituitary melanotrope cells of the amphibian Xenopus laevis through activation of a dopamine (D2) receptor that couples to a Gi protein. Activated Gi protein subunits are known to affect voltage-operated Ca2+ currents (ICa). In the present study we investigated which Ca2+ currents are regulated by D2-receptor activation and which Gi protein subunits are involved. Whole-cell voltage-clamp patch-clamp experiments from holding potentials (HPs) of -80 and -30 mV show that 28.6 and 36.9%, respectively, of the total ICa was inhibited by apomorphin, a D2-receptor agonist. The inhibited current had fast activation and inactivation kinetics. From an HP of -80 mV, inhibition of N-type Ca2+ currents with omega-conotoxin GVIA and R-type current by SNX-482 reduced the efficacy of the apomorphin-induced inhibition. From an HP of -30 mV this reduction for omega-conotoxin GVIA was still observed. Blocking L-type current by nifedipine or P/Q-type current by omega-agatoxin IVA did not affect apomorphin-induced inhibition at either HP. Our results imply that D2-receptor activation inhibits both N- and R-type Ca2+ currents. Using a strong depolarizing pre-pulse partially reversed the inhibition of the total current by apomorphin. About 50% of this inhibition was achieved through interaction of Gbeta/gamma proteins, and this part of the inhibited ICa had fast activating and inactivating kinetics. However, the other part of the current inhibited by D2-receptor activation may proceed through Galpha-PKA phosphorylation.

Animals↗
PubMed2005

High-pressure freezing followed by cryosubstitution as a tool for preserving high-quality ultrastructure and immunoreactivity in the Xenopus laevis pituitary gland.

Subcellular localisation of proteins and peptides yields fundamental information about cell functioning. Immunoelectron microscopy is a powerful tool to achieve this goal, but combining good tissue preservation with strong immunoreactivity is a great challenge in electron microscopy. We have applied a novel approach, using high-pressure freezing (HPF) followed by cryosubstitution, to prepare the pituitary gland of the amphibian Xenopus laevis for immunogold-electron microscopy. In this way, we investigated the subcellular distribution of brain-derived neurotrophic factor and the amphibian neurohormone mesotocin in the pituitary neural lobe, and the peptide hormone alpha-melanophore-stimulating hormone and its protein precursor proopiomelanocortin in melanotrope cells of the pituitary intermediate lobe. In contrast to conventional chemical fixation (followed by cryosubstitution), HPF not only revealed strong immunoreactivity of the secretory products, but also provided excellent ultrastructural preservation of cell organelles, including secretory granule subtypes. We conclude that HPF followed by cryosubstitution provides a preparation technique of choice when both optimal tissue ultrastructure and strong immunoreactivity are required.

Animals↗
PubMed2005

The role of Munc18-1 in docking and exocytosis of peptide hormone vesicles in the anterior pituitary.

BACKGROUND INFORMATION: Many neurons secrete classical transmitters from synaptic vesicles as well as peptide transmitters from LDCVs (large dense-core vesicles). Little is known about the mechanistic differences between these two secretory pathways. The soluble protein Munc18-1 is essential for synaptic vesicle secretion [Verhage, Maia, Plomp, Brussaard, Heeroma, Vermeer, Toonen, Hammer, van den Berg, Missler, et al. (2000) Science 287, 864-869.]. RESULTS: In the present study, we tested if Munc18 genes are also involved in peptidergic secretion from LDCVs using the anterior pituitary as a model system. We show that Munc18-1 is the dominant isoform expressed in the anterior pituitary. In Munc18-1 null mutant mice, the anterior pituitary developed normally and the five major endocrine cell types had a normal distribution. However, circulating peptide hormone levels were decreased by up to 50-fold in the null mutant, whereas the intracellular levels were significantly higher than that in controls. Ultrastructural analysis using the tannic acid method revealed striking differences in the distribution of secretory vesicles: (i) the number of exocytotic figures was mostly decreased in the null mutants and (ii) the LDCVs accumulated near but not at their target membrane. This is in contrast with the apparently normal distribution of synaptic vesicles in developing synapses in the null mutant (Verhage et al., 2000). CONCLUSIONS: We conclude that Munc18-1 is involved in the secretion of peptide hormones and in the docking of LDCVs. These results unmask an apparent mechanistic difference between LDCVs and synaptic vesicles.

Animals↗
PubMed2005

Neuronal, neurohormonal, and autocrine control of Xenopus melanotrope cell activity.

Amphibian pituitary melanotropes are used to investigate principles of neuroendocrine translation of neural input into hormonal output. Here, the steps in this translation process are outlined for the melanotrope cell of Xenopus laevis, with attention to external stimuli, neurochemical messengers, receptor dynamics, second-messenger pathways, and control of the melanotrope secretory process. Emphasis is on the pathways that neurochemical messengers follow to reach the melanotrope. The inhibitory messengers, dopamine, gamma-aminobutyric acid, and neuropeptide Y, act on the cells by synaptic input from the suprachiasmatic nucleus, whereas the locus coeruleus and raphe nucleus synaptically stimulate the cells via noradrenaline and serotonin, respectively. Autoexcitatory actions are exerted by acetylcholine, brain-derived neurotrophic factor (BDNF), and the calcium-sensing receptor. At least six messengers released from the pituitary neural lobe stimulate melanotropes in a neurohormonal way: corticotropin-releasing hormone, thyrotropin-releasing hormone, BDNF, urocortin, mesotocin, and vasotocin. They all are produced by the magnocellular nucleus and coexist in various combinations in two types of neurohemal axon terminal. Most of the relevant receptors of the melanotropes have been elucidated. Apparently, the neural lobe has a dominant role in activating melanotrope secretory activity. The intracellular mechanisms translating the various inputs into cellular activities like biosynthesis and secretion constitute the adenylyl cyclase-cAMP pathway and Ca(2+) in the form of periodic changes of the intracellular Ca(2+) concentration, known as Ca(2+) oscillations. It is proposed that the pattern of these oscillations encodes specific regulatory information and that it is set by first messengers that control, for example, via G proteins and cAMP-related events, specific ion channel-mediated events in the membrane of the melanotrope cell.

Animals↗
PubMed2005

Brain-derived neurotrophic factor in the hypothalamo-hypophyseal system of Xenopus laevis.

Brain-derived neurotrophic factor (BDNF) is immunocytochemically demonstrated in the magnocellular nucleus and neural lobe of the pituitary gland of the amphibian Xenopus laevis. Immunoelectron microscopy shows BDNF in secretory granules of type A neurohemal axon terminals in the neural lobe of pituitary gland. It is proposed that BDNF released from the neural lobe acts as a neurohormone stimulating the secretory activity of the melanotrope cells in the intermediate pituitary lobe.

Animals↗
PubMed2004

The extracellular calcium-sensing receptor increases the number of calcium steps and action currents in pituitary melanotrope cells.

Secretion of alpha-melanophore-stimulating hormone (alpha-MSH) from the neuroendocrine melanotrope cells in the intermediate lobe of the pituitary gland of the clawed frog Xenopus laevis is regulated by various inhibitory, stimulatory and autocrine factors. The neuropeptide sauvagine stimulates alpha-MSH secretion by changing the pattern of intracellular Ca2+ oscillations and the electrical properties of the cell membrane. In the present study we investigated whether another secreto-stimulator, the extracellular Ca2+-sensing receptor (CaR), also affects the Ca2+ oscillatory pattern and electrical membrane properties. Using high-speed dynamic video-imaging we show that activation of the CaR with the specific agonist l-phenylalanine (l-Phe) changes the Ca2+ oscillatory pattern by increasing the number of Ca2+ steps, which are the "building blocks" of the oscillations. Moreover, using patch-clamp electrophysiology it is demonstrated that l-Phe affects membrane properties by increasing frequency and duration of action currents. Compared to sauvagine, the CaR has different effects on the action current parameters, suggesting that multiple mechanisms regulate the electrical properties of the melanotrope cell membrane and, thereby, the Ca2+ oscillation-dependent level of alpha-MSH secretion.

Action Potentials↗
PubMed2004

A single exposure to novelty differentially affects the accumbal dopaminergic system of apomorphine-susceptible and apomorphine-unsusceptible rats.

Individual differences in responses to mild, acute stressors in laboratory animals have commonly been observed in behavioural tests and at the level of hypothalamic-pituitary-adrenal axis responses. These differences are associated with dopamine transmission in the nucleus accumbens. Although the effect of mild stressors on dopamine transmission has been studied with microdialysis, it has not been studied at the level of the catecholaminergic network in the nucleus accumbens. In this study we have used microdialysis to measure extracellular concentrations of dopamine in vivo and immunocytochemistry for the enzyme tyrosine hydroxylase to assess the effect of a single exposure to novelty on the neurochemistry of the nucleus acc umbens in apomorphine-susceptible and apomorphine-unsusceptible rats. These rats are a valid animal model for studying individual differences in responses to environmental stressors and drugs of abuse. We demonstrated that a mild stressor like novelty increased the extracellular concentration of dopamine in the nucleus accumbens in apomorphine-susceptible rats to a larger and longer-lasting degree than in apomorphine-unsusceptible rats. Furthermore we demonstrated that novelty increased the tyrosine hydroxylase-immunoreactive fibre network in the nucleus accumbens shell of apomorphine-susceptible rats, which are rats that are particularly reactive to stressors, but not in the shell of apomorphine-unsusceptible rats, which are rats that are relatively stress-resistant. In conclusion, we have shown that the accumbal dopaminergic system of apomorphine-susceptible rats is more sensitive to an environmental stressor than that of apomorphine-unsusceptible rats. Combined with the fact that these animals also differ in their sensitivity to drugs of abuse, which are known to affect the dopaminergic system, these data provide a solid basis for further studying the differences in the dopaminergic responsiveness to drugs of abuse between apomorphine-susceptible and apomorphine-unsusceptible rats.

Animals↗
PubMed2004

Apomorphine-susceptible rats and apomorphine-unsusceptible rats differ in the tyrosine hydroxylase-immunoreactive network in the nucleus accumbens core and shell.

Individual variability in behavioural responses to stressors such as novelty and drugs of abuse is a well-known phenomenon in both animals and man. These individual differences are largely associated with differences in dopamine transmission in mesolimbic areas such as the nucleus accumbens. Apomorphine-susceptible (APO-SUS) rats and apomorphine-unsusceptible (APO-UNSUS) rats serve as a valid animal model for individual differences and these two types of rat differ in a number of behavioural, physiological, endocrinological and pharmacological parameters. In order to study the differences in the catecholaminergic network in the nucleus accumbens, possibly underlying at least some of the differences between the two types of rat, we quantified the extent of the tyrosine-hydroxylase immunoreactive (TH-IR) network and the number of TH-IR varicosities in subareas of the nucleus accumbens core and shell in naive rats. This study shows that the nucleus accumbens of APO-SUS rats has a more extensive fibre network and more varicosities than the nucleus accumbens of APO-UNSUS rats, and that the subarea of the shell contains more varicosities than the subarea of the core. These data provide a basis for further studying the structural and neurochemical properties of the nucleus accumbens contributing to individual differences in response to stressors such as novelty and drugs of abuse.

Animals↗
PubMed2004

Immunohistochemical localization of cocaine- and amphetamine-regulated transcript peptide in the central nervous system of the frog Rana esculenta.

The distribution of cocaine- and amphetamine-regulated transcript peptide (CARTp)- like immunoreactivity was studied only in the rat central nervous system (CNS). In mammals, CART peptides occur among others in brain areas that control feeding behavior. We mapped CARTp-immunoreactive structures in the CNS of the frog Rana esculenta and assumed that differences may exist in the CARTp-containing neuronal populations between the frog, which does not feed in winter, and the rat. In the forebrain, immunoreactive cells and fibers were found in the olfactory bulb, nucleus accumbens, amygdala, medial pallium, septum, striatum, the preoptic nuclei, ventromedial nucleus, central thalamic nucleus, and the hypothalamus. The optic pathway was free of immunoreactivity. The neurohypophysis showed intense immunostaining. In the mesencephalon, many cells were stained in the Edinger-Westphal nucleus, and a few in the optic tectum, where fibers were stained in all plexiform layers. In the retina, some cells in the inner nuclear layer contained CARTp. In the rhombencephalon, cells were stained in the raphe nuclei, central gray, nucleus of the solitary tract, and the vicinity of motor nuclei. Neurons of the motor cranial nerves were densely innervated by CARTp-positive fibers originating from the spinal cord. In the spinal cord, preganglionic cells were stained, and motoneurons were surrounded by immunoreactive varicose axon terminals. Major differences were found between the frog and the rat brains in the distribution of CARTp in the visual system, olfactory bulb, preoptic area, and the motor nuclei. Some of these differences may be related to feeding behavior of these animals.

Animals↗