Distribution of an enzyme which acetylates α-melanocyte stimulating hormone in rat brain and pituitary gland and effects of arcuate nucleus lesions

This study describes the distribution of an α-melanocyte stimulating hormone (α-MSH) acetyltransferase (MAT) in rat brain and pituitary gland. Highest activities of MAT were found in the neurointermediate lobe of the pituitary gland with the anterior lobe containing slightly less. Within the brain, lowest MAT activities were measured in the hypothalamus, the region which contained the highest concentrations of α-MSH. Relatively high enzyme activities of MAT were measured in the hippocampus, cortex and cerebellum—regions with very low α-MSH concentrations. The fact that MAT activity levels did not parallel α-MSH concentrations indicates that MAT was not solely localized to α-MSH synthesizing neurons or endocrine cells. Furthermore, arcuate nucleus lesions which depleted brain α-MSH failed to deplete MAT activity. Although MAT was not solely localized to α-MSH synthesizing cells, it may have functional significance for α-MSH acetylation due to compartmentalization with α-MSH in α-MSH synthesizing endocrine cells and neurons. Alternatively a second regionally specific MAT may exist.     

Apelin and the proopiomelanocortin system: a new regulatory pathway of hypothalamic α-MSH release

Neuronal networks originating in the hypothalamic arcuate nucleus (Arc) play a fundamental role in controlling energy balance. In the Arc, neuropeptide Y (NPY)-producing neurons stimulate food intake, whereas neurons releasing the proopiomelanocortin (POMC)-derived peptide α-melanocyte-stimulating hormone (α-MSH) strongly decrease food intake. There is growing evidence to suggest that apelin and its receptor may play a role in the central control of food intake, and both are concentrated in the Arc. We investigated the presence of apelin and its receptor in Arc NPY- and POMC-containing neurons and the effects of apelin on α-MSH release in the hypothalamus. We showed, by immunofluorescence and confocal microscopy, that apelin-immunoreactive (IR) neuronal cell bodies were distributed throughout the rostrocaudal extent of the Arc and that apelin was strongly colocalized with POMC, but weakly colocalized with NPY. However, there were numerous NPY-IR nerve fibers close to the apelin-IR neuronal cell bodies. By combining in situ hybridization with immunohistochemistry, we demonstrated the presence of apelin receptor mRNA in Arc POMC neurons. Moreover, using a perifusion technique for hypothalamic explants, we demonstrated that apelin-17 (K17F) increased α-MSH release, suggesting that apelin released somato-dendritically or axonally from POMC neurons may stimulate α-MSH release in an autocrine manner. Consistent with these data, hypothalamic apelin levels were found to be higher in obese db/db mice and fa/fa Zucker rats than in wild-type animals. These findings support the hypothesis that central apelin is involved in regulating body weight and feeding behavior through the direct stimulation of α-MSH release.     

Developmental switch in neuropeptide Y and melanocortin effects in the paraventricular nucleus of the hypothalamus

Homeostatic regulation of energy balance in rodents changes dramatically during the first 3 postnatal weeks. Neuropeptide Y (NPY) and melanocortin neurons in the arcuate nucleus, a primary energy homeostatic center in adults, do not fully innervate the paraventricular nucleus (PVN) until the third postnatal week. We have identified two classes of PVN neurons responsive to these neuropeptides, tonically firing neurosecretory (NS) and burst-firing preautonomic (PA) cells. In neonates, NPY could inhibit GABAergic inputs to nearly all NS and PA neurons, while melanocortin regulation was minimal. However, there was a dramatic, age-dependent decrease in NPY responses specifically in the PA neurons, and a 3-fold increase in melanocortin responses in NS cells. These age-dependent changes were accompanied by changes in spontaneous GABAergic currents onto these neurons. This primarily NPYergic regulation in the neonates likely promotes the positive energy balance necessary for growth, while the developmental switch correlates with maturation of homeostatic regulation of energy balance.     

Expression of NPY-immunoreactive neurons in the hypothalamus of the cycling ewe

The purpose of the study was to localise neuropeptide Y (NPY) immunoreactive (ir) neurons in the hypothalamus during two phases of the oestrous cycle in the ewe. Hypothalamic tissue was collected from Polish Merino ewes (n=8) in the follicular (15th day) and preovulatory (17th day) phases of the oestrous cycle. NPY-ir neurons were detected in the hypothalamus using immuohistochemistry followed by image analysis; positive staining was expressed as the percentage of stained area and optical density. Two populations of the NPY-positive neurons were detected and evaluated in the infundibular and periventricular nuclei of the hypothalamus. The population of NPY-ir neurons located in the infundibular nucleus exhibited a prominent expression of NPY immunoreactivity in the perikarya and fibres only during the preovulatory phase. Both, percent area and the optical density of NPY immunostaining measured in this area were higher (P < 0.01) in the preovulatory than in the follicular phase. Another population of NPY-ir neurons was localised in the periventricular nucleus and did not show any changes during the two phases of the cycle. The present study suggests that NPY-ir neurons present in the infundibular nucleus can play a role in the preovulatory GnRH discharge from the median eminence.     

Leptin receptor long-form splice-variant protein expression in neuron cell bodies of the brain and co-localization with neuropeptide Y mRNA in the arcuate nucleus.

Reduced leptin (Ob protein) signaling is proposed to be a stimulus for the activation of neuropeptide Y (NPY) gene activity and increased expression of mRNA for the long form of the leptin receptor (Ob-Rb) in the hypothalamic arcuate nucleus. To determine if Ob-Rb protein is expressed in arcuate nucleus NPY neurons, we developed an affinity-purified polyclonal antibody against amino acids 956-1102 of human Ob-Rb. This antibody specifically recognizes the cytoplasmic tail of Ob-Rb and does not react with shorter leptin-receptor variants. Western immunoblots of Ob-Rb-transfected COS cells showed a single 150-kD band, and immunofluorescence revealed intense perinuclear staining in the cytoplasm. A 150-kD band was also present in Western immunoblots of hypothalamus. Immunocytochemical staining of brain slices revealed immunoreactive Ob-Rb protein concentrated in many neuronal cell bodies in the same regions of the forebrain that also express Ob-Rb mRNA. In the hypothalamus, Ob-Rb-positive cell bodies were abundant in the arcuate nucleus and ventromedial nucleus, with lesser numbers in the dorsomedial nucleus and paraventricular nucleus. Immunostaining was also detected in cell bodies of pyramidal cell neurons of the pyriform cortex and cerebral cortex, in neurons of the thalamus, and on the surface of ependymal cells lining the third ventricle. The choroid plexus, which expresses the short Ob-Ra form, was negative. Combined immunocytochemistry for Ob-Rb protein and fluorescence in situ hybridization for NPY mRNA identified arcuate nucleus neurons containing both NPY mRNA and Ob-Rb protein. The present finding of Ob-Rb protein in neurons that express NPY mRNA supports the hypothesis that arcuate nucleus NPY neurons are direct targets of leptin and play an important role in regulation of food intake and body weight.     

The distribution of gonadotropin-releasing hormone (GnRH) neurons and fibers throughout the chick brain (Gallus domesticus)

Summary Nerve fibers and perikarya containing gonadotropin-releasing hormone (GnRH-like) immunoreactivity were investigated in the brain of the three-week-old chick, Gallus domesticus using the technique of immunocytochemistry. Six major groups of perikarya were found to include the olfactory bulb, olfactory tubercle/lobus parolfactorius, nucleus accumbens, septal preoptic hypothalamic region (three sub-nuclei), lateral anterior thalamic nucleus and in and about the oculomotor complex. The immunostaining was unusual in the latter group, suggesting that the neurons may contain a GnRH-II like material. Immunoreactive fibers for GnRH were found throughout the entire brain extending from the olfactory bulbs to the caudal brainstem. Two anatomical areas, not emphasized in the past literature, which had distinct GnRH-like immunoreactivity, included the lateral anterior thalamic nucleus and the preoptic recess. The former included a group of GnRH perikarya that is also known to be a retino-recipient area while the latter contained neuronal terminals some of which appeared to be contacting the cerebrospinal fluid of the preoptic recess. An attempt was made to list all anatomical structures that contained or were juxta-positioned to sites that displayed immunoreactive perikarya and fibers including circumventricular organs.Abbreviations used in figure legends Ac Nucleus accumbens - Ap Archistriatum posterior - APH Area parahippocampalis - AVT Area ventralis (Tsai) - BO Bulbus olfactorius - CA Commissura anterior (rostralis) - CDL Area corticoidea dorsolateralis - CO Chiasma opticum - CP Commissura posterior - CPi Cortex piriformis - CPP Cortex praepiriformis - CT Commissura tectalis - CTz Corpus trapezoideum - EW Nucleus of Edinger-Westphal - FV Funiculus ventralis - GCt Substantia grisea centralis - GLv Nucleus geniculatus lateralis, pars ventralis - HD Hyperstriatum dorsale - HM Nucleus habenularis medialis - Hp Hippocampus - ICo Nucleus intercollicularis - IH Nucleus inferior hypothalami - IN Nucleus infundibuli hypothalami - IP Nucleus interpeduncularis - LA Nucleus lateralis anterior (rostralis) thalami - LHy Regio lateralis hypothalami - LPO Lobus parolfactorius - LSO Organum septi lateralis (lateral septal organ) - LT Lamina terminalis - ME Eminentia mediana - INT. Z Internal zone - EXT. Z External zone - ML Nucleus mamillaris lateralis - MM Nucleus mamillaris medialis - nBOR Nucleus opticus basalis (n. of basal optic root) - nCPa Nucleus commissurae pallii - N III Nervus oculomotorius - N V Nervus trigeminus - n V M Nucleus mesencephalicus nervi trigemini - OA Nucleus olfactorius anterior (rostralis) - OMdl Nucleus nervi oculomotorii, pars dorsomedialis - OMv Nucleus nervi oculomotorii, pars ventralis - OVLT Organum vasculosum laminae terminalis - P Glandula pinealis - PA Palaeostriatum augmentatum (caudate putamen) - PHN Nucleus periventricularis hypothalami - POM Nucleus praeopticus medialis - POMn Nucleus praeopticus medianus - POP Nucleus praeopticus periventricularis - PP Palaeostriatum primitivum - PT Nucleus praetectalis - PVN Nucleus paraventricularis magnocellularis - RPaM Nucleus reticularis paramedianus - RPR Recessus praeopticus - b, RPR Basal region, RPR - F, RPR Floor, RPR - R, RPR Roof, RPR - S Nucleus tractus solitarii - SCO Organum subcommissurale - SGP Stratum griseum periventriculare - SHL Nucleus subhabenularis lateralis - SL Nucleus septalis lateralis - SM Nucleus septalis medialis - SO Stratum opticum - SSO Organum subseptale - TO Tuberculum olfactorium - TIO Tractus isthmo-opticus - TPc Nucleus tegmenti pedunculopontinus, pars compacta (substantia nigra) - TrO Tractus opticus - TSM Tractus septomesencephalicus - VeD Nucleus vestibularis descendens - VeM Nucleus vestibularis medialis - VL Ventriculus lateralis - VLT Nucleus ventrolateralis thalami - VO Ventriculus olfactorius - V III Ventriculus tertius (third ventricle)     

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.     

Expression of neuropeptide Y and agouti-related peptide in the hypothalamic arcuate nucleus of newborn neurogenin3 null mutant mice

Mice deficient in neurogenin 3 (Ngn3) fail to generate pancreatic endocrine cells and intestinal endocrine cells. Hypothalamic neuropeptides implicated in the control of energy homeostasis might also be affected in Ngn3 homozygous null mutant mice. We investigated the expression of two prominent orexigenic neuropeptides, neuropeptide Y (NPY) and agouti-related protein (AgRP), in the hypothalamic arcuate nucleus of newborn wild-type and Ngn3 null mutant mice. Immunohistochemical analysis demonstrated that, in Ngn3 null mutants, the number of NPY-immunoreactive neurons and nerve fibers was markedly increased in the arcuate nucleus, and the nerve fibers were widely distributed in the hypothalamic area, including the paraventricular and dorsomedial nuclei. Little increase of AgRP immunoreactivity was detected in the arcuate nucleus of mutant mice. In situ hybridization analysis confirmed the increased population of the NPY neurons in the arcuate nucleus of the mutants. The NPY mRNA level, as estimated by laser capture microdissection and real-time quantitative polymerase chain reaction, was 371% higher in Ngn3 null mutants than in wild-type mice. AgRP mRNA levels did not differ significantly between the null mutants and wild-type mice. Thus, up-regulation of the hypothalamic NPY system is probably a feature characteristic of Ngn3 null mice.     

Leptin sensitive neurons in the hypothalamus.

A major paradigm in the field of obesity research is the existence of an adipose tissue-brain endocrine axis for the regulation of body weight. Leptin, the peptide mediator of this axis, is secreted by adipose cells. It lowers food intake and body weight by acting in the hypothalamus, a region expressing an abundance of leptin receptors and a variety of neuropeptides that influence food intake and energy balance. Among the most promising candidates for leptin-sensitive cells in the hypothalamus are arcuate nucleus neurons that co-express the anabolic neuropeptides, neuropeptide Y (NPY) and agouti-related peptide (AGRP), and those that express proopiomelanocortin (POMC), the precursor of the catabolic peptide, alphaMSH. These cell types contain mRNA encoding leptin receptors and show changes in neuropeptide gene expression in response to changes in food intake and circulating leptin levels. Decreased leptin signaling in the arcuate nucleus is hypothesized to increase the expression of NPY and AGRP. Levels of leptin receptor mRNA and leptin binding are increased in the arcuate nucleus during fasting, principally in NPY/AGRP neurons. These findings suggest that changes in leptin receptor expression in the arcuate nucleus are inversely associated with changes in leptin signaling, and that the arcuate nucleus is an important target of leptin action in the brain.     

Moderate long-term modulation of neuropeptide Y in hypothalamic arcuate nucleus induces energy balance alterations in adult rats

Neuropeptide Y (NPY) produced by arcuate nucleus (ARC) neurons has a strong orexigenic effect on target neurons. Hypothalamic NPY levels undergo wide-ranging oscillations during the circadian cycle and in response to fasting and peripheral hormones (from 0.25 to 10-fold change). The aim of the present study was to evaluate the impact of a moderate long-term modulation of NPY within the ARC neurons on food consumption, body weight gain and hypothalamic neuropeptides. We achieved a physiological overexpression (3.6-fold increase) and down-regulation (0.5-fold decrease) of NPY in the rat ARC by injection of AAV vectors expressing NPY and synthetic microRNA that target the NPY, respectively. Our work shows that a moderate overexpression of NPY was sufficient to induce diurnal over-feeding, sustained body weight gain and severe obesity in adult rats. Additionally, the circulating levels of leptin were elevated but the immunoreactivity (ir) of ARC neuropeptides was not in accordance (POMC-ir was unchanged and AGRP-ir increased), suggesting a disruption in the ability of ARC neurons to response to peripheral metabolic alterations. Furthermore, a dysfunction in adipocytes phenotype was observed in these obese rats. In addition, moderate down-regulation of NPY did not affect basal feeding or normal body weight gain but the response to food deprivation was compromised since fasting-induced hyperphagia was inhibited and fasting-induced decrease in locomotor activity was absent.These results highlight the importance of the physiological ARC NPY levels oscillations on feeding regulation, fasting response and body weight preservation, and are important for the design of therapeutic interventions for obesity that include the NPY.     

Galanin and NPY, two peptides with multiple putative roles in the nervous system.

In the present brief overview we summarize results from several studies focusing on two neuropeptides, galanin and neuropeptide Y (NPY) in discrete neuronal systems, where they coexist with classic transmitters. On the basis of studies in different animal models we propose that these peptides may be involved in regulation of certain CNS functions and that drugs acting on their receptors may be of use in new therapeutic strategies. At the spinal level galanin and NPY are regulated in DRG neurons by nerve injury and in dorsal horn neurons by inflammation. It is possible that this leads to attenuation of pain sensitivity. Moreover, both peptides may exert trophic effects, for example to enhance regeneration. In the hypothalamic arcuate nucleus NPY and its receptors are part of the feeding circuitry, and we suggest that derangement of these NPY neurons may at least in part underlay the lethal phenotype of anorectic mice, which die 22 days postnatally after showing decreased food intake and growth retardation. Expression of NPY and NPY receptors is changed in the hippocampus of mice comparatively early after prion inoculation, indicating that this peptide system is affected in this spongiform degenerative disease in a region of importance for learning and memory. Finally, galanin is co-localized with classic monoamine transmitters in two central systems, the dorsal raphe serotonin neurons and the locus coeruleus noradrenergic neurons. In both cases galanin causes hyperpolarization (at high concentrations) and prolongs monoamine-induced outward currents (at low concentrations), thus modulating activity in two systems of importance for many brain functions including mood regulation. It may therefore be interesting to analyse to what extent drugs affecting galaninergic transmission also may be efficient in the treatment of, for example, depression.     

Comparative immunocytochemical localization of putative opioid ligands in the central nervous system

Summary We report a detailed comparative immunocytochemical mapping of enkephalin, CCK and ACTH/gb-endorphin immunoreactive nerves in the central nervous system of rat and guinea pig. Enkephalin immunoreactivity was detected in many groups of nerve cell bodies, fibers and terminals in the limbic system, basal ganglia, hypothalamus, thalamus, brain stem and spinal cord. -endorphin and ACTH immunoreactivity was limited to a single group of nerve cell bodies in and around the arcuate nucleus and in fibers and terminals in the midline areas of the hypothalamus, thalamus and mesencephalic periaqueductal gray with lateral extensions to the amygdaloid area. Cholecystokinin immunoreactive nerve fibers and terminals displayed a distribution similar to that of enkephalin in many regions; but striking differences were also found. An immunocytochemical doublestaining technique, which allowed simultaneous detection of two different peptides in the same tissue section, showed that enkephalin-, CCK- and ACTH/-endorphin-immunoreactive nerves although closely intermingled in many brain areas, occurred separately. The distributions of nerve terminals containing these neuropeptides showed striking overlaps and also paralleled the distribution of opiate receptors. This may suggest that enkephalin, CCK, ACTH and -endorphin may interact with each other and with opiate receptors.Index of Abbreviations CA Commissura anterior - CAI Capsula interna - CO Chiasma opticum - CPF Cortex piriformis - CSDD Commissura supraoptica dorsalis, pars dorsalis (Ganser) - CSDV Commissura supraoptica dorsalis, pars ventralis (Meynert) - FMP Fasciculus medialis prosencephali - FOR Formatio reticularis - GD Gyrus dentatus - GP Glubus pallidus - H Habenula - HI Hippocampus - S Subiculum - SGCD Substantia grisea centralis, pars dorsalis - SGCL Substantia grisea centralis, pars lateralis - SGPV Substantia grisea periventricularis - SNC Substantia nigra, zona compacta - SNL Substantia nigra, pars lateralis - ST Stria terminalis - STP Stria terminalis, pars precommissuralis - TD Tractus diagonalis (Broca) - TO Tractus opticus - TSHT Tractus septohypothalamicus - TUOP Tuberculum olfactorium, pars corticalis - SUM Decussatio supramamillaris - a Nucleus accumbens - ac Nucleus amygdaloideus centralis - aco Nucleus amygdaloideus corticalis - am Nucleus amygdaloideus medialis - ar Nucleus arcuatus - cp Nucleus caudatus putamen - dcgl Nucleus dorsalis corporis geniculati lateralis - em Eminentia mediana - fm Nucleus paraventricularis, pars magnocellularis - fp Nucleus paraventricularis, pars parvocellularis - ha Nucleus anterior (hypothalami) - hd Nucleus dorsomedialis (hypothalami) - hl Nucleus lateralis (hypothalami) - hp Nucleus posterior (hypothalami) - hpv Nucleus periventricularis (hypothalami) - hv Nucleus ventromedialis (hypothalami) - ip Nucleus interpeduncularis - mcgm Nucleus marginalis corporis geniculatic medialis - mm Nucleus mammillaris medialis - ml Nucleus mammillaris lateralis - mh Nucleus medialis habenulae - p Nucleus pretectalis - pf Nucleus parafascicularis - pom Nucleus preopticus medialis - pop Nucleus preopticus periventricularis - posc Nucleus preopticus, pars suprachiasmatica - pt Nucleus paratenialis - pvs Nucleus periventricularis stellatocellularis - re Nucleus reuniens - sc Nucleus suprachiasmaticus - sl Nucleus septi lateralis - so Nucleus supraopticus - st Nucleus interstitialis striae terminalis - tad Nucleus anterior dorsalis thalami - tam Nucleus anterior medialis thalami - tav Nucleus anterior ventralis thalami - td Nucleus tractus diagonalis (Broca) - th Nuclei thalami - tl Nucleus lateralis thalami - tlp Nucleus lateralis thalami, pars posterior - tm Nucleus medialis thalami - tml Nucleus medialis thalami, pars lateralis - tmm Nucleus medialis thalami, pars medialis - tpo Nucleus posterior thalami - tr Nucleus reticularis thalami - tv Nucleus ventralis thalami - tvd Nucleus ventralis thalami, pars dorsomedialis - tvm Nucleus ventralis medialis thalami, pars magnocellularis     

Distribution of pro-opiomelanocortin and its peptide end products in the brain and hypophysis of the aquatic toad, Xenopus laevis

Using in situ hybridization with a pro-opiomelanocortin (POMC)-mRNA probe and immunocytochemistry with antisera to POMC and to various POMC-derived peptides, it is shown that melanotrope cells in the pars intermedia of the hypophysis of the South African aquatic toad Xenopus laevis contain POMC, α-melanophore-stimulating hormone (α-MSH), γ-MSH, acetylated and non-acetylated endorphins and adrenocorticotropic hormone (ACTH). With the exception of γ-MSH, these peptides are also found in the corticotrope cells in the rostral pars distalis. In the Xenopus brain, neuronal cell bodies in the ventral hypothalamic nucleus express POMC, α-MSH, γ-MSH, non-acetylated endorphins and ACTH, neurones in the anterior preoptic area reveal POMC, α-MSH, γ-MSH and non-acetylated endorphin, neurones in the suprachiasmatic nucleus contain α-MSH, non-acetylated endorphin and ACTH and neurones in the posterior tubercle show α-MSH, non-acetylated endorphin and ACTH immunoreactivities. In the locus coeruleus POMC and ACTH coexist, whereas α-MSH and non-acetylated endorphin occur together in the nucleus accumbens, the striatum and the nucleus of the paraventricular organ. Finally, α-MSH alone is present in the olfactory bulb, the medial septum, the medial and lateral parts of the amygdala, the ventromedial and posterior thalamic nuclei, the optic tectum and the anteroventral tegmental nucleus, and non-acetylated endorphin alone appears in the epiphysis. It is suggested that neurones that form POMC-derived peptides may play a direct or indirect role in the control of POMC-producing hypophyseal cells and/or in the physiological processes these endocrine cells regulate. This idea is supported by the fact that the suprachiasmatic nucleus and the locus coeruleus, both involved in melanotrope cell control, show POMC and POMC-peptide expression. A possible involvement in melanotrope and/or corticotrope control of the anterior preoptic and ventral hypothalamic nuclei, which both express POMC and various POMC-derived peptides, deserves future attention.     

Rutecarpine ameliorates bodyweight gain through the inhibition of orexigenic neuropeptides NPY and AgRP in mice

Orexigenic neuropeptides NPY and AgRP play major roles in feeding and are closely related to obesity and diabetic metabolic syndrome. This study explored the inhibitory effect of rutecarpine on feeding and obesity in high-fat-diet-induced (C57BL/6) and leptin-deficient (ob/ob) obese mice. Both mice strains developed obesity, but the obesity was inhibited by the reduced food intake resulting from rutecarpine treatment (0.01%, p < 0.01). Blood cholesterol, non-fasting glucose, insulin, and leptin levels were reduced, compared with the control group. Rutecarpine inhibited the expression of NPY and AgRP in the arcuate nucleus (ARC) of the hypothalamus and suppressed the expression of both neuropeptides in N29-4 neuronal cells. These results indicate that rutecarpine ameliorates obesity by inhibiting food intake, which involves inhibited expression of the orexigenic neuropeptides NPY and AgRP.     

Neuropeptide Y content in the hypothalamic paraventricular nucleus responds to fasting and refeeding in broiler chickens

To examine the neural mechanism by which hypothalamic neuropeptide Y (NPY) regulates energy homeostasis and feeding behavior in commercial broilers, we measured NPY content in several hypothalamic regions of birds that were fasted and then refed. After fasting for 48 and 72 h, body weight significantly decreased, and food intake significantly increased during the subsequent refeeding. The lost body weight was not restored to ad libitum feeding levels even after 3 days of refeeding. Plasma glucose concentration and body fat content significantly decreased and plasma non-esterified fatty acid (NEFA) concentration significantly increased after 48- and 72-h fasting. Refeeding for 24 h restored plasma metabolites and body fat content to pre-fasting levels. NPY content in the paraventricular nucleus (PVN) and infundibular nucleus significantly increased during fasting, and NPY content of the PVN was restored to pre-fasting levels after 24-h refeeding. However, there was no significant change in the NPY content of the lateral hypothalamic area during fasting or refeeding. The present results of changes in the hypothalamic NPY content during fasting and refeeding support the hypothesis that NPY plays a central role in regulation of energy homeostasis, with especially important effect on feeding behavior and body weight in broiler chickens.     

Cytoarchitectonic pattern of the hypothalamus in the turtle,Lissemys punctata granosa

Summary In the hypothalamus of the turtle, Lissemys punctata granosa, two magnocellular and 23 parvocellular neuronal complexes can be distinguished. The magnocellular complexes include the nucleus supraopticus and the nucleus paraventricularis; paraventricular neurons are partly arranged in rows parallel to the third ventricle. Most infundibular parvocellular nuclei display neurons disposed in rows parallel to the ventricular surface. In the preoptic region, the prominent parvocellular neuronal complexes encompass the nucleus periventricularis anterior, lateral preoptic area, the nucleus of the anterior commissure and the nucleus suprachiasmaticus. The prominent nucleus periventricularis posterior extends caudad and shows neurons arranged in vertical rows parallel to the third ventricle. Other parvocellular nuclei of the rostral hypothalamus are composed of clustered subunits. The nucleus arcuatus is a fairly large nuclear entity extending from the level marked dorsally by the nucleus paraventricularis to the area occupied by the nucleus of the paraventricular organ. A well-developed ventromedial nucleus is located ventrolateral to the paraventricular organ. The prominent paraventricular organ consists of tightly arranged neurons, some of which possess apical projections into the third ventricle; it is surrounded by the nucleus of the paraventricular organ. Nucleus hypothalamicus medialis et lateralis, nucleus hypothalamicus posterior and the nuclei recessus infundibuli are further nuclear units of the tuberal region. The caudal end of the hypothalamus is marked by the nucleus mamillaris; its neurons are scattered among the fibers of the retroinfundibular commissure. The median eminence is well developed and shows a large medial and two lateral protrusions into the infundibular recess.     

NPY-mRNA expressions in the nucleus accumbens,caudate putamen and cerebral cortex of apomorphine-susceptible and apomorphine-unsusceptible rats

Using the apomorphine-induced stereotyped gnawing response as a selection criterion, two distinct groups of rats can be distinguished, apomorphine-susceptible (APO-SUS) and apomorphine-unsusceptible (APO-UNSUS) rats. These two lines differ in several components of both striatal and extrastriatal areas. This study deals with the expression of neuropeptide Y (NPY)mRNA-expressing neurons in the nucleus accumbens, caudate putamen and cerebral cortex of both rat lines, using non-radioactive in situ hybridisation. The morphology of the neurons in the three regions is similar, viz. oblong, rectangular or triangular, with two or three processes. The neurons are homogeneously distributed in all regions, and in the nucleus accumbens they are particularly numerous ventrally to the anterior commissure. Using automated image analysis, the mean numerical density of NPYmRNA-positive neurons per brain region and the mean NPYmRNA expression level per neuron per brain region were determined. No differences appear in the numerical densities of NPYmRNA-containing neurons in the nucleus accumbens, caudate putamen and cortex between APO-SUS and APO-UNSUS rats. However, distinct differences between the rat lines are present in the level of NPYmRNA expression per neuron in the nucleus accumbens and in the caudate putamen, showing that NPY contributes to the differential neurochemical make-up of these rat lines that is responsible for their obvious differences in behaviour, physiology and immune competence.     

The neuroendocrine pathways and mechanisms for the control of the reproduction in female pigs

Within the hypothalamic-pituitary-gonad (HPG) axis, the major hierarchical component is gonadotropin-releasing hormone (GnRH) neurons, which directly or indirectly receive regulatory inputs from a wide array of regulatory signals and pathways, involving numerous circulating hormones, neuropeptides, and neurotransmitters, and which operate as a final output for the brain control of reproduction. In recent years, there has been an increasing interest in neuropeptides that have the potential to stimulate or inhibit GnRH in the hypothalamus of pigs. Among them, Kisspeptin is a key component in the precise regulation of GnRH neuron secretion activity. Besides, other neuropeptides, including neurokinin B (NKB), neuromedin B (NMB), neuromedin S (NMS), α-melanocyte-stimulating hormone (α-MSH), Phoenixin (PNX), show potential for having a stimulating effect on GnRH neurons. On the contrary, RFamide-related peptide-3 (RFRP-3), endogenous opioid peptides (EOP), neuropeptide Y (NPY), and Galanin (GAL) may play an inhibitory role in the regulation of porcine reproductive nerves and may directly or indirectly regulate GnRH neurons. By combining data from suitable model species and pigs, we aim to provide a comprehensive summary of our current understanding of the neuropeptides acting on GnRH neurons, with a particular focus on their central regulatory pathways and underlying molecular basis.     

Connectivity of the auditory forebrain nuclei in the Guinea Fowl (Numida meleagris)

Summary Injection of tritiated leucine and proline into the nucleus ovoidalis of the Guinea Fowl (Numida meleagris) produces terminal labeling in the palaeostriatum and in three adjacent zones (field L₁–L₃) of the auditory neostriatum (AN). L₂, situated between L₁ and L₃, receives the main input and corresponds to the former field L of Rose. These neuroanatomically defined zones of the auditory neostriatum are also characterized by differing properties of their neurons. Injection of radioactive material into the auditory neostriatum produces labeling of (i) a palaeostriatal, (ii) a ventral hyperstriatal, and (iii) an additional neostriatal area (Nd). Injection into the hyperstriatum ventrale reveals connections (i) to field L₂, (ii) to the palaeostriatum, (iii) to Nd, and (iv) to the archistriatum. After injection into the palaeostriatum, labeling can be observed (i) in the neostriatum dorsale, (ii) in the hyperstriatum ventrale, (iii) in the archistriatum, (iv) in the diencephalic nuclei, nucleus ansae lenticularis and nucleus spiriformis lateralis, and (v) in the mesencephalic nuclei, nucleus tegmenti pedunculo-pontinus and nucleus intercollicularis. These results show that a widespread connectivity exists among primary and presumably higher order auditory areas in the forebrain of birds. Connections also exist between these auditory areas and presumed vocal-motor areas (neostriatum dorsale, archistriatum, nucleus intercollicularis).Abbreviations A Archistriatum - AL Ansa lenticularis - AN Auditory neostriatum - Bas Nucleus basalis - CA Commissura anterior - Cb Cerebellum - CP Commissura posterior - DLP Nucleus dorsolateralis posterior thalami - DTh Dorsal thalamus - E Ectostriatum - EM Nucleus ectomamillaris - FA Tractus fronto-archistriatalis - FPL Fasciculus prosencephali lateralis - GLv Nucleus geniculatus lateralis, pars ventralis - HA Hyperstriatum accessorium - HD Hyperstriatum dorsale - HIS Hyperstriatum intercalatum superius - HV Hyperstriatum ventrale - HVc Hyperstriatum ventrale, pars caudale - I Injection site - ICo Nucleus intercollicularis - ICT Nucleus intercalatus thalami - Imc Nucleus isthmi, pars magnocellularis - Ipc Nucleus isthmi, pars parvocellularis - l₁, L₂, L₃ Auditory neostriatum: zones L₁, L₂, L₃ - LAD Lamina archistriatalis dorsalis - LH Lamina hyperstriatica - LMD Lamina medullaris dorsalis - LPO Lobus parolfactorius - M Mesencephalon - MLd Nucleus mesencephalicus lateralis, pars dorsalis - N Neostriatum - nAL Nucleus ansae lenticularis - Nc Neostriatum caudale - Nd Neostriatum dorsale - OM Tractus occipito-mesencephalicus - OMv Nucleus nervi oculomotorii, pars ventralis - Ov Nucleus ovoidalis - PA Palaeostriatum augmentatum - PP Palaeostriatum primitivum - PT Nucleus praetectalis - PVM Nucleus periventricularis magno-cellularis - RSd Nucleus reticularis superior, pars dorsalis - RSv Nucleus reticularis superior, pars ventralis - Rt Nucleus rotundus - SMe Stria medullaris - SpL Nucleus spiriformis lateralis - SpM Nucleus spiriformis medialis - SRt Nucleus subrotundus - TeO Tectum opticum - TOv Tractus ovoidalis - TPc Nucleus tegmenti pedunculo-pontinus - TrO Tractus opticus - TSM Tractus septo-mesencephalicus - Ve Ventricle The authors are indebted to Mrs. I. Röder and Mrs. M. Hansel for their aid in the preparation of the histological material and the illustrationsThis work was supported by the Deutsche Forschungsgemeinschaft, Sche 132/4