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Lateral Hypothalamic Area (lateral + hypothalamic_area)
Selected AbstractsOrexins (hypocretins) actions on the GHRH/somatostatin-GH axisACTA PHYSIOLOGICA, Issue 3 2010M. López Abstract The secretion of growth hormone (GH) is regulated through a complex neuroendocrine control system that includes two major hypothalamic regulators, namely GH-releasing hormone (GHRH) and somatostatin (SST) that stimulate and inhibit, respectively, GH release. Classical experiments involving damage and electrical stimulation suggested that the lateral hypothalamic area (LHA) modulated the somatotropic axis, but the responsible molecular mechanisms were unclear. Evidence obtained during the last decade has demonstrated that orexins/hypocretins, a family of peptides expressed in the LHA controlling feeding and sleep, play an important regulatory role on GH, by inhibiting its secretion modulating GHRH and SST neurones. Considering that GH release is closely linked to the sleep,wake cycle and feeding state, understanding orexin/hypocretin physiology could open new therapeutic possibilities in the treatment of sleep, energy homeostasis and GH-related pathologies, such as GH deficiency. [source] Genetic mapping of Foxb1-cell lineage shows migration from caudal diencephalon to telencephalon and lateral hypothalamusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2008Tianyu Zhao Abstract The hypothalamus is a brain region with vital functions, and alterations in its development can cause human disease. However, we still do not have a complete description of how this complex structure is put together during embryonic and early postnatal stages. Radially oriented, outside-in migration of cells is prevalent in the developing hypothalamus. In spite of this, cell contingents from outside the hypothalamus as well as tangential hypothalamic migrations also have an important role. Here we study migrations in the hypothalamic primordium by genetically labeling the Foxb1 diencephalic lineage. Foxb1 is a transcription factor gene expressed in the neuroepithelium of the developing neural tube with a rostral expression boundary between caudal and rostral diencephalon, and therefore appropriate for marking migrations from caudal levels into the hypothalamus. We have found a large, longitudinally oriented migration stream apparently originating in the thalamic region and following an axonal bundle to end in the anterior portion of the lateral hypothalamic area. Additionally, we have mapped a specific expansion of the neuroepithelium into the rostral diencephalon. The expanded neuroepithelium generates abundant neurons for the medial hypothalamus at the tuberal level. Finally, we have uncovered novel diencephalon-to-telencephalon migrations into septum, piriform cortex and amygdala. [source] Nociceptin/Orphanin FQ Peptide in Hypothalamic Neurones Associated with the Control of Feeding BehaviourJOURNAL OF NEUROENDOCRINOLOGY, Issue 2 2010N. Maolood Nociceptin/orphanin FQ (N/OFQ), an endogenous peptide agonist of the opioid N/OFQ receptor, has been implicated in the regulation of energy balance. In the present study, we have used immunohistochemistry to investigate the cellular localisation and colocalisation of N/OFQ-immunoreactive cell bodies in hypothalamic regions containing neurones producing orexigenic or anorexigenic transmitters. In colchicine-treated rats, N/OFQ immunoreactivity was demonstrated in many cell bodies of the arcuate nucleus (Arc), paraventricular nucleus (PVN) and lateral hypothalamic area (LHA). Double-labelling revealed that N/OFQ was present in some neurones located in the ventrolateral part of the Arc producing pro-opiomelanocortin, as shown by the presence of the anorexigenic peptides ,-melanocyte-stimulating hormone (,-MSH) and cocaine- and amphetamine-regulated transcript and, occasionally, in single neurones of the ventrolateral Arc producing orexigenic agouti-related peptide, but not neuropeptide Y. N/OFQ immunoreactivity was also demonstrated in a few tyrosine hydroxylase- or dynorphin (DYN)-containing neurones in the dorsomedial part of the Arc. In the parvocellular PVN, N/OFQ was demonstrated in some thyrotrophin-releasing hormone- or DYN-, but not corticotrophin-releasing hormone-containing neurones. Most N/OFQ-immunoreactive neurones in the LHA contained orexin- and DYN, but not melanin-concentrating hormone. The results obtained, demonstrating the presence of N/OFQ in some ,-MSH- and in many orexin-containing neurones, suggest a functional relationship between these neuropeptides and N/OFQ in the control of feeding behaviour and body weight. [source] Projections of RFamide-related Peptide-3 Neurones in the Ovine Hypothalamus, with Special Reference to Regions Regulating Energy Balance and ReproductionJOURNAL OF NEUROENDOCRINOLOGY, Issue 8 2009Y. Qi RFamide-related peptide-3 (RFRP-3) is a neuropeptide produced in cells of the paraventricular nucleus and dorsomedial nucleus of the ovine hypothalamus. In the present study, we show that these cells project to cells in regions of the hypothalamus involved in energy balance and reproduction. A retrograde tracer (FluoroGold) was injected into either the arcuate nucleus, the lateral hypothalamic area or the ventromedial nucleus. The distribution and number of retrogradely-labelled RFRP-3 neurones was determined. RFRP-3 neurones projected to the lateral hypothalamic area and, to a lesser degree, to the ventromedial nucleus and the arcuate nucleus. Double-label immunohistochemistry was employed to identify cells receiving putative RFRP-3 input to cells in these target regions. RFRP-3 cells were seen to project to neuropeptide Y and pro-opiomelanocortin neurones in the arcuate nucleus, orexin and melanin-concentrating hormone neurones in the lateral hypothalamic area, as well as orexin cells in the dorsomedial nucleus and corticotrophin-releasing hormone and oxytocin cells in the paraventricular nucleus. Neurones expressing gonadotrophin-releasing hormone in the preoptic area were also seen to receive input from RFRP-3 projections. We conclude that RFRP-3 neurones project to hypothalamic regions and cells involved in regulation of energy balance and reproduction in the ovine brain. [source] Appetite Regulatory Neuropeptides are Expressed in the Sheep Hypothalamus Before BirthJOURNAL OF NEUROENDOCRINOLOGY, Issue 6 2004B. S. Mühlhäusler Abstract In the adult, a hypothalamic neural network acts to maintain energy balance in response to nutritional feedback from the periphery. Although there is an immediate requirement for this system to be functional at birth, it is unknown whether the components of this central neural network are expressed in the developing brain before birth. We therefore examined in the fetal sheep hypothalamus during late gestation gene expression for leptin receptor (OB-Rb) and neuropeptides that regulate energy balance in the adult. Brains were collected from fetal sheep at 110 days (n = 12) and 140 days of gestation (n = 5) (term = 150 days) and gene expression was detected in all hypothalami using in situ hybridization with radiolabelled riboprobes for OB-Rb, neuropeptide Y (NPY), agouti-related peptide, pro-opiomelanocortin and cocaine- and amphetamine-regulated transcript (CART). All mRNAs were expressed in the arcuate nucleus of fetuses at both time points. Additional sites of mRNA expression were the dorsomedial hypothalamus (DMH) for NPY, the paraventricular nucleus (PVN), ventromedial hypothalamus (VMH) and lateral hypothalamic area for CART, and the DMH, PVN and VMH for OB-Rb. We have therefore demonstrated that adult-like localization of gene expression for OB-Rb and key appetite regulatory neuropeptides is established in the ovine hypothalamus before birth. Thus, the fetus possesses a central appetite regulatory neural network with the potential to respond to changes in nutrient supply, which could impact on energy balance regulation both before and after birth. [source] Sensitivity of Galanin- and Melanin-Concentrating Hormone-Containing Neurones to Nutritional Status: An Immunohistochemical Study in the Ovariectomized EweJOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2003E. Chaillou Abstract The sensitivities of galanin and melanin-concentrating hormone (MCH) neuronal systems to nutrition are poorly understood in sheep compared to rodents. The aim of this study was to describe the changes in the numbers of galanin and MCH neurones in ovariectomized ewes submitted to different nutritional levels. In the first experiment, ewes were fed ad libitum or food deprived for 24 h. In the second experiment, two groups of ewes were fed at maintenance level (group 100) or undernourished (group 40) for 167 days, after which one-half of each group was killed or refed ad libitum (group 100R and 40R) for 4 days. The MCH neuronal population located in the lateral hypothalamic area was not affected by these nutritional changes. Long-term undernutrition enhanced the number of galanin neurones located in the infundibular nucleus and the dorsal hypothalamic area (DHA), refeeding resulted in an increase of neurones in the DHA and preoptic area, but short-term starvation had no effect on any galanin subpopulations. Our data suggest that the sensitivity of MCH neuronal populations to nutrition in sheep differs from that of rodents. Various populations of galanin-containing neurones differ in sensitivity in ewes subjected to long undernutrition and refeeding but not to short starvation. [source] Chemical Coding of GABAB Receptor-Immunoreactive Neurones in Hypothalamic Regions Regulating Body WeightJOURNAL OF NEUROENDOCRINOLOGY, Issue 1 2003M. Bäckberg Abstract ,-aminobutyric acid (GABA) interacts with hypothalamic neuronal pathways regulating feeding behaviour. GABA has been reported to stimulate feeding via both ionotropic GABAA and metabotropic GABAB receptors. The functional form of the GABAB receptor is a heterodimer consisting of GABAB receptor-1 (GABABR1) and GABAB receptor-2 (GABABR2) proteins. Within the heterodimer, the GABA-binding site is localized to GABABR1. In the present study, we used an antiserum to the GABABR1 protein in order to investigate the cellular localization of GABABR1-immunoreactive neurones in discrete hypothalamic regions implicated in the control of body weight. The colocalization of GABABR1 immunoreactivity with different chemical messengers that regulate food intake was analysed. GABABR1-immunoreactive cell bodies were found in the periventricular, paraventricular (PVN), supraoptic, arcuate, ventromedial hypothalamic, dorsomedial hypothalamic, tuberomammillary nuclei and lateral hypothalamic area (LHA). Direct double-labelling showed that glutamic acid decarboxylase (GAD)-positive terminals were in close contact with GABABR1-containing cell bodies located in all these regions. In the ventromedial part of the arcuate nucleus, GABABR1-immunoreactive cell bodies were found to contain neuropeptide Y, agouti-related peptide (AGRP) and GAD. In the ventrolateral part of the arcuate nucleus, GABABR1-immunoreactive cell bodies were shown to contain pro-opiomelanocortin and cocaine- and amphetamine-regulated transcript. In the LHA, GABABR1 immunoreactivity was present in both melanin-concentrating hormone- and orexin-containing cell populations. In the tuberomammillary nucleus, GABABR1-immunoreactive cell bodies expressed histidine decarboxylase, a marker for histamine-containing neurones. In addition, GAD and AGRP were found to be colocalized in some nerve terminals surrounding GABABR1-immunoreactive cell bodies in the parvocellular part of the PVN. The results may provide a morphological basis for the understanding of how GABA regulates the hypothalamic control of food intake and body weight via GABAB receptors. [source] Demonstration of an orexinergic central innervation of the pineal gland of the pigTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 2 2004Chiara Fabris Abstract Orexins/hypocretins, two isoforms of the same prepropeptide, are widely distributed throughout the brain and are involved in several physiological and neuroendocrine regulatory patterns, mostly related to feeding, sleep, arousal, and cyclic sleep-wake behaviors. Orexin-A and orexin-B bind with different affinities to two G-protein-coupled transmembrane receptors, orexin-1 and orexin-2 receptors (OR-R1 and OR-R2, respectively). Because of the similarities between the human and the swine brain, we have studied the pig to investigate the orexinergic system in the diencephalon, with special emphasis on the neuroanatomical projections to the epithalamic region. By using antibodies against orexin-A and orexin-B, immunoreactive large multipolar perikarya were detected in the hypothalamic periventricular and perifornical areas at the light and electron microscopic levels. In the region of the paraventricular nucleus, the orexinergic neurons extended all the way to the lateral hypothalamic area. Immunoreactive nerve fibers, often endowed with large varicosities, were found throughout the hypothalamus and the epithalamus. Some periventricular immunoreactive nerve fibers entered the epithalamic region and continued into the pineal stalk and parenchyma to disperse among the pinealocytes. Immunoelectron microscopy confirmed the presence of orexinergic nerve fibers in the pig pineal gland. After extraction of total mRNA from the hypothalamus and pineal gland, we performed RT-PCR and nested PCR using primers specific for porcine orexin receptors. PCR products were sequenced, verifying the presence of both OR-R1 and OR-R2 in the tissues investigated. These findings, supported by previous studies on rodents, suggest a hypothalamic regulation of the pineal gland via central orexinergic nervous inputs. J. Comp. Neurol. 471:113,127, 2004. © 2004 Wiley-Liss, Inc. [source] Characterization of CART neurons in the rat and human hypothalamusTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 1 2001Carol F. Elias Cocaine- and amphetamine-regulated transcript (CART) is a recently described neuropeptide widely expressed in the rat brain. CART mRNA and peptides are found in hypothalamic sites such as the paraventricular nucleus (PVH), the supraoptic nucleus (SON), the lateral hypothalamic area (LHA), the dorsomedial nucleus of the hypothalamus (DMH), the arcuate nucleus (Arc), the periventricular nucleus (Pe), and the ventral premammillary nucleus (PMV). Intracerebroventricular administration of recombinant CART peptide decreases food intake and CART mRNA levels in the Arc are regulated by leptin. Leptin administration induces Fos expression in hypothalamic CART neurons in the PVH, the DMH, the Arc, and the PMV. In the current study, we used double label in situ hybridization histochemistry to investigate the potential direct action of leptin on hypothalamic CART neurons and to define the chemical identity of the hypothalamic CART neurons in the rat brain. We found that CART neurons in the Arc, DMH, and PMV express long form leptin-receptor mRNA, and the suppressor of cytokine signaling-3 (SOCS-3) mRNA after an acute dose of intravenous leptin. We also found that CART neurons in the parvicellular PVH, in the DMH and in the posterior Pe coexpress thyrotropin-releasing hormone (TRH) mRNA. CART neurons in the magnocellular PVH and in the SON coexpress dynorphin (DYN), and CART cell bodies in the LHA and in the posterior Pe coexpress melanin-concentrating hormone (MCH) and glutamic acid decarboxylase (GAD-67) mRNA. In the Arc, a few CART neurons coexpress neurotensin (NT) mRNA. In addition, we examined the distribution of CART immunoreactivity in the human hypothalamus. We found CART cell bodies in the PVH, in the SON, in the LHA, in the Arc (infundibular nucleus) and in the DMH. We also observed CART fibers throughout the hypothalamus, in the bed nucleus of the stria terminalis, and in the amygdala. Our results indicate that leptin directly acts on CART neurons in distinct nuclei of the rat hypothalamus. Furthermore, hypothalamic CART neurons coexpress neuropeptides involved in energy homeostasis, including MCH, TRH, DYN, and NT. The distribution of CART cell bodies and fibers in the human hypothalamus indicates that CART may also play a role in the regulation of energy homeostasis in humans. J. Comp. Neurol. 432:1,19, 2001. © 2001 Wiley-Liss, Inc. [source] | ||||||||||