Expression and function of growth hormone in the nervous system: A brief review (original) (raw)
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Neural Growth Hormone: An Update
Journal of Molecular Neuroscience, 2003
It is now well established that growth hormone (GH) gene expression is not restricted to the pituitary gland and occurs in many extrapituitary tissues, including the central and peripheral nervous systems. Indeed, GH gene expression occurs in the brain prior to its ontogenic appearance in the pituitary gland, and GH may have evolved phylogenetically as a neuropeptide, rather than as an endocrine. Recent studies on the regulation and roles of neural GH in health and disease are the focus of this brief review.
Growth Hormone (GH) Action in the Brain Neural Expression of a GH-Response Gene
Journal of Molecular Neuroscience, 2002
The presence of growth hormone (GH) binding sites and GH-receptor (GHR)-immunoreactive proteins in the brain suggests it is a target site for GH action. This could, however, reflect the presence of GH-binding proteins (GHBP) that are not linked to intracellular signal-transduction mechanisms, rather than authentic receptors. The possibility that GH has actions in the brain therefore has been examined by determining an intracellular mediator of GH action.
Neuroendocrine regulation of growth hormone
European Journal of Endocrinology, 1995
This short review is focused on the neuroendocrine regulation of growth hormone (GH) pulsatile secretory pattern and GH gene expression. The neuronal network involved in the central control of GH includes extrahypothalamic neurons such as the noradrenergic and cholinergic systems, which regulate the two antagonistic neurohormonal systems: somatostatin (SRIH) and GH-releasing hormone (GHRH). Intrahypothalamic Proopiomelanocortin- and Galanin-containing interneurons also participate in the regulation of SRIH and GHRH neuronal activity, which also is dependent on sex steroids and GH and/or insulin-like growth factor I (IGF-I) feedback. cAMP (controlled mainly by GHRH and SRIH), thyroid and glucocorticoid hormones. IGF-I and activin are among the factors that regulate GH gene expression at the transcriptional level and may play a role in somatotroph differentiation and proliferation during ontogeny as well as physiological and pathological states such as acromegaly.
The Open Endocrinology Journal, 2012
Effects that growth hormone (GH) may exert on brain function have received attention among many researchers over the past two decades. In patients with impaired pituitary production of this hormone replacement therapies have been demonstrated not only to compensate for GH effects in peripheral organs but also to improve several behaviors related to the brain. For instance, available data suggests that subjects treated with GH have experienced significant improvements in concentration, memory, depression, anxiety and fatigue. Also, pituitary-ectomized male rats showing decreased ability in tasks related to learning and memory are seen to improve their performance in these items following GH replacement. The mechanism underlying these beneficial effects of GH has been the subject of studies in many laboratories. An important aspect in this regard is the discovery of specific receptors in various brain regions related to the functional anatomy of several behaviors affected by the hormone. The aim with this article is to review current knowledge on GH receptors in the brain and discuss possible mechanism for the action of the hormone in its ability to affects brain function.
A role for growth hormone in neurorestoration and neurogenic processes in the brain
The cerebral growth hormone (GH) axis plays an active role following ischemic injury to the brain. Studies have shown that both GH and its receptor are endogenously upregulated in response to ischemic injury and that GH administration post-injury confers significant neuroprotection. Furthermore, there is evidence that GH has trophic effects on neural stem cells (NSCs). However, whether GH can also aid long term recovery and/or have direct effects on neurogenic processes is unclear. Both in vivo and in vitro studies were carried out to address these issues. In vivo studies using the endothelin-1 model of focal ischemic stroke in adult rats demonstrated that a long-term unilateral continuous intracerebroventricular (ICV) infusion of GH is capable of targeting specific areas of active remodelling and neurogenic processes. Immunohistochemistry analyses revealed that ipsilaterally infused GH localised specifically to neuronal and glial progenitor cells within the ipsilateral subventricul...
Expression of growth hormone receptor in the human brain
Neuroscience Letters, 2000
This study was designed to investigate the presence of growth hormone receptor (GHR) expression in the human brain tissue, both normal and tumoral, as well as in the human glioblastoma cell line U87MG. Reverse transcription-polymerase chain reaction revealed the presence of GHR mRNA in all brain samples investigated and in U87MG cells. GHR immunoreactivity was also detected in this cell line using both immunocytochemistry and western blotting. All together, our data demonstrate the existence of GHR expression within the central nervous system (CNS), thus supporting a possible role for GH in the CNS physiology. q
Distribution of growth hormone-responsive cells in the brain of rats and mice
Brain Research, 2021
A growth hormone (GH) injection is able to induce the phosphorylated form of the signal transducer and activator of transcription 5 (pSTAT5) in a large number of cells throughout the mouse brain. The present study had the objective to map the distribution of GH-responsive cells in the brain of rats that received an intracerebroventricular injection of GH and compare it to the pattern found in mice. We observed that rats and mice exhibited a similar distribution of GH-induced pSTAT5 in the majority of areas of the telencephalon, hypothalamus and brainstem. However, rats exhibited a higher density of GH-responsive cells than mice in the horizontal limb of the diagonal band of Broca (HDB), supraoptic and suprachiasmatic nuclei, whereas mice displayed more GH-responsive cells than rats in the hippocampus, lateral hypothalamic area and dorsal motor nucleus of the vagus (DMX). Since both HDB and DMX contain acetylcholine-producing neurons, pSTAT5 was colocalized with choline acetyltransferase in GH-injected animals. We found that 50.0 ± 4.5% of cholinergic neurons in the rat HDB coexpressed GH-induced pSTAT5, whereas very few co-localizations were observed in the mouse HDB. In contrast, rats displayed fewer cholinergic neurons responsive to GH in the DMX at the level of the area postrema. In summary, pSTAT5 can be used as a marker of GH-responsive cells in the rat brain. Although rats and mice exhibit a relatively similar distribution of GH-responsive neurons, some species-specific differences exist, as exemplified for the responsiveness to GH in distinct populations of cholinergic neurons. 2015). GHR expression is found in numerous organs, but the classical biological functions of GH are mediated by the liver, skeletal muscle, bones and adipose tissue. In several tissues, GH stimulates the expression of insulin-like growth factor-1, which acts as an important mediator of GH's actions in the body (List et al., 2014). Thus, either through the direct activation of GHR or indirectly via insulin-like growth factor-1, GH stimulates cell proliferation, tissue growth and protein synthesis. Additionally, GH regulates several metabolic aspects, including insulin sensitivity and fatty acid mobilization/deposition (
Endocrinology, 1998
Recent studies suggest that GH may modulate emotion, behavior, or stress response by its direct actions on the brain, and possible expression of the GH gene in the brain has been predicted. In this study we have investigated whether and where the GH gene is expressed in the brain and how it is regulated. Ribonuclease protection assay and 5Ј-rapid amplification of complementary DNA ends-PCR analyses indicated that the GH gene was expressed in rat brain, initiating at the identical transcription start point as that for pituitary GH gene expression. The brain GH messenger RNA was predominantly detected in the lateral hypothalamus (lh) by in situ reverse transcription-PCR analysis. GH gene expression in the brain was significantly enhanced by GH-releasing hormone administration and was rapidly repressed by exposure to restraint stress in the water, whereas the changes in pituitary GH messenger RNA contents in these circumstances were relatively smaller. The results of the present study suggest that the brain GH is predominantly expressed in lh under the control of physiological conditions to play a role in the modulation of brain functions.
Neuroendocrine Control of Growth Hormone Secretion
Acta Paediatrica, 1989
The secretion of growth hormone (GH) is regulated through a complex neuroendocrine control system, especially by the functional interplay of two hypothalamic hypophysiotropic hormones, GH-releasing hormone (GHRH) and somatostatin (SS), exerting stimulatory and inhibitory influences, respectively, on the somatotrope. The two hypothalamic neurohormones are subject to modulation by a host of neurotransmitters, especially the noradrenergic and cholinergic ones and other hypothalamic neuropeptides, and are the final mediators of metabolic, endocrine, neural, and immune influences for the secretion of GH. Since the identification of the GHRH peptide, recombinant DNA procedures have been used to characterize the corresponding cDNA and to clone GHRH receptor isoforms in rodent and human pituitaries. Parallel to research into the effects of SS and its analogs on endocrine and exocrine secretions, investigations into their mechanism of action have led to the discovery of five separate SS receptor genes encoding a family of G protein-coupled SS receptors, which are widely expressed in the pituitary, brain, and the periphery, and to the synthesis of analogs with subtype specificity. Better understanding of the function of GHRH, SS, and their receptors and, hence, of neural regulation of GH secretion in health and disease has been achieved with the discovery of a new class of fairly specific, orally active, small peptides and their congeners, the GH-releasing peptides, acting on specific, ubiquitous seven-transmembrane domain receptors, whose natural ligands are not yet known.
Sensitivity of rat forebrain neurons to growth hormone-releasing hormone
Peptides, 1985
The effects ofiontophoretically applied human pancreatic growth hormone-releasing factor (hpGRF), peptide histidine isoleucine (PHI-27), and somatostatin (SS) on the extracellular activity of single cells in the hypothalamus, thalamus, and cortex of the rat brain were studied in urethane-anesthetized, male rats. Neurons with membrane sensitivity to hpGRF, PHI-27, and SS were present in each brain region. Although neurons excited by these peptides were encountered in thalamus and hypothaiamus, depression of neuronal firing was the predominant response observed. Overall, the neurons responding to hpGRF also possessed membrane sensitivity to PHI-27, whereas, the hpGRF sensitive neurons appeared to be more divided as to their ability to respond to SS. The results clearly demonstrate that hpGRF and PHI-27 are capable of affecting the membrane excitability of neurons in several brain regions. The distribution of neurons sensitive to hpGRF suggests that hypothalamic GRF, in addition to its well documented role in the regulation of pituitary growth hormone secretion, may subserve other physiological events in the rat central nervous system as a neurotransmitter and/or neuromodulator. Growth hormone-releasing hormone Somatostatin Peptide histidine isoleucine Electrophysiology