Expression of orexin receptors in the pituitary.
Orexin receptors type 1 (OX1R) and type 2 (OX2R) are G protein-coupled receptors whose structure is highly conserved in mammals. OX1R is selective for orexin A, and OX2R binds orexin A and orexin B with similar affinity. Orexin receptor expression was observed in human, rat, porcine, sheep as well as Xenopus laevis pituitaries, both in the adenohypophysis and in the neurohypophysis. The expression level is regulated by gonadal steroid hormones and GnRH. The majority of orexins reaching the pituitary originate from the lateral hypothalamus, but due to the presence of the receptors and the local production of orexins in the pituitary, orexins could deliver an auto/paracrine effect within the gland. Cumulative data indicate that orexins are involved in the regulation of LH, GH, PRL, ACTH, and TSH secretion by pituitary cells, pointing to orexins' effect on the functioning of the endocrine axes. Those hormones may also serve as a signal linking metabolic status with endocrine control of sleep, arousal, and reproduction processes.
Department of Animal Physiology, University of Warmia and Mazury in Olsztyn, Olsztyn-Kortowo, Poland.
Tadeusz
T
Kaminski
Nina
N
Smolinska
D000818:Animals; D005786:Gene Expression Regulation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D009479:Neuropeptides / Q000235:genetics / Q000378:metabolism; D064446:Orexin Receptors; D000068797:Orexins; D010902:Pituitary Gland / Q000294:innervation / Q000378:metabolism*; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D018013:Receptors, Neuropeptide / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
C000596229:HCRT protein, human; C578626:HCRTR2 protein, human; C578627:Hcrtr1 protein, rat; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide