Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endothelins (ETs) were initially thought to be primarily involved in the control of cardiovascular activity, but the presence of ETs and their receptors in a wide variety of other tissues has suggested a much broader range of functions. Specific receptors for ETs are found in nonvascular tissues including neuronal, neuroendocrine, and endocrine cells. In addition, immunoreactive ETs are present in the brain, pituitary, and peripheral endocrine tissues. However, the ET levels in hypothalamo-hypophysial portal and peripheral blood are low, suggesting that the ET system participates in neuroendocrine regulation through paracrine and/or autocrine mechanisms. Both ETA and ETB receptors are expressed in the hypothalamus, adrenal, parathyroid glands, pancreas, ovary, uterus, placenta, and prostate, while only ETA receptors are expressed in GT1 neurons, anterior pituitary cells, alpha T3-1 immortalized gonadotropes, parathyroid-derived cells, thyrocytes, testicular Leydig and Sertoli cells, normal and neoplastic ovarian granulosa cells, chondrocytes, and other cell types. Activation of ET receptors elicits the sequence of cellular events typical of Ca(2+)-mobilizing receptors, with prominent increases in phosphoinositide hydrolysis and elevations of [Ca2+]i that occur in oscillatory and nonoscillatory modes depending on the cell type. ET-induced activation of the phosphoinositide/Ca(2+)- mobilizing pathway in neuronal and endocrine cells is associated with rapid stimulation of secretory responses, including release of gonadotropin-releasing hormone, oxytocin, vasopressin, substance P, atrial natriuretic peptides, gonadotropins, thyrotropin, growth hormone, parathyroid hormone, aldosterone, and catecholamines. On the other hand, ET has inhibitory actions on prolactin, progesterone, and renin release. In addition to stimulating phospholipase C-dependent pathways, ETs also activate phospholipase D-and MAP-kinase-dependent pathways in some of their target cells, as well as expression of early response genes and increased mitogenic activity. In many neuroendocrine cells, ET induces rapid and marked desensitization of its signaling system, in association with extensive internalization of ET receptors and reduced signaling and secretory responses. These findings raise the possibility that ETs participate in the control of secretory responses in the hypothalamo-pituitary system and peripheral endocrine cells, as well as in long-term aspects of regulation in certain neuroendocrine cells.
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PMID:Expression and signal transduction pathways of endothelin receptors in neuroendocrine cells. 881 99

Although it is well known that progesterone alters uterine contractility and plays an important role in maintenance of pregnancy, the biochemical mechanisms by which progesterone alters uterine contractility in human gestation are less clear. In this investigation we sought to identify progesterone-induced adaptations in human myometrial smooth muscle cells that may alter Ca2+ signaling in response to contractile agents. Cells were treated with vehicle or the progesterone analog medroxyprogesterone acetate (MPA) for 5 days, and intracellular free Ca2+ concentration ([Ca2+]i) was quantified after treatment with oxytocin (OX) or endothelin (ET)-1. OX- and ET-1-induced increases in [Ca2+]i were significantly attenuated in cells pretreated with MPA in a dose-dependent manner. Progesterone receptor antagonists prevented the attenuated Ca2+ transients induced by MPA. ETA and ETB receptor subtypes were expressed in myometrial cells, and treatment with MPA resulted in significant downregulation of ETA and ETB receptor binding. MPA did not alter ionomycin-stimulated increases in [Ca2+]i and had no effect on inositol trisphosphate-dependent or -independent release of Ca2+ from internal Ca2+ stores. We conclude that adaptations of Ca2+ homeostasis in myometrial cells during pregnancy may include progesterone-induced modification of receptor-mediated increases in [Ca2+]i.
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PMID:Effect of progesterone on intracellular Ca2+ homeostasis in human myometrial smooth muscle cells. 995 Jul 65

Endothelin-1 (ET-1) in the central nervous system has been suggested to produce suppressive effects on pain transmission. We investigated the manner by which ET-1 exerts this action. ET-1 administered intracerebroventricularly produced a dose-dependent antinociceptive effect in a thermal pain test that utilized a spinal reflex to determine nociceptive thresholds. This suggested that the antinociceptive effect of ET-1 involved a descending pain inhibitory system. The antinociceptive effect was blocked by an ETA receptor antagonist but not by an ETB receptor antagonist, indicating that the action was mediated through the ETA receptor. Antagonists of opioid receptors, serotonin receptors, alpha-2 adrenergic receptors, oxytocin receptors, and dopamine receptors did not block the antinociceptive effect of ET-1. Thus, major descending inhibitory systems were probably not involved. The antinociceptive effect was blocked by intracerebroventricular administration of an alpha-1 adrenergic receptor antagonist. This indicated that the antinociceptive effect involved the activation of a supraspinal noradrenergic pathway, which in turn may activate a still unknown descending pain inhibitory system.
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PMID:Inhibitory actions of endothelin-1 on pain processing. 1583 10