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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oxytocin (OT) generally has a stimulatory effect on ACTH secretion both in vitro and in vivo. As part of a study of ACTH-releasing factors in hypophysial portal blood, the effects of i.v. OT administration on plasma ACTH levels were tested in urethane-anesthetized rats. Surprisingly, i.v. injection of 10 micrograms OT lowered plasma ACTH levels by about 35% (P less than 0.01). It was reasoned that this paradoxical inhibition of ACTH secretion by OT might be mediated by inhibition of the unusually high rate of peripheral catecholamine secretion in this model. Measurement of plasma catecholamines before and after i.v. administration of 10 micrograms OT revealed a 53% inhibition of EPI (P less than 0.01) and 43% inhibition of NE (P less than 0.05). Administration of the beta-adrenergic antagonist propranolol (400 micrograms) 15 min before the beginning of the experiment completely blocked the inhibitory effects of OT on ACTH secretion and in fact unmasked the stimulatory effects of OT normally seen in conscious animals and in vitro. Superfused bisected adrenal glands exposed to 10(-6) M OT for 10 min secreted more than 30% less EPI and NE than control adrenals suggesting that the inhibition of EPI and NE secretion by OT in vivo occurs, at least in part, directly at the level of the adrenal. The data support the hypothesis that peripheral catecholamines may at times be directly involved in the control of ACTH secretion and also suggest that OT, which has recently been identified in the adrenal medulla, may have important paracrine functions in the regulation of adrenal catecholamine secretion.
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PMID:Oxytocin inhibits ACTH and peripheral catecholamine secretion in the urethane-anesthetized rat. 301 59

We tested the hypotheses that 1) epidural anesthesia at parturition would block both peripheral and central release of oxytocin and eliminate the development of maternal behavior in primiparous heifers and 2) estradiol priming, genital stimulation, and appropriate neonatal stimuli would induce maternal behavior in nulliparous heifers. In experiment 1, primiparous crossbred heifers (n = 13) with cannulas in the third cerebroventricle (IIIV) were assigned randomly to receive epidural treatments of saline (SAL; n = 6) or lidocaine HCl (EPI; n = 7) at the onset of labor induced between Days 270 and 280 of gestation. Epidural anesthesia blocked (P < 0.001) both central and peripheral release of oxytocin and markedly reduced (P < 0.05) or eliminated licking behaviors during a 3-h period following parturition as compared with SAL. Following approximately 1 wk of controlled daily suckling, during which calves were permitted access only to the inguinal region of their dams (three times daily for 10 min each time), a second maternal behavior test was performed. Although licking behavior remained markedly reduced (P < 0.001) in the EPI compared with the SAL groups, all heifers accepted their calf at the udder. In experiments 2-4, neither estradiol priming in ovariectomized heifers nor estradiol plus progesterone in intact heifers resulted in an induction of maternal behaviors following genital stimulation and presentation of a neonate wetted with amniotic fluid. Pelvic sensory deficits apparently block oxytocin release and disturb both short-latency and long-term maternal behaviors but do not result ultimately in rejection of the calf. Combinations of hormonal, sensory, olfactory, and visual cues observed previously to induce maternal behavior in nulliparous ewes do not appear adequate for induction of maternal behavior in nulliparous heifers.
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PMID:Physiological regulation of maternal behavior in heifers: roles of genital stimulation, intracerebral oxytocin release, and ovarian steroids. 1142 Feb 52