Effects of β-endorphin fragments on plasma levels of vasopressin

Effect of the Opioid Peptide Beta-Endorphin on the in vivo Release of Vasopressin in Rats under Various Conditions

“…It was already known from results in this laboratory that endorphins exert an inhibitory influence on VP levels of rats under normal and stimulated conditions [28,29). From the present results of the dose-effect relationship studies we can conclude that PE is far more potent in situations in which levels are osmotically stimulated by water depriva tion than under basal or HIS-stimulated conditions.…”

“…After development of specific radioimmunoassay (RIA) systems, sensitive enough to measure directly VP levels in plasma [5,20], it was in fact found by several authors that plasma VP levels of normal rats decreased significantly after treatment with opiates or opioid peptides [I, 28, 29]. On the other hand, some authors do find an increase of VP after treatment with morphinomimetics [7,22,32].The present study was designed to extend previous find ings in our laboratory on the inhibitory effect of intracerebroventricularly administered ((-endorphin ((3E) on VP lev els in plasma of normal and water-deprived rats [28,29], Time course and dose effect studies were performed with |(E in normal rats, and in rats with osmotically stimulated VP levels a dose-response relationship study was per formed with ((E. Besides, experiments were included on the effect of (3E on elevated VP levels induced by administra tion of histamine (HIS). Also the influence of the opiate antagonist naloxone (NAL) on |)E-mediated effects was in vestigated.…”

Hypophyseal Hormone Levels in Blood and Cerebrospinal Fluid in Response to Histamine and Pentylenetetrazol

“…Numerous stimuli including water deprivation, hemorrhage and the administration of hypertonic solutions of NaCl or mannitol, or substances as dopamine, histamine, acetylcho line, or angiotensin II enhance the secretion of AVP from the posterior lobe of the pituitary into the blood [8,10,13,14,31,34], Plasma levels of AVP are also affected by admin istration of (3-endorphin or its fragments [36,37]. The secre tion of OXT into the peripheral blood is affected by labor, suckling, water deprivation, hemorrhage and by the admin istration of angiotensin II [I, 6, 15, 19,42] and it seems like ly that dopaminergic systems are also involved in the regu lation of the release of OXT into the blood [24,38].…”