Serotonergic involvement in stress-induced vasopressin and oxytocin secretion

Department of Medical Physiology, The Panum Institute, Rigshospitalet, University of Copenhagen, Blegdamsvej 3, DK-2200N Copenhagen, Denmark. hsj@mfi.ku.dk

OBJECTIVE: To investigate the involvement of serotonin (5-hydroxytryptamine - 5-HT) receptors in mediation of stress-induced arginine vasopressin (AVP) and oxytocin (OT) secretion in male rats. DESIGN: Experiments on laboratory rats with control groups. METHODS: Different stress paradigms were applied after pretreatment with intracerebroventricular infusion of saline or different 5-HT antagonists. RESULTS: Restraint stress (5 min), hypotensive hemorrhage or dehydration for 24 h increased AVP secretion fivefold and OT secretion threefold. Swim stress for 3 min had no effect on AVP secretion, but increased OT secretion threefold. Ether vapor or hypoglycemia had no effect on AVP or OT secretion. The restraint stress-induced AVP response was inhibited by pretreatment with the 5-HT(2A+2C) antagonists ketanserin (KET) and LY-53857 (LY) and the 5-HT(3+4) antagonist ICS-205930 (ICS), whereas the 5-HT(1A) antagonist WAY-100635 (WAY) had no effect. The OT response to restraint stress was inhibited by WAY, KET and LY but not by ICS. KET and LY inhibited OT response to dehydration, and LY inhibited OT response to hemorrhage. Neither of the antagonists affected AVP responses to dehydration or hemorrhage, nor the swim stress-induced OT response. CONCLUSION: 5-HT(2A), 5-HT(2C) and possibly 5-HT(3) and 5-HT(4) receptors, but not 5-HT(1A) receptors, are involved in the restraint stress-induced AVP secretion. 5-HT does not seem to be involved in the dehydration- or hemorrhage-induced AVP response. The restraint stress-induced OT response seems to be mediated via 5-HT(1A), 5-HT(2A) and 5-HT(2C) receptors. The dehydration and hemorrhage-induced OT responses are at least mediated by the 5-HT(2A) and 5-HT(2C) receptors. The 5-HT(3) and 5-HT(4) receptors are not involved in stress-induced OT secretion.

This article has been cited by other articles:

				K. Wolff, E. M. Tsapakis, A. R. Winstock, D. Hartley, D. Holt, M. L. Forsling, and K. J. Aitchison Vasopressin and oxytocin secretion in response to the consumption of ecstasy in a clubbing population J Psychopharmacol, May 1, 2006; 20(3): 400 - 410. [Abstract] [PDF]

				M. Tatewaki, C. Strickland, H. Fukuda, D. Tsuchida, E. Hoshino, T. N. Pappas, and T. Takahashi Effects of acupuncture on vasopressin-induced emesis in conscious dogs Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2005; 288(2): R401 - R408. [Abstract] [Full Text] [PDF]