Serotonergic involvement in stress-induced vasopressin and oxytocin secretion.
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.


METHODS
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.


CONCLUSIONS
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.
Jørgensen
Henrik
H
Department of Medical Physiology, The Panum Institute, Rigshospitalet, University of Copenhagen, Blegdamsvej 3, DK-2200N Copenhagen, Denmark. hsj@mfi.ku.dk
Knigge
Ulrich
U
Kjaer
Andreas
A
Warberg
Jørgen
J
D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism*; D003080:Cold Temperature; D003681:Dehydration / Q000378:metabolism; D006470:Hemorrhage / Q000378:metabolism; D007601:Jugular Veins; D008297:Male; D010121:Oxytocin / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012149:Restraint, Physical; D012701:Serotonin / Q000378:metabolism*; D012702:Serotonin Antagonists / Q000494:pharmacology; D013312:Stress, Physiological / Q000209:etiology / Q000378:metabolism*; D013550:Swimming
D012702:Serotonin Antagonists; D001127:Arginine Vasopressin; D012701:Serotonin; D010121:Oxytocin