The role of serotonergic neurons in intravenous hypertonic saline-induced secretion of vasopressin, oxytocin, and ACTH.
This study tested the effect of brain serotonin (5-HT) depletion on the secretion of oxytocin (OT), vasopressin (VP), and adrenocorticotropin (ACTH) due to an osmotic load. The 5-HT neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) was used to deplete brain 5-HT. The OT, VP, and ACTH osmotic sensitivity (slope of delta[OT]/delta[Osm]) and the osmotic threshold (X intercept of delta[OT]/delta[Osm]) were evaluated. Depletion of brain 5-HT decreased the OT osmotic sensitivity by > 80% (p < 0.001) without changing the OT osmotic threshold. Brain 5-HT depletion had no effect on the VP osmotic sensitivity and increased the VP osmotic threshold from 287.8 +/- 1.5 to 293.1 +/- 2.0 mOsm/kg (p < 0.05). The plasma ACTH increase due to infusion of hypertonic saline was not affected by brain 5-HT depletion. Brain 5-HT depletion significantly (p < 0.01) decreased the pituitary content of OT and VP by 38 and 32%, respectively, without changing ACTH content. These results provide evidence for a functional role of serotonergic neurons in osmoregulation of plasma and pituitary concentration of OT and VP, but not ACTH.
Saydoff
J A
JA
University of Wisconsin, School of Veterinary Medicine, Department of Comparative Biosciences, Madison 53706.
Carnes
M
M
Brownfield
M S
MS
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000324:Adrenocorticotropic Hormone / Q000097:blood / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism; D007262:Infusions, Intravenous; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010121:Oxytocin / Q000097:blood / Q000378:metabolism*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012016:Reference Values; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage / Q000494:pharmacology*; D012701:Serotonin / Q000378:metabolism / Q000502:physiology*; D014667:Vasopressins / Q000097:blood / Q000378:metabolism*
D012462:Saline Solution, Hypertonic; D014667:Vasopressins; D015116:5,7-Dihydroxytryptamine; D012701:Serotonin; D010121:Oxytocin; D000324:Adrenocorticotropic Hormone