Different effects of the GABAergic agent sodium valproate on the oxytocin responses to angiotensin II and insulin-induced hypoglycemia in normal men.
The present study was performed in order to establish whether angiotensin II (ANG II) and/or insulin-induced hypoglycemia exert their oxytocin (OT)-releasing effects by interacting with a GABAergic pathway. For this purpose, in 14 normal men the OT responses to ANG II (infusion for 60 min of successively increasing doses of 4, 8 and 16 ng/kg.min, each dose for 20 min; n = 7) or to insulin (0.15 IU/kg)-induced hypoglycemia (n = 7) were evaluated with or without previous treatment with the GABAergic agonist sodium valproate (600 mg in 3 divided doses, p.o.). In all subjects insulin produced a similar hypoglycemic response regardless of sodium valproate administration. Both ANG II and insulin-induced hypoglycemia produced significant increases in plasma OT levels (mean peaks were about 60% higher than baseline). The pretreatment with sodium valproate was unable to change the OT response to hypoglycemia, whereas it abolished the ANG-II-induced OT rise. These data suggest that in man a GABAergic mechanism is involved in the regulation of the OT response to ANG II, but not in the mediation of poglycemia-induced OT release.
Chiodera
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P
Cattedre di Endocrinologia e Patologia Costituzionale, Università di Parma, Italia.
Coiro
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V
D000328:Adult; D000804:Angiotensin II; D001786:Blood Glucose / Q000378:metabolism; D006801:Humans; D007003:Hypoglycemia / Q000139:chemically induced / Q000503:physiopathology*; D007328:Insulin; D008297:Male; D010121:Oxytocin / Q000378:metabolism*; D014635:Valproic Acid / Q000494:pharmacology*
D001786:Blood Glucose; D007328:Insulin; D000804:Angiotensin II; D010121:Oxytocin; D014635:Valproic Acid