title: Oxytocin predominantly excites putative oxytocin neurons in the rat supraoptic nucleus in vitro.
abstract: To determine the oxytocin (OXT) sensitivity of neurons in the supraoptic nucleus (SON), extracellular recordings were made from the rat hypothalamic slice preparation. OXT added to the bathing medium (3 X 10(-7) M) excited 13 (93%) of 14 cells which fired continuously (average 4.9 +/- 0.7 spikes/s) and 26 (81%) of 32 cells which fired slowly and irregularly (average 1.4 +/- 0.4 spikes/s). By contrast, only 2 (8%) of 26 phasically firing neurons were excited and none of the SON cells tested were inhibited. The excitation was reversibly antagonized by a synthetic OXT analogue, 1-deamino-[2-(O-methyltyrosine), 4-valine, 8-D-arginine]vasopressin. The results suggest that OXT exerts predominantly excitatory effects in the SON and that putative OXT cells are more likely to be affected than putative vasopressin cells.
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001127:Arginine Vasopressin / Q000031:analogs & derivatives / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D009474:Neurons / Q000145:classification* / Q000187:drug effects / Q000502:physiology; D010121:Oxytocin / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013495:Supraoptic Nucleus / Q000187:drug effects / Q000502:physiology*
chemical_list: D001127:Arginine Vasopressin; D010121:Oxytocin; C016180:argipressin, Val(4)-