Endothelin-3 directly affects neurons in the anteroventral third ventricle region and supraoptic nucleus of the rat hypothalamus in vitro.
Extracellular recordings were made from anteroventral third ventricle (AV3V) and supraoptic nucleus (SON) neurons of rat hypothalamus in slice preparations. ET-3 was applied at concentrations of 10(-10) to 3 x 10(-7) M. Of 119 AV3V neurons tested, 21 (18%) were excited, 8 (6%) were slightly inhibited, and 90 (76%) were unaffected. The threshold concentration to evoke responses was approximately 10(-8) M. Excitatory responses of the AV3V neurons to ET-3 remained in a Ca(2+)-free medium. Of 120 SON neurons tested, 46 were phasic (putative vasopressin neuron) and 74 were nonphasic (putative oxytocin neuron). Of 46 phasic neurons tested, 26 (56.5%) were inhibited by ET-3, 20 (43.5%) were nonresponsive, and none was excited. Of 74 nonphasic neurons tested, 14 (19%) neurons were inhibited by ET-3, 60 (81%) were nonresponsive, and none was excited. These results suggest that ET-3 has dual effects on AV3V and SON neurons and the mechanisms of the responses may be different in the AV3V and SON neurons.
Yamashita
H
H
First Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan.
Yamamoto
S
S
Inenaga
K
K
Kannan
H
H
D000818:Animals; D002552:Cerebral Ventricles / Q000187:drug effects*; D004594:Electrophysiology; D016232:Endothelins / Q000494:pharmacology*; D007031:Hypothalamus / Q000187:drug effects*; D066298:In Vitro Techniques; D008297:Male; D009474:Neurons / Q000187:drug effects*; D051381:Rats; D011919:Rats, Inbred Strains; D013495:Supraoptic Nucleus / Q000187:drug effects*
D016232:Endothelins