Inhibitory action of adrenocorticotrophin on rat arcuate neurons in vitro

Abstract

Extracellular recordings were made from 52 units in perifused 300 μm thick slices of rat hypothalamus taken parallel to the ventricular surface of the arcuate nucleus and kept at 37 °C in an organ bath. Addition of 8 nM adrenocorticotrophic hormone (ACTH) to the perfusate reversibly and rapidly inhibited 15 of the 38 units found within 300 μm of the ventricular surface (in the arcuate nucleus), and there were no comparable excitations. A prompt and reversible excitation of 6 14 units by ACTH was found when records were made from units found 300-600 μm lateral to the ventricle in the lateral arcuate region. It is suggested that ACTH may be an inhibitory transmitter in the arcuate nucleus and that this action may be an inhibition of ACTH-containing neurons. © 1985.