AJP - Regulatory, Integrative and Comparative Physiology, Vol 255, Issue 1 134-R140, Copyright © 1988 by American Physiological Society
A novel endogenous sugar acid depolarizes ventromedial hypothalamic neurons in vitro
A. Fukuda, Y. Oomura, C. R. Plata-Salaman, T. Minami and C. Ito
Department of Physiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
2-Buten-4-olide (2-B-4-O) has been identified in the serum of fasted rats
and proved to act as a feeding suppressant. The effect of 2-B-4-O on
neurons in the ventromedial hypothalamic (VMH) nucleus was investigated
with intracellular recordings in brain slice preparations of rats. 2-B-4-O,
applied by perfusion (0.1-10 mM) or drops (50-100 mM), dose dependently
depolarized 30% of the VMH neurons tested. The depolarization by 2-B-4-O
application persisted after complete elimination of synaptic inputs during
perfusion with Ca2+-free/high-Mg2+ solution. The depolarization,
accompanied by a decrease in membrane conductance, reversed polarity around
-95 mV and was dependent on extracellular K+ concentration. The VMH neurons
depolarized by 2-B-4-O had some specific electrophysiological properties
corresponding with those of glucoreceptor neurons. The results suggest that
2-B-4-O directly excites VMH neurons, presumed to be glucoreceptor neurons,
by decreasing K+ conductance, and this effect may participate in the
feeding suppressive action of 2-B-4-O.
