Direct action of mazindol on guinea-pig ventromedial hypothalamic neurons: intracellular studies in slice preparation.

Neuronal responses in the ventromedial hypothalamic nucleus (VMH) to mazindol (MZD) were examined by intracellular recordings in hypothalamic slices in vitro. Bath application of MZD caused depolarization of the membrane by 8.0 +/- 3.4 mV (mean +/- S.D.) associated with an increase in the input membrane resistance (23.0 +/- 5.8%) among 20% of the cells examined. Current-voltage plots, obtained simultaneously, showed the reversal potential between -80 and -90 mV. These results indicate that MZD depolarizes VMH neurons by reducing the K+ conductance, through a mechanism similar to that of glucose, and the anorectic action of MZD can be explained by its direct effects on the VMH.