Activation of the renal sympathetic nerve by leptin microinjection into the ventromedial hypothalamus in rats.

Leptin produced in white adipose tissue activates sympathetic nerve activity via the ventromedial hypothalamus (VMH) within the central nervous system (CNS). Using an electrophysiological technique, we investigated whether direct microinjection of leptin into the VMH elevates renal sympathetic nerve activity (RSNA) and blood pressure (BP) in anesthetized rats. Microinjection of leptin (100 ng/microL) into the VMH caused significant activation of RSNA from 25 minutes after administration but no affect on BP. We concluded that leptin-induced elevation of RSNA is mediated via the VMH or its vicinity within the CNS.