Leptin Acts in the Forebrain to Differentially Influence Baroreflex Control of Lumbar, Renal, and Splanchnic Sympathetic Nerve Activity and Heart Rate

Although leptin is known to increase sympathetic nerve activity (SNA), we tested the hypothesis that leptin also enhances baroreflex control of SNA and heart rate (HR). Using α-chloralose anesthetized male rats, mean arterial pressure (MAP), HR, lumbar SNA (LSNA), splanchnic SNA (SSNA), and renal SNA (RSNA) were recorded before and for 2 hours after lateral cerebroventricular leptin or artificial cerebrospinal fluid administration. Baroreflex function was assessed using a 4-parameter sigmoidal fit of HR and SNA responses to slow ramp (3–5 minutes) changes in MAP, induced by intravenous infusion of nitroprusside and phenylephrine. Leptin (3 μg) increased ( P