Effects of central administration of resistin on renal sympathetic nerve activity in rats fed a high fat diet; a comparison with leptin

Abstract

Resistin acts centrally to increase renal sympathetic nerve activity (RSNA). This is similar to leptin. In high fat fed animals, the sympatho-excitatory effects of leptin are retained, in contrast to the reduced actions of leptin on dietary intake. In the present study we investigated whether the sympatho-excitatory actions of resistin were influenced by a high fat diet. Further, since resistin and leptin combined can induce a greater sympatho-excitatory response than each alone in rats fed a normal chow diet, we investigated whether a high fat diet (22%) could influence this centrally mediated interaction. MAP, HR and RSNA were recorded before and for 3 hours after intracerebroventricular saline (control) (n=5), leptin (7 μg; n=4), resistin (7 μg; n=5) and leptin and resistin combined (n=6). Leptin alone and resistin alone significantly increased RSNA (71±16%, 62±4% respectively). When leptin and resistin were combined there was a significantly greater increase in RSNA (195±41%) compared to either hormone alone. MAP and HR responses were not significantly different between hormones. When the responses in high fat fed rats were compared to normal chow fed rats, there were no significant differences in the maximum RSNA responses. The findings indicate that sympatho-excitatory effects of resistin on RSNA are not altered by high fat feeding, including the greater increase in RSNA observed when resistin and leptin are combined. Our results suggest that diets rich in fat do not induce resistance to the increase in RSNA induced by resistin alone or in combination with leptin.

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