Decreased Serum Leptin Concentration Independent of Dietary Composition In Hypertensive Non Obese Rats.

Abstract

Leptin, an adipokine produced by adipocytes, is closely linked to obesity, insulin resistance and hypertension. Studies in obese models show an association between hyperleptinemia, hypertension and cardiac hypertrophy. The effect of hypertension on leptin concentration and fat depots in non-obese models is not known. We hypothesized that i) chronic hypertension would elevate serum leptin, and ii) high fat diet would exacerbate this change. Four groups of 11 wks male Dahl salt-sensitive rats (n=10) were fed diets composed of either low fat/high carbohydrate (CHO) diet (LF/LS; 10% kcal fat 70% kcal CHO), low fat/high CHO diet + salt (LF/HS), high fat/low CHO (HF/LS), or high fat/low CHO + salt (HF/HS; 60% kcal fat, 10% CHO) (6% NaCl was added in high salt groups) for 12 wks. Blood pressure (BP) was measured by tail cuff before and after 12 wks on diets. Serum leptin was measured by ELISA. Body weight was not different among groups. Salt feeding lead to significant elevation in systolic BP compared to LS groups (p<0.05). HF/LS group had slightly elevated BP compared to LF/LS. Surprisingly, hypertension was associated with reductions in serum leptin irrespective of diet. Serum leptin positively correlated with adipose tissue mass (epididymal + intra-abdominal fat). This study shows that in a non obese model of hypertension, chronic pressure overload was associated with a reduction in serum leptin in part, as a consequence of reductions in adipose tissue mass, suggestive of decreased leptin secretion from adipose tissue. These effects were independent of dietary fatty acid composition.