ABSTRACT
Unsaturated fatty acids are known to decrease serum leptin level. Considering that wild pistachio oil is a rich source of UFA and the reciprocal effects between leptin and thyroid hormones, the aim of the present study was to investigate the impact of dietary wild pistachio oil on serum leptin concentration and its relationship with thyroid hormones. We took 28 healthy adult male rats and divided them randomly in to the four groups; group 1 a control, and the other 3 groups received a normal diet without, 5, 10 and 20% of wild pistachio oil, respectively. RIA for thyroid hormones assay [T3 and T4] and ELISA for leptin, fT3 and fT4 measurement were used. After 60 days, serum leptin levels reduced with increasing wild pistachio oil concentration in the diet; in the control group with normal diet, no significant alterations were seen. This reduction also was not statistically significant in the 10% wild pistachio oil group, whereas differences between groups were significant, indicating the increasing effects of increased amounts of wild pistachio oil percent on the reduction process observed. Pearson correlation coefficients were calculated between leptin and thyroid hormones in the different sampling times. Control group did not have any significant correlation. In group 2 [fed with 5% wild pistachio oil], leptin concentration had a negative significant correlation with T4 and fT3 and a positive significant correlation with fT4 in the third stage of sampling [day 30]. A positive significant correlation between leptin concentration and fT4 in the fifth stage of bleeding [day 60] was observed in group 3 [fed with 10% wild pistachio oil]. In group 4 [fed with 20% wild pistachio oil] a significant negative correlation between leptin concentration and fT3 was observed in the second stage of sampling [day 15]. Wild pistachio oil has a high content of unsaturated fatty acids, and reductions in serum leptin levels in the rats studied can be due to these acids. Oral consumption of wild pistachio oil has a positive effect on reduction leptin and LDL-cholesterol thyroid hormones and prevention of cardiovascular diseases