Effect of photoperiod and seasonal fruit consumption on hypothalamic leptin sensitivity in obese animals. (A,B) Serum leptin was measured in animals fed a cafeteria diet (CD) + vehicle or 100 mg/kg of lyophilized grapes or cherries for 7-week-period and submitted to long-day (LD) or short-day (SD) light cycle. (C,D) Gene expression of long form of leptin receptor (Obrb) and negative regulator molecules Socs3 and Ptp1b were analyzed. Values were normalized against LD-vehicle group for leptin concentration and gene expression. Data represent mean ± SE (n = 6). P, photoperiod effect; F, fruit effect; F*P, interaction of photoperiod and fruit treatment assessed by two-way ANOVA (P < 0.05). Different letters denote significant changes assessed by one-way ANOVA and Tukey’s post hoc test (P < 0.05). *Effect of photoperiod in fruit treated groups; #Effect of fruit in photoperiod group determined by Student’s t test (P < 0.05).