Oral solution of fructose promotes SREBP-1c high-expression in the hypothalamus of Wistar rats.

Objective: We evaluate whether the consumption of fructose for 8 weeks affects enzymes and transcription factors of the lipogenic and inflammatory pathways in the hypothalamus of Wistar rats. Methods: At 30 days, the animals were divided into groups: Control (C) and Fructose (F) and maintained with free access to feed and filtered water (C) or aqueous solution of purified fructose at 20% (F). RT-PCR and Western blotting were performed for the target genes and proteins. Results: In F group, results showed a lower feed intake, an increase in glycemia (146.20 ± 6.09 vs. 102.32 ± 4.58; n: 9) and triacylglycerol (F: 191.65 ± 13.51 vs. C: 131.69 ± 6.49; n: 9) and there was no difference in water and energy consumption. We identified a higher content of acetyl-CoA carboxylase (ACC) (F: 133.93 ± 5.58 vs. C: 100 ± 0.0; n: 9-10) and NFκB (F: 125.5 ± 8.85 vs. C: 100 ± 0; n: 14) in group F, whereas fatty acid synthase (FAS) was lower (F: 85.90 ± 4.81 vs. C: 100 ± 0.0; n: 4-6). SREBP-1c gene expression was higher in F vs. C group (F: 4.08 ± 0.44 vs. C: 1.13 ± 0.15; n: 5-6), although we did not found difference between groups in the gene expression for ACC, SREBP-2, and NFκB. Discussion: Dietary fructose can change important lipogenic and inflammatory factors in the hypothalamus of rats and it leads to regulation of transcription factors before changes in body mass are evident.

Intermittent food restriction in female rats induces SREBP high expression in hypothalamus and immediately postfasting hyperphagia.

OBJECTIVE: We investigated the effect of intermittent food restriction (IFR) cycles on hypothalamic expression of lipogenic proteins and induction of overeating. METHODS: Female Wistar rats were distributed in three groups: free access to feed (control, C), 2 d feed restriction at 50% of C intake followed by 3 d (restricted 3, R3) or 5 d (restricted 5, R5) ad libitum feeding. After 6 wk, the rats were submitted to euthanasia and collected the hypothalamus and blood. The deposits of retroperitoneal, mesenteric, and gonadal fat were weighed. The expression of the mRNA for sterol regulatory element binding protein (SREBP) 1c and 2 and acetyl-CoA carboxylase in the hypothalamus were determined by real-time polymerase chain reaction, and glucose and triacylglycerol were evaluated by a commercial kit. Body mass and food intake were measured daily. RESULTS: IFR promoted increased expression of SREBP-2 in both treated groups and, in R5, increased expression of SREBP-1c. The serum triacylglycerol, mesenteric deposit, and total fat content were higher in R3. Neither of the treatment intervals altered the expression of the mRNA of acetyl-CoA carboxylase enzyme but induced hyperglycemia and higher food intake immediately after food restriction. CONCLUSION: IFR affected the expression of SREBP-1c in R5 and SREBP-2 in the hypothalamus and caused overeating immediately after fasting in both groups. We suggest that hypothalamic and peripheral alterations, coupled with compulsive eating behavior in the ad libitum period, indicate risks for diabetes mellitus and recovery of body mass after interruption of IFR.