Intermittent food restriction upregulates critical hypothalamic genes involved in energy regulation imbalance.

The effect of intermittent food restriction (IFR) on the Central Nervous System is unclear, especially when alternated with an obesity-inducing diet (DIO). This study aimed to evaluate key genes involved in energy-regulation imbalance in the hypothalamus after IFR and DIO alternation. Therefore, 45-d-old female Wistar rats were divided into 4 groups: standard control (ST-C), fed with an ad libitum standard diet; DIO control (DIO-C), fed with a DIO in the first and last 15 d of the intervention and a standard diet between the 16th and 45th day; standard restricted (ST-R), fed with a standard diet in the first and last 15 d of the intervention followed by IFR at 50% of the ST-C diet between the 16th and 45th day; and DIO restricted (DIO-R), fed with a DIO in the first and last 15 d of the intervention and subjected to IFR under the same conditions as the ST-R group. At 105 d of age, animals were euthanized, and the hypothalamus was removed for quantitative polymerase chain reaction analysis. The ST-R and DIO-R groups showed higher inhibitor of nuclear factor kappa-B kinase subunit beta (P < 0.001; P = 0.029) and nuclear factor kappa B (P < 0.001; P = 0.029) gene expression when compared with the ST-C group. The same held true for the JNK (P = 0.001; P = 0.003) and PPARα genes (both P < 0.001). Instead, the DIO-R group exhibited higher CCL5 gene expression than the ST-C (P = 0.001) and DIO-C (P < 0.001) groups, whereas all groups had higher SOCS3 gene expression than did the ST-C group. These data together suggest that IFR, whether combined with DIO or not, alters the expression of critical genes involved in energy regulation imbalance in the hypothalamus, which warrants caution and more research, because long-term usage might be hazardous.

Fasting and refeeding cycles alter subcutaneous white depot growth dynamics and the morphology of brown adipose tissue in female rats.

Intermittent food restriction (IFR) is used mainly for weight loss; however, its effects on adipose tissue are not known when alternating with an obesogenic diet. To demonstrate its effects on morphological dynamics of fat deposits, female Wistar rats were distributed into groups: standard control (ST-C), with commercial diet; DIO control (DIO-C), with a diet that induces obesity (DIO) during the first and last 15 d, replaced by a standard diet for thirty intermediate days; standard restricted (ST-R), with standard diet during the first and last 15 d, with six cycles of IFR at 50 % of ST-C; and DIO restricted (DIO-R), in DIO during the first and last 15 d, with six cycles of IFR at 50 % of DIO-C. At 105 d of life, white adipose tissue (WAT) and brown adipose tissue (BAT) deposits were collected, weighed and histology performed. The DIO-R group showed higher total food intake (DIO-R 10 768·0 (SEM 357·52) kJ/g v. DIO-C 8868·6 (SEM 249·25) kJ/g, P < 0·0001), energy efficiency during RAI (DIO-R 2·26 (SEM 0·05) g/kJ v. DIO-C 0·70 (SEM 0·03) g/kJ, P < 0·0001) and WAT (DIO-R 5·65 (SEM 0·30) g/100 g v. DIO-C 4·56 (SEM 0·30) g/100 g) than their respective control. Furthermore, IFR groups presented hypertrophy of WAT and BAT, as well as fibrosis in BAT. Thus, IFR can establish prospective resistance to weight loss by favouring changes in adipose tissue morphology, increased energy intake and efficiency. Finally, the DIO diet before and after IFR aggravates the damages caused by the restriction.

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.

Restricción alimentaria intermitente: repercusiones en la regulación de la homeostasis energética hipotalámica y tejido adiposo / Intermittent food restriction: repercussions in the regulation of hypothalamic energy homeostasis and adipose tissue

La práctica de restricción alimentaria intermitente (RAI) bien como sus variaciones, es utilizada por individuos con intensión de pérdida de masa corporal. Existen evidencias científicas favorables a esta práctica; no obstante, son insuficientes los estudios que muestren las consecuencias a largo plazo y sus repercusiones en el control de la homeostasis energética en el sistema nervioso central (SNC). Considerando su creciente utilización, tanto como su recomendación y además de la controversia existente en la bibliografía, la presente revisión tiene como objetivo mostrar los efectos de la RAI sobre la regulación central de la homeostasis energética registrados en la literatura.

The practice of intermittent food restriction (IFR) along its variations, is used by individuals with an intentional loss of body mass. There is scientific evidence favorable to this practice; however, studies showing the long term consequences and their impact on the control of energy homeostasis at the level of the central nervous system (CNS) are insufficient. Considering the increase in its use, as well as in its recommendation and the great controversy existing in the bibliography, the present review aims to show the effects of RAI on the central regulation of energy homeostasis reported in the literature.

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.