Efeito da suplementação dietética com farinha de feijão branco (Phaseolus vulgaris L.) sobre o metabolismo de ratos obesos induzidos por superalimentação precoce

Abstract

The use of functional foods has been widely applied as a tool for preventive intervention in the development of metabolic diseases. We aimed to investigate the effect of a diet supplemented with white bean flour (Phaseolus vulgaris L.) on body composition, glucose homeostasis and central insulin responsiveness in rats metabolically programmed for early obesity induced by litter reduction during lactation. At day 3 of life, litters were standardized to 3 pups per lactating mother (NR group), while the control group was adjusted to 8 pups per lactating mother (NP group). At day 12 of lactation, milk samples were collected and at days 6, 11 and 16, the milk intake of the pups was measured. At weaning (day 22 of life), each group was subdivided into two subgroups: NP-DP and NR-DP groups, fed a standard rodent diet, and NP-FB and NR-FB groups, fed a standard rodent diet supplemented with 2.5% white bean meal (FB) from weaning to adulthood. Throughout the experimental period the epso gain, food and water intake of the animals were measured every other day. As adults, after 95 days of age, all groups underwent intraperitoneal glucose tolerance test (ipGTT), intraperitoneal insulin tolerance test (ipITT), and underwent intracerebroventricular (icv) injection of insulin. At 100 days of age, the rats were euthanized for removal of tissue samples (white and brown adipose tissue, and skeletal muscle), for biometric evaluation; as well as blood collection for further biochemical evaluations and hypothalamus for the quantification of inflammatory markers. In relation to the milk of the NP rats, an increase in the levels of glucose (41.02%), triglycerides (14.24%), total cholesterol (16.66%), fat content (48.88%) and energy content (42.87%) was observed in the milk of the NR rats (P<0.05). During lactation, NR rats showed 16.64% increase in body weight gain, and higher milk intake, compared to NP rats (P<0.001). Over the post-weaning period, NR rats were 7.78% heavier than NP rats (P<0.05), and supplementation of the diet with FB was able to prevent this body weight gain. Compared to the NP-DP rats, the animals in the NR-DP group showed an obese phenotype, hyperphagia, hyperglycemia, dyslipidemia, glucose intolerance, and central and peripheral insulin resistance (P<0.05). On the other hand, this picture of metabolic dysfunction was not observed in the NR-FB group. As for hypothalamic proinflammatory markers, NR-DP rats showed elevated levels of TNF-α (47.52%; P<0.01), IL-1β (43.21%; P<0.01), and IL-6 (85.61%; P<0.001) relative to NP-DP. Where as, compared with NR-DP rats, NR-FB rats, showed a reduction in all these cytokines. We conclude that supplementation with white bean flour was able to prevent the development of obesity (accumulation of visceral fat deposits), and increase lean body mass, as well as to improve glycemic and insulinemic homeostasis and attenuate the hypothalamic inflammatory process in rats from a reduced litter size.