Efeito da suplementação dietética com cálcio sobre a plasticidade ontogenética no modelo de superalimentação pós-natal

Abstract

Obesity is associated with diabetes, oxidative stress, liver steatosis, changes in hormonal sensitivity and reduction of the thermogenic capacity of the brown adipose tissue (BAT). In obesity, changes in mesocorticolimbic dopaminergic signaling can lead to palatable food addiction. All these features contribute to low energy expenditure and high food intake. To evaluate the long-term effects of childhood obesity we used the model of litter size reduction. The litters were adjusted to three pups at the 3rd day of lactation (SL group). The control group contained 10 pups per litter until weaning (NL group). On PN120, SL offspring were subdivided into: SL (standard diet); SL-Ca (calcium supplementation 10 g CaCO3/kg chow for 60 days). Food intake and body weight were recorded during the all period. On PN175, animals were subjected to a food challenge: animals could choose between high-fat (HFD) and high-sucrose diets (HSD). We evaluated: hormones (ELISA, RIA and chemicluminescence), the protein contents in liver, visceral adipose tissue (VAT), BAT and in brain areas (Western blotting) and the enzymatic activities in liver and plasma (kinetics assays). At PN21, PN120 e PN180, the BAT autonomic nerve function was determined in vivo. At weaning, the SL rats had high higher oxidative stress in liver and plasma and lower VAT catecholamine sensitivity. At adulthood, the calcium supplementation was able to improve the redox balance liver and plasma, the insulin sensitivity, and the liver steatosis. The alteration in the metabolism /action of vitamin D and glucocorticoids in the VAT as well as the reduced BAT thermogenic capacity contributed to the higher visceral adiposity in SL group. The calcium supplementation normalized, in part, these changes. The postnatal early overfeeding reduced the brain dopaminergic signaling and increased the preference for fat, while the calcium supplementation normalized the dopaminergic signaling in hypothalamus and the food preference. Our data highlight the benefits of the dietetic calcium supplementation, which can be promising to minimize the disruptions associated with obesity and metabolic syndrome in obese animals overfeed during the lactation.