The effect of brown adipose tissue transplantation on blood metabolic factors and sex hormones and breast milk nutrient composition and antioxidant status in obese and normal weight rats

Abstract

Abstract Purpose: Brown adipose tissue (BAT) is a metabolically active tissue, which helps to reduce weight and manage obesity and blood sugar. There are numerous studies performed to increase the amount of BAT to manage metabolic disorders such as obesity and diabetes. Therefore, it is suggested that it could possibly be effective in the treatment of gestational diabetes and obesity. Because of lack of sufficient data regarding possible adverse effects of high amounts of this tissue (such as production of free radicals by its high metabolism, or consumption of nutrients requiring for mother and fetus), the present study aimed to examine the effects of BAT transplantation in pregnancy and lactation of obese dams and offsprings. Methods: Eighty Wistar rats (aged four weeks and weighed > 70g) enrolled to the study and were fed with cafeteria or normal diet for two months to induce obesity and then, the operation of BAT transplantation was done. The obese rats were assigned into following groups: “control-control”, “control-sham”, “control-donor”, “control-receiver”, "cafeteria-control”, ”cafeteria–sham”, “cafeteria–donor” and “cafeteria–receiver”. The rats were mated with male rats after about three weeks. Milk samples were collected to analyze milk composition (including nutrient composition and antioxidant status) five times over lactation period. Dams were sacrificed after weaning and samples of blood were collected to determine blood glucose, insulin, lipid profile and sex hormones. Statistical analysis was done using SPSS (version 23), with a P<0.05 as the level of significance. Results: No adverse effect was found for BAT transplantation over pregnancy and/or lactation period. Offspring death was observed during lactation and in cafeteria group it was significantly more than normal fed rats (p<0.01). However, there were no differences in death rate among the groups. The omission of BAT resulted in weight gain while receiving BAT led to weight reduction among dams and offspring. Only offspring birth weight in cafeteria–receivers was significantly greater than control–receivers (p<0.05). Feeding with cafeteria diet resulted in lipid profile impairment (by increasing TG and LDL and reducing HDL) as well as insulin resistance (FBS, insulin and HOMA-IR) in dams (more obvious among donor groups) (p<0.01). BAT transplantation could alleviate these metabolic outcomes. Hormonal changes were not significantly different among the groups. Indeed, some changes in milk composition including total fat, fatty acid content and minerals were found which the total fat was increased because of cafeteria diet (p<0.001) and the iron of milk was significantly reduced due to surgical process (p<0.01). Conclusion: The results of this experimental study indicate that increased BAT seems to have beneficial effects on metabolic changes following cafeteria diet and no specific adverse effect was observed associated with increasing BAT. However, further investigation is required to confirm these findings.