Efeitos da dieta materna rica em linhaça durante a lactação sobre a composição corporal e função tireóidea de ratos na idade adulta

Abstract

Flaxseed (Linum usitatissimum) presents high number of substances with beneficial effects that reduce obsesity, blood glucose and dyslipidemia, protecting the cardiovascular system. We aimed to evaluate the maternal flaxseed diet during lactating upon body composition, glucose homeostase, lipid and protein, leptinemia, adiponectinemia and insulinemia, thyroid function, and leptin signaling pathway in the hypothalamus-pituitary-thyroid axis in the offspring at 21 and 180 days old. Lactating rats were divided into: (1) Controls (C), diet containing 20% casein; (2) Flaxseed (F), diet with additional 25% of flaxseed, containing 18.9% protein (13.9% from casein and 5% from flaxseed). The offspring were sacrificed at 21 and 180 days of age to determinate: glycemia, albumin, leptin, adiponectin, TSH, free T4 and total T3. The animals were completely eviscerated to obtain the carcass by body composition analysis. The maternal food intake and body mass were measured daily during the lactation, and after weaning were monitored once every 4 days until they were 180 days old. The dams of F group presented no changes in body mass and food intake. During the lactation the F offspring showed higher body mass and after weaning they presented a higher transitory body mass until 180 days old. At 21 days old, F group showed lower total and subcutaneous fat mass, total cholesterol, triacylglycerol, albumin, insulin, total T3 and D1 liver activity; and higher subcutaneous adipocytes area, leptin, TSH and Ob-R, STAT3 and p-STAT expression in pituitary (p<0,05). At 180 days old, F group presented lower glycemia, adiponectin, free T4 and D1 and D2 activity in thyroid; and higher visceral and subcutaneous adipocytes area, insulin, Ob-R expression in thyroid and D2 activity in brown adipose tissue (p<0,05). In conclusion, maternal flaxseed diet during lactation affects body composition, lipid profile, glucose homeostasis and thyroid function. The metabolic and hormonal impression in lactation programs for changes in adiposity, insulin resistance and possible thyroid dysfunction. Thus, flaxseed use should be viewed with caution during breastfeeding.