PREGNANCY FOLLOWED BY LACTATION

PREGNANCY FOLLOWED BY LACTATION PROMOTES LONG-TERM CHANGES IN BODY WEIGHT AND LEPTIN SENSITIVITY Pryscila Dryelle Sousa TEIXEIRA¹, Angela Maria RAMOS-LOBO¹, Isadora Clivatti FURIGO¹, João Alfredo PEDROSO¹, Jose DONATO JUNIOR¹ ¹Department of Physiology and Biophysics, ICB/USP, Sao Paulo – Brazil

INTRODUCTION: Pregnancy leads to extensive adaptations in female’s body, including by changing the long-term responses to certain hormones and the predisposition to obesity and diabetes. AIM: Determine whether the experience of pregnancy, followed or not by lactation, can lead to metabolic programming and affect hormonal responses in mice. METHODOLOGY: C57BL/6 Female mice (9 weeks old) were distributed in 3 groups (virgin, pregnancy, pregnancy with lactation). Those of the "pregnancy" and "pregnancy with lactation" groups were bred until pregnancy. Mice in the pregnancy group had the pups removed after birth, whereas mice in pregnancy with lactation group were allowed to nurse the pups until 21-28 days of lactation. After pup removal the females were gathered in cages and their body weights were monitored for 25 weeks. After the follow-up period, the females were subjected to in vivo tests to evaluate glucose tolerance, as well as insulin and leptin sensitivity. Food and water intake, ambulatory movements and VO2 were measured by OXYMAX CLAMS system. The estrous cycle was observed for standardization before euthanasia (diestrus). Body composition was determined by weighing four adipose tissue depots. We also collected serum, hypothalamus and liver for further analysis. RESULTS: Immediately after pregnancy, females had higher body weight than the virgins and this difference remains for eight weeks. After this period, only the "pregnancy with lactation" group had a higher body weight compared to virgin group. This difference was confirmed when we assessed the adiposity (p