In utero and lactational exposure to metformin induces reproductive alterations in male rat offspring.

Metformin (MET) is prescribed for the treatment of type 2 diabetes mellitus and gestational diabetes. Although MET crosses the placenta, it is considered safe throughout gestation. However, it has been shown in humans that maternal exposure to MET increases sex hormone binding globulin levels in newborns, and in rats it decreases the testosterone concentration at gestational day (GD) 16.5. Therefore, the present study evaluated if maternal exposure to MET could interfere with reproductive parameters of male offspring. Wistar female rats were treated with MET 293mg/kg/day, by gavage from GD0 to GD21 (METG) or GD0 until lactational day (LD) 21 (METGL) and the control groups received water. Sexual behavior of male offspring was affected in both MET groups. However, a decrease in the sperm count was observed only in METGL group. These results suggest that MET exposure induced alterations in reproductive parameters of male offspring in adulthood depending on exposure time.