Diabetic female rats exhibit defensive aggression during mating

Abstract

Introduction. Few reports have analyzed the putative association between diabetes mellitus type 1 (DM1) and aggressiveness. A previous study using a model of DM1 reported an increase in aggressive behaviors (AB) of females against the male during mating, which was prevented by insulin. However, it was unclear if such aggression was defensive or offensive. Objective. To evaluate the different components of aggressiveness of hyperglycemic female rats in two distinct mating paradigms. Method. DM1 was modeled in OVX Wistar rats by injecting streptozotocin (STZ) diluted in citrate buffer (50 mg/kg, i.p., for 2 consecutive days). Ten days later, female rats were treated with estradiol benzoate (10 microg, -24 hours) and progesterone (3 mg, -4 hours). A group of STZ-treated animals was administered with a long-acting insulin analogue (glargine) every 12 hours for 8 days. Aggression was recorded in non-paced mating (NPM) and paced mating (PM) paradigms. We registered: the first attack latency (FAL), the proportion of females that presented AB and its type (boxing, bites, lateral kicks and twist) and if AB were exhibited defensively or offensively. Results. Hyperglycemic rats showed an increase in lateral kicks in NPM, whereas in PM they exhibited an increase in bites. These behaviors were always defensive and there were no changes in FAL. Insulin reduced AB. Discussion and conclusion. Data indicate that the aggressiveness of hyperglycemic female rats is a form of defense against the proximity of the male and add information about the role of insulin on their modulation.