Effects of methamphetamine on alloparental behavior in male and female prairie voles

Abstract

Psychostimulant abuse is associated with a variety of impairments in social functioning, including an increased frequency of depression and aggression and deficits in social cognition. Psychostimulants reduce social investigation in rats and mice; however, it is less clear how other forms of social behavior (e.g., prosocial behavior) are affected. Females are also generally more sensitive to the effects of psychostimulants on locomotion and stereotyped behavior, which suggests that females might also display greater disruption of prosocial behavior. In order to test the hypothesis that psychostimulants reduce prosocial behavior and that females are more vulnerable, we treated adult male and female prairie voles with methamphetamine for three days (0, 0.2 or 2.0mg/kg, i.p.) and examined effects on locomotion and alloparental behavior. The lower methamphetamine dose increased activity in the open field in males and reduced locomotion in females. Methamphetamine-treated males took longer to enter the pup chamber, but both sexes displayed reduced pup contact following treatment with the lower methamphetamine dose. The methamphetamine-induced reduction in prosocial behavior was not associated with changes in pup-directed aggression in males or females. In order to investigate potential mechanisms underlying these changes in behavior, we measured adrenal weights as a proxy for activation of the hypothalamic-pituitary-adrenal (HPA) axis. The higher methamphetamine dose increased adrenal weights. Collectively, these data demonstrate that methamphetamine administration reduces alloparental behavior in both sexes and that females are more sensitive to some of the effects of this drug (e.g., locomotion/stereotyped behavior and possibly stimulation of the HPA axis).