Long-term effects of early adolescent methamphetamine exposure on depression-like behavior and the hypothalamic vasopressin system in mice.

Methamphetamine (MA) has neurotoxic effects on the adult human brain that can lead to deficits in behavior and cognition. However, relatively little research has examined the behavioral or neurotoxic effects of MA in adolescents. The rising rates of adolescent MA use make it imperative that we understand the long-term effects of MA exposure on the adolescent brain and how these effects may differ from those seen in adults. In this study, the long-term effects of MA exposure during early adolescence on behavior and the vasopressin system in the paraventricular nucleus of the hypothalamus in late adolescent and adult male and female C57BL/6J mice were examined. MA exposure increased depression-like behavior in the Porsolt forced swim test in both late adolescent and adult male and female mice. Late adolescent male mice exposed to MA also showed a decrease in the number of vasopressin-immunoreactive neurons in the paraventricular nucleus compared to sex-matched saline-treated controls. Thus, similar to humans exposed to MA during adolescence, mice exposed to MA during adolescence show increased depression-like behavior later in life. These changes in behavior may be related to MA-induced alterations in vasopressin and the hypothalamic-pituitary-adrenal axis, especially in males.