Amphetamine treatment affects the extra-hypothalamic vasopressinergic system in a sex- and nucleus-dependent manner.

The lateral septum (LS), a brain structure implicated in addictive behaviours, regulates the activation of dopaminergic neurones in the ventral tegmental area. Vasopressinergic projections from the extended amygdala to the LS, which are sexually dimorphic, could be responsible for the vulnerability to addiction in a sex-dependent manner. The present study aimed to investigate the modulatory effects of amphetamine (AMPH) on the expression of vasopressin (AVP) in the vasopressinergic extra-hypothalamic system in sensitised male and female rats. Adult male and female Sprague-Dawley rats underwent an AMPH-locomotor sensitisation protocol. Acute AMPH increased AVP mRNA expression in the medial amygdala (MeA), whereas AMPH-induced sensitisation increased AVP mRNA expression in the bed nucleus of the stria terminalis (BNST) only in females. Interestingly, the increase in AVP expression in BNST was higher in oestrus females compared to dioestrus females and acute AMPH resulted in a decrease in AVP levels in the LS, only in males. Thus, there are complex and region-specific interactions between AMPH and the extra-hypothalamic vasopressinergic system in the brain, underlying possible alterations in different behaviours caused by acute and chronic AMPH exposure.