Angiotensin II AT1 Receptors Are Involved in Neuronal Activation Induced by Amphetamine in a Two-Injection Protocol

It was already found that Ang II AT₁ receptors are involved in the neuroadaptative changes induced by a single exposure to amphetamine, and such changes are related to the development of behavioral and neurochemical sensitization. The induction of the immediately early gene c-fos has been used to define brain activated areas by amphetamine. Our aim was to evaluate the participation of AT₁ receptors in the neuronal activation induced by amphetamine sensitization. The study examined the c-fos expression in mesocorticolimbic areas induced by amphetamine challenge (0.5 mg/kg i.p) in animals pretreated with candesartan, a selective AT₁ receptor blocker (3 mg/kg p.o × 5 days), and amphetamine (5 mg/kg i.p) 3 weeks before the challenge. Increased c-fos immunoreactivity was found in response to the amphetamine challenge in the dorsomedial caudate-putamen and nucleus accumbens, and both responses were blunted by the AT₁ receptor blocker pretreatment. In the infralimbic prefrontal cortex, increased c-fos immunoreactivity was found in response to amphetamine and saline challenge, and both were prevented by the AT₁ receptor blocker. No differences were found neither in ventral tegmental area nor prelimbic cortex between groups. Our results indicate an important role for brain Ang II in the behavioral and neuronal sensitization induced by amphetamine.