There is evidence of a bidirectional communication between Central Nervous System and Immune System, and that psychostimulant drugs could influence the immune response. Repeated treatment with psychostimulant causes long-lasting behavioral sensitization and associated neuroadaptations. Although behavioural, neurochemical and neuroendocrine sensitization induced by a single psychostimulant exposure has also been reported, information on the immune consequences of a single psychostimulant exposure is sparse. Wistar rats received an acute (5mg/kg IP) amphetamine (AMPH) treatment and the proliferative response was assessed 4 days, 1 and 3 weeks after injection. A single exposure to AMPH caused a time-dependent decrease in the concanavalin-A-induced lymphocyte proliferation that remains for at least 1 week after injection. Since no residual effect was observed 3 weeks following AMPH treatment, a challenge injection (0.5 or 1mg/kg IP) of AMPH was administered at this time. Pre-exposure to AMPH sensitized the lymphoproliferative response to AMPH at 3 weeks after treatment. Because these data closely resemble those reported previously for behavioral, neurochemical, and neuroendocrine AMPH pre-treatment effects, it is concluded that a single exposure to AMPH is sufficient to induce long-term sensitization also at immune level in rats.
