Amphetamine triggers long-lasting effects in CNS and IS: is the proenkephalin system a possible common mediator?

ASSIS, MA; PADRÓS, MR; ROSETE, M; DURÁN, S; SOTOMAYOR, C; VINDROLA, O; CANCELA, LM

San Diego, EEUU

Congreso; 34th Annual Meeting of Neuroscience; 2004

There is evidence of a bidirectional communication between Central Nervous System (CNS) and Immune System (IS), and that opioids exert a modulatory role on the immune response. Our main goal was to study: 1) the influence of acute and chronic d-amphetamine treatment on ConA-induced lymphocyte proliferation in rats, 2) the participation of dopaminergic and opioidergic systems in these effects, 3) the amphetamine-induced effects on proenkephalin and derived peptides in immune organs and different CNS areas. Wistar rats received chronic (1 or 2mg/kg/day/ five days IP) or acute (2.5 or 5mg/kg IP) amphetamine; four days after the last injection the proliferative response was assessed. Since similar immunosuppressive effects were observed following acute and chronic treatments, Naloxone, SCH-23390 and Sulpiride were given only before 5mg/kg amphetamine. Since all antagonists abolished the amphetamine-induced effects on IS, dopamine and opioid systems seem to be involved. The proenkephalin and derived peptides levels in the CNS and IS were studied following 5mg/kg amphetamine. An increase in Met-enkephalin was observed in spleen, thymus, nucleus accumbens and prefrontal cortex. These changes in Met-enkephalin point out that it could be used as a common biological marker of pertinent stimuli (i.e. psychostimulant drug) acting at SI and SNC, and reflect the functional changes at both levels