Could Modafinil Prevent Psychostimulant Addiction? An Experimental Study in Rats

Addiction is a serious health problem which leads to general social impairment. The period of adolescence plays a significant role in drug abuse liability. Psychostimulants, such as modafinil (MOD), are majorly used by teenagers seeking improvements in cognition, which contributes to its indiscriminate use. This study aimed to investigate the influence of MOD (64 mg/kg by gavage, once a day) treatment during adolescence [post-natal day (PND) 28-42] on amphetamine (AMPH, 4 mg/kg i.p.)-conditioned place preference (CPP) in early adulthood (PND 60). Our findings showed that AMPH increased CPP for the drug and anxiety-like behaviours; on the other hand, AMPH decreased the number of crossings and recognition index. In addition, AMPH decreased catalase activity and increased reactive species, malondialdehyde and carbonyl protein levels in the hippocampus. AMPH also increased pro-brain derived neurotrophic factor (BDNF), tyrosine kinase receptor B, dopamine transporter, D1R and decreased BDNF and D2R immunoreactivity. Contrarily, animals pre-exposed to MOD showed reduced AMPH-CPP, no locomotor impairment, less anxiety-like behaviours and no memory deficits. In addition, MOD showed antioxidant activity by preventing AMPH-induced oxidative damage in the hippocampus. Moreover, molecular analysis showed that MOD was able to modulate the hippocampal dopaminergic system, thus preventing AMPH-induced impairments. Animals that received MOD during adolescence showed reduced AMPH-CPP in early adulthood. These unexpected behavioural effects of MOD on CPP could be due to its hippocampal dopaminergic system modulation, mainly by its action on D1R, which is closely linked to drug addiction. Nevertheless, further studies are necessary.