Agmatine blocks ethanol-induced locomotor hyperactivity in male mice

Abstract

Ethanol-induced locomotor activity is associated to rewarding effects of ethanol and ethanol dependence. Agmatine is a novel endogenous ligand at α 2-adrenoceptors, imidazoline and N-methyl- d-aspartate (NMDA) receptors, as well as a nitric oxide synthase (NOS) inhibitor. There is no evidence presented for the relationship between the acute locomotor stimulating effect of ethanol and agmatine. Thus, the present study investigated the effects of agmatine on acute ethanol-induced locomotor hyperactivity in mice. Adult male Swiss–Webster mice (26–36 g) were used as subjects. Locomotor activity of the mice was recorded for 30 min immediately following intraperitoneal administration of ethanol (0.5, 1 and 2 g/kg) or saline (n = 8 for each group). Agmatine (5, 10 and 20 mg/kg) or saline was administered intraperitoneally to another four individual groups (n = 8 for each group) of the mice 20 min before the ethanol injection. In these groups, locomotor activity was also recorded immediately following ethanol (0.5 g/kg) injection for 30 min. Ethanol (0.5 g/kg) produced some significant increases in locomotor activity of the mice. Agmatine (5–20 mg/kg) significantly blocked the ethanol (0.5 g/kg)-induced locomotor hyperactivity. These doses of agmatine did not affect the locomotor activity in naive mice when they were administered alone. Our results suggest that agmatine has an important role in ethanol-induced locomotor hyperactivity in mice. There may be a relationship between the addictive psychostimulant effects of the ethanol and central agmatinergic system.