Behavioural pharmacologyImidazoline binding sites mediates anticompulsive-like effect of agmatine in marble-burying behavior in mice

Agmatine is a cationic amine formed by decarboxylation of l-arginine by the mitochondrial enzyme arginine decarboxylase and widely distributed in mammalian brain. Although the precise function of endogenous agmatine has been largely remained unclear, its exogenous administration demonstrated beneficial effects in several neurological and psychiatric disorders. This study was planned to examine the role of imidazoline binding sites in the anticompulsive-like effect of agmatine on marble-burying behavior. Agmatine (20 and 40 mg/kg, ip), mixed imidazoline I1/α2 agonists clonidine (60 µg/kg, ip) and moxonidine (0.25 mg/kg, ip), and imidazoline I2 agonist 2- BFI (10 mg/kg, ip) showed significant inhibition of marble burying behavior in mice. In combination studies, the anticompulsive-like effect of agmatine (10 mg/kg, ip) was significantly potentiated by prior administration of moxonidine (0.25 mg/kg, ip) or clonidine (30 µg/kg,) or 2-BFI (5 mg/kg, ip). Conversely, efaroxan (1 mg/kg, ip), an I1 antagonist and idazoxan (0.25 mg/kg, ip), an I2 antagonist completely blocked the anticompulsive-like effect of agmatine (10 mg/kg, ip). These drugs at doses used here did not influence the basal locomotor activity in experimental animals. These results clearly indicated the involvement of imidazoline binding sites in anti-compulsive-like effect of agmatine. Thus, imidazoline binding sites can be explored further as novel therapeutic target for treatment of anxiety and obsessive compulsive disorders.