(3,4-Dihydroxyphenylimino)-2-imidazoline (DPI) and its action at noradrenergic and dopaminergic receptors in the nucleus accumbens of rats: mesolimbic catecholamine receptors and hyperactivity.

Bilateral administration of ergometrine into the nucleus accumbens of rats pretreated 1-3 min earlier with intra-accumbens injections of noradrenaline, phenylephrine, clonidine and phentolamine has been found to produce a normal ergometrine-induced hyperactivity. In contrast, low doses of dopamine and (3,4-dihydroxyphenylimino)-2-imidazoline (DPI) and only high doses of clonidine and phentolamine have been found to attenuate the ergometrine response. These data together with the finding that phentolamine is unable to alter DPI's ability to suppress the ergometrine response provide direct evidence that the latter DPI effect is certainly not due to its ability to act as an agonist at alpha-NE receptors within the nucleus accumbens of rats.