Differential effects of drawing and indirect dopamine agonists on the induction of gnawing in C57BI/6J mice

Compared the ability of indirect dopamine (DA) agonists to induce gnawing behavior (GB) in male C57BL/6J mice with that of direct DA agonists acting at DA D-sub-1 or D-sub-2 receptor subtypes. Eight Ss were used per dose. Holes left by Ss on corrugations of packing cardboard were used as an objective index of GB. Indirect DA agonists, including DA releasers such as fencamfamine and amfonelic acid and DA uptake inhibitors such as cocaine and nomifensine, produced dose-dependent increases in GB. None of the direct agonists (e.g., apomorphine, quinpirole) increased GB. The dopaminergic nature of GB was confirmed in studies in which a host of compounds (e.g., nicotine, caffeine, dizocilpine) with primary actions at nondopaminergic sites did not induce GB. Given the general contrast between the effects of direct and indirect DA agonists, this procedure could serve as a rapid in vivo method of distinguishing direct- from indirect-acting DA agonists. ((c) 1997 APA/PsycINFO, all rights reserved)