Alpha 2-adrenergic antagonists effect on amphetamine-induced behaviors.

The effects of alpha 2-adrenergic antagonists on amphetamine-induced locomotion and stereotypy were studied in mice. Six alpha 2-antagonists (i.e., yohimbine, rauwolscine, piperoxan, tolazoline, RX781094, and RS21361) selectively attenuated amphetamine-induced increases in locomotion at doses which did not effect amphetamine-induced stereotypies. Higher doses of the antagonists which attenuated baseline stereotypies also attenuated amphetamine-induced increases in stereotypies. The effect of the alpha 2-antagonists was qualitatively similar to that observed with the atypical antipsychotic clozapine. Furthermore, the in vivo relative potency of the alpha 2-antagonists in the present study was comparable to that reported in other studies. These results suggest that alpha 2-adrenergic receptors may modulate the effects of amphetamine on locomotion in mice.