Functional antagonism of amphetamine versus ethanol on adrenergic neurotransmission in vas deferens of adolescent rats

Abstract

Because of the few studies that emphasize the in vivo use of amphetamine and ethanol, and their consequences on autonomic neurotransmission, we decided to study the effect of these drugs on peripheral noradrenergic neurotransmission of young animals. We used contractions of the vas deferens of adolescent rats as a model for the study of pre-treatment with both agents. The 30 to 40 day old adolescent rats were pre-treated with amphetamine, at doses of 3mg/kg, or ethanol at doses of 1.2 g/kg. Both agents were also used simultaneously to investigate possible interactions. The group treated with amphetamine showed a potentiation of the vas deferens contractions evoked by noradrenaline and barium (about 20%), as well as time-response contractions of calcium (about 20%). However, the response to electrical field stimulation (EFS) was not significantly changed, but the content of noradrenaline was reduced by about 50%. The group treated with ethanol showed a decrease in vas deferens contractility to noradrenaline, phenylephrine, and barium, by less than 20%. In this group, contraction by EFS was reduced by about 40% (Tonic, 2 Hz) and 20% (Phasic, 5 Hz), but the response to calcium was not changed. As after amphetamine, the content of noradrenaline was reduced by about 50%. In the group treated with amphetamine+ethanol all the changes described after the single treatments with amphetamine or ethanol were neutralized. It is concluded that a functional antagonism was shown between amphetamine and ethanol when administered simultaneously on peripheral sympathetic neurotransmission in vas deferens of adolescent animals.