influence of acute treatment with sibutramine on the sympathetic neurotransmission of the young rat vas deferens the effects of acute treatment with sibutramine on the peripheral sympathetic neurotransmission in vas deferens of young rats were still not evaluated therefore we carried out this study in order to verify the effects of acute sibutramine treatment on the neuronal and exogenous agonistinduced contractions of the young rat vas deferens young 45dayold male wistar rats were pretreated with sibutramine 6 mgkg and after 4h the vas deferens was used for experiment the acute treatment with sibutramine was able to increase the potency pd2 of noradrenaline and phenylephrine moreover the efficacy emax of noradrenaline was increased while the efficacy of serotonin and nicotine were decreased the maximum effect induced by a single concentration of tyramine was diminished in the vas deferens from treated group moreover the leftward shift of the noradrenaline curves promoted by uptake blockers cocaine and corticosterone and adrenoceptor antagonist propranolol was reduced in the vas deferens of treated group the initial phasic and secondary tonic components of the neuronalevoked contractions of vas deferens from treated group at the frequencies of 2 hz were decreased moreover only the initial phasic component at 5 hz was diminished by the acute treatment with sibutramine in conclusion we showed that the acute treatment with sibutramine in young rats was able to affect the peripheral sympathetic nervous system by inhibition of noradrenaline uptake and reduction of the neuronal content of this neurotransmitter leading to an enhancement of vas deferens sensitivity to noradrenaline