Effects of chronic antidepressant treatment on alpha 1- and alpha 2-adrenoceptors in the rat anococcygeus muscle.
The effects of a single administration (48 hours) and of chronic (14 days) treatment with tricyclic (desipramine, nortryptiline) and nontricyclic (mianserin, nomifensine) antidepressant drugs on responses of the isolated anococcygeus muscle to the alpha 2-adrenoceptor agonist xylazine (inhibition of contraction to field stimulation at 1 Hz) and to the alpha 1-adrenoceptor agonist phenylephrine (contraction of the muscle) have been studied. Of the drugs used only desipramine and nortryptiline administered chronically reduced the responsiveness of the anococcygeus muscle to phenylephrine suggesting a desensitization of postsynaptic alpha 1-adrenoceptors. Long-term but not acute administration of antidepressants resulted in significant decrease in sensitivity of presynaptic alpha 2-adrenoceptors to xylazine. These results show that the adaptative changes of alpha-adrenoceptors in the rat anococcygeus muscle following long-term administration may depend on the efficiency to inhibit the neuronal uptake and the ability to antagonize alpha 1-adrenoceptors.
Vila
E
E
Department de Farmacologia i Psiquiatria, Universitat Autònoma de Barcelona, Bellaterra, Spain.
Sallés
J
J
Badia
A
A
D000818:Animals; D000928:Antidepressive Agents / Q000008:administration & dosage / Q000494:pharmacology*; D003042:Cocaine / Q000494:pharmacology; D003891:Desipramine / Q000494:pharmacology; D004558:Electric Stimulation; D008297:Male; D008803:Mianserin / Q000494:pharmacology; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000187:drug effects* / Q000378:metabolism; D009627:Nomifensine / Q000494:pharmacology; D009647:Normetanephrine / Q000494:pharmacology; D009661:Nortriptyline / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D014991:Xylazine / Q000494:pharmacology
D000928:Antidepressive Agents; D011942:Receptors, Adrenergic, alpha; D009647:Normetanephrine; D009627:Nomifensine; D010656:Phenylephrine; D008803:Mianserin; D014991:Xylazine; D011433:Propranolol; D009661:Nortriptyline; D003042:Cocaine; D003891:Desipramine