Are beta- and alpha 2-adrenoceptors co-regulated during their stimulation? Behavioral studies.
The effects of beta-, and alpha 1-antagonists on the clenbuterol- and clonidine-induced depression of the exploratory activity was measured in rats in the open field test. The ability of clenbuterol (0.5 mg/kg) to reduce exploration was antagonized by 1-propranolol, significantly reduced by rauwolscine and unchanged by corynanthine and prazosin. Clonidine (0.2 mg/kg)-induced hypoactivity was significantly reduced by all the used adrenergic antagonists. A combined treatment with non-sedative doses of clenbuterol and clonidine significantly reduced exploration. Results suggest that both beta- and alpha 2-adrenoceptors are involved in clenbuterol- and clonidine-induced sedation. Moreover, they may indicate the existence of beta- and alpha 2-adrenoceptor interaction.
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D005106:Exploratory Behavior / Q000187:drug effects*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000502:physiology*
D000317:Adrenergic alpha-Antagonists; D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D003000:Clonidine