title: An alpha-adrenoceptor-mediated mechanism of hypoactivity induced by beta-amyrin palmitate.
abstract: Inhibitory effects of beta-amyrin palmitate in locomotor activity of mice were studied by combining this compound with alpha-adrenergic agonists or antagonists and a dopaminergic agonist. beta-Amyrin palmitate (2.5, 5.0 and 10.0 mg kg-1, i.p.) decreased locomotor activity of mice in a dose-dependent manner. It enhanced hypoactivity of mice treated with clonidine (0.025 mg kg-1, i.p.) and antagonized hyperactivity produced by phenylephrine (40 micrograms, i.c.v.). The inhibitory action of beta-amyrin palmitate was not affected by yohimbine (1.5 mg kg-1, i.p.), but was potentiated by prazosin (0.75 mg kg-1, i.p.). When combined with a dopaminergic agonist, apomorphine (2.0 mg kg-1, i.p.), beta-amyrin palmitate (5.0 and 10.0 mg kg-1, i.p.) did not affect locomotor stimulation produced by apomorphine. These results suggest that beta-amyrin palmitate might inhibit alpha 1-adrenoceptors.
authors.affiliation: Pharmaceutical Institute, Tohoku University, Sendai, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Subarnas
authors.forename: T
authors.initials: T
authors.lastname: Tadano
authors.forename: K
authors.initials: K
authors.lastname: Kisara
authors.forename: Y
authors.initials: Y
authors.lastname: Ohizumi
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology*; D001058:Apomorphine / Q000494:pharmacology; D003000:Clonidine / Q000494:pharmacology; D015259:Dopamine Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009043:Motor Activity / Q000187:drug effects*; D009828:Oleanolic Acid / Q000031:analogs & derivatives; D010656:Phenylephrine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D014315:Triterpenes / Q000494:pharmacology*; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D000928:Antidepressive Agents; D015259:Dopamine Agents; D011942:Receptors, Adrenergic, alpha; D014315:Triterpenes; C079349:beta-amyrin palmitate; D010656:Phenylephrine; D015016:Yohimbine; D009828:Oleanolic Acid; D003000:Clonidine; D001058:Apomorphine; D011224:Prazosin