title: Biphasic effects of morphine on locomotor activity in hamsters.
abstract: Two experiments investigated the dose and time related effects of morphine sulfate on the running wheel activity of golden Syrian hamsters. Compared with saline controls, a low dose (5 mg/kg) increased locomotor activity, whereas high doses (10, 20 and 40 mg/kg) produced an initial dose-related depression in activity, a gradual dose-related recovery and finally a period of hyperactivity. The results are discussed in terms of similar biphasic effects of morphine observed in rats.
mesh_terms: D000818:Animals; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D005260:Female; D008297:Male; D008647:Mesocricetus; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D013997:Time Factors
chemical_list: D009020:Morphine