title: Effect of various pretreatments on the hypothermic activity of repin in naive rats.
abstract: Repin is a sesquiterpene lactone found in Centaurea solstitialis, a plant responsible for Parkinson-like disease in horses. Repin, on intraperitoneal (i.p.) injection, produces a dose-dependent and highly significant hypothermia in naive rats. The hypothermia is long-lasting with a peak 3 h after the injection and a return to normal temperature after more than 8 h. The effects of atropine sulfate, atropine methylbromide, propranolol, metergoline, ketanserin, diphenhydramine and apomorphine pretreatment on repin-induced hypothermia were investigated. None of the pretreatments directly antagonized repin's hypothermic effect. However, partial but significant reversals of hypothermia by atropine sulfate, metergoline, ketanserin, diphenhydramine and apomorphine were observed 2-4 h after the repin injection. These late-onset effects are probably due to secondary physiological mechanisms. On the other hand, propranolol, at 20 mg/kg i.p., clearly accentuated both the early-onset (30-90 min) and late-onset (2-4 h) hypothermic effects of repin.
authors.affiliation: Department of Physiology-Pharmacology, School of Pharmacy, University of the Pacific, Stockton, CA 95211, USA.
authors.forename: S
authors.initials: S
authors.lastname: Akbar
authors.forename: D S
authors.initials: DS
authors.lastname: Fries
authors.forename: M H
authors.initials: MH
authors.lastname: Malone
mesh_terms: D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001831:Body Temperature / Q000187:drug effects; D003603:Cytotoxins / Q000494:pharmacology*; D007035:Hypothermia / Q000378:metabolism*; D008297:Male; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012717:Sesquiterpenes / Q000494:pharmacology*
chemical_list: D003603:Cytotoxins; D012717:Sesquiterpenes; C064339:repin; D001285:Atropine; D011433:Propranolol