title: Extract of Hypericum perforatum blocks caffeine-induced locomotor activity in mice: a possible role of nitric oxide.
abstract: The present study investigated the effects of HPE on caffeine-induced locomotor activity in mice. Caffeine (4-16 mg/kg) or saline were given to adult male Swiss-Webster mice, and the locomotor activity was immediately measured for 30 min. HPE (6-48 mg/kg) and saline were injected to another group of mice and the locomotor activity was measured 20 min later. HPE (6-24 mg/kg) was also administered to another group of mice 20 min before caffeine (16 mg/kg) injections and the locomotor activity was recorded for 30 min immediately after caffeine administrations. Finally l-arginine (1 g/kg) was administered i.p. 20 min before HPE (6 mg/kg) and the locomotor activity was measured as mentioned above. Each group of mice was used only once. Caffeine produced some significant increases in locomotor activity of the mice. HPE (6-24 mg/kg) significantly blocked the caffeine-induced locomotor hyperactivity. Pretreatment of l-arginine (1 g/kg) reversed the inhibitory effect of HPE (6 mg/kg) on caffeine-induced locomotor activity without producing any significant effect on locomotor activity of the mice when it was administered alone. The results suggest that HPE blocks caffeine-induced locomotor hyperactivity in mice. Furthermore, the inhibitory effect of HPE on caffeine-induced locomotor activity may be related to its NOS inhibitory property.
authors.affiliation: Department of Medical Pharmacology, Psychopharmacology Research Unit, Faculty of Medicine, Gulhane Military Medical Academy, Ankara, Turkey. tuzbay@gata.edu.tr
authors.forename: I Tayfun
authors.initials: IT
authors.lastname: Uzbay
authors.forename: Ilke
authors.initials: I
authors.lastname: Coskun
authors.forename: Hakan
authors.initials: H
authors.lastname: Kayir
authors.forename: Nilgun
authors.initials: N
authors.lastname: Ozturk
authors.forename: Yusuf
authors.initials: Y
authors.lastname: Ozturk
mesh_terms: D000818:Animals; D001120:Arginine / Q000494:pharmacology; D002110:Caffeine / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D020902:Hypericum / Q000737:chemistry*; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects*; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010936:Plant Extracts / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D010936:Plant Extracts; D009569:Nitric Oxide; D002110:Caffeine; D001120:Arginine; D019001:Nitric Oxide Synthase