title: Topically applied caffeine induces miosis in the ketamine/xylazine anesthetized rat.
abstract: The aim of the present study was to examine if topically applied caffeine influences pupil size in ketamine/xylazine anesthetized animals. Two experiments were carried out. In the first experiment, caffeine was topically applied to one of the eyes of 10 ketamine/xylazine anesthetized animals, while vehicle only was topically applied to the contralateral eye. In the second experiment, caffeine was topically applied to both eyes in one group of 10 ketamine/xylazine anesthetized rats, while in another group both eyes vehicle only was topically applied to both eyes. In both experiments pupil diameter was measured at 0, 10, 20, 40 and 60 min after topical application. In three of the animals, the pupil was dilated with tropicamide 5 mg/ml at 60 min after the topical application of caffeine and the pupil diameter was measured. The first experiment showed a relative miosis in caffeine treated eyes as compared to the vehicle treated eye, that changed over time. The second experiment in line with the first experiment, also showed that topically applied caffeine causes a relative miosis as compared to vehicle only that changes over time. Eyes treated with caffeine reacted with quick dilatation after tropicamide application. Topical caffeine antagonizes ketamine/xylazine anesthesia induced mydriasis in a time dependent manner.
authors.affiliation: Gullstrand Lab. Ophthalmology, Dept. of Neuroscience, Uppsala University, University Hospital, SE-751 85 Uppsala, Sweden. Electronic address: martin.kronschlager@neuro.uu.se.
authors.forename: Martin
authors.initials: M
authors.lastname: Kronschläger
authors.affiliation: Gullstrand Lab. Ophthalmology, Dept. of Neuroscience, Uppsala University, University Hospital, SE-751 85 Uppsala, Sweden.
authors.forename: Zhaohua
authors.initials: Z
authors.lastname: Yu
authors.affiliation: Gullstrand Lab. Ophthalmology, Dept. of Neuroscience, Uppsala University, University Hospital, SE-751 85 Uppsala, Sweden.
authors.forename: Nooshin
authors.initials: N
authors.lastname: Talebizadeh
authors.affiliation: Herzog Carl-Theodor Eye Clinic, Munich, Germany.
authors.forename: Linda Maren
authors.initials: LM
authors.lastname: Meyer
authors.affiliation: Gullstrand Lab. Ophthalmology, Dept. of Neuroscience, Uppsala University, University Hospital, SE-751 85 Uppsala, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Söderberg
mesh_terms: D000287:Administration, Topical; D058647:Adrenergic alpha-2 Receptor Agonists / Q000008:administration & dosage; D019162:Anesthetics, Combined / Q000008:administration & dosage*; D000818:Animals; D002110:Caffeine / Q000008:administration & dosage*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage*; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage; D007274:Injections, Intraperitoneal; D007649:Ketamine / Q000008:administration & dosage*; D015877:Miosis / Q000139:chemically induced*; D011680:Pupil / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014991:Xylazine / Q000008:administration & dosage*
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D019162:Anesthetics, Combined; D000697:Central Nervous System Stimulants; D018691:Excitatory Amino Acid Antagonists; D014991:Xylazine; D002110:Caffeine; D007649:Ketamine
keywords: caffeine; ketamine; miosis; pupil diameter; xylazine