Buspirone, but not sumatriptan, induces miosis in humans: Relevance for a serotoninergic pupil control*

✍ Scribed by Fanciullacci, Marcello; Sicuteri, Riccardo; Alessandri, Massimo; Geppetti, Pierangelo

• Publisher: Nature Publishing Group
• Year: 1995
• Tongue: English
• Weight: 650 KB
• Volume: 57
• Category: Article
• ISSN: 0009-9236
• DOI: 10.1016/0009-9236(95)90161-2

✦ Synopsis

Buspirone, but not sumatriptan, induces miosis in humans: Relevance for a serotoninergic pupil control Ba&mtd ad objective: Drugs that act on the serotoninergic system have been shown to influence the pupil size. However, the 5hydroxytryptamine (5HT) receptor type or subtype that af%xts pupil diameter has not been defined in humans. With a placebo-controlled, double-blind randomized design, we investigated in healthy volunteers the effect on pupil size of buspirone and sumatriptan, which mainly act on 5-HT1*-and the 5-HT,-like receptors, respectively. Met&odr: The pupil area was measured by means of a videopupillometer before and after a single oral administration of placebo or of three different doses of active drugs. Heart rate and arterial blood pressure were recorded after pupil area measurement. Rtzults: Buspirone (5, 10, and 20 mg) caused a dose-dependent miosis. Sumatriptan (50, 100, and 200 mg) did not atfect the pupil size. Twenty milligrams of buspirone reduced the mydriasis induced by pretreatment with homatropine eyedrops. A 20 mg dose of buspirone reduced blood pressure without change in heart rate, whereas buspirone, at doses lower than 20 mg, and sumatriptan did not affect heart rate and blood pressure. Conclwimos: This study suggests that buspirone, but not sumatriptan, the selective agonist of 5-HTr-like receptors, causes miosis in humans by activation of 5-HT,, receptors, possibly located in the central nervous system where they inhibit iris sympathetic pathways. Measurement of pupil size seems to provide a valuable and sensitive index of 5-HT,, receptor function in humans.