Melatonin does not increase IOP significantly in rabbits.
New Zealand white rabbits have a circadian rhythm of intraocular pressure; pressure is higher during the dark than during the light. We explored the possibility that the dark phase increase of serum and/or ocular melatonin plays a role in regulating the rhythm of intraocular pressure. Exogenous melatonin was delivered by four routes: topical application (0.1 and 10 micrograms), intravenous injection (1 microgram), intravitreal injection (9 micrograms) and intra-arterial infusion (50 ng and 1 microgram). Melatonin delivered by these routes did not increase intraocular pressure. We also measured the concentration of melatonin in the aqueous after unilateral intra-arterial infusion to confirm that melatonin delivered by this route reached the eye. The concentration was 419 +/- 99 and 109 +/- 17 pg/ml (n = 8, p < 0.025) in the ipsilateral and contralateral eyes, respectively. The concentration of melatonin in the aqueous after intra-arterial infusion of saline was less than the sensitivity of the assay (< 16 pg/ml, n = 6). The results of these experiments indicate that melatonin does not increase IOP significantly under the experimental conditions employed in this study.
Kiuchi
Y
Y
Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, CT.
Mockovak
M E
ME
Gregory
D S
DS
D000287:Administration, Topical; D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism; D002940:Circadian Rhythm; D007261:Infusions, Intra-Arterial; D007275:Injections, Intravenous; D007429:Intraocular Pressure / Q000187:drug effects*; D008297:Male; D008550:Melatonin / Q000008:administration & dosage / Q000494:pharmacology*; D011817:Rabbits; D011863:Radioimmunoassay; D014822:Vitreous Body / Q000187:drug effects
D008550:Melatonin