OCULAR ACTIVITY OF TOPICALLY ADMINISTERED ANANDAMIDE IN THE RABBIT

Marijuana and its psychoactive constituents, cannabinoids, reduce intr aocular pressure (IOP) in humans and animals. Because anandamide, a re cently discovered endoge nous ligand of cannabinoid receptors, reporte dly shows cannabimimetic pharmacological activity, we examined its eff ect on the eye. Varying amounts of anandamide, in 50 mu L of light min eral oil, were topically applied to a rabbit eye and changes in IOP an d ocular symptoms were monitored. Anandamide (50 mu g to 1 mg) induced a significant decrease in IOP within 1 hour after administration; max imum reduction occurred at 2 hours; and there was a return to baseline by 7 hours following administration. A noticeable hyperemia of conjun ctival blood vessels was also noted 2 hours after administration. Neit her mineral oil alone or with palmitylethanolamide (an analogue of ana ndamide) caused a significant decrease in IOP or conjunctival hyperemi a. This study indicates that anandamide does produce cannabimimetic ef fects in rabbit eyes. (C) 1997 Japanese Ophthalmological Society.