Caffeine, Nicotine and MDMA Effects on Retina suggestive of Potential Functional Consequences

Abstract

The implications of the use of psychoactive substances, that are usually abused on the retina are yet to be adequately explored. The retina is neural in nature. Most investigations on psychoactive agents have only studied their effects on the brain and behaviour. The mechanisms employed by these agents in producing their effects on the brain suggest that the retina, being neural, might also be significantly affected by the use of the substances. This research investigated the effects of the prolonged use of caffeine, nicotine and 4-methylenedioxymethamphetamine [MDMA] on the retina. Juvenile male experimental Wistar were grouped and administered the lower and higher dose of each agent while a reference group remained as the Group A. Groups B and C received the lower [30mg/kg body weight]and the higher [50mg/kg body weight]doses of caffeine respectively; Groups D and E received the lower [10mg/kg body weight] and higher [20mg/kg body weight] doses of nicotine respectively while Groups F and G received the lower [20 mg/kg body weight] and the higher [40 mg/kg body weight] doses of MDMA respectively. The substances had effects on the thickness of the retina with higher doses in each instance causing reductions in retina thickness; the patterns of GFAP expression were also aberrant with the MDMA treated groups being most aberrant. There was no sign of extensive loss of any type of retinal cells. Rhodopsin expression generally demonstrated active rods and provided insight into relatively heathy cones. There is evidence that these agents altered retina thickness and GFAP expression but without extensive disruptions to serve as pathological hallmarks of retina degeneration. The consequences of these might be further investigated.