Effects of 3,4-methylenedioxymethamphetamine administration on retinal physiology in the rat.

Summary

A single dose of MDMA (ecstasy) given to rats temporarily alters retinal function, as measured by electroretinograms. Three hours after administration, both MDMA-treated and high-temperature control rats showed larger and faster retinal responses, suggesting that the acute effects are partly due to MDMA-induced hyperthermia. After 24 hours, MDMA-treated animals still had increased responses in the outer retinal layers (photoreceptors and bipolar cells), even after temperature effects subsided, indicating a direct subacute effect of the drug. These changes returned to normal within seven days. The findings provide direct evidence that MDMA can enhance outer retinal activity, which may help explain visual disturbances reported by human users.

Study at a glance

Abstract

3,4-Methylenedioxymethamphetamine (MDMA; ecstasy) is known to produce euphoric states, but may also cause adverse consequences in humans, such as hyperthermia and neurocognitive deficits. Although MDMA consumption has been associated with visual problems, the effects of this recreational drug in retinal physiology have not been addressed hitherto. In this work, we evaluated the effect of a single MDMA administration in the rat electroretinogram (ERG). Wistar rats were administered MDMA (15 mg/kg) or saline and ERGs were recorded before (Baseline ERG), and 3 h, 24 h, and 7 days after treatment. A high temperature (HT) saline-treated control group was also included. Overall, significantly augmented and shorter latency ERG responses were found in MDMA and HT groups 3 h after treatment when compared to Baseline. Twenty-four hours after treatment some of the alterations found at 3 h, mainly characterized by shorter latency, tended to return to Baseline values. However, MDMA-treated animals still presented increased scotopic a-wave and b-wave amplitudes compared to Baseline ERGs, which were independent of temperature elevation though the latter might underlie the acute ERG alterations observed 3 h after MDMA administration. Seven days after MDMA administration recovery from these effects had occurred. The effects seem to stem from specific changes observed at the a-wave level, which indicates that MDMA affects subacutely (at 24 h) retinal physiology at the outer retinal (photoreceptor/bipolar) layers. In conclusion, we have found direct evidence that MDMA causes subacute enhancement of the outer retinal responses (most prominent in the a-wave), though ERG alterations resume within one week. These changes in photoreceptor/bipolar cell physiology may have implications for the understanding of the subacute visual manifestations induced by MDMA in humans.