Chronic cocaine effects in retinal metabolism and electrophysiology: treatment with topiramate.
OBJECTIVE
Cocaine abuse is a major public health problem with multiple-related complications. Indeed, cocaine can affect almost every organ of the human body, but little is known about its effects on the visual system. The main purpose of this work was to study if topiramate was able to reverse changes in retinal metabolism and retinal function induced by chronic cocaine exposure in adult rats.


METHODS
Sixteen Wistar rats were treated with a daily oral dose of cocaine during 36 days. Sixteen rats receiving NaCl 0.9% served as controls. Eight control and eight cocaine animals were administered topiramate from day 18 to day 36 of the experiment. Malondialdehyde (MDA), glutathione (GSH) and glutamate content, as well as glutathione peroxidase (GPx) activity in retina tissue homogenates were determined. Retinal function was assessed by electroretinogram (ERG).


RESULTS
Glutamate concentration was increased in the retinas of cocaine-treated rats. No changes in oxidative stress parameters were observed in the retinas of cocaine-treated rats when compared with the control ones. Cocaine induced a decrease in the a-wave and b-wave ERG amplitude. The administration of topiramate reversed cocaine-induced increase in glutamate concentration and had little effect on a-wave and b-wave ERG amplitude. Topiramate, a drug used during the last decade for the treatment of epileptic seizures, is able to reverse the cocaine-induced alterations observed in retinal glutamate concentration.


CONCLUSIONS
We can conclude that retinal glutamate metabolism and function may be affected by exposure to cocaine. We confirm that topiramate, a treatment recently proposed for cocaine dependence, is also able to recover partially cocaine-induced changes in the retina.
Departamento Ciencias Biomédicas, Instituto de Ciencias Biomédicas, Universidad CEU Cardenal Herrera , Moncada , Spain .
Maria V
MV
Sánchez-Villarejo
Rosa
R
López-Pedrajas
Violeta
V
Sánchez-Vallejo
José M
JM
Genovés
María
M
Muriach
Jorge M
JM
Barcia
Francisco J
FJ
Romero
María
M
Miranda
D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology; D002908:Chronic Disease; D003042:Cocaine / Q000494:pharmacology*; D019970:Cocaine-Related Disorders / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D004734:Energy Metabolism / Q000187:drug effects; D005632:Fructose / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D010084:Oxidation-Reduction / Q000187:drug effects; D017208:Rats, Wistar; D012160:Retina / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D000077236:Topiramate; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014792:Visual Acuity / Q000187:drug effects
D000927:Anticonvulsants; D014662:Vasoconstrictor Agents; D000077236:Topiramate; D005632:Fructose; D003042:Cocaine