Haloperidol abolished glutamate release evoked by photic stimulation of the visual cortex in rats.
There is evidence that systemic administration of haloperidol, a dopamine receptor blocker, attenuates visual cortex evoked potentials. However, there is scarce information on cortical neurochemical changes associated with haloperidol effects on visual function. The present experiment was designed to investigate: (1) the effect of photic stimulation on glutamate release in the visual cortex; and (2) whether systemic administration of haloperidol would affect those neurochemical changes. Microdialysis probes were implanted in the occipital cortex. Glutamate levels were measured every 30 s using capillary zone electrophoresis. Extracellular glutamate levels increased to about 282% 30 s after photic stimulation started and remain elevated for the 3 min that the photic stimulation lasted. Haloperidol (1.5 and 5 mg/kg, i.p.) completely suppressed the increased of glutamate efflux during photic stimulation. Finally, it was also found that the highest dose of haloperidol (5 mg/kg) did not change glutamate basal levels. The results are discussed with reference to possible dopaminergic actions on the visual system function.
Department of Physiology, Medical School, Los Andes University, Apartado de correos # 109, Merida 5101-A, Venezuela. remarca@hotmail.com
Elbert
E
Reyes
Sergio
S
Rossell
Daniel
D
Paredes
Pedro
P
Rada
Sonia
S
Tucci
Luis E
LE
Gonzalez
Luis
L
Hernández
D000818:Animals; D018492:Dopamine Antagonists / Q000494:pharmacology*; D004586:Electrophoresis; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D018698:Glutamic Acid / Q000187:drug effects / Q000378:metabolism*; D006220:Haloperidol / Q000494:pharmacology*; D008297:Male; D017551:Microdialysis; D010775:Photic Stimulation; D051381:Rats; D017208:Rats, Wistar; D014793:Visual Cortex / Q000187:drug effects* / Q000378:metabolism*
D018492:Dopamine Antagonists; D018698:Glutamic Acid; D006220:Haloperidol