THE EFFECTS OF PARTIAL BILATERAL LESIONING OF SUBSTANTIA NIGRA IN A GENETIC ABSENCE EPILEPSY RAT MODEL

Abstract

Objective: "Genetic Absence Epilepsy Rats fromStrasbourg" (GAERS), an inbred Wistar strain,serve as an experimental venue. These ratsgenerate spontaneous spike-and-wavedischarges (SWD) and have increased yaminobutyricacid (GABA) levels in theventrolateral thalamus (VLT). Recently,substantia nigra pars reticulata (SNpr) wasreported to act as an endogeneous inhibitorymechanism in the generation, onset andmaintenance of various types of seizures. Thepresence of tonic control exerted by SNpr inabsence seizures should also be tested inGAERS.Methods: In this current study, GABA and Lglutamicacid release in VLT of GAERS withpartial bilateral electrolytic lesions of SNpr wasevaluated by using microdialysis technique withfluorescent detection.Results: GABA levels in VLT were 0.12±0.04 pMand 0.24±0.08 pM in sham-lesioned and SNprlesionedGAERS, respectively. L-glutamic acidlevel was found to be 0.415±0.150 pM in shamlesionedgroup and 0.324±0.094 pM in SNprlesionedGAERS. Statistical analysis revealed nosignificant difference between sham-lesionedand SNpr-lesioned rats. The number and theduration of SWD were also similar in two groups.Conclusion: These findings show that SNprdoes not exert a tonic control in GAERS and weassume that intact SNpr acts as a site that mayexert an inhibition on target structures whenactivated in GAERS.Key Words: GAERS (Genetic AbsenceEpilepsy Rats from Strasbourg), GABA (yaminobutyricacid), Substantia nigra,Ventrolateral thalamus, Absence epilepsy,Microdialysis, Nigral control of epilepsy.