Methylmercury increases glutamate extracellular levels in frontal cortex of awake rats.
A current hypothesis about methylmercury (MeHg) neurotoxicity proposes that neuronal damage is due to excitotoxicity following glutamate uptake alterations in the astrocyte. By sampling from a microdialysis probe implanted in the frontal cortex of adult Wistar rats, we measured the effects of acute exposure to either 10 or 100 microM MeHg through the microdialysis probe, on glutamate extracellular levels in 15 awake animals. After baseline measurements, the perfusion of MeHg during 90 min induced immediate and significant elevations in extracellular glutamate at 10 microM (9.8-fold, P<.001) and at 100 microM (2.4-fold, P=.001). This in vivo demonstration of increments of extracellular glutamate supports the hypothesis that dysfunction of glutamate neurotransmission plays a key role in MeHg-induced neural damage.
Juárez
B I
BI
Departamento de Bioquímica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, Av. Venustiano Carranza 2405, S.L.P., C.P. 78210, Mexico.
Martínez
M L
ML
Montante
M
M
Dufour
L
L
García
E
E
Jiménez-Capdeville
M E
ME
D000818:Animals; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005110:Extracellular Space / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D005625:Frontal Lobe / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D018698:Glutamic Acid / Q000378:metabolism*; D020262:Mercury Poisoning, Nervous System / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D008767:Methylmercury Compounds / Q000633:toxicity*; D017551:Microdialysis; D009410:Nerve Degeneration / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D015854:Up-Regulation / Q000187:drug effects* / Q000502:physiology
D008767:Methylmercury Compounds; D018698:Glutamic Acid