Cerebellar thiol status and motor deficit after lactational exposure to methylmercury.
This study examined the exclusive contribution of methylmercury (MeHg) exposure through maternal milk on biochemical parameters related to the thiol status (glutathione (GSH) levels, glutathione peroxidase (GPx) and glutathione reductase (GR) activities) in the cerebellums of suckling mice. The same biochemical parameters were also evaluated in the cerebellums of mothers, which were submitted to a direct oral exposure to MeHg (10 mg/L in drinking water). With regard to the relationship between cerebellar function and motor activity, the presence of signs of motor impairment was also evaluated in the offspring exposed to MeHg during lactation. After the treatment (at weaning period), the pups lactationally exposed to MeHg showed increased levels of mercury in the cerebellum compared to pups in the control group and a significant impairment in the motor performance in the rotarod apparatus. In addition, these pups showed decreased levels of GSH in the cerebellum compared to pups in the control group. In dams, MeHg significantly increased the levels of cerebellar GSH and the activities of cerebellar GR. However, this was not observed in pups. This study indicates that (1) the exposure of lactating mice to MeHg causes significant impairments in motor performance in the offspring which may be related to a decrease in the cerebellar thiol status and (2) the increased GSH levels and GR activity, observed only in the cerebellums of MeHg-exposed dams, could represent compensatory pathophysiologic responses to the oxidative effects of MeHg toward endogenous GSH.
Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, 88040-900, Florianópolis, SC, Brazil.
Jeferson L
JL
Franco
Adriana
A
Teixeira
Flávia C
FC
Meotti
Camila M
CM
Ribas
James
J
Stringari
Solange C
SC
Garcia Pomblum
Angela M
AM
Moro
Denise
D
Bohrer
André V
AV
Bairros
Alcir L
AL
Dafre
Adair R S
AR
Santos
Marcelo
M
Farina
D000818:Animals; D000833:Animals, Suckling; D002531:Cerebellum / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D005260:Female; D005978:Glutathione / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000378:metabolism*; D005980:Glutathione Reductase / Q000378:metabolism*; D007774:Lactation; D008297:Male; D020262:Mercury Poisoning, Nervous System / Q000378:metabolism / Q000503:physiopathology; D008767:Methylmercury Compounds / Q000633:toxicity*; D051379:Mice; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D011247:Pregnancy; D011897:Random Allocation
D008767:Methylmercury Compounds; D005979:Glutathione Peroxidase; D005980:Glutathione Reductase; D005978:Glutathione; C004925:methylmercuric chloride