Chronic exposure of nicotine modulates the expressions of the cerebellar glial glutamate transporters in rats.
Rats were given nicotine (25 ppm) in their drinking water at the start of their mating period in order to study the expressions of glutamate transporter subtypes in cerebellar astrocytes following the chronic exposure of nicotine after mating. After the offspring were delivered, each group was divided into two subgroups. One group, the control group, was given distilled water only and the other group, the experimental group, was given distilled water containing nicotine. The cerebellar astrocytes were prepared from 7 day-old pups at each group. Ten days after the cells were cultured, the expression of the glutamate transporter subtypes (GLAST and GLT-1) was determined using immunochemistry and immunoblotting. During the continuous treatments, the developmental expression patterns of the GLAST and GLT-1 in the cerebellum were also determined from 2, 4 and 8 week-old rats. The expression levels of GLAST in cultured astrocytes of both the pre- or post-natally exposed groups were higher than those of the control group. However, these expression levels of the continuously exposed group were lower than those of the control group. Compared to those of the control group, the GLT-1 expression levels of all the nicotine-treated groups were higher, particularly in the continuously treated group. According to the results from the immochemistry procedure, the cerebellar GLAST and GLT-1 expression levels of all nicotine-treated groups were lower than those of the control group at each age. However, the immunoblotting procedure showed that the cerebellar GLT-1 expression levels of all the nicotine-treated groups were higher than those of the control group, except for the rats that were continuously exposed for 8 weeks using immunoblotting. These results suggest that the expression of the glial GLAST and GLT-1 are altered differently depending on the initial exposure time and the particular period of nicotine exposure. In addition, nicotine exposure during gestation has persistent effects on glial cells.
Lim
Dong Koo
DK
College of Pharmacy and Institute for Drug Development, Chonnam National University, Kwangju 500-757, Korea. dklim@chonnam.ac.kr
Kim
Han Soo
HS
D027322:Amino Acid Transport System X-AG / Q000235:genetics*; D000818:Animals; D002478:Cells, Cultured; D002531:Cerebellum / Q000187:drug effects / Q000473:pathology*; D004781:Environmental Exposure / Q000009:adverse effects*; D027342:Excitatory Amino Acid Transporter 2 / Q000187:drug effects / Q000235:genetics*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006168:Guinea Pigs; D008297:Male; D009457:Neuroglia / Q000737:chemistry*; D009538:Nicotine / Q000009:adverse effects* / Q000493:pharmacokinetics; D051381:Rats; D017207:Rats, Sprague-Dawley
D027322:Amino Acid Transport System X-AG; D027342:Excitatory Amino Acid Transporter 2; D009538:Nicotine