Decreased expression of glutamate dehydrogenase by prolonged intake of monosodium glutamate in rat brain.
One-week-old albino female rats were kept for 1 year in equal groups with or without monosodium glutamate in their drinking water. The concentrations of the glutamate in the brain crude extracts of the monosodium glutamate treated group were twofold higher than those of the control group. There were no significant changes in body weight, brain weight, and protein content, and total RNA and DNA content also did not vary in the two groups of rats. The activities of glutamate dehydrogenase (GDH) were decreased with a 45% reduction in V(max) values in the monosodium glutamate treated group compared to those in the control group, whereas no significant changes were observed in K(m) values between the two groups. The concentration of the enzyme on the Western blot analysis was significantly decreased in the monosodium glutamate treated group, whereas the level of GDH mRNA remained unchanged, suggesting a post-transcriptional control of the expression of GDH or an increased rate of degradation of enzyme protein. These results indicate that the prolonged monosodium glutamate feeding reduces the activity of GDH and subsequently decreases the catabolism of glutamate in rat brain.
Yoon
Hye-Young
HY
Department Biochemistry, University of Ulsan College of Medicine, 388-1 Pungnap-dong, Songpa-ku, Seoul 138-736, Korea.
Hwang
Sang-Hyun
SH
Kim
Ue
U
Hwang
Onyou
O
Kim
Donghou
D
Choi
Young
Y
Cho
Sung-Woo
SW
D000818:Animals; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000187:drug effects* / Q000201:enzymology* / Q000473:pathology; D004247:DNA / Q000187:drug effects / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects* / Q000502:physiology; D005260:Female; D005526:Food, Formulated; D005969:Glutamate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism / Q000494:pharmacology*; D019636:Neurodegenerative Diseases / Q000139:chemically induced / Q000201:enzymology / Q000473:pathology; D009474:Neurons / Q000187:drug effects* / Q000201:enzymology* / Q000473:pathology; D009929:Organ Size / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D012333:RNA, Messenger; D018698:Glutamic Acid; D004247:DNA; D005969:Glutamate Dehydrogenase