Decline in Glucokinase Activity in the Arcuate Nucleus of Streptozotocin-Induced Diabetic Rats

Glucokinase (GK) is known to be the critical glucose sensor of pancreatic B-cells. However, the localization and functional role of GK in the brain remains to be elucidated. In this study, we measured both the activity and mRNA level of GK in the hypothalamic nuclei and the cortex of rats injected i...

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Bibliographic Details
Published in:Biological & pharmaceutical bulletin 2006, Vol.29(2), pp.216-219
Main Authors: Nishio, Takashi, Toyoda, Yukiyasu, Hiramatsu, Masayuki, Chiba, Taku, Miwa, Ichitomo
Format: Article
Language:English
Subjects:
Animals
arcuate nucleus
Arcuate Nucleus of Hypothalamus - enzymology
Blood Glucose - analysis
Blotting, Western
Cerebral Cortex - enzymology
Diabetes Mellitus, Experimental - enzymology
Glucokinase - biosynthesis
Glucokinase - metabolism
glucokinase activity
glucokinase mRNA
hyperglycemia
hypothalamus
Insulin - blood
Male
Rats
Rats, Wistar
Reverse Transcriptase Polymerase Chain Reaction
RNA, Messenger - biosynthesis
Streptozocin
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Summary:Glucokinase (GK) is known to be the critical glucose sensor of pancreatic B-cells. However, the localization and functional role of GK in the brain remains to be elucidated. In this study, we measured both the activity and mRNA level of GK in the hypothalamic nuclei and the cortex of rats injected intraperitoneally with streptozotocin or vehicle. GK activity was measured by a fluorometric assay; and the GK mRNA level, by use of the real-time reverse transcription polymerase chain reaction. GK activity in vehicle-treated rats was high in the arcuate nucleus, moderate or low in the ventromedial nucleus, lateral hypothalamic area, and paraventricular nucleus, and very low in the cortex. The order of GK mRNA level was almost the same as that of GK activity. GK activity and GK mRNA level only in the arcuate nucleus of streptozotocin-treated rats at 7 d, but not at 2 d, after treatment were lower than those of vehicle-treated rats. The results suggest that prolonged hyperglycemia induced by diabetes decreased the activity of GK in the arcuate nucleus.
ISSN:0918-6158
1347-5215
DOI:10.1248/bpb.29.216