Effect of Reversing Dark-Light Cycles on Normal Diurnal Variation and Related Metabolic Disturbance in Rats

Kuang-Chung Shih ； Liahng-Yirn Liu ； Ching-Fai Kwok ； Chii-Min Hwu ； Chi-Chang Juan ； Yung-Pei Hsu ； Low-Tone Ho

《The Chinese Journal of Physiology》 50卷2期 (2007/04) Pp. 69-76

並列摘要

Diurnal variation of glucose tolerance and insulin action was studied in male Sprague-Dawley rats with a normal or reversed light-dark cycle. A series of experiments conducted was at 12 AM and 12 PM in the two groups. All measurements were separated by a recovery period of at least 3 days and preceded by a 16-hour fast. Glucose tolerance and insulin action were measured by both an oral glucose tolerance test and intraperitoneal insulin tolerance test. Normal light-dark cycle rats had significantly (P＜0.05) greater insulin sensitivity at 12 PM than at 12 AM, whereas reversed light-dark cycle rats had the opposite results (P ＜ 0.05). Rats in the normal light-dark cycle group had a significantly higher growth hormone concentration at 12 AM than at 12 PM, whereas rats in the reversed group had the opposite results. Measurement of insulin-stimulated glucose uptake of isolated adipocytes preincubated with or without 100 ng/ml growth hormone at 37°C for 5 hours revealed that approximately 30% of insulinstimulated glucose uptake was suppressed when adipocytes were treated with growth hormone. These results indicate that male rats exhibit significant diurnal variation of glucose tolerance and insulin sensitivity, and suggest that the concomitant diurnal variation of growth hormone may have a superimposed and amplifying effects on this variation.

並列關鍵字

Insulin sensitivity ； diurnal variation ； and growth hormone

參考文獻

Birnbaum, R.S.,Goodman, H.M.(1979).Comparison on several insulin-like effects of growth hormone.Horm. Metab. Res..11,136-142.

Bolli, G.B.,De Feo, P.,De Cosmo, S.,Perriello, G.,Ventura, M.M.,Calcinaro, F.,Lolli, C.,Campbell, P.,Brunetti., P.,Gerich, J.E.(1984).Demonstration of a dawn phenomenon in normal human volunteers.Diabetes.33,1150-1153.

Carroll, K.F.,Nestel, P.J.(1973).Diurnal variation in glucose tolerance and insulin secretion in man.Diabetes.22,333-348.

Castro, F.C.,Delgado, E.F.,Bezerra, R.M.,Lanna, D.P.(2004).Effects of growth hormone on insulin signal transduction in rat adipose tissue maintained in vitro.Endocr. Res..30,225-238.

Chou, Y.C.,Perng, J.C.,Juan, C.C.,Jang, S.Y.,Kwok, C.F.,Chen, W.L.,Fong, J.C.,Ho, L.T.(1994).Endothelin-1 inhibits insulin-stimulated glucose uptake in isolated rat adipocytes.Biochem. Biophys. Res. Commun..202,688-693.