title: Biphasic effects of dexamethasone on glycogen metabolism in primary cultured rat hepatocytes.
abstract: Glucocorticoids (GC), the basic function of which is modulating carbohydrates metabolism, play a critical role in stress response by enhancing the organism's resistance. It is widely believed that they could promote glycogen synthesis. However, it is doubtful whether GC can still stimulate glycogen deposition in stress response, as it is known that glucose is imperatively needed at that time. Here, we used primary cultured rat hepatocytes to investigate the effects of GC on glycogen metabolism in vitro to exclude other influences in stress. The results showed that dexamethasone (Dex) played biphasic effects on hepatocytes glycogen metabolism depending on its dosage and the duration of stimulation. Dex could decrease glycogen content of hepatocytes in the higher concentration within a relatively shorter period of time, which could not be blocked by cycloheximide. Therefore, dual roles in hepatic glycogen metabolism played by GC were demonstrated, and a non-genomic mechanism might be involved in the glycogenolytic action of GC. We postulated that the biphasic effects of GC on hepatic glycogen metabolism might be of important significance in stress response.
authors.affiliation: Laboratory of Stress Medicine, Department of Nautical Medicine, Second Military Medical University, 800 Xiangyin Road, Shanghai 200433, PR China.
authors.forename: X-F
authors.initials: XF
authors.lastname: Zheng
authors.forename: L
authors.initials: L
authors.lastname: Liu
authors.forename: J
authors.initials: J
authors.lastname: Zhou
authors.forename: M-Y
authors.initials: MY
authors.lastname: Miao
authors.forename: J-R
authors.initials: JR
authors.lastname: Zhou
authors.forename: D
authors.initials: D
authors.lastname: Zhu
authors.forename: Z-F
authors.initials: ZF
authors.lastname: Xia
authors.forename: C-L
authors.initials: CL
authors.lastname: Jiang
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology*; D005938:Glucocorticoids / Q000494:pharmacology*; D022781:Hepatocytes / Q000187:drug effects* / Q000378:metabolism; D008112:Liver Glycogen / Q000378:metabolism*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D005938:Glucocorticoids; D008112:Liver Glycogen; D003907:Dexamethasone; D003513:Cycloheximide