Enhancement of glucose uptake in 3T3-L1 adipocytes by Toona sinensis leaf extract.
The effects of substances extracted from Toona sinensis leaves, using 50% alcohol/water, on cellular [3H]-2-deoxyglucose uptake in differentiated cultured 3T3-L1 adipocytes were investigated. Following treatment of cells with 0.001, 0.01, or 0.1 mg/mL extracts for 60 minutes, [3H]-2-deoxyglucose uptake increased from a basal value of 0.23 nmol/min/mg protein to 0.30, 0.33, and 0.38 nmol/min/mg protein, respectively. In insulin-stimulated cells, cellular [3H]-2-deoxyglucose uptake was enhanced by Toona sinensis leaf extract from a basal value of 0.35 nmol/min/mg protein to 0.41, 0.46, and 0.52 nmol/min/mg protein, respectively. Cellular glucose uptake was also enhanced by Toona sinensis leaf extract after incubation of cells with 20 mM glucose for 48 hours. Cellular glucose uptake with a combination of Toona sinensis leaf extract and insulin was significantly inhibited by pretreatment of cells with the protein synthesis inhibitor cycloheximide and the protein kinase C inhibitor calphostin C in normal-, medium- and high-glucose media. However, the glucose uptake-enhancing effect of Toona sinensis leaf extract was not diminished by cycloheximide and calphostin C in the absence of insulin. These results indicate that enhancement of cellular glucose uptake by Toona sinensis leaf extract in basal and insulin-stimulated 3T3-L1 adipocytes may be mediated by distinct mechanisms.
Yang
Yu-Chiao
YC
Department of Pharmacology, Kaohsiung Medical University, Kaohsiung, Taiwan.
Hsu
Hseng-Kuang
HK
Hwang
Jia-Huae
JH
Hong
Show-Jen
SJ
D016475:3T3 Cells / Q000187:drug effects / Q000378:metabolism; D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D003847:Deoxyglucose / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology; D051379:Mice; D018515:Plant Leaves / Q000737:chemistry
D004365:Drugs, Chinese Herbal; D007328:Insulin; D003847:Deoxyglucose; D005947:Glucose