Lack of the stimulatory effect of guanine nucleotide on diacylglycerol generation in permeabilized adipocytes from diabetic rats.
Insulin caused an 8- or a 3-fold increase in lipogenesis in control rats (C) or diabetic rats (DM), respectively. Following insulin treatment for DM, insulin resistance was clearly reversed. Phospholipase C (PLC) caused a 4-fold increase in lipogenesis in C, but not in DM. Insulin treatment partially restored PLC-induced lipogenesis. Insulin or PLC increased protein kinase C (PKC) activity in the membrane fraction in C, but not in DM. Insulin treatment partially restored insulin- or PLC-stimulated PKC activity. 5'-Guanylylimidodiphosphate (Gpp(NH)p) exerted a stimulatory effect on diacylglycerol (DAG) generation in permeabilized adipocytes from C, but not in DM. Insulin treatment partially restored the stimulatory effect of Gpp(NH)p. These findings suggest that a particular G protein(s) is involved in the regulation of DAG generation in adipocytes, and that diabetes leads to a functional or quantitative abnormality in G protein and G protein-PLC. Insulin therapy partially restored G protein-PLC dependent glucose uptake.
Izawa
T
T
Department of Health and Sports Sciences, University of Electro-Communications, Tokyo, Japan.
Saitou
S
S
Mochizuki
T
T
Komabayashi
T
T
D017667:Adipocytes / Q000187:drug effects* / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D004075:Diglycerides / Q000096:biosynthesis*; D019204:GTP-Binding Proteins / Q000378:metabolism; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology*; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D010738:Type C Phospholipases / Q000378:metabolism
D001786:Blood Glucose; D004075:Diglycerides; D007328:Insulin; D006165:Guanylyl Imidodiphosphate; D011493:Protein Kinase C; D010738:Type C Phospholipases; D019204:GTP-Binding Proteins