title: Physical exercise enhances protein kinase C delta activity and insulin receptor tyrosine phosphorylation in diabetes-prone psammomys obesus.
abstract: We recently reported that physical exercise prevents the progression of type 2 diabetes mellitus in Psammomys obesus, an animal model of nutritionally induced type 2 diabetes mellitus. In the present study we characterized the effect of physical exercise on protein kinase C delta (PKC delta) activity, as a mediator of the insulin-signaling cascade in vivo. Three groups of Psammomys obesus were exposed to a 4-week protocol: high-energy diet (HE/C), high-energy diet and exercise (HE/EX), or low-energy diet (LE/C). None of the animals in the HE/EX group became diabetic, whereas all the animals in the HE/C group became diabetic. After overnight fast, intraperitoneal (IP) insulin (1U) caused a greater reduction in blood glucose levels in the HE/EX and LE/C groups compared to the HE/C group. Tyrosine phosphorylation of insulin receptor (IR), insulin receptor substrate-1 (IRS-1), and phosphatidylinositol 3 kinase (PI3 kinase) was significantly higher in the HE/EX and LE/C groups compared with the HE/C group. Finally, IR-associated PKC delta was higher in the HE/EX and LE/C groups compared to the HE/C group. Coprecipitation of PKC delta with IR was higher in the HE/EX and LE/C groups compared to the HE/C group. Thus, we suggest that 4 weeks of physical exercise results in improved insulin-signaling response in Psammomys obesus accompanied by a direct connection between PKC delta and IR. We conclude that this mechanism may be involved in the preventive effect of exercise on type 2 diabetes mellitus in Psammomys obesus.
authors.affiliation: Heller Institute of Medical Research and the Pediatric Division, Sheva Medical Center, Tel Aviv, Israel.
authors.forename: Yuval
authors.initials: Y
authors.lastname: Heled
authors.forename: Yair
authors.initials: Y
authors.lastname: Shapiro
authors.forename: Yoav
authors.initials: Y
authors.lastname: Shani
authors.forename: Dani S
authors.initials: DS
authors.lastname: Moran
authors.forename: Leah
authors.initials: L
authors.lastname: Langzam
authors.forename: Liora
authors.initials: L
authors.lastname: Braiman
authors.forename: Sanford R
authors.initials: SR
authors.lastname: Sampson
authors.forename: Joseph
authors.initials: J
authors.lastname: Meyerovitch
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D015153:Blotting, Western; D001835:Body Weight / Q000502:physiology; D003920:Diabetes Mellitus / Q000378:metabolism*; D005849:Gerbillinae / Q000378:metabolism*; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D008297:Male; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000201:enzymology / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011233:Precipitin Tests; D011493:Protein Kinase C / Q000378:metabolism*; D051745:Protein Kinase C-delta; D011972:Receptor, Insulin / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D007328:Insulin; D009124:Muscle Proteins; D014443:Tyrosine; D019869:Phosphatidylinositol 3-Kinases; D011972:Receptor, Insulin; D011493:Protein Kinase C; D051745:Protein Kinase C-delta