Euglycemia in Diabetic Rats Leads to Reduced Liver Weight via Increased Autophagy and Apoptosis through Increased AMPK and Caspase-3 and Decreased mTOR Activities

J Diabetes Res. 2015:2015:497431. doi: 10.1155/2015/497431. Epub 2015 Apr 28.

Abstract

Euglycemia is the ultimate goal in diabetes care to prevent complications. However, the benefits of euglycemia in type 2 diabetes are controversial because near-euglycemic subjects show higher mortality than moderately hyperglycemic subjects. We previously reported that euglycemic-diabetic rats on calorie-control lose a critical liver weight (LW) compared with hyperglycemic rats. Here, we elucidated the molecular mechanisms underlying the loss of LW in euglycemic-diabetic rats and identified a potential risk in achieving euglycemia by calorie-control. Sprague-Dawley diabetic rats generated by subtotal-pancreatectomy were fed a calorie-controlled diet for 7 weeks to achieve euglycemia using 19 kcal% (19R) or 6 kcal% (6R) protein-containing chow or fed ad libitum (19AL). The diet in both R groups was isocaloric/kg body weight to the sham-operated group (19S). Compared with 19S and hyperglycemic 19AL, both euglycemic R groups showed lower LWs, increased autophagy, and increased AMPK and caspase-3 and decreased mTOR activities. Though degree of insulin deficiency was similar among the diabetic rats, Akt activity was lower, and PTEN activity was higher in both R groups than in 19AL whose signaling patterns were similar to 19S. In conclusion, euglycemia achieved by calorie-control is deleterious in insulin deficiency due to increased autophagy and apoptosis in the liver via AMPK and caspase-3 activation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenylate Kinase / metabolism*
  • Animals
  • Apoptosis / physiology*
  • Autophagy / physiology*
  • Blood Glucose / metabolism*
  • Caspase 3 / metabolism*
  • Diabetes Mellitus, Experimental / metabolism*
  • Diabetes Mellitus, Experimental / pathology
  • Liver / metabolism*
  • Liver / pathology
  • Male
  • Organ Size
  • Phosphorylation
  • Rats
  • Rats, Sprague-Dawley
  • Signal Transduction
  • TOR Serine-Threonine Kinases / metabolism*

Substances

  • Blood Glucose
  • mTOR protein, rat
  • TOR Serine-Threonine Kinases
  • Adenylate Kinase
  • Caspase 3