AMP kinase is a key enzyme involved with energy regulation, the intake of macronutrients, the uptake of glucose and fatty acids by cells and the metabolic combustion of fatty acids. We hypothesized that in patients with hypogonadism associated with diabetes, its expression and activity are diminished since there is a quantitative and qualitative loss of skeletal muscle function. Twenty-two men with HH and T2DM were compared with 20 eugonadal men with T2DM at baseline. From the HH patients, 12 were treated with testosterone 200mg every 2 weeks injected intramuscularly for 24 weeks, during which their plasma concentrations were maintained in the physiological range. Hyperinsulinemic, euglycemic clamps (HEC) were carried out prior to and after testosterone replacement and fat (abdomen) and muscle (quadriceps) biopsies were carried out prior to and after HEC procedure on each occasion. In the hypogonadal state, the expression and the activity (measured as phoso-T172-AMPK-α) of AMP kinase-α was significantly lower in HH patients than eugonadal diabetics both in adipose tissue and skeletal muscle by 37% and 29%, respectively, for expression and by 22.1% and 28%, respectively for activity. Following testosterone, there was no change in expression but there was a significant increase in AMP kinase activity by 69±31% (from 14.9±2.8 to 22.8±2.2U/ml, p<0.05) in the muscle but not in the adipose tissue. At the end of the treatment and following the hyperinsulinemic euglycemic clamp, there was a significant increase in AMP kinase expression by 41±9% and 46±11% in adipose tissue and muscle, respectively, while there was only a modest increase (NS) in activity in both tissues. Clearly, therefore, testosterone is an important modulator of AMP kinase activity. This effect of testosterone may contribute to the increase in glucose uptake and an improvement in insulin sensitivity since AMP kinase also induces an increase in Akt-2 and GLUT-4 expression.
S. Dhindsa: None. H. Ghanim: None. M. Batra: Speaker's Bureau; Self; Eli Lilly and Company. A. Chaudhuri: Speaker's Bureau; Self; AstraZeneca, Eli Lilly and Company, Boehringer Ingelheim Pharmaceuticals, Inc., Merck & Co., Inc., Novo Nordisk Inc.. S. Abuaysheh: None. P. Dandona: Advisory Panel; Self; AstraZeneca. Consultant; Self; AstraZeneca. Research Support; Self; AstraZeneca.