Endocrine Abstracts

Background: Dopaminergic agonists have been proved to improve control of diabetes and lipids. Central dopaminergic activity can be measured by apomorphin test (apomorphin increases GH and decreases prolactin levels, which is a marker of dopaminergic activity).

The aim of our study was to evaluate the relationship between central dopaminergic activity and metabolic parameters in healthy men.

Methods: We examined 42 healthy men (average age 43.5±7.4 years, BMI 27.4±5.7 kg/m²), anthropometric (waist-hip ratio, blood pressure and body fat by bioimpedance) and metabolic (glycaemia, lipids, HbA1c) parameters were measured and HOMA index of insulin resistance was calculated at the beginning of the study. Sublingual apomorphine (0.033 mg/kg with 4 mg as the highest dose) was administered and basal prolactin and GH were measured in −30, −15, 0, 15, 30, 45, 60, 75, 90, 120, 50, 180 min. Area under the curve for prolactine (AUCPRL) and GH (AUCGH) was calculated using trapezoideal rule. Euglycemic–hyperinsulinemic clamp (insulin 1 mg/kg per min) was performed and glucose disposal (M) calculated. Linear regression was used for statistical analysis.

Results: Negative correlation was observed between AUCPRL resp. AUCGH and total cholesterol (r=−0.52, P=0.001; resp. r=−0.34, P=0.04), triglycerides (r=−0.42, P=0.009; resp. −0.36, P=0.03), HOMA index (r=−0.33, P=0.043; resp. r=−0.5, P=0.001), percentage of body fat (r=−0.44, P=0.009; resp. r=−0.45, P=0.007), BMI (r=−0.36, P=0.013; resp. r=−0.56, P=0.0001). Negative correlation was also found between AUCGH and HbA1c (r=−0.55, P=0.0001), AUCGH and diastolic blood pressure (r=−0.35; P=0.039), waist hip ratio (r=−0.46; P=0.006) and age (r=−0.53; P=0.001), whereas positive correlation between AUCGH and M (r=0.36. P=0.039).

Conclusion: Higher central dopaminergic activity is connected with lower total cholesterol, triglycerides, HbA1c and lower insulin resistance in healthy men.