Neuropeptide Y in obese women during treatment with adrenergic modulation drugs

Background: The aim of the study is the assessment whether weight loss treatment with adrenergic modulation drugs modifies neuropeptide Y (NPY) plasma concentration in obese women. Material and methods: 13 obese women (BMI 38.3±4.4) were tested before and subsequently 10 and 20 days after weight loss treatment. The treatment consisted of a very low caloric diet of 400 kcal (1670 kJ) daily combined with ephedrine with caffeine (E+C) or ephedrine with caffeine and yohimbine (E+C+Y) administered for 10 days using the cross-over method. The patients underwent physical examination, including heart rate and blood pressure measurements, spectral heart rate variability (HRV) at rest and after 3 minute handgrip and a 15 minute cycloergometer exercise at 75 W. All the above mentioned tests were carried out thrice in each patient. In 13 obese patients and in 6 control women plasma NPY concentrations were determined by a specific radioimmunoassay using rabbit anti-NPY antiserum and a standard synthetic porcine NPY (Peninsula Lab.). Results: Plasma NPY concentrations were significantly lower in the obese persons compared with the control group. During weight loss treatment with adrenergic modulation drugs no changes in plasma NPY were found ar rest and after physical exercise. Also no differences in HRV indices were observed. Conclusions: 1. Low plasma NPY concentration observed in obesity may be a contraregulatory factor that could prevent further weight increase. 2. Weight reduction treatment did not affect plasma NPY concentration and cardiovascular response to physical exercise. 3. The doses of adrenergic modulation drugs used in our study did not induce any serious side effects, and were so low that no change of plasma NPY concentration and cardiovascular responses were observed at rest.