Human galanin secretion is increased upon normal exercise test in middle-age individuals

Galanin, a neuropeptide, is found in the central nervous system and in a nu mber of nonbrain areas including adrenal sympathetic medullar tissue and pa ncreas. Several studies involve galanin in the regulation of GH, which resp onds to stressful stimuli. This study refers to the investigation of the ef fect of a 20-min exercise on plasma human galanin (hGAL) and GH in middle-a ged healthy volunteer adults. Thirteen individuals, 5 males and 8 females a ged 40-50 years (44.7 +/- 2.95) were selected on the basis of normal body m ass index (22.5 +/- 2.3 kg/m(2)) and the absence of endocrine or any other abnormality. Basal concentrations of GH and hGAL were measured between 0800 and 0900h after an overnight fast. Post exercise levels were recorded afte r termination of the stressful test and 15 min thereafter. GH and hGAL were determined by an immunoradiometric and radioimmunoassay, respectively. The exercise-potentiated GH response in all subjects with post-exercise levels significantly higher (11.09+/-1.8 ng/ml vs 1.27+/-0.7 ng/ml, p<0.0001, F=3 2.44) with the peak in the hormone level detected 15 min after the end of e xercise (12.09+/-1.96 ng/ml). Plasma hGAL levels were also substantially af fected by the acute exercise test, in that post exercise peripheral blood c oncentration was significantly higher from the basal values (21.51+/-9.94 v s 13.46+/-7.2 pg/ml, p<0.02, F=5.50). Again the hGAL values peaked 15 min a fter the end of exercise (24.0+/-10.5 pg/ml, P<0.015, F = 4.68). However, t he time-correlation of the increments of GH and hGAL did not reach a statis tically significant level (20 min: r=0.41, p=0.161., 35 min: r=-0.095, P=0. 758). These results clearly show an independence of the two hormones. The r esponsivity of hGAL of middle-aged individuals to the exercise stimulus mig ht be due to the higher releasable pool of the hormone.