Human Galanin Secretion is Increased Upon Normal Exercise Test in Middle-Age Individuals

Abstract

Galanin, a neuropeptide, is found in the central nervous system and in a number of nonbrain areas including adrenal sympathetic medullar tissue and pancreas. Several studies involve galanin in the regulation of GH, which responds to stressful stimuli. This study refers to the investigation of the effect of a 20-min exercise on plasma human galanin (hGAL) and GH in middle-aged healthy volunteer adults. Thirteen individuals, 5 males and 8 females aged 40-50 years (44.7 +/- 2.95) were selected on the basis of normal body mass index (22.5 +/- 2.3 kg/m2) 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 after 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=32.44) with the peak in the hormone level detected 15 min after the end of exercise (12.09 +/- 1.96 ng/ml). Plasma hGAL levels were also substantially affected by the acute exercise test, in that post exercise peripheral blood concentration was significantly higher from the basal values (21.51 +/- 9.94 vs 13.46 +/- 7.2 pg/ml, p<0.02, F=5.50). Again the hGAL values peaked 15 min after the end of exercise (24.0 +/- 10.5 pg/ml, P<0.015, F = 4.68). However, the time-correlation of the increments of GH and hGAL did not reach a statistically 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 responsivity of hGAL of middle-aged individuals to the exercise stimulus might be due to the higher releasable pool of the hormone.

Exercise offers anxiolytic potential: A role for stress and brain noradrenergic-galaninergic mechanisms

“…It is interesting to note that both voluntary and forced exercise increase prepro-galanin mRNA in the locus coeruleus (O’Neal et al, 2001). Supporting the functional relevance of these data, plasma galanin secretion is also increased after an acute bout of exercise in humans (Legakis et al, 2000). Increases in galanin expression in the locus coeruleus is correlated with increases in the distance ran on a wheel, suggesting a dose-dependent effect of exercise on brain galanin (Eisenstein and Holmes, 2007; Holmes et al, 2006; Sciolino et al, 2012).…”

Physiology, Signaling, and Pharmacology of Galanin Peptides and Receptors: Three Decades of Emerging Diversity

“…However, exercise alone seems not to be sufficient to increase plasma galanin levels in rats, and the effect also requires glucose (Milot and Trudeau, 1997). Data on the influence of exercise on plasma galanin levels in humans are scarce and inconclusive, with both an increase in plasma galanin levels and no change after exercise being reported (Ceresini et al, 1997;Legakis et al, 2000).…”

“…126 2011, 2012), chronic constriction nerve injury (Nahin et al, 1994), orofacial pain (Tokunaga et al, 1992), exercise (Legakis et al, 2000), electroconvulsive stimulation (Christiansen, 2011), and herpes simplex virus infection (Henken and Martin, 1992).…”

Heterogeneous Forms of Immunoreactive Galanin in Human Plasma; Higher Levels in Men than in Women

“…Plasma levels of galanin show peaks but no distinct circadian rhythm [29], and may possibly be influenced by exercise [30]. In women, plasma galanin has been related to menstrual status and body weight [31 ± 34] with higher levels in premenopausal and in obese women.…”