Endocrine Abstracts

Worldwide numerous active individuals take phosphodiesterase type 5 inhibitors (PDE-5i), furthermore, to our knowledge, the effects of these drugs on hormone secretion has not been adequately investigated. In particular, considering that a) PDE-5i influence NO bioavailability, b) NO is one of the mediators of the hypothalamus–pituitary–adrenal (HPA) axis response to stress, and, c) physical exercise-related stress activate HPA axis, we investigated whether PDE-5i influence the salivary adrenal steroids responses to a maximal exercise test in healthy athletes. We studied 9 healthy male trained after signing the informed consent and our University Ethical approval. In the experimental phase, each subject performed, with a double blind design, two incremental exercise tests on a cycle ergometer, either after a single morning oral administration of one tablet of placebo or tadalafil (20 mg). Oxygen consumption (VO₂), blood lactate, respiratory exchange ratio, rate of perceived exertion, arterial blood pressure (BP), heart frequency (HR), and oxygen pulse (VO₂/HR), were evaluated immediately before and during exercise (at individual ventilatory and anaerobic thresholds, IVT and IAT), at VO₂ max and during recovery. Salivary cortisol, DHEAS, testosterone and their ratios (T/C, DHEAS/C) were evaluated by RIA before starting and at the end of exercise, and at thirty minutes during recovery. In contrast with placebo, tadalafil reduced systolic BP either before (P<0.05) and after exercise (at 3 min of recovery P<0.05) and decrease VO₂/HR at IVT (P=0.03). Salivary cortisol increased immediately after exercise both after placebo and after tadalafil administration (P=0.04 and P=0.02, respectively), with significant higher post-exercise salivary cortisol levels after tadalafil administration (P=0.03 versus placebo). Tadalafil administration was able to modify the salivary cortisol response to exercise related stress. Further studies are necessary to confirm our results. Administration was able to modify the salivary cortisol response to exercise related stress. Further studies are necessary to confirm our results. Tadalafil administration was able to modify the salivary cortisol response to exercise related stress. Further studies are necessary to confirm our results. Tadalafil administration was able to modify the salivary cortisol response to exercise related stress. Further studies are necessary to confirm our results.