From what I've gathered, the entire premise behind X-Factor is the up-regulation of PGF2 alpha, in response to high-intensity exercise.... thereby enhancing skeletal muscle development.
Apparently.... melatonin has been shown (in vivo) to significantly inhibit PGF2 formation.
Melatonin effect on arachidonic acid metabolism to cyclooxygenase derivatives in human platelets
Abstract: The effect of melatonin on thrombin-induced [3H]-arachidonic acid (AA) metabolism to cyclooxygenase derivatives was determined in platelets obtained from normal volunteers at 0830 and 2030 h. Percent conversion of radioactive AA was generally greater at 2030 h than at 0830 h for every cyclooxygenase derivative analyzed. Micromolar or greater concentrations of melatonin decreased significantly the conversion of [3H]-AA to prostaglandin (PG) F2 and thromboxane (Tx) B2, and inhibited slightly the conversion to PGE2 and PGD2. After preincubation of platelets with 1 mM imidazole, the melatonin inhibitory effect was significant for PGF2 only. Melatonin (106 M) showed a significant inhibitory influence on platelet ATP release induced by phorbol-12 myristate-13 acetate (PMA) at 2030 h, an effect inhibited by 1 mM aspirin. These results indicate that at pharmacological concentrations melatonin inhibits human platelet cyclooxygenase.
Blackwell Synergy - J Pineal Res, Volume 11 Issue 3-4 Page 111 - October 1991 (Article Abstract)
Apparently.... melatonin has been shown (in vivo) to significantly inhibit PGF2 formation.
Melatonin effect on arachidonic acid metabolism to cyclooxygenase derivatives in human platelets
Abstract: The effect of melatonin on thrombin-induced [3H]-arachidonic acid (AA) metabolism to cyclooxygenase derivatives was determined in platelets obtained from normal volunteers at 0830 and 2030 h. Percent conversion of radioactive AA was generally greater at 2030 h than at 0830 h for every cyclooxygenase derivative analyzed. Micromolar or greater concentrations of melatonin decreased significantly the conversion of [3H]-AA to prostaglandin (PG) F2 and thromboxane (Tx) B2, and inhibited slightly the conversion to PGE2 and PGD2. After preincubation of platelets with 1 mM imidazole, the melatonin inhibitory effect was significant for PGF2 only. Melatonin (106 M) showed a significant inhibitory influence on platelet ATP release induced by phorbol-12 myristate-13 acetate (PMA) at 2030 h, an effect inhibited by 1 mM aspirin. These results indicate that at pharmacological concentrations melatonin inhibits human platelet cyclooxygenase.
Blackwell Synergy - J Pineal Res, Volume 11 Issue 3-4 Page 111 - October 1991 (Article Abstract)