Methylxanthines and Reproduction

Abstract

Reproduction is the process by which organisms create descendants. In human reproduction, two kinds of sex cells, or gametes, are involved. Sperm, the male gamete, and egg egg , or ovum ovum Vedi egg , the female gamete, must meet in the female reproductive system to create a new individual and both the female and the male reproductive systems are essential to the occurrence of reproduction. Scientific reports dealing with the effects of methylxanthines on reproduction are mostly centred on the use of these compounds as phosphodiesterase inhibitors that, by maintaining high intracellular levels of cyclic AMP (cAMP) cyclic AMP , will affect the gametes differently. High cAMP levels will sustain sperm sperm maturation while they hold the oocytes in mitotic arrest. Caffeine caffeine , being the methylxanthine most widely consumed by every segment of the population, has been the subject of greatest interest among health professionals and researchers. Conflicting results still seem to characterize the association between male/female caffeine caffeine consumption in adult life and semen quality/fertility fertility , although moderate daily caffeine consumption of levels up to 400-450 mg/day (5.7-6.4 mg/kg/day in a 70-kg adult) do not seem to be associated with adverse effects, i.e. general toxicity, effects on bone status and calcium balance, cardiovascular effects, behavioural changes, increased incidence of cancer, or effects on male fertility. A clear stimulation of egg-laying by the coffee leaf pest Leucoptera coffeella was recently reported, providing support for the hypothesis that caffeine, in a dose-dependent way, in insects stimulates egg-laying, thus leading to the death of coffee trees.

The association between caffeine and alcohol consumption and IVF/ICSI outcomes: A systematic review and dose–response meta‐analysis

“…Caffeine, the most widely consumed methylxanthine, can act as a non‐selective adenosine antagonist within the human body and therefore increase the intracellular concentration of cAMP and induce an increase in catecholamine excretion in the mother and fetus, which may lead to uteroplacental vasoconstriction and hypoxia. 32 , 42 , 43 , 44 In addition, it was reported that caffeine may alter circulating levels of luteal estrogens and sex hormone‐binding globulin, suggesting that caffeine may exert a potential detrimental effect on the reproductive system by affecting the hypothalamic–pituitary–gonadal axis. 45 However, the results were inconsistent and detailed mechanisms or pathways are still poorly understood.…”

Participation of IP3R, RyR and L-type Ca2+channel in the nuclear maturation ofRhinella arenarumoocytes

“…This result may be explained by differences in the organization of the ER or by the lower sensitivity of ryanodine receptors in this species. In addition, it was reported that caffeine may modify the activity of phosphodiesterase to induce an increase in cAMP levels (Kren et al ., 2004; Mishra & Joy, 2006; Minelli & Bellezza, 2011) that could inhibit meiosis resumption. Our experiments cannot rule out the possibility that the inhibitory effect of cAMP may be more important than the stimulatory effect of the Ca 2+ released by RyR activation.…”

A Toxicological Evaluation of Methylliberine (Dynamine®)

“…In all female animals of the treated and control groups, the histology of the ovaries, uterus, and vagina were normal. E ects on spermatogenesis (and testicular atrophy) are well known with respect to the methylxanthines, and have been observed in rats, rabbits, and roosters and are generally thought to be reversible up on cessation of treatment [34]. Gans, observed these e ects in ca eine-and theobromine-treated rats [32] while Weinberger et al also observed them at high dietary doses in ca eine-, theobromine-, and theophylline-treated rats [35].…”

“…Gans, observed these e ects in ca eine-and theobromine-treated rats [32] while Weinberger et al also observed them at high dietary doses in ca eine-, theobromine-, and theophylline-treated rats [35]. ese e ects, at least with respect to ca eine, have been largely attributed to suppression of follicle-stimulating hormone [34]. Testicular atrophy and inhibition of spermatogenesis have also been observed in rats treated with theacrine.…”