Endocannabinoids and kisspeptins: two modulators in fight for the regulation of GnRH activity.

The master system in the control of reproductive functions is the communication into the hypothalamus-pituitary-gonadal axis (HPG), whose main actor is the hypothalamic gonadotropin releasing hormone (GnRH). Such a decapeptide triggers the release of pituitary gonadotropins [Follicular Stimulating Hormone (FSH) and Luteinizing Hormone (LH)] which in turn reach the gonads, induce the biosynthesis of steroids (mainly testosterone in males and estradiol/progesterone in females) and of other non steroidal substances (i.e. activin, follistastin, inhibin) modulating the gametogenesis in both sexes. In the last decades, a significant upsurge of studies aimed to define seveal actors and mechanisms supporting reproductive activity. Ultra short, short and long feedback in HPG communication finely modulate reproduction. Nevertheless, this picture is still puzzling and the complete knowledge of the full process has to be unravelled.