Kisspeptin is a neuropeptide that is present in the hypothalamus, which regulates the release of hormones such as gonadotropin releasing hormone (GnRH). GnRH stimulates the pituitary gland to secrete luteinising hormone and follicle stimulating hormone. These two hormones act on the testes in men and the ovaries in women to produce sex-steroids, such as testosterone and oestradiol.
A number of studies have shown that extrahypothalamic kisspeptin signalling encourages sexual and emotional brain processing and links it to the control of the HPG axis. Specifically, it has been demonstrated that kisspeptin increases the release of LH and testosterone from the pituitary gland, and that a single intravenous kisspeptin bolus significantly increases plasma levels of these hormones.
However, it is unclear whether this effect is a result of the direct action of kisspeptin on the pituitary gland or due to indirect mechanisms. To determine this, we measured the effect of a continuous intravenous infusion of kisspeptin on LH and testosterone secretion in healthy men and hypotestosteronaemic T2DM patients with type 2 diabetes.
The results showed that a continuous intravenous administration of kisspeptin, which stimulates the release of endogenous GnRH in turn, restores normal LH and testosterone secretion in hypotestosteronaemic T2DM men. These results suggest that kisspeptin might be a viable alternative to the current treatment of hypotestosteroneaemia in T2DM patients, which is based on exogenous administration of hCG. This more physiological stimulation of the production of LH and testosterone from the pituitary could be safer and reduce the risks associated with the overstimulation of the ovaries commonly observed in patients treated with hCG.