PDYN and hypogonadism: The kisspeptin-neurokinin B-dynorphin pathway acts on the hypothalamus to upregulate and downregulate the release of GnRH.17 It has potential to be used both in patients with hypogonadism to increase GnRH and sex steroid production, and conversely to suppress GnRH production and thus the HPT axis as a potential contraceptive,18 but we are not aware of any current trials related to male contraception.