Hexarelin analogues as inducers of penile erection

Penile erection is the result of an extremely complex interaction involving the central and peripheral nervous systems which eventually leads to relaxation of the corpora. cavernosa. In recent years, detailed knowledge of both the local and, to a lesser extent, central mechanisms involved has contributed to the development of numerous drugs that may be useful in the treatment of erectile dysfunction. These proerectile drugs act on various targets by different mechanisms of action and may have a positive influence on erectile dysfunction even in the presence of other complications. Hexarelin analogues are short peptides (3-7 amino acids) derived from hexarelin, a peptide originally characterized for its ability to release growth hormone. Some hexarelin analogues induce erection when injected into the paraventricular nucleus of the hypothalamus, one of the brain regions responsible for the control of erectile function, apparently through activation of central oxytocinergic neurotransmission, while others induce erection when given systemically, although to a lesser extent. As several analogues have potency comparable to that of other types of agents that induce erection by acting on the hypothalamic nucleus (e.g., apomorphine, oxytocin and excitatory amino acids), hexarelin analogues may prove to be potential agents for the treatment of erectile dysfunction.