Species differences in the sensitivity to GnRH analogs

The effects of several GnRH agonists and antagonists with high biological activity, have been investigated in rats, mice, rabbits and monkeys. Striking differences exist in the response of different species to the antigonadal and antipituitary effects of these peptides. Of all the animals studied, the rat is the most sensitive. The magnitude of the response to GnRH agonists seems to depend on the sensitivity of the pituitary and the presence of GnRH receptors in the target organs. Findings from animal models require careful interpretation before predictions can be made regarding their possible effects in the human.