Although hypothalamic LH- and FSH- releasing factors (LRF and FRF) have been discovered since 1960 (1, 2, 3, 4, 5) and 1964 (6, 7, 8) respectively, only a little work was done until now on their mechanism of action. Three possibilities at least can be envisaged (9): 1, a stimulation of excretion (or discharge) of hormone stored in the pituitary, 2. a direct or indirect action on synthesis of hormone in the appropriate cells, 3. an effedt on activation of hormonal precursors.
