Roelfsema F, et al. - In the present study, researchers tested the premise that moderately increased serum estradiol (E₂) levels stimulate GH, and that progesterone (P4) modulates E₂-stimulated GH secretion. The study sample consisted of 4 parallel groups of randomly assigned 40 postmenopausal women. According to findings, physiological concentrations of low range E₂ do not affect pulsatile GH secretion spontaneously or stimulated by ghrelin. P4, on the other hand, inhibits concentration-dependent fashion of GH stimulated by ghrelin.