A mathematical model quantifying GnRH-induced LH secretion from gonadotropes

A mathematical model is developed to investigate the rate of release of luteinizing hormone (LH) from pituitary gonadotropes in response to short pulses of gonadotropin-releasing hormone (GnRH). The model includes binding of the hormone to its receptor, dimerization, interaction with a G protein, production of inositol 1,4,5-trisphosphate, release of Ca2+ from the endoplasmic reticulum, entrance of Ca2+ into the cytosol via voltage-gated membrane channels, pumping of Ca2+ out of the cytosol via membrane and endoplasmic reticulum pumps, and release of LH. Cytosolic Ca2+ dynamics are simplified (i.e., oscillations are not included in the model), and it is assumed that there is only one pool of releasable LH. Despite these and other simplifications, the model explains the qualitative features of LH release in response to GnRH pulses of various durations and different concentrations in the presence and absence of external Ca2+.