Mathematical model of testosterone regulation by pulse-modulated feedback

A mathematical model of the pulse-modulated regulation of non-basal testosterone secretion in the male is introduced. The suggested model is of third order, reflecting the three most significant hormones in the regulation loop, but yet is shown to be capable of sustaining periodic solutions with one or two pulses of gonadotropin-releasing hormone (GnRH) in each period. Lack of stable periodic solutions is otherwise a main shortcoming of existing low-order hormone regulation models. The periodic mode with two GnRH pulses in the least period has not yet been described in medical literature but is supported by experimental data.