A delay-differential equations model of prolactin secretion: Effects of dopamine and thyrotropin-releasing hormone

Abstract

Prolactin, a polypeptide hormone released by the pituitary gland, plays an important role in lactation and reproduction. The disorder in prolactin secretion may lead to several diseases such as hyperprolactinemia and reproductive disturbances, In this paper, we develop a delay-differential equations model of prolactin secretion based on the effects of dopamine and thyrotropin-releasing hormone. By applying a Hopf bifurcation analysis to our model, the conditions are derived under which our model exhibits a periodic solution corresponding to the normal secretory pattern of prolactin which has been observed as a series of pulses, occurring every 2-3 hours. The irregular pattern of prolactin secretion which has been observed clinically in patients with microprolactinoma and macroprolactinoma are then investigated numerically.