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Pregnancy‐Induced Adaptation in the Neuroendocrine Control of Prolactin Secretion
Author(s) -
Grattan David R.,
Steyn Frederik J.,
Kokay Ilona C.,
Anderson Greg M.,
Bunn Stephen J.
Publication year - 2008
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/j.1365-2826.2008.01661.x
Subject(s) - prolactin , endocrinology , medicine , hyperprolactinaemia , placental lactogen , dopamine , prolactin cell , secretion , anterior pituitary , biology , pituitary gland , pregnancy , hormone , fetus , placenta , genetics
During pregnancy, neuroendocrine control of prolactin secretion is markedly altered to allow a state of hyperprolactinaemia to develop. Prolactin secretion is normally tightly regulated by a short‐loop negative‐feedback mechanism, whereby prolactin stimulates activity of tuberoinfundibular dopamine (TIDA) neurones to increase dopamine secretion into the pituitary portal blood. Dopamine inhibits prolactin secretion, thus reducing prolactin concentrations in the circulation back to the normal low level. Activation of this feedback secretion by placental lactogen during pregnancy maintains relatively low levels of prolactin secretion during early and mid‐pregnancy. Despite the continued presence of placental lactogen, however, dopamine secretion from TIDA neurones is reduced during late pregnancy. Moreover, the neurones become completely unresponsive to endogenous or exogenous prolactin at this time, allowing a large nocturnal surge of prolactin to occur from the maternal pituitary gland during the night before parturition. In this review, we describe the changing patterns of prolactin secretion during pregnancy in the rat, and discuss the neuroendocrine mechanisms controlling these changes. The loss of response to prolactin is an important maternal adaptation to pregnancy, allowing the prolonged period of hyperprolactinaemia required for mammary gland development and function and for maternal behaviour immediately after parturition, and possibly also contributing to a range of other adaptive responses in the mother.