Prolactin Maintains Mating-Induced Prolactin Surges
Central prolactin does not initiate prolactin secretory rhythm
MONDAY, March 23 (HealthDay News) -- Prolactin injected directly into the brains of rats can induce a prolactin secretory rhythm similar to that induced after mating, but only maintains and does not initiate mating-induced prolactin surges, according to a study published online March 12 in Endocrinology.
To determine whether secretion of prolactin in response to mating stimulus of the uterine cervix was responsible for the maintenance of subsequent prolactin surges, Cleyde V. Helena of Florida State University in Tallahassee and colleagues examined prolactin release after injection of ovariectomized rats with sheep prolactin and after injection of a prolactin antagonist.
The researchers found that prolactin injected centrally induced prolactin surges similar to those observed after mating, while peripheral injection induced surges that were delayed and of lesser amplitude. Central injection of a prolactin antagonist blocked cervical stimulation-induced prolactin surges and the accompanying increase in dopaminergic activity, except if the antagonists were given only on the day of mating.
"These results demonstrate that prolactin acts centrally to induce the prolactin rhythm and that prolactin in the brain is essential for the maintenance, but not for the initiation of the cervical stimulation-induced rhythmic prolactin surges," Helena and colleagues conclude.