Prolactin

About: Prolactin is a research topic. Over the lifetime, 22356 publications have been published within this topic receiving 609537 citations. The topic is also known as: lactotropin, & PRL,.

Effects of a dopamine antagonist on the release of gonadotropin and prolactin in normal women and women with hyperprolactinemic anovulation.

Abstract: Administration of a dopamine (DA) antanonist, metoclopramide (MCP) resulted in dose-related acute increments of circulating levels of LH and FSH in patients with hyperprolactinemic anovulation due to pituitary microadenoma but not in normal cycling women during the early follicular phase. Concomitant PRL responses to MCP in hyperprolactinemic patients were 1/10 those observed in the cycling women. These findings suqgest a relative DA excess at the hypothalamic LRF neurons and a relative DA deficiency at the adenoma lactotroph of hyperprolactinemic patients as compared to cycling women.

Tissue-specific gene expression in the pituitary: the glycoprotein hormone alpha-subunit gene is regulated by a gonadotrope-specific protein.

Abstract: The molecular mechanisms for the development of multiple distinct endocrine cell types in the anterior pituitary have been an area of intensive investigation. Though the homeodomain protein Pit-1/GHF-1 is known to be involved in differentiation of the somatotrope and lactotrope lineages, which produce growth hormone and prolactin, respectively, little is known of the transcriptional regulators important for the gonadotrope cell lineage, which produces the glycoprotein hormones luteinizing hormone and follicle-stimulating hormone. Using transgenic mice and transfection into a novel gonadotrope lineage cell line, we have identified a regulatory element that confers gonadotrope-specific expression to the glycoprotein hormone alpha-subunit gene. A tissue-specific factor that binds to this element is purified and characterized as a 54-kDa protein which is present uniquely in cells of the gonadotrope lineage and is not Pit-1/GHF-1. The human and equine alpha-subunit genes are also expressed in placental cells. However, the previously characterized placental transcription factors designated TSEB and alpha-ACT are not found in the pituitary gonadotrope cells, indicating that independent mechanisms confer expression of these genes in the two different tissues.

Serum Prolactin Levels in Rats with Pituitary Transplants or Hypothalamic Lesions

Abstract: Serum prolactin levels were determined by radioimmunoassay in hypophysectomized, ovariectomized rats bearing 0, 1, 2, or 4 anterior pituitaries (AP) underneath the kidney capsule at 1, 2, 4, 6, 8, and 10 weeks after transplantation. Rats with no AP transplants had barely detectable levels of serum prolactin, whereas rats with 1 AP transplant from female cycling rats had serum prolactin values as high as those seen in estrous rats (120 ng/ml serum). In rats bearing 2 AP transplants, serum prolactin increased to 170 ng/ml serum, whereas 4 AP transplants elevated serum prolactin to 250 ng/ml, which is about equivalent to that in lactating postpartum rats (280 ng/ml). Injections of estradiol benzoate (1 µg/day for 5 days) into rats bearing 0, 1, 2, or 4 AP transplants, beginning 10 weeks after transplantation, increased serum prolactin over pre-treatment levels, except in the rats with no pituitary transplants. Bilateral lesions placed in the median eminence or anterior hypothalamus of ovariectomized rats significantly increased serum prolactin to 125 and 85 ng/ml, respectively, as compared with sham-lesioned controls (20 ng/ml). Posterior hypothalamic lesions increased serum prolactin concentration slightly and lesions in the amygdaloid nuclei had no effect. These results indicate that removal of hypothalamic inhibition of prolactin release by pituitary transplantation or by appropriate lesion placement in the hypothalamus results in elevated serum prolactin levels.