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,.

Interleukin involvement in anterior pituitary cell growth regulation: effects of IL-2 and IL-6.

Abstract: The pituitary gland plays a central role in the interactions between the immune and neuroendocrine systems. The expression of receptors for interleukin-1 (IL-1), IL-2, and IL-6 and the intrinsic production of these ILs by pituitary cells have been described. Previous studies have focused on the way cytokines influence hormone secretion. We have determined whether, in addition to these effects, ILs could affect pituitary cell proliferation. In GH3 cells, both IL-2 (1-100 U/ml) and IL-6 (10-500 U/ml) significantly stimulated [3H]thymidine incorporation and cell count. In contrast, inhibitory effects of both IL-2 and IL-6 at the same concentrations were observed on normal rat anterior pituitary cell growth. This finding was clearly evident when cells were cultured in Minimum Essential Medium-D-valine medium, a condition that results in cultures virtually free of fibroblasts. Autoradiographic studies confirmed that [3H]thymidine was only incorporated in the nucleus of nonfibroblastic pituitary cells. No direct correlation between the effects of IL-2 and IL-6 on cell growth and hormone secretion was apparent. By immunofluorescence, we observed IL-2 receptor expression on GH3 cells and, for the normal rat cultures, a high percentage of PRL-secreting and a lower percentage of GH-producing cells expressing IL-2 receptors, providing new evidence for a direct site of action of IL-2 on pituitary cells. Considering that uncontrolled division of cells may result from either excessive growth stimulation or deficient growth inhibition, the regulation of pituitary cell growth by IL-2 and IL-6 together with their intrinsic pituitary production could be of potential importance in pituitary adenoma pathogenesis.

Estrogen control of prolactin synthesis in vitro

Abstract: Primary cultures of rat pituitary cells respond to estradiol-17beta by increased incorporation of radiolabeled precursors into prolactin but not into the bulk of other cellular proteins The rate of increase in prolactin synthesis is dose dependent, reaching maximal levels in the physiological range of estradiol At a concentration of 1 nM, estradiol, diethylstilbestrol, and estriol are stimulatory whereas androgens, progesterone, and corticosterone are without significant effect Exposure of pituitary cells to 10 nM estradiol resulted in a 500% increase in prolactin synthesis after 7 days of culture The results indicate that estradiol can stimulate prolactin synthesis through direct action on the pituitary

Elevated androgens and prolactin in aromatase-deficient mice cause enlargement, but not malignancy, of the prostate gland.

Abstract: Although androgens are the main steroids controlling the growth of the mammalian prostate, increasing evidence demonstrates that estrogens also regulate prostate development and growth. This study describes the effects of estrogen deficiency using aromatase knockout mice (ArKO) with targeted disruption of the cyp19 gene. Serum and tissue testosterone and 5α-dihydrotestosterone as well as serum PRL levels are significantly (P < 0.05) elevated in mature male ArKO mice. Histological, stereological, and immunohistochemical studies demonstrated enlargement of the ventral, anterior, and dorsolateral lobes of the prostate in young and older ArKO mice. Hyperplasia of the epithelial, interstitial, and luminal compartments was identified and associated with up-regulation of androgen receptors. There was no evidence of malignancy as the animals aged (up to 56 weeks). The changes observed in the prostates of ArKO mice were unaffected by maintaining mice on regular or soy-free diets. It is concluded in ArKO mice that,...

Prolactin, Growth Hormone, and Insulin-like Growth Factor-I in the Immune System

Abstract: Publisher Summary This chapter examines whether pituitary hormones prolactin (PRL), growth hormone (GH), and insulin-like growth factors (IGF)-I are indeed full-fledged immunological growth and differentiation factors. The chapter presents ample evidence that the receptors for PRL, GH, and IGF-I are differentially expressed on several leukocyte populations. Moreover, PRL, GH, and IGF-I are produced by minor populations of leukocytes. The role played by these factors in the development and the function of the immune system, ignored until recently, is now the subject of intense investigation. The immune system contains both a PRL- and GH-secreting complex and target cells that express receptors for and respond to PRL and GH. Some effects of GH are mediated through the local production of IGF-I. PRL, GH, and IGF-I are thus paracrine or autocrine immunologic growth and differentiation factors. A weakened version of that hypothesis states that PRL, GH, and IGF-I are immunoregulatory hormones; the immune system is one of their targets but local production is negligible. An extreme view holds that PRL, GH, and IGF-I play little if any role in the development and the function of the human immune system. PRL, GH, and IGF-I hold promise as therapeutic agents in various forms of hemopoietic failure and immune deficiency. Also, dopaminergic agents and somatotropin analogs may be useful in the treatment of autoimmune diseases and the studies of the specific regulation of these hormones in the lymphohemopoietic system can lead to the development of specific clinical tools that interfere with local production of these hormones.