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,.

Plasma prolactin concentrations and risk of postmenopausal breast cancer.

Abstract: Prolactin is important in human breast development, and substantial laboratory and in vitro data suggest a role in mammary carcinogenesis. Therefore, we conducted a prospective case-control study nested within the Nurses’ Health Study cohort to examine, in detail, the association between plasma prolactin concentrations and postmenopausal breast cancer by cancer invasiveness, estrogen receptor/progesterone receptor status, and other subject characteristics, including postmenopausal hormone use. Blood samples were collected from 1989 to 1990 and prolactin was measured by microparticle enzyme immunoassay. The analysis included 851 cases of postmenopausal breast cancer diagnosed after blood collection and before June 2000, in which there were one or two controls ( n = 1,275) matched on age, postmenopausal hormone use, fasting status, and time of day and month of blood collection. Prolactin was associated with a modestly increased risk of postmenopausal breast cancer [relative risk, top versus bottom quartile, 1.34; 95% confidence interval (CI), 1.02–1.76; P -trend = 0.01]. The association differed by estrogen receptor/progesterone receptor status ( P -heterogeneity = 0.03). The relative risk was 1.78 (95% CI, 1.28, 2.50; P -trend P -trend = 0.28) for estrogen receptor−/progesterone receptor−, and 1.94 (95% CI, 0.99, 3.78; P -trend = 0.12) for estrogen receptor+/progesterone receptor− breast cancers. Associations generally were similar for ductal and lobular carcinomas ( P -heterogeneity = 0.43) and by tumor size ( P -heterogeneity = 0.24). Among estrogen receptor+/progesterone receptor+ cancers, the association did not significantly differ by postmenopausal hormone use, years between blood draw and diagnosis, or after adjustment for estradiol (relative risk, 1.93; 95% CI, 1.16, 3.22; P -trend = 0.01). Our prospective data suggest that plasma prolactin concentrations are associated with an increased risk of postmenopausal breast cancer, particularly for estrogen receptor+/progesterone receptor+ cancers, and independently of estradiol.

Induction of Mammary Gland Development in Estrogen Receptor-α Knockout Mice

Abstract: Mammary glands from the estrogen receptor-a knockout (alphaERKO) mouse do not undergo ductal morphogenesis or alveolar development. Disrupted ERalpha signaling may result in reduced estrogen-responsive gene products in the mammary gland or reduced mammotropic hormones that contribute to the alphaERKO mammary phenotype. We report that circulating PRL is reduced in the female alphaERKO mouse. Implantation of an age-matched, heterozygous ERalpha pituitary isograft under the renal capsule of 25-day-old or 12-week-old alphaERKO mice increased circulating PRL and progesterone levels, and induced mammary gland development. Grafted alphaERKO mice also possessed hypertrophied corpora lutea demonstrating that PRL is luteotropic in the alphaERKO ovary. By contrast, ovariectomy at the time of pituitary grafting prevented mammary gland development in alphaERKO mice despite elevated PRL levels. Hormone replacement using pellet implants demonstrated that pharmacological doses of estradiol induced limited mammary ductal elongation, and estradiol in combination with progesterone stimulated lobuloalveolar development. PRL alone or in combination with progesterone or estradiol did not induce alphaERKO mammary growth. Estradiol and progesterone are required for the structural development of the alphaERKO mammary gland, and PRL contributes to this development by inducing ovarian progesterone levels. Therefore, the manifestation of the alphaERKO mammary phenotype appears due to the lack of direct estrogen action at the mammary gland and an indirect contributory role of estrogen signaling at the hypothalamic/pituitary axis.

Specific prolactin binding sites in the prostate and testis of rats.

Abstract: Specific binding sites for prolactin have been detected in membrane preparations from the testis, epididymis, seminal vesicles and prostate of male rats. The binding was time and temperature dependent. In prostatic tissue the binding of prolactin was a saturable process with an association constant (Ka) of 3 i 109M−1 and a binding capacity of 125 femtomoles per mg of protein. The binding of prolactin to the prostate was inhibited only by lactogenic hormones. In the testis the low binding of prolactin increased slightly from 20 to 70 days of age. On the other hand, in the prostate the highest specific binding was found in membrane preparations from 20-day-old rats while 270-day-old rats had only 10% as much specific binding. The administration of estrogen also lowered prolactin binding to prostatic membranes. Castration caused an even greater decrease in the binding of [l25I]iodoPRL in the prostate whereas in the liver this procedure resulted in a major increase in the binding of labeled prolactin. (Endocr...