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,.

Some ultrastructural effects of insulin, hydrocortisone and prolactin on mammary gland explants.

Abstract: The effects of insulin, hydrocortisone, and prolactin on the morphology of explants from midpregnant mouse mammary glands were studied. Insulin promotes the formation of daughter cells within the alveolar epithelium which are ultrastructurally indistinguishable from the parent cells. The addition of hydrocortisone to the medium containing insulin brings the daughter cells to a new, intermediate level of ultrastructural development by effecting an extensive increase of the rough endoplasmic reticulum (RER) throughout the cytoplasm and an increase in the lateral paranuclear Golgi apparatus. When prolactin is added to the insulin-hydrocortisone medium, the daughter cells complete their ultrastructural differentiation. There is a translocation of the RER, Golgi apparatus, and nucleus and the appearance of secretory protein granules within the cytoplasm. There is excellent correlation between the ultrastructural appearance of the alveoli and their capacity to synthesize casein.

Prolactin administration following hemorrhagic shock improves macrophage cytokine release capacity and decreases mortality from subsequent sepsis.

Abstract: Although prolactin is reported to counteract the immunosuppressive effects of glucocorticoids, cyclosporine, and morphine, it remains unknown whether prolactin has any salutary effects on the depressed immune responses following severe hemorrhage. To study this, mice were bled to and maintained at a mean arterial pressure of 35 mm Hg for 60 min, then adequately resuscitated and divided into two groups. One group received saline vehicle, while the other group received prolactin (100 micro g/25 g body weight, s.c.) immediately before resuscitation. Two hours thereafter, peritoneal (pMphi) and splenic macrophages (sMphi) were harvested and assessed not only for their ability to release IL-1 and IL-6, but also for cytokine gene expression using semiquantitative reverse transcription and PCR. In an additional group, mice were subjected to sepsis by cecal ligation and puncture 3 days after hemorrhage. Hemorrhage markedly decreased the ability of pMphi and sMphi to release IL-1 and IL-6. This was, however, associated with increased mRNA expression for IL-1beta and IL-6 and increased serum corticosterone levels. Following prolactin treatment of hemorrhaged mice, IL-1beta and IL-6 mRNA levels as well as cytokine release capacity and blood corticosterone levels were comparable to the values in sham animals. Prolactin also improved the survival of animals subjected to sepsis after hemorrhage. Thus, the immunosuppression following hemorrhage appears to be mediated and modulated by hormones from the hypothalamic-pituitary-adrenal axis. Furthermore, prolactin represents a novel immunomodulating hormone for the treatment of immunodepression encountered after hemorrhagic shock and for decreasing the mortality from subsequent sepsis under those conditions.

Reproducibility of Plasma Steroid Hormones, Prolactin, and Insulin-like Growth Factor Levels among Premenopausal Women over a 2- to 3-Year Period

Abstract: Few studies have evaluated whether a single blood hormone measurement, as is available in most epidemiologic studies, sufficiently characterizes a premenopausal woman's long-term hormone levels; there is particular concern whether sex steroid hormones, which fluctuate during the menstrual cycle, are reliable. We conducted a prospective study within the Nurses' Health Study II to examine the reproducibility of plasma estrogens, androgens, progesterone, prolactin, sex hormone binding globulin, insulin-like growth factor-I (IGF-I), and IGF binding protein-3 (IGFBP-3). One blood sample per year over 3 years was collected from 113 premenopausal women during both the follicular and luteal phases of the menstrual cycle. We calculated intraclass correlation coefficients (ICC) across the three samples for all women. Among estrogens, ICCs ranged from 0.38 (estradiol) to 0.60 (estrone sulfate) in the follicular phase and from 0.44 (estrone) to 0.69 (estrone sulfate) in the luteal phase. Among androgens, ICCs ranged from 0.58 (androstenedione) to 0.94 [dehydroepiandrostenedione sulfate (DHEAS)] in the follicular phase and from 0.56 (testosterone) to 0.81 (DHEAS) in the luteal phase. When values were averaged across the follicular and luteal phases, the ICC for prolactin was 0.64 whereas ICCs for IGF-I and IGFBP-3 were 0.86 and 0.82, respectively. The ICC for progesterone in the luteal phase was only 0.29. These data suggest that for androgens, estrone sulfate, prolactin, IGF-I, and IGFBP-3, a single measurement can reliably categorize average levels over at least a 3-year period in premenopausal women. For estrone and estradiol, where ICCs were relatively low, it is important to use reproducibility data such as those to correct for measurement error in epidemiologic studies.

Alcohol and the male reproductive system.

Abstract: Alcohol use affects all three parts of the hypothalamic-pituitary-gonadal (HPG) axis, a system of endocrine glands and hormones involved in male reproduction. Alcohol use is associated with low testosterone and altered levels of additional reproductive hormones. Researchers are investigating several potential mechanisms for alcohol's damage. These mechanisms are related to alcohol metabolism, alcohol-related cell damage, and other hormonal reactions associated with alcohol consumption. Chronic alcohol use in male rats also has been shown to affect their reproductive ability and the health of their offspring. KEY WORDS: hypothalamic-pituitary-gonadal axis; reproductive effects of AODU (alcohol and other drug use); male; reproductive system; testicles; nitric oxide; oxidation; ethanol-to-acetaldehyde metabolism; apoptosis; luteinizing hormone-releasing hormone; fertility; opioids The endocrine system, which is made up of several hormoneproducing organs throughout the body, is integral to all normal body functions, including growth, development, metabolism, and reproduction. This article reviews research on the effect of alcohol use on the part of the endocrine system involved in male reproduction, the hypothalamic-pituitary-gonadal (HPG) axis. This system of endocrine glands and hormones includes a brain region called the hypothalamus; the pituitary gland, located at the base of the brain; and the male gonads (testes). The article also highlights promising new strategies for preventing or reversing alcohol's harmful effects on the male reproductive system and describes research investigating the molecular mechanisms by which alcohol acts on this system. OVERVIEW OF THE MALE REPRODUCTIVE SYSTEM Of the three components of the HPG axis, the hypothalamus and the pituitary gland have solely regulatory functions, which are mediated by the hormones they produce and secrete, as described in the next paragraph. The third component-the testes-also produces key hormones, including testosterone, which control male sexual characteristics and behaviors. In addition, the testes are responsible for sperm production. The hypothalamus produces luteinizing hormone-releasing hormone (LHRH), which is released in pulses into a system of blood vessels that connect the hypothalamus and the pituitary gland. In response to the LHRH signal, the pituitary gland produces two protein hormones called gonadotropins. These two gonadotropin hormones-luteinizing hormone (LH) and follicle-stimulating hormone (FSH)-are then released into the body's general circulation and act primarily at the level of the gonads. In males, LH stimulates testosterone production from specialized cells called Leydig cells. FSH is important to sperm maturation in another compartment of the testes, the epididymis. Testosterone circulates in the blood back to the hypothalamic-pituitary unit and regulates the further production and secretion of LHRH and LH (see figure 1). When the system is functioning normally, a low testosterone level results in a rise in pituitary gonadotropins. Prolactin, a third reproductive hormone synthesized in the pituitary gland, is important to normal LHRH synthesis and secretion. Low levels of testosterone (i.e., hypogonadism) in adult men have been associated with a variety of medical problems including accelerated osteoporosis, decreased muscle and prostate function, anemia, altered immune function, and decreased reproductive ability (Klein and Duwall 1994; Jackson and Klerekoper 1990; Azad et al. 1991; Berczi et al. 1981; Hadley 1988). Each of these conditions can cause significant health problems. These effects of low testosterone are greater in adult men who have had low testosterone levels since adolescence compared with adult men who experience diminished testosterone levels only in adulthood (Hadley 1988; Yen and Jaffe 1991). An adolescent or teenager who experiences short-term, intermittent decreases in testosterone or permanent hypogonadism is predisposed to experience these problems later in life. …

Hormonal regulation of radioiodide uptake activity and Na+/I- symporter expression in mammary glands.

Abstract: The observation that radioiodide uptake (RAIU) activity, mediated by the Na+/I- symporter (NIS), is significantly increased in lactating breast suggests that RAIU and NIS expression in mammary gland are modulated by hormones involved in active lactation. We showed that both the NIS expression level and RAIU in rat mammary gland are maximal during active lactation compared to those in the mammary glands of virgin and pregnant rats as well as the involuting mammary gland. In the lactating mammary gland, NIS is clustered on the basolateral membrane of alveolar cells as a lesser glycosylated form than NIS in thyroid. The RAIU of lactating mammary gland was partially inhibited by treatment with a selective oxytocin antagonist or bromocriptine, an inhibitor of PRL release. These findings suggest that RAIU and NIS expression in mammary gland are at least in part modulated by oxytocin and PRL. Indeed, we showed that NIS messenger ribonucleic acid level was increased in a dose-dependent manner by oxytocin and PRL in histocultured human breast tumors.