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,.

Dietary protein and(or) energy restriction in mares: plasma growth hormone, IGF-I, prolactin, cortisol, and thyroid hormone responses to feeding, glucose, and epinephrine.

Abstract: Sixteen light horse mares were fed diets of bermudagrass hay and a corn/cottonseed hull-based supplement formulated to contain either 100% (control) or 50% (restricted) of the protein and(or) energy requirements for maintenance in a 2 x 2 factorial arrangement of treatments. Plasma IGF-I, prolactin, cortisol, triiodothyronine, and thyroxine were monitored for 33 d. On the 27th d, frequent blood samples were drawn throughout the day for the measurement of growth hormone (GH), and on the 29th d, an epinephrine challenge and an i.v. glucose tolerance test (IVGTT) were performed in the morning and afternoon, respectively. Restriction of protein and(or) energy reduced (P .1) by restriction of protein and(or) energy. Plasma prolactin concentrations were low throughout the experiment and after the IVGTT, but they increased (P = .003) after feeding. Protein restriction increased (P = .09) the occurrence of GH episodes during the 14-h feeding period on d 27; the greatest effect occurred in the mares restricted in both nutrients. In contrast, energy restriction reduced (P = .05) the GH response to epinephrine injection. We conclude that 1) protein deficiency in mares increases GH secretion, whereas energy restriction alone does not, 2) a deficiency in energy and(or) protein reduces IGF-I secretion, and 3) prolactin concentrations increase after feeding, even at a time of year when secretion rates are naturally low.

Effects of estradiol-17beta and pimozide on prolactin synthesis in male and female rats.

Abstract: The effects of in vivo treatment with estradiol-17β and pimozide on the in vitro incorporation of radioactive amino acids into prolactin were determined. The synthesis of anterior pituitary proteins was examined in a double label experiment in which pituitaries from ovariectomized, female rats were incubated with [14C]leucine and pituitaries from rats receiving estradiol injections were incubated with [3H]leucine. Electrophoresis of the combined samples demonstrated that estradiol specifically increased incorporation into prolactin, but not other pituitary proteins. The quantitation of prolactin synthesis was compared using gel electrophoresis and immunoprecipitation. The methods yielded results which were indistinguishable quantitatively and both methods demonstrated the ability of estradiol to stimulate prolactin synthesis. Anterior pituitaries were able to incorporate [3H]leucine into total protein, prolactin and growth hormone for at least 6 h in vitro. Differences between pituitaries from control and...

Effect of estradiol-17 β on the cytology of the liver, gonads and pituitary, and on plasma electrolytes in the female freshwater eel

Abstract: Female freshwater eels injected with estradiol-17β (E2) for 15–78 days appear paler and secrete more mucus than controls. The resulting strongly opalescent blood plasma indicates that vitellogenin synthesis occurs in the liver, which shows a significant hypertrophy, an increased vacuolization (lipid material) and glycogen depletion. Plasma sodium is lowered, but calcium levels are considerably increased. The gonosomatic index increases (0.92±0.1 to a maximum of 2.21). Oocytes are enlarged, but the incorporation of vitellogenin remains discrete. Gonadotrophs (GTH cells), small and scarcely visible in the pituitary of control eels, are hypertrophied and contain numerous glycoprotein granules after E2-administration. E2 may act on the pituitary and/or hypothalamus via a positive feedback to induce gonadotrophin (GTH) synthesis; GTH release seems to be very limited as indicated by the ovarian response. The differentiation of GTH cells in eels treated with fish pituitary extracts is most probably due to secretion of E2 by the ovary, which reacts on the pituitary. Various hypotheses are considered to explain the low GTH release. Thyrotrophs, somatotrophs and prolactin cells of the pituitary are stimulated. In the pars intermedia, MSH and PAS-positive cells appear less active. A possible antidopaminergic effect of E2 is discussed. E2 administration constitutes a simple and economic technique to induce the synthesis of GTH and will facilitate the biochemical and biological study of the latter hormone in eels.