NCBI Summary:
This gene encodes the anterior pituitary hormone prolactin. This secreted hormone is a growth regulator for many tissues, including cells of the immune system. It may also play a role in cell survival by suppressing apoptosis, and it is essential for lactation. Alternative splicing results in multiple transcript variants that encode the same protein. [provided by RefSeq, Aug 2011]
General function
Ligand, Hormone
Comment
Cellular localization
Secreted
Comment
Evidence of altered dopaminergic modulation of prolactin and thyrotropin secretion in patients with polycystic ovary syndrome. Velardo A et al. (1991) In order to evaluate the functional activity of the tubero-infundibular dopaminergic system in polycystic ovary syndrome (PCOS), we analysed the prolactin (PRL) and thyrotropin (TSH) responses to the dopamine antagonist sulpiride. We studied 8 euthyroid women affected by PCOS and 7 normal women. The mean baseline PRL values were normal in both groups. After sulpiride administration the incremental area under the PRL profile in PCOS was significantly lower than in normal subjects (p less than 0.01). The mean basal plasma TSH levels were significantly higher in the PCOS than in the control group (p less than 0.01). After sulpiride administration the incremental area under the TSH profile was significantly lower in PCOS patients than in normal women (p less than 0.01). The higher basal plasma levels of TSH, the blunted response of PRL and the lack of response of TSH to sulpiride in PCOS suggest a relative decrease of the dopaminergic activity in PCOS patients.//////////////////
Ovarian function
Luteinization, Luteolysis
Comment
Expression regulated by
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Ovarian localization
Luteal cells
Comment
Bovine corpus luteum is an extrapituitary site of prolactin production Shibaya M, et al .
Prolactin (PRL) is known to be synthesized not only in the anterior pituitary, but also in other organs including the ovary. Among its various functions, PRL is regarded as the most important constituent of the luteotropic complex in rodents and pigs. The purpose of the present study was to determine whether PRL is produced locally in bovine corpus luteum (CL) and to determine its possible roles in CL. In the present study, we examined changes during the luteal phase in (1) the expressions of PRL and PRL receptors (long form: l-PRLR, short form: s-PRLR) in CL and (2) the localization of PRL in CL. We also measured the levels of PRL mRNA in cultured luteal cells and luteal endothelial cells. Furthermore, the effect of PRL on progesterone (P4) and prostaglandin (PG) F2alpha production by cultured bovine luteal cells was examined. Semiquantitative RT-PCR analysis revealed that the mRNAs for PRL and its two receptors, l- and s-PRLR, were expressed in all luteal stages examined. PRL mRNA expression was less in the regressed stage (days 19-21 after ovulation) than in the other stages. Both l-PRLR and s-PRLR mRNA expressions were higher in the late luteal stage (days 15-17) than in the other stages, while the ratio of l-PRLR to s-PRLR was less in the regressed stage than in the other stages. PRL mRNA was also detected in cultured luteal cells and luteal endothelial cells. PRL protein was immunohistochemically detected only in CL of the mid- and regressed stages. It was detected in smooth muscle cells of the intraluteal arterioles and endothelial cells but not in luteal cells and other cell types of CL. Exposure of cultured luteal cells obtained from mid-stage CL (days 8-12) to bovine PRL (100, 200 ng/ml) for 24 hr did not affect P4 and PGF2alpha production by the cells. The present study demonstrates for the first time the expressions of PRL and PRLR mRNA in bovine CL throughout the luteal phase. The overall results strongly suggest that the bovine CL is an extrapituitary site of PRL production. Mol. Reprod. Dev. (c) 2006 Wiley-Liss, Inc.
Follicle stages
Comment
The Expression of Prolactin and its Cathepsin D-mediated Cleavage in the bovine Corpus luteum vary with the Oestrous cycle. Erdmann S et al. In the corpus luteum (CL), blood vessels develop, stabilize, and regress. This depends on the ratio of pro- and anti-angiogenic factors, which change during the ovarian cycle. The present study focuses on the possible roles of 23-K prolactin (PRL) in the bovine CL and its anti-angiogenic N-terminal fragments after extracellular cleavage by cathepsin D (Cath D). Prolactin RNA and protein were demonstrated in the CL tissue, in luteal endothelial cells and steroidogenic cells. Cath D was detected in CL tissue, cell extracts and corresponding cell supernatants. In the intact CL, 23-K PRL levels decreased gradually, whereas Cath D levels concomitantly increased between early to late luteal stages. In vitro, PRL cleavage occurred in the presence of acidified homogenates of CL tissue, cells and corresponding cell supernatants. Similar fragments were obtained with purified Cath D, and their appearance was inhibited by pepstatin A. The aspartic protease specific substrate MOCAc-GKPILF~FRLK(Dnp)-D-R-NH2 was cleaved by CL cell supernatants, providing further evidence for Cath D activity. 16-K PRL inhibited proliferation of luteal endothelial cells accompanied by an increase in cleaved caspase-3. In conclusion: (1) The bovine CL is able to produce PRL and to process it into anti-angiogenic fragments by Cath D activity. (2) PRL cleavage might mediate angioregression during luteolysis. Key words: prolactin fragments, lysosomal proteases, acidic microenvironment, extracellular proteolysis, ovary.