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At least 541 records · Page 30Linked to original sources
PubMed1992

The rat prolactin gene is expressed in brain tissue: detection of normal and alternatively spliced prolactin messenger RNA.

Previous work by our laboratory has described the presence and widespread distribution of a PRL-like immunoreactive protein in brain. The persistence of this PRL in brain after hypophysectomy provided substantial evidence that brain PRL represented the product of a synthetic pool separate from that of the anterior pituitary PRL. To pursue this concept of independent synthesis further, we sought to determine whether brain tissue expressed PRL mRNA. Although we were easily able to detect a single species of PRL mRNA in pituitary by Northern hybridization, we could not visualize message in hypothalamus or extrahypothalamic brain by this technique. Therefore, we performed the polymerase chain reaction on cDNAs from anterior pituitary, hypothalamus, discrete extrahypothalamic brain regions, and other tissues. Hypothalamus and extrahypothalamic brain parts, including the cerebellum, caudate, brain stem, amygdala, thalamus, cortex, and hippocampus, were all positive to varying degrees. Lung and liver were negative, and anterior pituitary was consistently positive. All positive tissues, including anterior pituitary, expressed two hybridization signals: the expected amplified product and another smaller one. The smaller amplified product is presumably the result of an alternatively spliced transcript that is missing part of the PRL gene. Hypophysectomized animals did not express PRL message in brain, but expression was restored in hypophysectomized animals treated with testosterone. Transcripts for Pit-1 (GHF-1), a transcription factor important in regulation of pituitary PRL, were not detected in hypothalamus or any of the extrahypothalamic brain parts. The finding of testosterone stimulation of brain PRL message and undetectable levels of Pit-1 (GHF-1) in hypothalamic and extrahypothalamic brain regions indicates that the transcriptional regulation of PRL in the brain is different from that in the anterior pituitary.

Animals↗
PubMed1996

Synthesis and release of glycosylated prolactin in transfected cells with human prolactin complementary deoxyribonucleic acid.

To analyze how the synthesis and release of glycosylated PRL (G-PRL) is regulated, we transfected human PRL complementary deoxyribonucleic acid (cDNA) into three different cell lines consisting of GH3 cells that originated in rat pituitary tissue, Chinese hamster ovary cells, and COS-1 cells generated from monkey renal tissue. 35S-labeled PRLs produced by the cells were immunoprecipitated with anti-human PRL antiserum, and the ratios of G-PRL to total PRL were compared. PRLs of 23 kDa and 25 kDa were detected in the cell lysate and medium. The 25-kDa PRL was confirmed to be a glycosylated form by endoglycosidase treatments. The ratios of G-PRL/total PRL were 0.17-0.33, which were similar in lysates and media and among different cell lines. Pulse-chase experiments revealed that the autonomaous secretion rates of G-PRL and non-glycosylated PRL were almost identical. These results indicate that synthesis and secretion kinetics of human PRL may not be affected by its glycosylation in the cells transfected with PRL cDNA.

Animals↗
PubMed1985

Modulation of postinhibitory increase in plasma prolactin by domperidone in patients with prolactin secreting adenoma.

To evaluate the PRL secretory mechanism in patients with PRL-secreting adenoma (PRL-oma), plasma PRL responses to dopamine (DA) were studied in these cases and in normal subjects. Plasma PRL values showed clear decreases during the infusion of DA (5 micrograms/kg/min for 90 min) in both 6 normal and 7 PRL-oma subjects (%decrease: 43.8 +/- 3.9% vs. 53.9 +/- 5.6%; NS) and postinhibitory increases after the termination. However, the postinhibitory increase occurred more promptly and markedly in PRL-oma patients than in normal subjects, i.e. the postinhibitory increase exceeded the basal level 45 min after the termination of DA infusion in PRL-oma patients, whereas the increase in normal subjects did not exceed the basal level even 90 min after the infusion. When domperidone was injected at the termination of DA infusion, the postinhibitory increases were significantly enhanced in either PRL-oma or normal subjects. The maximal increments in plasma PRL in the combination test of DA plus domperidone were significantly larger in PRL-oma patients, but were almost the same in normal controls, compared to the single domperidone test. In contrast, TRH did not modify the postinhibitory rises in 9 PRL-oma patients. These results indicate that the secretory properties and the sensitivities of lactotrophs to decreasing action of DA might be different between PRL-oma patients and normal controls. Further, the postinhibitory rebound phenomenon in PRL-oma patients is possibly determined by an overshoot of PRL storage concomitantly with a decreasing DA action.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1992

A normal ovulatory woman with hyperprolactinemia: presence of anti-prolactin autoantibody and the regulation of prolactin secretion.

We present the case of a normal ovulatory woman with marked hyperprolactinemia and no evidence of a pituitary adenoma on CT and MRI. Gel filtration studies showed that most immunoreactive PRL was eluted as 150K-170K macroprolactin. Anti-PRL autoantibody was detected and Scatchard analysis revealed a low-affinity (the association constant: 1.29 x 10(7) l/mol), high-capacity (the maximal binding capacity: 1174 micrograms/l) antibody. Dopamine had little suppressive effect on PRL levels and an antidopaminergic agent elicited an augmented response of PRL secretion. These results suggest that the presence of anti-PRL autoantibody may delay the clearance of PRL and/or may alter the central regulation of PRL secretion.

Adult↗
PubMed1994

Effects of anti-prolactin autoantibodies on serum prolactin measurements.

The influence of anti-PRL autoantibodies on PRL measurements determined by immunoassays was investigated in 10 patients with anti-PRL autoantibodies. Four different immunoassay systems (two double-antibody radioimmunoassays (RIAs), a single-antibody RIA and an immunoradiometric assay (IRMA)) were examined. Total and free PRL were extracted from sera by precipitating gamma-globulin with polyethylene glycol with and without acidification, respectively. PRL values determined by direct measurement were compared with total PRL values. The proportion of free to total PRL levels determined by each immunoassay in sera with anti-PRL autoantibodies was significantly lower than in control sera. Values obtained by direct measurement of PRL (a routine assay procedure) in control sera were similar to total PRL values, whereas in sera with anti-PRL (a routine assay procedure) in control sera were similar to total PRL values, whereas in sera with anti-PRL autoantibodies the values varied from one immunoassay to the other. In sera with anti-PRL autoantibodies, double-antibody RIA 1, RIA 2 and single-antibody RIA 3 yielded values lower for PRL than for total PRL (52 +/- 15% in RIA 1, 40 +/- 8.8% in RIA 2, 40 +/- 14% in RIA 3), while PRL levels determined by IRMA were not significantly different (112 +/- 14%). Immunoglobulin G purified from serum with anti-PRL autoantibodies dose-dependently decreased the recovery of PRL assayed by the double-antibody technique, while it did not affect that by IRMA. These data suggest that the presence of anti-PRL autoantibodies gives variable results depending on the immunoassays used.(ABSTRACT TRUNCATED AT 250 WORDS)

Autoantibodies↗