• The Korean Journal of Zoology
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• v.33 no.2
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• pp.183-190
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• 1990

The present study exarnines the physiological alteradons in prolactin (PRL) messenger ribonucleic acid (mRNA) and serum PRL levels during the rat estrous cycle and the effed of naloxone, an endogenous oploid peptide receptor antagonist, on PRL gene expression during the rat estrous cycle. Adult female rats exhibiting at least two consecutive 4-day estrous cycles were used in this study. A single injection of naloxone (2mg/kg b.w.) or saline was given sc 30 mm prior to decapitation. Animals were sacrificed at 10:00 h of each stage of the estrous cycle, and at 2-h intervals from 10:00 h to 20:00 h during the proestrus. PRL mRNA and serum PRL levels were determined by a RNA-blot hybridization with the rat PRL cDNA probe and by a PRL radjoimmunoassay, respectively. PRL mRNA and serum PRL levels were not dramatically altered in the morning of each stage of diestrus I, II and proestrus, and naloxone failed to modify the two parameters. During estrus naloxone clearly suppressed serum PRL levels, but it was unable to modify PRL mRNA levels. A more detailed examination of the proestrus stage revealed that PRL mRNA and serum PRL levels were fluctuated as a function of time: PRL mRNA levels reached a maximum level at 12:00 h and gradually decreased until 18:00 h. PRL mRNA levels then rose at 20:00 h. No difference of PRL mRNA levels between the control and naloxone-treated groups was observed. Changes in serum PRL levek during proestrus were conversely related to changes in PRL mRNA: serum PRL levels were low from 10:00 h to 14:00 h, then increased and reached a maximum level at 16:00-18:00 h. Following then, serum PRL levels were decreased. Naloxone was effective in suppressing the charaderistic afternoon surge of PRL from 16:00 h to 20:00 h. These data clearly showed that alterations in PRL mRNA levels were conversely correlated with changes mn serum PRL levels on proestrus, indicating a differential regulation of PRL gene expression and secretion.

• Korean Journal of Biological Psychiatry
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• v.3 no.1
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• pp.121-126
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• 1996

Objects : There is considerable interest in the role of serotonin(5-HT) in the pathophysiology of schizophrenia. Cimetidine, $H_2$ antagonist, produces transient increase in serum prolactin(PRL) levels by indirect serotonergic mechanism in man following intravenous administration. Therefore the authors investigated the effects of cimetidine on serum PRL levels of male unmedicated schizophrenics. Method : Baseline serum prolactin level and psychopathology were measured at 9:00 AM. in the two groups(12 positive schizophrenics, 7 negative schizophrenics) and $T_{30}$ levels were measured 30 minutes after intravenous injection of cimetidine (ie, 9:30 AM) Results: 1) Baseline prolactin levels were not different in the three groups. 2) Prolactin levels of 30 minutes after intravenous injection of cimetidine($T_{30}$) compared with baseline prolactin levels were increased all in the three groups. 3) Degrees of interval change from baseline to $T_{30}$ were significantly different between normal control and negative schizophrenics(p<0.05). Conclusion : The prolactin response to cimetidine was significantly blunted in negative male schizophrenics than normal control. These data are consistent with the hypothesis of an abnormality of serotonergic activity, including down-regulation $5-HT_2$ receptors, in male negative schizophrenics.

• The Korean Journal of Zoology
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• v.34 no.3
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• pp.426-431
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• 1991

The present study examines the effect of naloxone, mu-opioid receptor antagonist, on prolactin (PRL) gene expression and secretion induced by estradiol (I) treahent in vivo. Adult rats were ovariectomized (OW) and implanted with Silastic capsules containing either vehicle (oil) or E. Three days later, NAL (2 mg/kg BW) or saline urere injected 30 min prior to sacrifice. To examine PRL secretion in vitro, the pituitaries were incubated in the superfusion system for 3 hrs. Superfusates were collected at 10 min intenrals on ice and subjected to PRL radioimmunoassay. Endogenous release of PRL in OU( + I rats was signifcantlv higher than that in OVX rats (mean $\pm$ SE; 24.5 $\pm$ 3.1 vs 14.5 $\pm$ 2.9 ns/10 min). A single injection of NAL clearly inhibited PRL release in Nitro from pituitaries derived from OW + I rats, but not from OW group. PRL myNA was determined by RNA-blot hybridisation assay with nicktranslated PRL CDNA. E stimulated PRL mRNA about 3 fold over that shown in OW group. Treahent of NAL suppressed the I-stimulated PRL myNA in OVX + I group, but not in OVX group. These data clearly showed that the NAL-induced inhibition of PRL secretion was well correlated with changes in PRL mRNA level and this inhibitory process appears to be mediated in I-dependent manner.

• Clinical and Experimental Reproductive Medicine
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• v.11 no.2
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• pp.5-15
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• 1984

본 연구는 황체기 단축현상(Short luteal phase, SLP) 을 가진 한국여성의 월경주기내 Prolactin 호르몬의 농도변화를 정상월경주기 (Normal luteal phase, NLP)와 비교하고져 하였다. 한편, Circadian rhythm 내 PRL 농도의 변화를 비교하고 임신기간중 PRL의 농도변화를 방사면역측정법(RIA) 으로 조사하였다. SLP여성의 PRL 농도는 후기의 여포성숙기(Late follicular phase) 및 초기황체형성기(Early IuteaI phase) 정상에 비하여 현저히 낮았다. 정상 월경주기에서는 PRL/Progesterone(mU/1/mg/ml)의 비율이 후기 여포성숙기까지 증가한 후 LH Peak day 이후 감소하는데 반하여 SLP여성의 비율은 조기 여포성숙기부터 계속적인 감소현상을 보였다. 또한 취침전 (04:00시) PRL의 농도는 SLP여성에게는 현저히 낮았다. 임신주기중 PRL의 농도는 4개월째 1,077mU/l 에서부터 9개월째 4,462mU/l까지 점진적인 증가를 하였다. 위의 결과로 보아 황체기단축현상은 PRL의 분비이상이 하나의 주요요인이 될 수 있으며, 특히 PRL/Progesterone의 농도비율이 SLP의 판정에 한 지표가 될 수 있을 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.7
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• pp.1031-1034
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• 1999

Circulating lymphocytes collected from control and heat-stressed buffaloes were subjected to in vitro culture with glucocorticoids, epinephrine or serotonin and their effect, if any, on the release of intracellular prolactin (PRL) was studied using ELISA and C-ELISA techniques. It was noted from the study that PRL level was higher in lymphocytes than in plasma of the control and heat-stressed animals, and that the PRL levels increased in the plasma of heat-stressed animals compared to that of non stressed animals with a significant decrease in lymphocytic PRL content by heat stress. Epinephrine and serotonin significantly increased the release of intracellular PRL from the lymphocytes of both in the control and the heat-stressed buffaloes but release of PRL from lymphocyte was not significantly changed by cortisol treatment in both control and heat-stressed buffaloes as compared to epinephrine and serotonin in vitro. When lympocytes were incubated with serotonin, it caused drastic lysis of the lymphocytes but epinephirine and cortisol did not show any lysis. It may be concluded from this study that hormones like epinephrine or serotonin known to increase during stress, release intracellular PRL from lymphocytes, the satellite PRL storage/synthesizing organ of blood, although the mechanism of the release is different.

• Journal of Embryo Transfer
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• v.13 no.2
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• pp.179-190
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• 1998

Prolactin (PRL) surge in cycling rats at proestrous afternoon has previously been reported as an inducer of apoptotic cell death of luteal cells. This death-inducing action of PRL seeins unusual, because PRL can he categorized as a cell-survival factor, if other known physiological functions of PRL are taken into account. In this study, the apoptotic action of PRL was assessed in cultured cells prepared from rat luteal tissue and underlying molecular /cellular mechanism of PRL-induced luteolysis was analyzed. The latest crop of corpora lutea (CLs) were enucleated from rat ovaries at 18:00 h on the proestrous day before the next ovulation. Donor rats were pretreated with CB154, a dopamine agonist, in order to he exempted from the endogenous PRL surge. The harvested GLs were dispersed and cultured with or without PRL (2$\mu$g /ml) for 24 or 48 h. An addition of PRL to the culture medium changed the parameters indicative of cell death via apoptosis: a decrease in cell viability (MTT) and an increase in chromatin condensation. Most of the DNA breakdown in nuclei induced by PRL occurred in steroidogenic cells which were identified by 3$\beta$-HSD activity staining, and the number of 3$\beta$-HSD-positivecells were significantly decreased. Interestingly, most of the cells with an apoptotic nucleus adhered to one or more intact and seemingly non-steroidogenic cells. Because the expression of Fas has heen shown to be abundant in murine ovary, and Fas is known to have an exact physiological role in occurrence of apoptotic cell death, the membrane form-Fas ligand (rnFasL) was quantified in the cell lysate. An addition of PRL increased expression of mFasL. Moreover, an addition of concanavalin A (ConA), a T-cell specific activator, in place of PRL, enhanced the apoptotic parameters. Cumulatively, the apoptotic PRL action was addressed to cells unknown than steroidogenic lute~ cells. The most prohable candidate for the direct target cells is Tcells in the luteal tissue that can express mFasL in response to PRL.

• Molecules and Cells
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• v.22 no.2
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• pp.189-197
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• 2006

Prolactin (PRL) is a pituitary hormone involved in various physiological processes, including lactation, mammary development, and immune function. To further investigate the in vivo and comparative endocrine roles of PRL, mouse PRL cDNA fused to the cytomegalovirus promoter, was introduced into muscle by direct injection. Previously we studied the function of rat PRL using the same protocol. PRL mRNA was detected in the muscle following injection by RT-PCR and subsequent Southern blot analysis. PRL was also detected and Western blot analysis revealed a relatively high level of serum PRL. In the pCMV-mPRL-injected female mice, the estrous cycle was extended, especially in diestrus stage and the uterus thickening that was shown in normal estrous stage was not observed. In the pCMV-mPRL-injected male mice, new blood vessels were first found at 5 weeks of age and fully developed blood vessels were found after 8 weeks in the testis. The number of Leydig cells increased within the testis and the testosterone level in serum was observed high. Finally, the number of white blood cells (WBCs) increased in the pCMV-mPRL-injected mice. The augmentation of WBCs persisted for at least 20 days after injection. When injection was combined with adrenalectomy, there was an even greater increase in number of WBCs, especially lymphocytes. This increase was returned normal by treatment with dexamethansone. Taken together, our data reveal that intramuscularly expressed mouse PRL influences reproductive functions in female, induces formation of new blood vessels in the testis, and augments WBC numbers. Of notice is that the Leydig cell proliferation with increased testosterone was conspicuously observed in the pCMV-mPRL-injected mice. These results also suggest subtle difference in function of PRL between mouse and rat species.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.4
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• pp.459-462
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• 2006

Prolactin (PRL) plays an important role in promoting mammalian mammary gland development, and milk production during lactation. Therefore the PRL gene was chosen as a candidate gene for milk traits in Holstein dairy cows. PCR-SSCP and PCR-RFLP were used to analyze genetic variations in the 5' regulation region of the PRL gene. In this part of the gene, two new polymorphic sites were detected in the Chinese Holstein dairy cows. One was a XbaI-RFLP locus, and the other was an SSCP locus. Statistical analysis showed that the XbaI-RFLP locus and the SSCP locus had a significant positive effect on milk traits.

• Animal cells and systems
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• v.4 no.1
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• pp.71-76
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• 2000

The aim of this study was to investigate expression patterns of the prolactin (PRL) and c-fos genes by 17$\beta$-estradiol (17$\beta$-E) and stress in the mouse pituitary. In the pituitary, the levels of PRL mRNA were found high with some fluctuation at 30, 50, and 90 min whereas the levels of PRL mRNA were low at 120 min when ovariectomized female mice were injected with 17$\beta$-E or vehicle. PRL mRNA levels began to increase again at 4 h and remained high up to 24 h only in the 17$\beta$-E- treated mice. The overall changes in c-fos mRNA by 17$\beta$-E were very similar to those in PRL mRNA in the pituitary. Subsequent study revealed that these high initial levels of PRL and c-fos mRNAs were caused by stress during Injection, not by 17$\beta$-E, since vehicle injection alone into the ovariectomized mice could increase the levels of PRL and c-fos mRNAs. The stress-induced elevations of PRL and c-fos mRNAs were inhibited by bromocriptin, a dopamine agonist, suggesting that the dopaminergic system is involved in the action route of injection stress. In addition, the induced levels of c-fos mRNA by 17$\beta$-E and stress in the pituitary were very low compared with those in the uterus. The time course changes in c-fos mRNA level were different between the pituitary and uterus. Taken together, these data indicate that PRL and c-tos gene expression in the pituitary are regulated by 17$\beta$-E and stress in a parallel manner, supporting the notion that c-Fos plays a role in regulation of PRL gene expression.

• Animal cells and systems
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• v.3 no.3
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• pp.311-317
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• 1999

Prolactin (PRL) was reported to be locally synthesized in many brain areas including the hypothalamus, thalamus (TH) and hippocampus (HIP). In the pituitary lactotrophs, PRL synthesis is dependent upon a pituitary-specific transcription factor, Pit-1. In the present study, we attempted to identify Pit-1 or Pit-1-like protein in brain areas known as the synthetic sites of PRL. Reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot analysis showed the same Pit-1 transcripts in brain areas such as the medial basal hypothalamus (MBH), preoptic area (POA), TH, and HIP with the Pit-1 transcripts in the anterior pituitary (AP). Electrophoretic mobility shift assay (EMSA) was run with nuclear protein extracts from brain tissues using a double strand oligomer probe containing a putative Pit-1 binding domain. Shifted bands were found in EMSA results with nuclear proteins from MBH, POA, TH and HIP. Specific binding of the Pit-1-like protein was further confirmed by competition with an unlabeled cold probe. Antisense Pit-1 oligodeoxynucleotide (Pit-1 ODN), which was designed to bind to the Pit-1 translation initiation site and block Pit-1 biosynthesis, was used to test Pit-1 dependent brain PRL transcription. Two nmol of Pit-1 ODN was introduced into the lateral ventricle of a 60-day old male rat brain. RNA blot hybridization and in situ hybridization indicated a decrease of PRL mRNA signals by the treatment of Pit-1 ODN. Taken together, the present study suggests that Pit-1 may play an important role in the transcriptional regulation of local PRL synthesis in the brain.