Prolactin mRNA Research Articles

Possible involvement of thyrotropin-releasing hormone receptor 3 in the release of prolactin in the metamorphosing bullfrog larvae

In amphibians, thyrotropin (TSH), corticotropin (ACTH) and prolactin (PRL) are regarded as the major pituitary hormones involved in metamorphosis, their releasing factors being corticotropin-releasing factor (CRF), arginine vasotocin (AVT), and thyrotropin-releasing hormone (TRH), respectively. It is also known that thyrotropes and corticotropes are equipped with CRF type-2 receptor and AVT V1b receptor, respectively. As for PRL cells, information about the type of receptor for TRH (TRHR) through which the action of TRH is mediated to induce the release of PRL is lacking. In order to fill this gap, an attempt was made to characterize the TRHR subtype existing in the PRL cells of the anterior pituitary gland of the bullfrog, Rana catesbeiana. We cloned cDNAs for three types of bullfrog TRHRs, namely TRHR1, TRHR2 and TRHR3, and confirmed that all of them are functional receptors for TRH by means of reporter gene assay. Analyses with semi-quantitative reverse transcription-PCR and in situ hybridization revealed that TRHR3 mRNA is expressed in the anterior lobe and that the signals reside mostly in the PRL cells. It was also noted that the expression levels of TRHR3 mRNA in the anterior pituitary as well as in the PRL cells of metamorphosing tadpoles elevate as metamorphosis progresses. Since the pattern of changes in TRHR3 mRNA levels in the larval pituitary is almost similar to that previously observed in the pituitary PRL mRNA and plasma PRL levels, we provide a view that TRHR3 mediates the action of TRH on the PRL cells to induce the release of PRL that is prerequisite for growth and metamorphosis in amphibians.

Leptin Stimulates Prolactin mRNA Expression in the Goldfish Pituitary through a Combination of the PI3K/Akt/mTOR, MKK3/6/p38MAPK and MEK1/2/ERK1/2 Signalling Pathways.

Leptin actions at the pituitary level have been extensively investigated in mammalian species, but remain insufficiently characterized in lower vertebrates, especially in teleost fish. Prolactin (PRL) is a pituitary hormone of central importance to osmoregulation in fish. Using goldfish as a model, we examined the global and brain-pituitary distribution of a leptin receptor (lepR) and examined the relationship between expression of lepR and major pituitary hormones in different pituitary regions. The effects of recombinant goldfish leptin-AI and leptin-AII on PRL mRNA expression in the pituitary were further analysed, and the mechanisms underlying signal transduction for leptin-induced PRL expression were determined by pharmacological approaches. Our results showed that goldfish lepR is abundantly expressed in the brain-pituitary regions, with highly overlapping PRL transcripts within the pituitary. Recombinant goldfish leptin-AI and leptin-AII proteins could stimulate PRL mRNA expression in dose- and time-dependent manners in the goldfish pituitary, by both intraperitoneal injection and primary cell incubation approaches. Moreover, the PI3K/Akt/mTOR, MKK3/6/p38MAPK, and MEK1/2/ERK1/2—but not JAK2/STAT 1, 3 and 5 cascades—were involved in leptin-induced PRL mRNA expression in the goldfish pituitary.

Expression of Prolactin Receptor mRNA in Lactotrophs and Somatotrophs of the Chicken Anterior Pituitary Gland.

Prolactin (PRL) is a hormone mainly secreted by the anterior pituitary gland. In birds, PRL exerts a variety of physiological functions in target tissues expressing the PRL receptor (PRLR). In chicken, the PRLR mRNA is abundant in the anterior pituitary gland, but its regional and cellular localization are unknown. In the present study, we investigated the expression of the PRLR mRNA in cephalic and caudal lobes of the chicken anterior pituitary gland. Real-time polymerase chain reaction (PCR) revealed high levels of PRLR mRNA in both cephalic and caudal lobes. In situ hybridization revealed that the PRLR mRNA was distributed in a wide area of both lobes, and co-localized with the PRL and growth hormone (GH) mRNAs in the cephalic and caudal lobes, respectively. These results suggest that PRL exerts autocrine/paracrine effects through PRLR on PRL-producing lactotrophs and GH-producing somatotrophs in the chicken anterior pituitary gland.

Icaritin inhibits decidualization of endometrial stromal cells.

The aim of the present study was to investigate the effects of Icaritin on the proliferation and decidualization of endometrial stromal cells (ESCs). A total of 20 specimens of endometrium were collected during hysterectomy at the Gynecology Department of Shenzhen Nanshan People's Hospital (Shenzhen, China) between August 2014 and December 2015. The endometrium was digested with high concentrations of collagenase and DNase and filtered with meshes, and then the glandular epithelial and stromal cells were separated by the adhesion purification method. The purity of stromal cells was identified by vimetin and cytokeratin 7 immunostaining. The estradiol + progesterone (E2+P4) and/or cyclic adenosine monophosphate (cAMP) were added to induce an in vitro decidualization model, which was used to analyze the effect of Icaritin on the decidualization ability of the human ESCs. The decidualization markers of human ESCs, prolactin (PRL) and insulin-like growth factor-binding protein 1 (IGFBP-1), was analyzed by reverse-transcription quantitative polymerase chain reaction measurements of the mRNA levels, PRL immunostaining and ELISA analysis of the IGFBP-1 protein levels in the cells or cell culture supernatant separately. The results demonstrated that treatment with E2+P4 and/or cAMP for 96 h was able to induce decidualization in ESCs, and that the cells demonstrated polygon-shaped epithelioid changes. The cell nuclei revealed multinuclear changes, and the cells were also observed to be large and round in shape. The PRL expression and upregulated IGFBP-1 mRNA and protein levels in the E2+P4+cAMP treatment group indicated successful decidualization of the in vitro model. However, the addition of Icaritin inhibited the expression of PRL and IGFBP-1 mRNA, as well as IGFBP-1 protein in the induced ESCs compared with groups without Icaritin. These results suggest that Icaritin was able to inhibit the expression of decidualization-related genes in ESCs in vitro. However, the exact mechanisms require further investigation.

Effects of Pup Separation on Stress Response in Postpartum Female Rats.

There is a complex collection of neuroendocrine function during the postpartum period. Prolactin (PRL) released by suckling stimulus and its PRL receptors (PRL-R) in the central nervous system (CNS) are involved in hyporesponsiveness of the hypothalamic-pituitary-adrenal (HPA) axis in lactating mammals including rodents and humans. It is not clear how long it takes to reestablish the attenuated HPA axis activity of lactating rats to a pre-pregnancy state after pup separation. We first tested the hypothesis that HPA axis activity in response to an acute stress in postpartum rats would return to a pre-pregnancy state after pup separation. Restraint stress for 30 min was performed at the end of pup separation as an acute stressor. Plasma levels of corticosterone (CORT) were measured following restraint stress or no-stress (control) in virgin rats and postpartum rats housed with their pups or with pup removal for different periods of time of one hour, 24 h, or eight days. We then tested the hypothesis that circulating PRL level and CNS PRL-R gene expression were involved in mediating the acute stress response in postpartum rats. Plasma levels of PRL and PRL-R mRNA levels in the choroid plexus of the CNS were determined in both no-stress and stress, virgin rats, and postpartum rats housed with their pups or with pup removal for various periods, and their correlation with plasma CORT levels was assessed. The results demonstrated that PRL levels declined to virgin state in all postpartum rats separated from their pups, including the dams with one-hour pup separation. Stress-induced HPA activity dampened in lactating rats housed with pups, and returned to the pre-pregnancy state after 24 h of pup separation when both circulating PRL level and CNS PRL-R expression were restored to a pre-pregnancy state. Additionally, basal plasma CORT and CNS PRL-R expression were significantly correlated in rats with various pup status. This study suggested that stress-induced HPA activation occurred when PRL-R expression was similar to the level of virgin females, indicating that PRL-R upregulation contributes to an attenuated HPA response to acute stress. Understanding neuroendocrine responses to stress during the postpartum period is critical to understand postpartum-related neuropsychiatric illnesses and to maintain mental health in postpartum women.

Regulatory role of melatonin and BMP-4 in prolactin production by rat pituitary lactotrope GH3 cells

The effects of melatonin on prolactin production and its regulatory mechanism remain uncertain. We investigated the regulatory role of melatonin in prolactin production using rat pituitary lactotrope GH3 cells by focusing on the bone morphogenetic protein (BMP) system. Melatonin receptor activation, induced by melatonin and its receptor agonist ramelteon, significantly suppressed basal and forskolin-induced prolactin secretion and prolactin mRNA expression in GH3 cells. The melatonin MT2 receptor was predominantly expressed in GH3 cells, and the inhibitory effects of melatonin on prolactin production were reversed by treatment with the receptor antagonist luzindole, suggesting functional involvement of MT2 action in the suppression of prolactin release. Melatonin receptor activation also suppressed BMP-4-induced prolactin expression by inhibiting phosphorylation of Smad and transcription of the BMP-target gene Id-1, while BMP-4 treatment upregulated MT2 expression. Melatonin receptor activation suppressed basal, BMP-4-induced and forskolin-induced cAMP synthesis; however, BtcAMP-induced prolactin mRNA expression was not affected by melatonin or ramelteon, suggesting that MT2 activation leads to inhibition of prolactin production through the suppression of Smad signaling and cAMP synthesis. Experiments using intracellular signal inhibitors revealed that the ERK pathway is, at least in part, involved in prolactin induction by GH3 cells. Thus, a new regulatory role of melatonin involving BMP-4 in prolactin secretion was uncovered in lactotrope GH3 cells.

HCG activates Epac-Erk1/2 signaling regulating Progesterone Receptor expression and function in human endometrial stromal cells.

How does hCG signal in human endometrial stromal cells (ESCs) and what is its role in regulating ESC function? hCG signaling in ESCs activates the extracellular signal-regulated protein kinases 1 and 2 (Erk1/2) pathway through exchange protein activated by cyclic AMP (cAMP) (Epac) and transiently increases progesterone receptor (PR) transcript and protein expression and its transcriptional function. hCG is one of the earliest embryo-derived secreted signals in the endometrium, which abundantly expresses LH/hCG receptors. hCG signals through cAMP/protein kinase A (PKA) in gonadal cells, but in endometrial epithelial cells, hCG induces Erk1/2 activation independent of the cAMP/PKA pathway. Few data exist concerning the signal transduction pathways triggered by hCG in ESCs and their role in regulation of ESC function. This is an in vitro study comprising patients undergoing benign gynecological surgery (n = 46). Endometrial samples were collected from normal cycling women during the mid-secretory phase for ESCs isolation. The study conducted in an academic research laboratory within a tertiary-care hospital. The activation of the Erk1/2 signal transduction pathway elicited by hCG was evaluated in ESC. Signaling pathway inhibitors were used to examine the roles of PKA, PI3K, PKC, adenylyl cyclase and Epac on the hCG-stimulated up-regulation of phospho-Erk1/2 (pErk1/2). Erk1/2 phosphorylation was determined by immunoblot. siRNA targeting Epac was used to investigate the molecular mechanisms. To assess the role of Erk1/2 signaling induced by hCG on ESC function, gene expression regulation was examined by immunofluorescence and real-time quantitative PCR. The role of PR on the regulation of transcript levels was studied using progesterone and the PR antagonist RU486. All experiments were conducted using at least three different cell culture preparations in triplicate. Addition of hCG to ESCs in vitro induced the phosphorylation of Erk1/2 through cAMP accumulation. Such induction could not be blocked by inhibitors for PKA, PKC and PI3K. Epac inhibition and knockdown with siRNA prevented pErk1/2 induction by hCG. ESCs stimulated with hCG for up to 72 h showed a significant increase in PR mRNA and immunofluorescent label at 48 h only; an effect that was abrogated with the mitogen-activated protein kinase kinase inhibitor UO126. In addition, the hCG-activated Erk1/2 pathway significantly decreased the mRNA levels for secreted frizzled-related protein 4 (SFRP4) at 24 h, whereas it increased those for homeobox A10 (HOXA10) at 48 h (P = 0.041 and P = 0.022 versus control, respectively). Prolactin mRNA levels were not significantly modified. HOXA10 mRNA up-regulation by hCG was not enhanced by co-stimulation with progesterone; however, it was completely abolished in the presence of RU486 (P = 0.036 hCG versus hCG + RU486). N/A. This is an in vitro study utilizing stromal cell cultures from human endometrial tissues. Furthermore, results obtained should also be confirmed in vivo in the context of the whole human endometrial tissue and hormonal milieu. The in vitro experiments using hCG have been conducted without other hormones/factors that may also modulate the ESCs response to hCG. We have determined that hCG induces the PR through the Erk1/2 pathway in ESCs which may render them more sensitive to progesterone, increasing our understanding about the effects of hCG at the embryo-maternal interface. The activation of such a pathway in the context of the hormonal milieu during the window of implantation might contribute to a successful dialog between the embryo and the uterus, leading to appropriate endometrial function. Defective hCG signaling in the endometrial stromal tissue may lead to an incomplete uterine response, compromising embryo implantation and early pregnancy. This work was supported by the National Fund for Scientific and Technological Development, Government of Chile (FONDECYT) grants 11100443 and 1140614 (A.T.-P.). The authors have no conflicts of interest to declare.

Effect of salsolinol on ACTH and cortisol response to handling stress in early anestrous sheep

Inhibition of hypothalamic–pituitary–adrenal (HPA) axis activity by salsolinol was demonstrated in lactating sheep. We assessed whether salsolinol regulates, besides lactation, also adrenocorticotropic hormone (ACTH) and cortisol release, and if its action is prolactin-dependent. We examined two groups of early anestrous sheep, which received for three days salsolinol or vehicle-only intracerebroventricular injections, and a group of lactating sheep injected with the vehicle only. On day 3, blood samples were collected for over six hours and the anterior pituitary was dissected. Plasma ACTH, cortisol, and prolactin concentrations, and proopiomelanocortin (POMC) and prolactin (PRL) mRNA expression within the anterior pituitary were assayed. In all groups, ACTH and cortisol concentrations were higher (P < 0.05 and P < 0.001) during the first half of sampling than in the second half; there were no differences in prolactin concentration. Lactating sheep had lower (P < 0.05 and P < 0.001) plasma ACTH and cortisol concentrations and higher (P < 0.001) plasma prolactin concentration than both groups of anestrous sheep during the first half of sampling. In the second half, there were no differences in ACTH and cortisol concentrations between all groups, but prolactin concentration was still higher (P < 0.001) in lactating animals. Salsolinol treatment decreased ACTH and cortisol concentrations during the first half of sampling (P < 0.05 and P < 0.001) compared to the anestrous controls, but had no effect on prolactin concentration. POMC mRNA expression was lower (P < 0.05) and PRL mRNA expression was higher (P < 0.05) in lactating sheep than in anestrous sheep. Salsolinol did not affect POMC and PRL mRNA expression. In conclusion, increased ACTH and cortisol concentrations during the first half of sampling occurred in response to handling stress. Salsolinol inhibited the HPA axis response to stress in early anestrous sheep, and it was unrelated to prolactin secretion.

Chronic endometritis modifies decidualization in human endometrial stromal cells

BackgroundChronic endometritis (CE) is a continuous inflammation of uterine endometrium, and it is usually symptomless. As CE has been thought not to affect the reproductive status and general health of affected women, its significance has not been explored. However, recent studies have shown that CE is related with repeated implantation failures after in vitro fertilization-embryo transfer, unexplained infertility, and recurrent miscarriages. As decidua differentiates to support the implantation process and maintains the pregnancy, we hypothesized that CE may influence the process of decidualization.MethodsSeventeen patients were employed in the experiment involving culture of endometrial stromal cells (ESCs). After obtaining endometrial samples, ESCs were harvested and cultured for 13 days. The concentrations in culture media and the protein expressions in ESCs of prolactin (PRL) and insulin-like growth factor binding protein-1 (IGFBP-1), two well known decidualization markers used in a large number of in vitro models, were analyzed by ELISA and Western blotting, respectively, and the cell numbers were also counted. The mRNA levels of PRL and IGFBP-1 were tested by quantitative real time polymerase chain reaction (RT-PCR). Since sex hormone induce proliferation and differentiation to decidua via binding to the sex hormone receptors (ERα, ERβ, PRA, and PRB), their expression was assessed in another 17 patients’ paraffin-embedded endometrial tissue specimens by immunohistochemistry and semi-quantified by H-score.ResultsIncreased cell numbers and reduced secretion of PRL and IGFBP-1 were detected by ELISA in the ESCs of CE patients after culture for 13 days compared with non-CE patients. The decreased protein expression of IGFBP-1 in ESCs of CE patients was detected by Western blotting. The decreased expression of PRL mRNA and IGFBP-1 mRNA were detected by RT-PCR. Increased expressions of ERα, ERβ, PRA, and PRB were observed in the stromal cells of CE patients in comparison to non-CE patients, whereas increased expressions of ERα and ERβ were detected in the glandular cells of CE.ConclusionOur data suggests that CE modifies decidualization of human ESC through untuning the function of sex steroid hormone receptor.

Therapeutic effects of Schisandra chinensis on the hyperprolactinemia in rat.

Prolactin (PRL) is secreted from the pituitary gland in response to eating, mating, and ovulation. Increased serum concentration of PRL during pregnancy contributes to enlargement of the mammary glands of the breasts and prepares for production of milk. However, high PRL levels derived from prolactinoma and hyperprolactinemia induce physiological disorders such as infertility and early menopause. Natural compounds isolated from S.chinensis have been known to possess anti-oxidative, anti-inflammatory and anti-diabetic effects. In the present study, we examined the therapeutic effect of S.chinensis and its single compounds on hyperprolactinemia in the pituitary gland. In rat pituitary cells, PRL expression levels were examined using real-time PCR and western blot assay. Crude S.chinensis extract and its single compound, gomisin N, reduced mRNA and protein levels of PRL in GH3 cells. In addition, cell proliferation and PRL target gene expression in cells were modulated by S.chinensis. Similar to the invitro experiments, crude S.chinensis extract and gomisin N reduced PRL levels in the pituitary and serum of immature female rats. These results show that S.chinensis and its single compound, gomisin N, are regulators of PRL production and may be candidates for treatment of hyperprolactinemia and prolactinoma.

Phosphatidic acid induces decidualization by stimulating Akt-PP2A binding in human endometrial stromal cells.

Decidualization of human endometrial stromal cells (hESCs) is crucial for successful uterine implantation and maintaining pregnancy. We previously reported that phospholipase D1 (PLD1) is required for cAMP-induced decidualization of hESCs. However, the mechanism by which phosphatidic acid (PA), the product of PLD1 action, might regulate decidualization is not known. We confirmed that PA induced decidualization of hESCs by observing morphological changes and measuring increased levels of decidualization markers such as IGFBP1 and prolactin transcripts (P < 0.05). Treatment with PA reduced phosphorylation of Akt and consequently that of FoxO1, which led to the increased IGFBP1 and prolactin mRNA levels (P < 0.05). Conversely, PLD1 knockdown rescued Akt phosphorylation. Binding of PP2A and Akt increased in response to cAMP or PA, suggesting that their binding is directly responsible for the inactivation of Akt during decidualization. Consistent with this observation, treatment with okadaic acid, a PP2A inhibitor, also inhibited cAMP-induced decidualization by blocking Akt dephosphorylation.

Inactivation of the melanin concentrating hormone system impairs maternal behavior

In order to prepare the mother for the demands of pregnancy and lactation, the maternal brain is subjected to a number of adaptations. Maternal behaviors are regulated by complex neuronal interactions. Here, we show that the melanin concentrating hormone (MCH) system is an important regulator of maternal behaviors.First, we report that melanin concentrating hormone receptor 1 knockout (MCHR1 KO) mice display a disruption of maternal behavior. Early postpartum MCHR1 KO females exhibit poor nesting, deficits in pup retrieval and maternal aggression. In addition, ablation of MCH receptors results in decreased milk production and prolactin mRNA levels. Then we show that these results are in line with those obtained in wild type mice (WT) treated with the specific MCHR1 antagonist GW803430. Furthermore, following pups retrieval, MCHR1 KO mice display a lower level of Fos expression than WT mice in the ventral tegmental area, and nucleus accumbens. With the progression of the lactation period, however, the MCHR1 KO mice improve maternal care towards their pups. This is manifested by an increase in the pups׳ survival rate and the decrease in pups׳ retrieval time beyond the second day after parturition.In conclusion, we show that the MCH system plays a significant role in the initiation of maternal behavior. In this context, MCH may play a role in integrating information from multiple sources, and connecting brain reward, homeostatic and regulatory systems.

Dysfunction of WNT4/WNT5A in deciduas: possible relevance to the pathogenesis of preeclampsia.

Preeclampsia affects 5-7% of all human pregnancies worldwide. It is characterized primarily by hypertension and proteinuria. Although the pathogenesis of preeclampsia is still not fully understood, the deficiency in decidualization is considered to have a role in this disease. WNT4 and WNT5A are highly expressed in the deciduas of mice and human beings; their deficiency causes the abnormality of mouse decidualization, and consequently affects the development of the placenta and the fetus. We aimed to define the roles of WNT4 and WNT5A in human decidulization and their relationship with preeclampsia. In this study, we investigated the expression of WNT4 and WNT5A in human deciduas and their functions during decidualization, as well as their relationship with preeclampsia. We obtained deciduas from 20 women whose pregnancies were complicated by severe preeclampsia and from 20 women with uncomplicated pregnancies, as well as human endometrial stromal cells (hESCs). The levels of WNT4 and WNT5A were examined by real-time PCR, immunohistochemistry, and western blotting in deciduas. The expression of WNT4 and WNT5A in cultured hESCs was determined during decidualization. Furthermore, the roles of WNT4, WNT5A, and BMP2 on decidualization as well as their interactions were studied in cultured hESCs by interference of their expression with specific small interfering RNA, respectively. WNT4 and WNT5A were present in the decidual tissues of women with preeclampsia and women with uncomplicated pregnancies. Their expression levels of mRNA and protein in women with severe preeclampsia were significantly lower compared with women with uncomplicated pregnancies (P < 0.05). WNT4 and WNT5A were upregulated in decidualized hESCs. Knocking down of BMP2 or WNT4 in hESCs resulted in a significant increase of WNT5A mRNA and a significant reduction in the transcription of decidualization markers, insulin-like growth factor binding protein1 and prolactin (P < 0.05). In addition, silencing of WNT5A resulted in a reduction of the transcription of insulin-like growth factor binding protein1 and prolactin mRNA (P < 0.05). Our data suggest that WNT4 and WNT5 are relevant to normal decidualization, and thus trophoblast invasion and implantation. Their deficiency is likely involved in the development of preeclampsia.

A favorable role of prolactin in human breast cancer reveals novel pathway-based gene signatures indicative of tumor differentiation and favorable patient outcome

Prolactin (PRL) hormone is known to play a key role in mammary gland development allowing for successful lactation. The role of this hormone in breast tumorigenesis is still controversial. Here, we evaluated PRL protein and gene expression levels in human breast cancer using tissue microarray of 100 breast cancer cases, as well as different publically available human breast cancer gene profiling databases. Interestingly, our results showed a significant downregulation of PRL expression in breast cancer compared to normal adjacent tissue. Moreover, expression of PRL was associated with more differentiated tumors, early stage, smaller tumor size and absence of distant metastasis. Importantly, our results indicate that higher PRL mRNA levels are significantly associated with prolonged relapse-free survival (RFS) in breast cancer patients (P=3.7 x 10(-9)). Additionally, examining expression of PRL pathway-based gene signature composed of PRL, PRLR, Jak2 and Stat5a showed a significant association with more differentiated tumors (P<.00001), prolonged RFS (P=1.8 x 10(-6)) as well as overall survival (OS) (P=.0026). As well, our results indicate that PRL-directed differentiation program in mammary epithelial cells offer good prognosis in human breast cancer. Indeed, expression of a gene signature composed of PRL-upregulated genes showed a significant association with well-differentiated tumors (P<.00001). Whereas expression of a gene signature composed of PRL-downregulated genes showed a significant association with shortened distant metastasis-free survival (DMFS) (P=.0086). Altogether our results highlight that PRL hormone and its signaling pathway may play an important role in maintaining tumor differentiation state and in turn better patient outcome.

Molecular endocrine changes of Gh/Igf1 axis in gilthead sea bream (Sparus aurata L.) exposed to different environmental salinities during larvae to post-larvae stages.

The influence of acclimation of the euryhaline gilthead sea bream (Sparus aurata) larvae/post-larvae to brackish water on growth, energetic contents, and mRNA levels of selected hormones and growth-regulating hypothalamic neurohormones was assessed. Specimens from 49days post-hatching were acclimated during 28days to two different environmental salinities: 38 and 20psu (as brackish water). Both groups were then transferred to 38psu and acclimated for an additional week. Early juveniles were sampled after 28days of acclimation to both salinities and one week after transfer to 38psu. Pituitary adenylate cyclase-activating peptide (adcyap1; pacap), somatostatin-I (sst1), growth hormone (gh1), insulin-like growth factor-I (igf1), and prolactin (prl) mRNA expression were all studied by QPCR. Post-larvae acclimated to 20psu showed better growth performance and body energetic content than post-larvae maintained at 38psu. prl, adcyap1, and igf1 mRNA expression levels increased in 20-psu-acclimated post-larvae but decreased upon transfer to 38psu. GH1 expression did not show significant changes under both experimental conditions. Our results suggested an enhanced general performance for post-larvae in brackish water, supported by the actions of adcyap1, igf1, and prl.

Prolactin mediates neuroprotection against excitotoxicity in primary cell cultures of hippocampal neurons via its receptor

Recently it has been reported that prolactin (PRL) exerts a neuroprotective effect against excitotoxicity in hippocampus in the rat in vivo models. However, the exact mechanism by which PRL mediates this effect is not completely understood. The aim of our study was to assess whether prolactin exerts neuroprotection against excitotoxicity in an in vitro model using primary cell cultures of hippocampal neurons, and to determine whether this effect is mediated via the prolactin receptor (PRLR). Primary cell cultures of rat hippocampal neurons were used in all experiments, gene expression was evaluated by RT-qPCR, and protein expression was assessed by Western blot analysis and immunocytochemistry. Cell viability was assessed by using the MTT method.The results demonstrated that PRL treatment of neurons from primary cultures did not modify cell viability, but that it exerted a neuroprotective effect, with cells treated with PRL showing a significant increase of viability after glutamate (Glu) – induced excitotoxicity as compared with neurons treated with Glu alone. Cultured neurons expressed mRNA for both PRL and its receptor (PRLR), and both PRL and PRLR expression levels changed after the excitotoxic insult. Interestingly, the PRLR protein was detected as two main isoforms of 100 and 40kDa as compared with that expressed in hypothalamic cells, which was present only as a 30kDa variant. On the other hand, PRL was not detected in neuron cultures, either by western blot or by immunohistochemistry. Neuroprotection induced by PRL was significantly blocked by specific oligonucleotides against PRLR, thus suggesting that the PRL role is mediated by its receptor expressed in these neurons. The overall results indicated that PRL induces neuroprotection in neurons from primary cell cultures.

Bovine lactotroph cultures for the study of prolactin synthesis functions.

The aim of this study was to establish a bovine anterior pituitary-derived lactotroph (BAPDL) line that expresses prolactin (PRL) in vitro to study the mechanisms of bovine PRL synthesis and secretion. Immunohistochemistry assay of PRL in the newborn calves' anterior pituitary glands showed that most lactotrophs were located within the superior border of the lateral wings of the anterior pituitary. Tissues of the superior border of the lateral wings of the anterior pituitary were dispersed and cultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum (FBS). The limiting dilution method was used to establish BAPDL from single cell clone. BAPDL cells constantly expressed mRNAs for PRL and pituitary-specific transcription factor 1 (Pit-1) gene and grew steadily and rapidly in the DMEM supplemented with 10% FBS. PRL immunoreactivity was present in BAPDL at passage 20. The concentration of bovine PRL in BAPDL at passage 20 culture supernatant was decreased to below 35% compared with that in BAPDL at passage 1. The effects of human epidermal growth factor (hEGF) and dopamine (DA) on the expression and secretion of PRL in BAPDL at passage 4 were also investigated. The results are consistent with those of previous studies. Thus, it can be used successfully for studying the mechanisms of stimuli regulating PRL synthesis and release.

Effects of Vasoactive Intestinal Polypeptide and Forskolin on mRNA Expression of Prolactin and Prolactin Regulatory Element-Binding Protein in the Anterior Pituitary Gland of Chicken Embryo and Laying Hens.

Vasoactive intestinal peptide (VIP) treatment induced mRNA expression of Prolactin (PRL) in the chicken anterior pituitary gland. VIP responsive element (VRE) of the PRL promoter was identified in the various bird species. However, transcription factor, which binds to VRE, has not yet been identified. Prolactin regulatory element-binding protein (PREB) gene cloned as a candidate transcription factor binds to VRE. Increases of mRNA levels of PRL and PREB during embryogenesis were identified. However, whether VIP affects levels of PRL and PREB mRNA during embryogenesis remains unknown. The effects of VIP and forskolin on mRNA expression of PRL and PREB in the embryonic anterior pituitary gland were assessed. Furthermore, administration of VIP to laying hens was conducted to examine the relationship between VIP and PREB mRNA expression. At day 14 of the embryonic growth stage, VIP treatment did not affect mRNA levels of either PRL or PREB, whereas forskolin treatment induced the increase of these mRNA levels. At day 20, both VIP and forskolin induced an increase of PRL and PREB mRNA levels. The administration of VIP significantly increased mRNA levels of PRL and PREB in the anterior pituitary gland of White Leghorn and Nagoya. These results indicate that the effects of VIP on PRL and PREB mRNA expression levels of VIP receptor may in turn affect PRL and PREB mRNA levels in the chicken anterior pituitary gland.

Increased Expression of TLR4 and TLR7 but Not Prolactin mRNA by Peripheral Blood Monocytes in Active Celiac Disease.

Celiac disease (CD) is an organ-specific autoimmune disease, and both adaptive and innate immunity are involved in its development. The aim of the study was to determine whether the markers of intestinal mucosal inflammation in CD can be detected in peripheral blood monocytes (PBMs), and whether the immune properties of PBMs change as the clinical signs and symptoms of CD improve after the introduction of a gluten-free diet (GFD). The focus was on changes in mRNA expression of selected toll-like receptors (TLR2, TLR4, TLR7), stress cytokine prolactin (PRL), and proand anti-inflammatory cytokines (TNF-α, IL-6, IL-12, IL-10) in PBMs. The study involved 20 CD patients diagnosed according to the European Society for Pediatric Gastroenterology, Hepatology and Nutrition criteria and Marsh criteria: 10 recently-diagnosed cases (rCD) and 10 on a GFD for a minimum of one year. The control group comprised 10 ageand sex-matched healthy volunteers. PBMs from peripheral blood specimens were separated using immunomagnetic CD14+ beads. Total RNA was isolated using a standard commercial kit. Cytokine and TLR mRNA levels were quantified by relative qPCR with PGK1 as a reference gene. Significantly higher expression of TLR4 and TLR7 mRNA was observed in PBMs from rCD patients compared to the healthy controls (1.63 times higher; p < 0.05). TLR7 mRNA levels in rCDs were also significantly elevated in comparison to the CD-GFD patients (2.11 times higher; p < 0.01). TNF-α mRNA expression tended to be higher in both groups of patients; by contrast, in IL-6 mRNA, a trend to a fourfold decrease was detected in PBMs from the CD-GFD subjects. IL-10, IL-12 and PRL levels did not differ among the groups. The data suggest that the inflammatory process in rCD intestinal mucosa and submucosa reflecting enterocyte damage can be detected in PBMs in peripheral blood. Further, the cytokine and TLR expression profile in PBMs alters after one year of GFD treatment.

Insulin-like growth factor 1 (IGF-1) regulates prolactin, growth hormone, and IGF-1 receptor expression in the pituitary gland of the gilthead sea bream Sparus aurata.

The role of insulin-like growth factor 1 (IGF-1) on regulation of growth hormone (GH) and prolactin (PRL) as well as the possible involvement of IGF-1 receptor subtype a (IGF-1Ra) mRNA was assessed in juvenile specimens of Sparus aurata. IGF-1Ra was successfully cloned, and active receptor domains were localized in its mRNA precursor. Also, phylogenetic analysis of the protein sequence indicated a closer proximity to IGF-1Ra isoform found in zebrafish and other teleosts, than to the isoform IGF-1Rb. The most abundant presence of IGF-1Ra mRNA was detected in white muscle, whereas head kidney showed the lowest gene expression among 24 different studied tissues. Pituitaries of juvenile specimens of S. aurata were incubated in vitro with different doses of IGF-1 (0, 1, 100, and 1000 ng mL(-1)) during a period of 10 h. Total RNA with a high quality could be obtained from these pituitaries. PRL mRNA expression significantly increased with increasing IGF-1 doses. Similarly, IGF-1Ra mRNA increased its expression in response to IGF-1. However, GH mRNA levels decreased in a dose-dependent manner after IGF-1 treatment. The contradictory responses of GH and PRL expressions to IGF-1 in our experiment are possibly mediated by IGF-1Ra presence on the somatotrophs and prolactotrophs. The increase in IGF-1Ra mRNA levels may be related to the proper activation of the PI3-K/Akt signal transduction pathways which are normally involved in GH and PRL regulation.