Effect of Hyperprolactinemia on Bone Metabolism: Focusing on Osteopenia/Osteoporosis.

Prolactin is a hormone secreted from lactotroph cells in the anterior pituitary gland to induce lactation after birth. Hyperprolactinemia unrelated to lactation is a common cause of amenorrhea in women of a childbearing age, and a consequent decrease in the gonadotropin-releasing hormone (GnRH) by a high prolactin level can result in decreased bone mineral density. Osteoporosis is a common skeletal disorder characterized by decreased bone mineral density (BMD) and quality, which results in decreased bone strength. In patients with hyperprolactinemia, changes in BMD can be induced indirectly by the inhibition of the GnRH-gonadal axis due to increased prolactin levels or by the direct action of prolactin on osteoblasts and, possibly, osteoclast cells. This review highlights the recent work on bone remodeling and discusses our knowledge of how prolactin modulates these interactions, with a brief literature review on the relationship between prolactin and bone metabolism and suggestions for new possibilities.

Effects of sustained hyperprolactinemia in late gestation on the mammary parenchymal tissue transcriptome of gilts.

BACKGROUND: Gilts experiencing sustained hyperprolactinemia from d 90 to 109 of gestation showed an early onset of lactogenesis coupled with premature mammary involution. To better understand the molecular mechanisms underlying the premature mammary involution observed in these gilts, a transcriptomic analysis was undertaken. Therefore, this study aimed to explore the effect of hyperprolactinemia on the global transcriptome in the mammary tissue of late gestating gilts and identify the molecular pathways involved in triggering premature mammary involution. METHODS: On d 90 of gestation, gilts received daily injections of (1) canola oil until d 109 ± 1 of gestation (CTL, n = 18); (2) domperidone (to induce hyperprolactinemia) until d 96 ± 1 of gestation (T7, n = 17) or; (3) domperidone (until d 109 ± 1 of gestation (T20, n = 17). Mammary tissue was collected on d 110 of gestation and total RNA was isolated from six CTL and six T20 gilts for microarray analysis. The GeneChip® Porcine Gene 1.0 ST Array was used for hybridization. Functional enrichment analyses were performed to explore the biological significance of differentially expressed genes, using the DAVID bioinformatics resource. RESULTS: The expression of 335 genes was up-regulated and that of 505 genes down-regulated in the mammary tissue of T20 vs CTL gilts. Biological process GO terms and KEGG pathways enriched in T20 vs CTL gilts reflected the concurrent premature lactogenesis and mammary involution. When looking at individual genes, it appears that mammary cells from T20 gilts can simultaneously upregulate the transcription of milk proteins such as WAP, CSN1S2 and LALBA, and genes triggering mammary involution such as STAT3, OSMR and IL6R. The down-regulation of PRLR expression and up-regulation of genes known to inactivate the JAK-STAT5 pathway (CISH, PTPN6) suggest the presence of a negative feedback loop trying to counteract the effects of hyperprolactinemia. CONCLUSIONS: Genes and pathways identified in this study suggest that sustained hyperprolactinemia during late-pregnancy, in the absence of suckling piglets, sends conflicting pro-survival and cell death signals to mammary epithelial cells. Reception of these signals results in a mammary gland that can simultaneously synthesize milk proteins and initiate mammary involution.

Hyperprolactinemia modifies extracellular matrix components associated with collagen fibrillogenesis in harderian glands of non- and pregnant female mice.

The harderian gland (HG) is a gland located at the base of the nictating membrane and fills the inferomedial aspect of the orbit in rodents. It is under the influence of the hypothalamic-pituitary-gonadal axis and, because of its hormone receptors, it is a target tissue for prolactin (PRL) and sex steroid hormones (estrogen and progesterone). In humans and murine, the anterior surface of the eyes is protected by a tear film synthesized by glands associated with the eye. In order to understand the endocrine changes caused by hyperprolactinemia in the glands responsible for the formation of the tear film, we used an animal model with metoclopramide-induced hyperprolactinemia (HPRL). Given the evidences that HPRL can lead to a process of cell death and tissue fibrosis, the protein expression of small leucine-rich proteoglycans (SLRPs) was analyzed through immunohistochemistry in the HG of the non- and the pregnant female mice with hyperprolactinemia. The SRLPs are related to collagen fibrillogenesis and they participate in pro-apoptotic signals. Our data revealed that high prolactin levels and changes in steroid hormones (estrogen and progesterone) can lead to an alteration in the amount of collagen, and in the structure of type I and III collagen fibers through changes in the amounts of lumican and decorin, which are responsible for collagen fibrillogenesis. This fact can lead to the impaired functioning of the HG by excessive apoptosis in the HG of the non- and the pregnant female mice with HPRL and especially in the HG of pregnancy-associated hyperprolactinemia.

Discovery of a new class of multi-target heterocycle piperidine derivatives as potential antipsychotics with pro-cognitive effect.

A series of benzoisoxazoleylpiperidine derivatives were synthesized by using the multi-target strategies and their potent affinities for dopamine (DA), serotonin (5-HT) and human histamine H3 receptors have been evaluated. Of these compounds, the promising candidate 4w displayed high affinities for D2, D3, 5-HT1A, 5-HT2A and H3, a moderate affinity for 5-HT6, negligible effects on the human ether-a-go-go-related gene (hERG) channel, low affinities for off-target receptors (5-HT2C, adrenergic α1 and H1). In addition, the animal behavioral study revealed that, compared to risperidone, compound 4w significantly inhibited apomorphine-induced climbing and MK-801-induced movement behaviors with a high threshold for catalepsy and low liabilities for weight gain and hyperprolactinemia. Results from the conditioned avoidance response test and novel object recognition task demonstrated that 4w had pro-cognitive effects. Thus, the antipsychotic drug-like activities of 4w indicate that it may be a potential polypharmacological antipsychotic candidate drug.

Adverse body composition and lipid parameters in patients with prolactinoma: a case-control study.

BACKGROUND: Hyperprolactinaemia might cause adverse metabolic effects. The aim of our study was to compare parameters of body composition, glucose and lipid metabolism between untreated patients with prolactinoma and controls and to assess changes after initiation of cabergoline. METHODS: Case-control study with a retrospectively analyzed follow-up in patients with prolactinoma after initiation of cabergoline therapy. RESULTS: 21 patients with prolactinoma (9 micro- and 12 macroprolactinomas; 7 females) and 30 controls were analyzed. Patients with prolactinoma had significantly higher BMI than controls; fat mass did not differ between groups. Only men - but not women - with prolactinoma had significantly higher fat mass at all six sites measured compared to controls. Levels of LDL (130 (107-147.5) vs. 94.5 (80-127.5) mg/dl, p < 0.001) were significantly higher, levels of HDL (56 ± 16.7 vs. 69.2 ± 14.6 mg/dl, p = 0.004) significantly lower than in controls. Fasting glucose, HOMA-IR, HbA1c, adiponectin, CRP, and homocysteine did not differ between groups. After a median of 10 weeks (IQR 7-18 weeks) after initiation of cabergoline, total (from 212.5 ± 36.2 to 196.9 ± 40.6 mg/dl, p = 0.018) and LDL cholesterol (130 (107-147.5) to 106.5 (94.3-148) mg/dl, p = 0.018) had significantly decreased. Analyzing men and women separately, this change occurred in men only. CONCLUSIONS: Reasons for the association between prolactin and metabolic parameters include direct effects of prolactin on adipose tissue, hyperprolactinaemia-triggered hypogonadism and dopamine-agonist therapy per se. Altered lipid metabolism in patients with prolactinoma might imply an increased cardiovascular risk, highlighting the necessity to monitor metabolic parameters in these patients.

Prolactin as a neuroendocrine clue in sexual function of women across the reproductive life cycle: an expert point of view.

Prolactin is a proteic hormone best known for its role in enabling the production of milk by female mammals. Secreted by the pituitary gland in response to the stimuli of eating, estrogen treatment, mating, ovulation and nursing, prolactin is involved in over 300 separate processes in a range of vertebrates, including humans. The hormone is released in a pulsatile manner and plays an essential role in metabolism, as well as in the regulation of the immune system and pancreatic development. Nevertheless, prolactin exerts other relevant roles, as it acts at the central nervous system level to modulate behavior, arousal and sexuality. In this experts' opinion, we aim to give insights into the main activities of prolactin to advance the ability of medical doctors and specialists in obstetrics and gynecology to provide more emphasis in their clinical practices to the link between prolactin and sexuality.

[Hyperprolactinemia in the postmenopause: versions and contraversions].

The prevalence of hyperprolactinemia in postmenopausal women is unknown and has been estimated as infrequent by many studies. Prolactinomas found after menopause are usually macroadenomas and remain unrecognized for a long time due to atypical clinical signs or their absence. The growth potential of prolactinomas persists after menopause, most of them are invasive and accompanied by high prolactin levels. Treatment with dopamine agonists is usually long-term, the goals of which are to reduce tumor size, normalize prolactin levels and the negative effects of hyperprolactinemia. Treatment with cabergoline makes it possible to achieve remission of the disease in the first years after discontinuation, however, the proportion of relapses in postmenopausal women increases 5 years after discontinuation of the drug. Remission of prolactinomas is not evident in postmenopausal women. The modern management of patients with prolactinoma and/or hyperprolactinemia does not have clear positions in the postmenopausal period. Controversial issues remain: an ambiguous relationship between prolactin levels and breast cancer, there are no convincing conclusions on the improvement of bone mineral density and/or a decrease in the risk of fractures with normalization of prolactin levels, there are no data on metabolic parameters after the end of treatment with dopamine agonists, conflicting information about the relationship of prolactin levels and the severity of the manifold manifestations of the climacteric syndrome. The use of estrogen-progestin drugs in women with hyperprolactinemia/prolactinomas is also not well understood. Thus, the problem of hyperprolactinemia in the perimenopausal and postmenopausal period is underestimated and requires additional research, as well as the development of diagnostic and therapeutic strategies for potential benefits in terms of weight loss, improving insulin sensitivity, reducing the risk of fractures, maintaining sexuality and psycho-emotional well-being.

Biochemical diagnosis in prolactinomas: some caveats.

Prolactinomas are the most frequently seen pituitary adenomas in clinical practice. A correct biochemical diagnosis of hyperprolactinemia is a prerequisite for further investigation but may be hampered by analytical difficulties as well as a large number of potentially overlapping conditions associated with increased prolactin levels. Suspicion should rise in patients whose symptoms and biochemical results do not match. Assay problems, macroprolactinemia, and high-dose hook effect are discussed as possible reasons for false positive or false negative prolactin levels. Physiological and pathological causes of hyperprolactinemia and their implications for interpreting prolactin results are reviewed.

Hyperprolactinemia and bone.

Prolactin (PRL) has direct and indirect effects on bone metabolism. Experimental studies showed that in the presence of high PRL levels bone resorption was increased as well as bone formation was suppressed. Increased PRL levels in humans caused a reduction in sex hormone levels which turn may have detrimental effects on bone. Patients with hyperprolactinemia did have often decreased bone mineral density as well as an increased risk of fractures. Since PRL control may be relevant to bone health it is a clinical open issue the inclusion of skeletal health in future guidelines as indication to proactive screening, prevention and treatment particularly in high risk patients such as hyperprolactinemic women after menopause and patients with drug induced hyperprolactinemia.

Axis-specific analysis and predictors of endocrine recovery and deficits for non-functioning pituitary adenomas undergoing endoscopic transsphenoidal surgery.

PURPOSE: Endoscopic transsphenoidal surgery (ETSS) is a well-established treatment for patients with nonfunctioning pituitary adenomas (NFPAs). Data on the rates of pituitary dysfunction and recovery in a large cohort of NFPA patients undergoing ETSS and the predictors of endocrine function before and after ETSS are scarce. This study is purposed to analyze the comprehensive changes in hormonal function and identify factors that predict recovery or worsening of hormonal axes following ETSS for NFPA. METHODS: A retrospective review of 601 consecutive patients who underwent ETSS between 2010 and 2018 at one institution was performed. Recovery or development of new hypopituitarism was analyzed in 209 NFPA patients who underwent ETSS. RESULTS: Patients with preoperative endocrine deficits (59.8%) in one or more pituitary axes had larger tumor volumes (P = 0.001) than those without preoperative deficits. Recovery of preoperative pituitary deficit occurred in all four axes, with overall mean recovery of 29.7%. The cortisol axis showed the highest recovery whereas the thyroid axis showed the lowest, with 1-year cumulative recovery rates of 44.3% and 6.1%, respectively. Postoperative hypopituitarism occurred overall in 17.2%, most frequently in the thyroid axis (24.3%, 27/111) and least frequently in the cortisol axis (9.7%, 16/165). Axis-specific predictors of post-operative recovery and deficiency were identified. CONCLUSIONS: Dynamic alterations in pituitary hormones were observed in a proportion of patients following ETSS in NFPA patients. Postoperative endocrine vulnerability, recovery, and factors that predicted recovery or loss of endocrine function depended on the hormonal system, necessitating an axis-specific surveillance strategy postoperatively.

A case of functioning gonadotroph adenoma in a reproductive aged woman.

A 34-year-old woman presented our hospital with complaint of irregular menstruation and abnormal uterine bleeding lasting for a month. After her second parturition at the age of 27, her menstrual cycle had been regular, but it suddenly became irregular at the age of 30. Transvaginal ultrasound revealed the presence of ovarian mass, and the patient underwent diagnostic laparoscopic surgery. Bilateral ovaries temporally shrink after puncture but the size soon resumed. Gonadotropins were almost normal, but estradiol and PRL levels turned out to be elevated, and cabergoline treatment was initiated. After referral to our hospital, we found that the ovaries showed multifollicular appearance. Brain magnetic resonance imaging showed an 18-mm macroadenoma in the suprasellar area. To suppress the secretion of endogenous gonadotropins and estrogen, low-dose estrogen-progestin was prescribed. Surprisingly, the treatment temporarily reduced the size of the ovaries. The patient was referred to a neurosurgeon, and a functioning gonadotroph adenoma was suspected. After the resection of the pituitary tumor, her menstrual cycle became regular, and the size of bilateral ovaries became normal. We also noticed that her ovarian reserve judged by anti-Müllerian hormone had been almost diminished after the surgical treatment, probably reflecting the exhaustion of follicular pool. Women with multifollicular ovaries and elevated estradiol levels may have functioning gonadotroph adenomas, although the level of FSH is relatively normal, and ovarian reserve can be followed by measuring anti-Müllerian hormone.

Treatment escape reduces the effectiveness of cabergoline during long-term treatment of acromegaly in monotherapy or in association with first-generation somatostatin receptor ligands.

BACKGROUND: Few studies evaluated the use of cabergoline (CAB) for acromegaly treatment in monotherapy or in combination with first-generation somatostatin receptor ligands (SRLs). AIM: To evaluate the efficacy, predictors of response and safety of CAB treatment in acromegaly both in monotherapy and in combination with SRLs. METHODS: We retrospectively collected demographic, biochemical, tumour and treatment data. Short-term disease control was defined as random GH level < 1.0 µg/L and normal age-matched IGF-I level after 3-6 months of treatment with the higher dose used. Long-term disease control was defined as maintenance of normal GH and IGF-I levels at the last visit (at least 9 months of treatment). RESULTS: Eighty-two patients were studied. The median total time of treatment in monotherapy or in combination with SRLs was 14 months (3-124) and 34 months (3-88), respectively. Short-term disease control was observed in 6 (21%) patients in the monotherapy group and in 20 (32%) in the combination group. Treatment escape was observed in 1 patient after 16 months of CAB monotherapy and in 6 (30%) patients with combination therapy (after a median of 38 months), resulting in long-term disease control of 18% and 23%, respectively. Hyperprolactinemia was a predictor of response to monotherapy and pretreatment GH level to combination treatment. CONCLUSION: We presented the results of the largest single-centre study with CAB in monotherapy and in combination with SRL. The efficacy of CAB in acromegaly seems to be lower than that of other drugs, and treatment escape may occur after a long-term follow-up.

Short-Term Hyperprolactinemia Reduces the Expression of Purinergic P2X7 Receptors during Allergic Inflammatory Response of the Lungs.

PURPOSE: We have previously shown that domperidone-induced short-term hyperprolactinemia reduces the lung's allergic inflammatory response in an ovalbumin antigenic challenge model. Since purinergic receptor P2X7R activity leads to proinflammatory cytokine release and is possibly related to the pathogenesis of allergic respiratory conditions, the present study was designed to investigate a possible involvement of purinergic and prolactin receptors in this phenomenon. METHODS: To induce hyperprolactinemia, domperidone was injected intraperitoneally in rats at a dose of 5.1 mg × kg-1 per day for 5 days. P2X7 expression was evaluated by lung immunohistochemistry while prolactin receptor expression in bronchoalveolar lavage leukocytes was analyzed through flow cytometry. RESULTS: Previous reports demonstrated that rats subjected to short-term hyperprolactinemia exhibited a decrease in leukocyte counts in bronchoalveolar lavage, especially granulocytes. Here, it is revealed that hyperprolactinemia promotes an increased expression of prolactin receptors in granulocytes. Also, increased expression of purinergic P2X7R observed in allergic animals was significantly reduced by hyperprolactinemia. CONCLUSIONS: Both purinergic and prolactin receptor expression changes occur during the anti-asthmatic effect of hyperprolactinemia.

Cooperative Synthesis of Dopamine in Rat Mediobasal Hypothalamus as a Compensatory Mechanism in Hyperprolactinemia.

Dopamine (DA), synthesized in the mediobasal hypothalamus by dopaminergic neurons containing two enzymes of DA synthesis - tyrosine hydroxylase and decarboxylase of aromatic L-amino acids, or by monoenzymatic non-dopaminergic neurons containing one DA synthesis enzyme in cooperation, is known to have an inhibitory effect on prolactin secretion. Deterioration of this inhibitory control leads to an increase in prolactin concentration in the blood and to the development of hyperprolactinemia syndrome. In a rat model of hyperprolactinemia induced by administration of a neurotoxin causing degeneration of dopaminergic and noradrenergic neurons, the level of DA first decreases, leading to an increase in prolactin level (decompensation stage), while later both levels are restored to normal (compensation stage). However, the mechanism of such compensation is still not clear. The aim of the present study was to analyze whether the increase in cooperative synthesis of DA by monoenzymatic neurons during hyperprolactinemia is a manifestation of a compensatory mechanism representing a particular case of neuroplasticity. The level of cooperative synthesis in the hyperprolactinemia model and in the control was estimated as the level of synthesis of DA and L-dihydroxyphenylalanine (L-DOPA) - an intermediate product of DA synthesis, when L-DOPA transfer from neurons containing tyrosine hydroxylase into neurons containing aromatic L-amino acid decarboxylase is inhibited. The level of DA synthesis during the decompensation stage was not changed, while during the compensation stage it was lower than the control. Along with a reduction in DA level, during the compensation stage an increase in the extracellular L-DOPA level in the medium was detected. Thus, the compensation of DA deficiency after degeneration of dopaminergic neurons in the mediobasal hypothalamus is due to the increase in cooperative synthesis of DA by monoenzymatic neurons containing one of the complementary enzymes of the DA synthesis pathway.

Chronic hyperprolactinemia evoked by disruption of lactotrope dopamine D2 receptors impacts on liver and adipocyte genes related to glucose and insulin balance.

We studied the impact of high prolactin titers on liver and adipocyte gene expression related to glucose and insulin homeostasis in correlation with obesity onset. To that end we used mutant female mice that selectively lack dopamine type 2 receptors (D2Rs) from pituitary lactotropes (lacDrd2KO), which have chronic high prolactin levels associated with increased body weight, marked increments in fat depots, adipocyte size, and serum lipids, and a metabolic phenotype that intensifies with age. LacDrd2KO mice of two developmental ages, 5 and 10 mo, were used. In the first time point, obesity and increased body weight are marginal, although mice are hyperprolactinemic, whereas at 10 mo there is marked adiposity with a 136% increase in gonadal fat and a 36% increase in liver weight due to lipid accumulation. LacDrd2KO mice had glucose intolerance, hyperinsulinemia, and impaired insulin response to glucose already in the early stages of obesity, but changes in liver and adipose tissue transcription factors were time and tissue dependent. In chronic hyperprolactinemic mice liver Prlr were upregulated, there was liver steatosis, altered expression of the lipogenic transcription factor Chrebp, and blunted response of Srebp-1c to refeeding at 5 mo of age, whereas no effect was observed in the glycogenesis pathway. On the other hand, in adipose tissue a marked decrease in lipogenic transcription factor expression was observed when morbid obesity was already settled. These adaptive changes underscore the role of prolactin signaling in different tissues to promote energy storage.

Effect of chronic cabergoline treatment and testosterone replacement on metabolism in male patients with prolactinomas.

INTRODUCTION: Hyperprolactinemia and hypogonadism are reportedly associated with an impaired metabolic profile. The current study aimed at investigating the effects of testosterone replacement and cabergoline (CAB) treatment on the metabolic profile in male hyperprolactinemic patients. PATIENTS AND METHODS: Thirty-two men with prolactinomas, including 22 with total testosterone (TT) <8 nmol/l (HG, 69%) and 10 with TT >8 nmol/l (non-HG, 31%), were entered in the study. In all patients, metabolic parameters were assessed at diagnosis and after 12- and 24-month treatment. RESULTS: Compared to non-HG patients, at baseline the HG patients had higher waist circumference (WC). TT significantly correlated with body mass index (BMI). Twelve-month CAB induced PRL normalization in 84%. HG prevalence significantly decreased (28%) and non-HG prevalence significantly increased (72%). Anthropometric and lipid parameters, fasting insulin (FI), insulin sensitivity index (ISI0), homeostatic model assessment of insulin secretion (HOMA-ß) and homeostatic model assessment of insulin resistance (HOMA-IR) significantly improved compared to baseline. TT was the best predictor for FI. Percent change (Δ) of TT significantly correlated with ΔCholesterol, ΔWeight and ΔBMI. Compared to non-HG patients, the HG patients had a higher weight, BMI, WC and HOMA-ß. In HG, testosterone replacement was started. After 24 months, PRL normalized in 97%. HG prevalence significantly decreased (6%) and non-HG prevalence significantly increased (94%). Anthropometric and lipid parameters, FI, ISI0, HOMA-ß and HOMA-IR significantly improved compared to baseline, with FI, ISI0, HOMA-ß and HOMA-IR further ameliorating compared to the 12-month evaluation. Compared to non-HG patients, the HG patients still had a higher weight, BMI and WC. CONCLUSIONS: In hyperprolactinemic hypogonal men, proper testosterone replacement induces a significant improvement in the metabolic profile, even though the amelioration in the lipid profile might reflect the direct action of CAB.

Efficacy and Mechanism of Action of Yiru Tiaojing Granule Against Hyperprolactinemia In Vitro and In Vivo.

Yiru Tiaojing Granule, a traditional Chinese medicine formula, is used to treat hyperprolactinemia. This study was conducted to evaluate the mechanism of action and pharmacological activity of Yiru Tiaojing Granule on prolactin secretion. The animal model of hyperprolactinemia was induced by metoclopramide. The dopamine D2 receptor in hyperprolactinemia rat models was analyzed by immunohistochemistry. The biochemical parameters, including a follicle-stimulating hormone, luteinizing hormone, estradiol, progesterone, testosterone, and prolactin, were measured by an enzyme-linked immunosorbent assay. Furthermore, the expression of prolactin and the dopamine D2 receptor was analyzed by Western blotting. The components in the Yiru Tiaojing Granule-medicated serum were assayed by liquid chromatography-tandem mass spectrometry. The Yiru Tiaojing Granule significantly decreased the prolactin level in the hyperprolactinemia rat model, and increased the estradiol, luteinizing hormone, and progesterone levels. The high and medium doses of Yiru Tiaojing Granule reduced dopamine D2 receptor expression in the brain (p < 0.001) and produced a similar effect on bromocriptine (p < 0.001). Yiru Tiaojing Granule-medicated serum reduced (p < 0.001) prolactin expression in MMQ cells in a concentration-dependent manner, but had no effects on GH3 cells. The level of the dopamine D2 receptor in MMQ cells was also increased dose-dependently (p < 0.05). In addition, the protein kinase A and cyclic adenosine monophosphate in MMQ cells were significantly attenuated dose-dependently by treatment with a high and medium dose of Yiru Tiaojing Granule-medicated serum (p < 0.05) and bromocriptine-medicated serum (p < 0.01). The results suggested that Yiru Tiaojing Granule was effective against hyperprolactinemia, and the activation of the dopamine D2 receptor, which was related to the second messenger cyclic adenosine monophosphate and protein kinase A, might be the potential mechanism.

Effects of metoclopramide-induced hyperprolactinemia on the prolactin and prolactin receptor expression of murine adrenal.

The aim of this study was to evaluate the effects of metoclopramide-induced hyperprolactinemia on the prolactin (PRL) and prolactin receptor's (PRLR) expression in the adrenal. For this purpose, a total of 12 animals with intact ovaries were allocated to two groups: G1 (saline solution) and G2 (metoclopramide). A total of 30 oophorectomized animals was randomized to five subgroups: G3 (saline solution), G4 (metoclopramide), G5 (metoclopramide + 17ß-estradiol), G6 (metoclopramide + progesterone), and G7 (metoclopramide + 17ß-estradiol + progesterone). Immunohistochemical analyses were evaluated semi-quantitatively. For PRLR, the area fraction of labeled cells (ALC) varied from 1 (0-10%) to 3 (> 50%). Based on the mean of the immunostaining intensity, G2 and G4 showed strong expression; G6 and G7 presented a mild reaction; and G1, G3, and G5 exhibited a weak reaction. Concerning PRL, the ALC varied from 1 (0-10%) to 3 (> 50%), and groups G6 and G7 showed a strong reaction; G2, G4, and G5 showed a mild reaction; and G1 and G3 exhibited a weak reaction. These findings suggest that metoclopramide-induced hyperprolactinemia increases PRL expression in the adrenal glands of mice. Furthermore, progesterone alone or in association with estrogen also increases PRL expression, but to a lesser extent.

The progesterone and estrogen modify the uterine prolactin and prolactin receptor expression of hyperprolactinemic mice.

The aim of this study was to evaluate the effects of metoclopramide-induced hyperprolactinemia on the prolactin (PRL) and PRL receptor's expression in the uterus of mice. For this purpose, 49 Swiss mice were divided into the following groups: GrSS (non-ovariectomized mice given vehicle); GrMET (non-ovariectomized mice treated with metoclopramide); OvSS (ovariectomized mice given vehicle); OvMET (ovariectomized mice treated with metoclopramide); OvMET+17ßE (ovariectomized mice treated with metoclopramide and 17ß estradiol); OvMET+MP (ovariectomized mice treated with metoclopramide and micronized progesterone); OvMET+17ßE+MP (ovariectomized mice treated with metoclopramide and a solution of 17ß estradiol and micronized progesterone). Immunohistochemical analyzes were evaluated semi-quantitatively. Our results showed that GrMET, OvMET+MP, and OvMET+17ßE+MP presented strong PRL expression. OvMET and OvMET+17ßE presented mild reaction, while GrSS and OvSS presented weak reaction. Concerning PRL receptor, OvMET+MP and OvMET+17ßE+MP showed strong reaction; GrMET, OvSS, and OvMET+17ßE showed mild reaction; and GrSS and OvMET showed weak reaction. These findings suggest that progesterone alone or in combination with estrogen may increase the expression of uterine PRL and PRL receptor.

Possible Recovery of Manifestation of Prolactin Receptor and Some of Its Target Proteins in the Liver and Kidney Cells of Female Rats after Relief of Cholestasis Complicated and Not Complicated by Hyperprolactinemia.

Immunohistochemistry with semi-quantitative analysis of computer images showed that prolactin receptor and cystic fi brosis transmembrane regulator (CFTR) in cholangiocytes of female rats elevated in cholestasis quickly respond to its relief. The effect of hyperprolactinemia on the extent of return of these proteins to baseline was different. Decompression of the bile duct abolishes the negative effect of hyperprolactinemia on CFTR expression and its positive effect on mrp3 expression in the proximal renal tubules. In renal medulla, mrp2 expression decreased when cholestasis was induced against the background of hyperprolactinemia and increases after its removal. Prolactin receptors and CFTR in cholangiocytes are most susceptible to the decrease in bile duct pressure. Changes in the expression of the studied proteins after cholestasis relief are apparently associated with attenuated toxicity of the products removed by the kidneys, which abolishes the effects of prolactin.