Immunoreactive Prolactin Research Articles

6619 An Unlikely Cause of Oligomenorrhea: Acromegaly Secondary to a Sparsely Granulated, Somatotroph-Lactotroph Adenoma

Abstract Disclosure: S.I. Alicea: None. Y. Wu: None. J. Marquez: None. C.S. Botero Suarez: None. M. Kinaan: None. Introduction: Acromegaly most commonly presents as a pituitary tumor that causes excessive production ofgrowth hormone (GH); and rarely due to excess of GHRH or ectopic production of GH. Approximately 15% of surgically removed pituitary adenomas represent GH-producing neoplasms, and about 5% are bihormonal, secreting both GH and prolactin (PRL). We present a case of an unexpected presentation of oligomenorrhea which ended up with the diagnosis of acromegaly secondary to plurihormonal mixed somatotroph-lactotroph sparsely granulated adenoma. Case Description A 32-year-old female with history of prediabetes was referred to our clinic by her gynecologistfor evaluation of oligomenorrhea which was initially attributed to polycystic ovarian syndrome.She reported menarche at age 10 and has experienced irregular menses and periods of amenorrhea over the years. Physical exam revealed macroglossia, a widened thickened nose, acanthosis nigricans in the neck skin folds, facial hair thickening, and significant thickening of all fingers, toes and soft tissues. Given physical exam findings, we evaluated the patient for acromegaly and lab testing revealed markedly high IGF I, mildly elevated prolactin, and hemoglobin A1C of 5.7%. An MRI of the brain with IV contrast revealed a heterogeneously enhancing pituitary macroadenoma measuring 2.9 x 2.9 x 2.2 cm with suprasellar extension resulting in mass effect on the optic chiasm without definite cavernous sinus extension. She was started on Cabergoline 0.5mg twice weekly temporarily and underwent pituitary transsphenoidal resection. Pathology results revealed tumor cells that were positive for Chromogranin and Cam5.2. About 10% of cells showed immunoreactivity for Prolactin and negative for TSH, ACTH, FSH, LH and immunostains. There was also weak focal (about 2%) immunoreactivity for GH. Occasional mitotic figures were present. The MIB-1 proliferation index was 3%. The reticulin stain demonstrates loss of acinar architecture, supporting the diagnosis. Aside from transient sodium fluctuations consistent with triphasic response, she had no long-lasting postoperative complications. One month after her surgery, her IGF I level and hemoglobin A1C are trending down and she reports symptomatic relief. She continues follow up in our clinic. Discussion This patient has acromegaly secondary to a mixed somatotroph-lactotroph sparsely granulated adenoma. Sparsely granulated adenomas are more common in younger populations, can be more aggressive, and are less responsive to somatostatin analogs. Early detection and treatment is imperative in the prevention of complications secondary to the disease. Our case will closely examine the differences in the clinical, prognostic, and pathologic features of sparsely- vs. densely granulated adenomas. We will also discuss the effects of acromegaly on gonadal function. Presentation: 6/1/2024

Seasonality of Reproduction in a Subtropical Free-Living Finch Amandava amandava: Plasticity of Adenohypophyseal Gonadotropes, Lactotropes, and Thyrotropes

Introduction: This study sought to decipher the mechanism of transitions between life-history stages in a seasonally reproducing subtropical finch, Amandava amandava delineating the plasticity of the gonadotropes (LH cells), lactotropes (PRL cells), and thyrotropes (TSH cells) in the pituitary gland including the pars tuberalis, with regard to the in situ expression, morphological characteristics, and alteration in the plasma levels of hormones. Methods: Immunohistochemistry of LH, PRL, TSH cells, morphometry and densitometry of expressed hormones (Image J software analysis), and ELISA for plasma hormonal levels were performed. Results: LH, PRL, and TSH cells showed remarkable plasticity during the annual seasonal reproductive cycle. In the PT, all the 3 cell types were detected during the breeding phase, with additional detection of the TSH immunoreactivity during the pre-breeding and the PRL immunoreactivity during post-breeding phases. Pars distalis (PD) expressions and the plasma levels of the LH and TSH were at the peak during the breeding phase, but the PRL peak was during the post-breeding phase. In addition to PRL in the neurohypophysis and in the median eminence, hypothalamic PRL, and TSH were also elucidated. Conclusions: This study suggests activation of the gonadal axis by the PT TSH which might transduce seasonal cues, but not specifically photoperiod, in the birds of the tropics/subtropics. Post-breeding phase sustained high plasma TSH and peak plasma PRL might coordinate the transition to the non-breeding phase including the trigger of parental care as the later hormone assigned with. Hypothalamic TSH and PRL might influence events of seasonality through central modulation.

FRI370 Hyperthyroidism And Acromegaly In A Patient With A Mature Plurihormonal PIT1 Lineage PitNET/Adenoma

Abstract Disclosure: D. Slack: None. A.C. Levine: None. Background: TSH- and GH-secreting pituitary neuroendocrine tumors (PitNETs) are both rare entities, with an incidence of 1 per million people and 1-4 per million people, respectively. Thyrotroph, somatotroph, and lactotroph cells have the same progenitor, regulated by the PIT1 transcription factor. Thus, it is not unusual for PIT1 positive tumors to exhibit immunhistochemical expression of TSH, GH, and prolactin. It is vanishingly rare, however, for these tumors to secrete multiple biologically active hormones with apparent clinical sequelae. We herein report on a case of a patient with a plurihormonal PIT1 lineage PitNET secreting prolactin with secondary amenorrhea, TSH causing central hyperthyroidism and GH resulting in acromegaly. Clinical Case: A 42-year-old woman with a 1-year history of amenorrhea presented with 3 months of progressive weight loss, fatigue, palpitations, and tremulousness. She was found to have central hyperthyroidism, with an elevated free T4 (>7.77 ng/dL, nl 0.82 – 1.77) and inappropriately normal TSH (3.25 uIU/mL, nl 0.45 – 4.5). Full endocrine workup confirmed central hyperthyroidism with elevated free T4 (5.02 ng/dL) and TSH (4.68 uIU/mL) and also demonstrated hyperprolactinemia (122 ng/mL, nl 4.8 – 23.3 ng/mL), elevated IGF-1 (795 ng/mL, nl 91 – 308 ng/mL), GH (19 ng/mL, nl 0 – 10) and free alpha subunit (28 ng/mL, nl <1.02). Over the ensuing 4 months, she noted enlargement of her lips, nose, feet, and hands. MRI demonstrated a pituitary macroadenoma measuring 2.2 cm x 2.7 cm x 2 cm with asymmetric extension into the left cavernous sinus and mild elevation of the adjacent optic chiasm. She underwent an uncomplicated transsphenoidal resection of the tumor with no residual tumor noted on post-op MRI. Discharge medications were hydrocortisone 10 mg AM and, 5 mg early afternoon and levothyroxine 50 mcg daily. One month postoperatively, labs were notable for a low TSH (0.16 mIU/L), normal free T4 (1.62 ng/dL), down-trending IGF-1 (339 ng/mL), and normal prolactin (15.1 ng/mL). Additionally, AM cortisol and ACTH levels remained normal after holding her morning dose of hydrocortisone. She reported resolution of all presenting symptoms of thyrotoxicosis as well as decreasing size of her hands, feet, and nose. Pathology revealed a mature plurihormonal PIT1-lineage PitNET, with immunoreactivity for PIT1, GH, TSH, and prolactin and MIB-1 index of 3%. Conclusion: This case demonstrates the potential for PitNETs to secrete multiple biologically active pituitary hormones, including prolactin, TSH and GH, highlighting the importance of maintaining an index of suspicion for pituitary causes in the evaluation of thyrotoxicosis and of considering the plurihormonal potential of PitNETs in patients presenting with multiple endocrinopathies. Presentation: Friday, June 16, 2023

The Choroid Plexus Is an Alternative Source of Prolactin to the Rat Brain.

Among the more than 300 functions attributed to prolactin (PRL), this hormone has been associated with the induction of neurogenesis and differentiation of olfactory neurons especially during pregnancy, which are essential for maternal behavior. Despite the original hypothesis that PRL enters the central nervous system through a process mediated by PRL receptors (PRLR) at the choroid plexus (CP), recent data suggested that PRL transport into the brain is independent of its receptors. Based on transcriptomic data suggesting that PRL could be expressed in the CP, this work aimed to confirm PRL synthesis and secretion by CP epithelial cells (CPEC). The secretion of PRL and the distribution of PRLR in CPEC were further characterized using an in vitro model of the rat blood-cerebrospinal fluid barrier. RT-PCR analysis of PRL transcripts showed its presence in pregnant rat CP, in CPEC, and in the rat immortalized CP cell line, Z310. These observations were reinforced by immunocytochemistry staining of PRL in CPEC and Z310 cell cytoplasm. A 63-kDa immunoreactive PRL protein was detected by Western blot in CP protein extracts as well as in culture medium incubated with rat pituitary and samples of rat cerebrospinal fluid and serum. Positive immunocytochemistry staining of PRLR was present throughout the CPEC cytoplasm and in the apical and basal membrane of these cells. Altogether, our evidences suggest that CP is an alternative source of PRL to the brain, which might impact neurogenesis of olfactory neurons at the subventricular zone, given its proximity to the CP.

Serum prolactin binding in various forms of hyperprolactinemia

Binding of 125I-labeled prolactin in the sera of women with different forms of hyperprolactinemia was studied. Antiprolactin autoantibodies were detected in the blood of 24% of women with idiopathic hyperprolactinemia. In contrast to idiopathic hyperprolactinemia, there were no autoantibodies to prolactin in pregnant women with physiological hyperprolactinemia and in hyperprolactinemia of tumor origin. These data indicate that the presence of these antibodies in circulating blood can be one cause of idiopathic hyperprolactinemia. Moreover, the prevalence of high-molecular form of immunoreactive prolactin in the blood can be due to binding of an appreciable amount of prolactin monomer to antiprolactin autoantibodies.

The macroprolactinemia phenomenon: origin and clinical diagnostic significance

The authors discuss the experimental and clinical data on the origin, properties, and diagnostic value of serum immunoreactive prolactin (irPRL) with a high molecular mass (macroprolactin, 100K-PRL). This form predominates in the blood of about 25% of women of a reproductive age with hyperprolactinemia. Comparison of the biochemical, immunochemical, and functional characteristics of the blood serum 100K-PRL and the monomeric fraction irPRL (23K-PRL) showed them to differ in principle. A low biological activity of 100K-PRL explains the absence of typical clinical signs of hyperprolactinemia in many women with macroprolactinemia. In contrast to 23K-PRL, 100K.-PRL weakly reacts to stimulants and inhibitors of PRL secretion by the pituitary. PRL-binding protein, apparently an immunoglobulin, is the basis of fraction 100K-PRL. The authors consider that analysis of not only total irPRL in the blood, but of its high and low-molecular forms be included in the algorithm of diagnostic search in some forms of hyperprolactinemia. This will help determine the treatment policy, because moderate hyperprolactinemia with predominating 100K- PRL as a rule cannot be corrected by dopamine agonists.

Molecular Evidence for Precursors of Sjögren's Foci in Histologically Normal Lacrimal Glands.

Understanding the formation of Sjogren’s lymphocytic infiltrates could permit earlier diagnosis and better outcomes. We submitted gene transcript abundances in histologically normal rabbit lacrimal glands to principal component analysis. The analysis identified a cluster of transcripts associated with Sjögren’s foci, including messenger RNAs (mRNAs) for C–X–C motif chemokine ligand 13 (CXCL13) and B-cell activating factor (BAFF), which dominated the major principal component. We interpreted the transcript cluster as the signature of a cluster of integrally functioning cells. Pregnancy and dryness increased the likelihood that the cluster would develop to high levels, but responses were subject to high levels of stochasticity. Analyzing microdissected samples from high- and low-cluster-level glands, we found that certain transcripts, including mRNAs for C–C motif chemokine ligand 21 (CCL21), CXCL13, cluster of differentiation 4 (CD4), CD28, CD25, BAFF, and interleukin 18 (IL-18) were significantly more abundant in immune cell clusters (ICs) from the high-cluster-level gland; mRNAs for CCL2, CD25, and IL-1RA were significantly more abundant in acinus-duct axis samples; mRNAs for CCL4, BAFF, IL-6, and IL-10 were more abundant in some acinus-duct samples; cells with high prolactin immunoreactivity were more frequent in interacinar spaces. In conclusion, integrated functional networks comprising Sjögren’s infiltrates, such as ICs, acinar cells, ductal cells, and interacinar cells, can form in histologically normal glands, and it is feasible to detect their molecular signatures.

ALK7 expression in prolactinoma is associated with reduced prolactin and increased proliferation.

Prolactinoma represents the most frequent hormone-secreting pituitary tumours. These tumours appear in a benign form, but some of them can reach an invasive and aggressive stage through an unknown mechanism. Discovering markers to identify prolactinoma proliferative and invading character is therefore crucial to develop new diagnostic/prognostic strategies. Interestingly, members of the TGFβ-Activin/BMP signalling pathways have emerged as important actors of pituitary development and adult function, but their role in prolactinomas remains to be precisely determined. Here, using a heterotopic allograft model derived from a rat prolactinoma, we report that the Activins orphan type I receptor ALK7 is ectopically expressed in prolactinomas-cells. Through immunohistological approaches, we further confirm that normal prolactin-producing cells lack ALK7-expression. Using a series of human tumour samples, we show that ALK7 expression in prolactinomas cells is evolutionary conserved between rat and human. More interestingly, our results highlight that tumours showing a robust expression of ALK7 present an increased proliferation as address by Ki67 expression and retrospective analysis of clinical data from 38 patients, presenting ALK7 as an appealing marker of prolactinoma aggressiveness. Beside this observation, our work pinpoints that the expression of prolactin is highly heterogeneous in prolactinoma cells. We further confirm the contribution of ALK7 in these observations and the existence of highly immunoreactive prolactin cells lacking ALK7 expression. Taken together, our observations suggest that Activin signalling mediated through ALK7 could therefore contribute to the hormonal heterogeneity and increased proliferation of prolactinomas.

Brain prolactin is involved in stress-induced REM sleep rebound

REM sleep rebound is a common behavioural response to some stressors and represents an adaptive coping strategy. Animals submitted to multiple, intermittent, footshock stress (FS) sessions during 96h of REM sleep deprivation (REMSD) display increased REM sleep rebound (when compared to the only REMSD ones, without FS), which is correlated to high plasma prolactin levels. To investigate whether brain prolactin plays a role in stress-induced REM sleep rebound two experiments were carried out. In experiment 1, rats were either not sleep-deprived (NSD) or submitted to 96h of REMSD associated or not to FS and brains were evaluated for PRL immunoreactivity (PRL-ir) and determination of PRL concentrations in the lateral hypothalamus and dorsal raphe nucleus. In experiment 2, rats were implanted with cannulas in the dorsal raphe nucleus for prolactin infusion and were sleep-recorded. REMSD associated with FS increased PRL-ir and content in the lateral hypothalamus and all manipulations increased prolactin content in the dorsal raphe nucleus compared to the NSD group. Prolactin infusion in the dorsal raphe nucleus increased the time and length of REM sleep episodes 3h after the infusion until the end of the light phase of the day cycle. Based on these results we concluded that brain prolactin is a major mediator of stress-induced REMS. The effect of PRL infusion in the dorsal raphe nucleus is discussed in light of the existence of a bidirectional relationship between this hormone and serotonin as regulators of stress-induced REM sleep rebound.

First evidence of a menstruating rodent: the spiny mouse (Acomys cahirinus)

Background Advances in research relating to menstruation and associated disorders (eg, endometriosis and premenstrual syndrome) have been hindered by the lack of an appropriate animal model. Menstruation, the cyclical shedding of the decidualized endometrium in the absence of pregnancy, is believed to be limited to 78 higher-order primates (human beings and Old World monkeys), 4 species of bat, and the elephant shrew. This represents only 1.5% of the known 5502 mammalian species and Objective Here we describe the first observation of menstruation in a rodent, the spiny mouse ( Acomys cahirinus ). Study Design Virgin female spiny mice (n = 14) aged 12–16 weeks were sampled through daily vaginal lavage for 2 complete reproductive cycles. Stage-specific collection of reproductive tissue and plasma was used for histology, prolactin immunohistochemistry, and enzyme-linked immunosorbent assay of progesterone (n = 4–5/stage of the menstrual cycle). Normally distributed data are reported as the mean ± SE and significant differences calculated using a 1-way analysis of variance. Nonnormal data are displayed as the median values of replicates (with interquartile range) and significant differences calculated using Kruskal-Wallis test. Results Mean menstrual cycle length was 8.7 ± 0.4 days with red blood cells observed in the lavages over 3.0 ± 0.2 days. Cyclic endometrial shedding and blood in the vaginal canal concluding with each infertile cycle was confirmed in all virgin females. The endometrium was thickest during the luteal phase at 322.6 μm (254.8, 512.2), when plasma progesterone peaked at 102.1 ng/mL (70.1, 198.6) and the optical density for prolactin immunoreactivity was strongest (0.071 ± 0.01 arbitrary units). Conclusion The spiny mouse undergoes spontaneous decidualization, demonstrating for the first time menstruation in a rodent. The spiny mouse provides a readily accessible nonprimate model to study the mechanisms of menstrual shedding and repair, and may therefore be useful in furthering studies of human menstrual and pregnancy-associated disorders.

First evidence of a menstruating rodent: the spiny mouse (Acomys cahirinus)

Advances in research relating to menstruation and associated disorders (eg, endometriosis and premenstrual syndrome) have been hindered by the lack of an appropriate animal model. Menstruation, the cyclical shedding of the decidualized endometrium in the absence of pregnancy, is believed to be limited to 78 higher-order primates (human beings and Old World monkeys), 4 species of bat, and the elephant shrew. This represents only 1.5% of the known 5502 mammalian species and <0.09% of these are nonprimates. Thus, many aspects of menstruation remain poorly understood, limiting the development of effective treatments for women with menstrual disorders. Menstruation occurs as a consequence of progesterone priming of the endometrial stroma and a spontaneous decidual reaction. At the end of each infertile cycle as progesterone levels decline the uterus is unable to maintain this terminally differentiated stroma and the superficial endometrium is shed. True menstruation has never been reported in rodents. Here we describe the first observation of menstruation in a rodent, the spiny mouse (Acomys cahirinus). Virgin female spiny mice (n= 14) aged 12-16 weeks were sampled through daily vaginal lavage for 2 complete reproductive cycles. Stage-specific collection of reproductive tissue and plasma was used for histology, prolactin immunohistochemistry, and enzyme-linked immunosorbent assay of progesterone (n= 4-5/stage of the menstrual cycle). Normally distributed data are reported as the mean ± SE and significant differences calculated using a 1-way analysis of variance. Nonnormal data are displayed as the median values of replicates (with interquartile range) and significant differences calculated using Kruskal-Wallis test. Mean menstrual cycle length was 8.7 ± 0.4 days with red blood cells observed in the lavages over 3.0 ± 0.2 days. Cyclic endometrial shedding and blood in the vaginal canal concluding with each infertile cycle was confirmed in all virgin females. The endometrium was thickest during the luteal phase at 322.6 μm (254.8, 512.2), when plasma progesterone peaked at 102.1 ng/mL (70.1, 198.6) and the optical density for prolactin immunoreactivity was strongest (0.071± 0.01 arbitrary units). The spiny mouse undergoes spontaneous decidualization, demonstrating for the first time menstruation in a rodent. The spiny mouse provides a readily accessible nonprimate model to study the mechanisms of menstrual shedding and repair, and may therefore be useful in furthering studies of human menstrual and pregnancy-associated disorders.

Abstract 3487: Alcohol programs the pituitary to produce aggressive prolactin-producing tumors

Abstract Chronic alcohol consumption is known to increase prolactin levels in blood and cell proliferation in pituitary prolactin-producing cells known as lactotropes, resulting in hyperprolactinemia in human and animals. We have recently shown that alcohol abuse during pregnancy result in fetal programming that alters lactotropic cell production of prolactin in the offspring during the adulthood. We determined whether fetal alcohol exposure increases the susceptibility to estrogen-induced pituitary prolactin-secreting tumors (prolactinomas). Pregnant Fischer 344 rats were fed between gestational days 7 and 21 with a liquid diet containing alcohol (AF), pair-fed with isocaloric liquid diet (PF), or fed ad libitum with rat chow (AD). At 90 days of age, female offspring rats were ovariectomized and received a subcutaneous estradiol implant. These rats were sacrificed at 3 moths after the estradiol implants. At the time of sacrifice, pituitaries of these animals were inspected for tumor and whole body were inspected for any tumor metastasis. Estradiol treatment increased pituitary weight about 5-folds in AD and PF treated groups and increased about 30-folds in the AF treated group. Most tumors in the AF group were hemorrhagic. About 30% AF rats had some tumors in the non-pituitary sites. AD and PF rats did not show any non-pituitary site tumor. Histopathological evaluation revealed that tumors in AF group were more densely packed cells as compare to the PF and AD groups who showed uniform cells with abundant cytoplasm. Pituitary tumor from AF animals showed strong nuclear p53, Ki67 and prolactin immunoreactivity. When AF rat pituitaries were grown in cultures, cells rapidly grew and formed colonies. Colony formation and rapid growth rate were not observed in cells of the pituitary from PF and AD rats. When pituitary tumor cells of AF-treated pituitary, but not AD- or PF-treated pituitaries were grown in ultra-low attachment plate, spheres developed. These spheres expressed genes and proteins related to multipotency (OCT4, NANOG, KLF4, SOX2, Nestin, CD34 and CD133). Differentiated cells from pituitary tumorspheres of AF animals successfully induce tumor in scid mice after three weeks from cells transplantation. In addition, pituitary tumor from AF animals showed strong immunoreactivity for N-cadherin and Snail, two epithelial-mesenchymal transitions (EMT) factors. Furthermore, RNA-seq of genes in tumor pituitaries of AF and AD rats revealed 8782 genes are significantly changed in AF compared to AD P&amp;lt;0.01. Many of these genes were involved in the cell migration, actin cytoskeletal regulation and cell-cell junction formations which are the most important phenotypes occur during EMT. These data provide evidence for the possible development of aggressive prolactinoma development in the pituitary after estrogen treatment in fetal alcohol exposed female rats. (This work is supported by a National Institute of Health grant R01 AA11591). Citation Format: Shaima Jabbar, Jinhee Park, William Belden, Dipak K. Sarkar. Alcohol programs the pituitary to produce aggressive prolactin-producing tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3487.

NG2 targets tumorigenic Rb inactivation in Pit1-lineage pituitary cells.

The proteoglycan neuron-glial antigen 2 (NG2) is expressed by oligodendrocyte progenitors, pericytes, and some cancerous cells where it is implicated in tumor development. We examined mice with NG2-driven pRb inactivation. Unexpectedly, NG2-Cre:pRb(flox/flox) mice developed pituitary tumors with high penetrance. Adenohypophysial neoplasms developed initially as multifocal lesions; by 1 year, large tumors showed brain invasion. Immunohistochemistry identified these as Pit1-lineage neoplasms, with variable immunoreactivity for growth hormone, prolactin, thyrotropin, and α-subunit of glycoprotein hormones. Other than modest hyperprolactinemia, circulating hormone levels were not elevated. To determine the role of NG2 in the pituitary, we investigated NG2 expression. Immunoreactivity was identified in anterior and posterior lobes but not in the intermediate lobe of the mouse pituitary; in the adenohypophysis, folliculostellate cells had the strongest NG2 immunoreactivity but showed no proliferation in response to Rb inactivation. Pit1-positive adenohypophysial cells were positive for NG2, but corticotroph and gonadotroph cells were negative. RT-PCR revealed NG2 expression in normal human pituitary and human pituitary tumors; immunohistochemistry localized NG2 in nontumorous human adenohypophysis with strongest positivity in folliculostellate cells, and in tumors of all types except corticotrophs. Functional studies in GH4 mammosomatotrophs showed that NG2 increases prolactin (PRL), reduces growth hormone (GH) expression, and enhances cell adhesion without influencing proliferation. In conclusion, NG2-driven pRb inactivation results in pituitary tumors that mimic endocrinologically inactive Pit1-lineage human pituitary tumors. This model identifies a role for NG2 in pituitary cell-type-specific functions and unmasks a protective role from Rb inactivation in folliculostellate cells; it can be used for further research, including preclinical testing of novel therapies.

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.

Giant Hemorrhagic Prolactinoma with Sparse Prolactin Expression Presenting with Thalamic Infarction—A Case Report

Pituitary tumors are the most common form of intracranial neoplasms. However, clinically relevant pituitary tumors presenting with disturbances of hormonal secretion or mass effect are rare and they only represent about 10 % of all surgically resected intracranial neoplasms. Prolactinomas are the most common types of pituitary adenomas. Generally, hormonal expression patterns provided by immunohistochemistry (IHC) studies are correlated with the clinical features and endocrine activity of the patients. Nonetheless, exceptions occur where the immunocytochemical staining is not concordant with the clinical picture. Pituitary adenomas presenting with apoplexy are well known. However, pituitary adenomas causing cerebral stroke and resulting in hemiplegia are unusual. Here, we report an unusual case of prolactinoma with cerebral stroke and sparse prolactin (PRL) expression. A 25-year-old woman complaining of amenorrhea, dysphasia, and left hemiplegia presented with serum PRL level in excess of 4,700 ng/ml. Pre-operational radiology images revealed a giant macroadenoma and a thalamic infarct due to carotid compression. Transcranial surgery was performed. IHC study of the adenoma revealed no hormonal expression other than sparse PRL immunoreactivity. Therefore, a sparsely granulated PRL cell adenoma was diagnosed. The patient is still under follow-up with continuing cabergoline treatment.

Tumour Necrosis Factor Alpha, Interferon Gamma and Substance P Are Novel Modulators of Extrapituitary Prolactin Expression in Human Skin

Human scalp skin and hair follicles (HFs) are extra-pituitary sources of prolactin (PRL). However, the intracutaneous regulation of PRL remains poorly understood. Therefore we investigated whether well-recognized regulators of pituitary PRL expression, which also impact on human skin physiology and pathology, regulate expression of PRL and its receptor (PRLR) in situ. This was studied in serum-free organ cultures of microdissected human scalp HFs and skin, i.e. excluding pituitary, neural and vascular inputs. Prolactin expression was confirmed at the gene and protein level in human truncal skin, where its expression significantly increased (p = 0.049) during organ culture. There was, however, no evidence of PRL secretion into the culture medium as measured by ELISA. PRL immunoreactivity (IR) in female human epidermis was decreased by substance P (p = 0.009), while neither the classical pituitary PRL inhibitor, dopamine, nor corticotropin-releasing hormone significantly modulated PRL IR in HFs or skin respectively. Interferon (IFN) γ increased PRL IR in the epithelium of human HFs (p = 0.044) while tumour necrosis factor (TNF) α decreased both PRL and PRLR IR. This study identifies substance P, TNFα and IFNγ as novel modulators of PRL and PRLR expression in human skin, and suggests that intracutaneous PRL expression is not under dopaminergic control. Given the importance of PRL in human hair growth regulation and its possible role in the pathogenesis of several common skin diseases, targeting intracutaneous PRL production via these newly identified regulatory pathways may point towards novel therapeutic options for inflammatory dermatoses.

The Secretory Pattern and Source of Immunoreactive Prolactin in Pregnant African (&lt;i&gt;Loxodonta africana&lt;/i&gt;) and Asian (&lt;i&gt;Elephas maximus&lt;/i&gt;) Elephants

The objective of the present study was to define the secretion of prolactin (PRL) in pregnant African and Asian elephants. Levels of immunoreactive (ir-) PRL in serum and placental homogenates were measured by a heterologous radioimmunoassay (RIA) based on an ovine and human RIA system, and the localization of ir-PRL in the placenta was detected by immunohistochemistry using anti-human PRL. Circulating ir-PRL clearly showed a biphasic pattern during pregnancy in African and Asian elephants. Serum levels of ir-PRL started to increase from the 4 - 6th month of gestation and reached the first peak level around the 11-14th month. A second peak of circulating ir-PRL levels was observed around the 18-20th month of gestation followed by an abrupt decline after parturition. In contrast, in a case of abortion of an African elephant, the second peak of ir-PRL was not observed, and the levels remained low for about four months until parturition. The weight of the fetus delivered at the 17th month of gestation was 23.5 kg, which was quite small compared with normal fetuses in previous reports. Ir-PRL was detected in placental homogenates, and immunolocalization was observed in trophoblasts in both the African and Asian elephants, indicating that the placenta is the source of ir-PRL during pregnancy in elephants. The present results clearly demonstrated that circulating ir-PRL shows a biphasic pattern during normal pregnancy and that the placenta appears to be an important source of circulating ir-PRL during pregnancy in both African and Asian elephants.

Ectopic secretion of GHRH by a pancreatic neuroendocrine tumor associated with an empty sella

Acromegaly is usually the result of a pituitary growth hormone cell-adenoma or is more rarely due to ectopic secretion of growth hormone releasing hormone (GHRH).We report the case of a 60-year-old woman with acromegaly due to a GH-RH-secreting pancreatic tumor. Laboratory evaluation confirmed the diagnosis of acromegaly. Magnetic resonance imaging revealed a partial empty sella with no signs of adenoma. Ultrasound sonography performed for abdominal pains showed a calcified large heterogeneous infrahepatic mass. Computed tomography scan discovered a heterogeneous pancreatic head mass with a diameter of 10 cm. Measurement of fasting plasma GHRH was performed showing a high concentration of 604 ng/L (normal 10–60). We therefore concluded that the acromegaly was caused by ectopic overproduction of GHRH likely due to the pancreatic tumor. The patient underwent a cephalic duodenopancreatectomy. Histology revealed a well-circumscribed tumor with organoid architecture. Immunohistochemistry demonstrated diffuse positivity for chromogranin A, neuronal specific enolase and synaptophysin and negative immunoreactivity for prolactin, GH and serotonin. These features were concordant with a well-differentiated neuroendocrine tumor of the pancreas. Surgical resection of this pancreatic tumor was followed by significant amelioration of acromegalic signs and normalization of GHRH and GH levels.

Thyrotropin-releasing hormone and oestrogen differentially regulate prolactin and prolactin receptor expression in female human skin and hair follicles in vitro

Human skin and scalp hair follicles are both a nonclassical target and an extrapituitary source of prolactin (PRL), which is a potent hair growth modulator. However, how the expression of PRL and PRL receptor (PRLR) is regulated in human skin is unknown. To investigate whether two key stimulators of pituitary PRL secretion, thyrotropin-releasing hormone (TRH) and oestrogen, also regulate cutaneous PRL and PRLR expression. Female scalp skin and/or microdissected hair follicles were treated for 6 days in serum-free organ culture with oestrogen (100 nmol L(-1)), TRH (1-10 ng mL(-1), 3-30 nm) or vehicle control. Quantitative immunohistomorphometry of skin and hair follicle sections was complemented with quantitative polymerase chain reaction for PRL and PRLR in cultured hair follicles and/or female human outer root sheath (ORS) keratinocytes. Oestrogen treatment significantly upregulated PRL and PRLR immunoreactivity in selected skin and hair follicle compartments, at the gene and protein level (P < 0.05). TRH significantly increased PRL immunoreactivity and transcription in hair follicles (P < 0.05); however, while it also increased PRLR transcription in hair follicles, it downregulated PRLR immunoreactivity in the hair follicle ORS (P < 0.05). Our pilot study shows that two key endocrine controls of pituitary PRL secretion, oestrogen and TRH, also regulate PRL and PRLR expression in human skin. This provides novel insights into the regulation of extrapituitary PRL and PRLR expression, and invites exploration of oestrogen and TRH as novel therapeutic agents in the management of skin and hair diseases characterized by aberrant PRLR-mediated signalling.

Acute Hypocalcemia Enhances Prolactin Levels : A Study before and after Oophorectomy

The effect of acute hypocalcemia on serum prolactin values was investigated in 13 female subjects before and after oophorectomy. An infusion of disodium-EDTA (50 mg/kg b.w., for 120 min) was administered to each patient. Ionized calcium, immunoreactive parathyroid hormone and prolactin serum levels were determined 15 min prior to the infusion, at the beginning of each infusion and thereafter at every 30 min interval. The decrease in serum ionized calcium induced by Na2-EDTA infusion was not influenced by surgery. Serum prolactin and parathyroid hormone values before and after oophorectomy showed a significant (p less than 0.01) increase at 90 and 120 min. The maximum serum prolactin increase was achieved at 120 min and was not influenced by oophorectomy. The results demonstrate that acute hypocalcemia increases serum prolactin levels in female subjects and suggest a possible role for parathyroid hormone and dopaminergic system, even if their interaction remains speculative.