PRL Response Research Articles

The diagnosis and prevalence of hypoprolactinemia in patients with panhypopituitarism and the effects on depression and sexual functions

PurposeWe aimed to investigate the prevalence and the diagnostic criteria of hypoprolactinemia in patients with panhypopituitarism and the effects of hypoprolactinemia on depression and sexual functions.Materials and methodsForty-eight patients with panhypopituitarism and 20 healthy volunteers were included. Basal hormone levels were measured and a TRH stimulation test was performed. For the evaluation of sexual functions, questionnaries of Female Sexual Functional Index (FSFI) for females and International Erectile Functional Index for males were performed to the subjects. Depressive symptoms were evaluated by Beck Depression Envontory score (BDI-II).ResultsThe peak PRL response to TRH stimulation test at 5th percentile in the control group was 18.6 ng/ml in males and 41.6 ng/ml in females and accepted as the cut-offs for sufficient response of PRL. Prolactin was insufficient in 42(87.5%) patients. A basal PRL level of ≤ 5.7 ng/ml in males and 7.11 ng/ml in females was 100% specific in predicting an inadequate response to TRH stimulation test with 80% and 70% sensitivity respectively. A basal PRL level of ≥ 8.5 ng/dl in males was 100% specific and 76% sensitive, and in females a level of ≥ 15.2 ng/dl was 96% specific and 66% sensitive in predicting an adequate response to TRH. PRL deficient patients with panhypopituitarism had higher depression scores compared to the controls, lower sexual function scores in males.ConclusionPRL deficiency is prevalent among individuals with panhypopituitarism, with the potential to result in elevated depression scores in both sexes and impaired sexual functions in males. A basal PRL level seems to be sufficient for the diagnosis of hypoprolactinemia in routine clinical practice.

Inhibition of Indoleamine 2,3-Dioxygenase in the Prelimbic and Infralimbic Cortices Exerts Antidepressant Effects through Different Pathways in ICV-STZ Rats

An intracerebroventricular injection of streptozotocin (ICV-STZ) is used to simulate sporadic alzheimer’s disease (sAD) in rats. Rats exhibit depression-like behaviors at the beginning of this model. Indoleamine 2,3-dioxygenase (IDO), a rate-limiting enzyme catalyzing the conversion of tryptophan to kynurenine, is closely related to AD and depression. Present study investigated the neurophysiological mechanism of depression-like behaviors in ICV-STZ rats with a focus on IDO-related kynurenine pathways. IDO was activated in both the prelimbic cortex (PrL) and infralimbic cortex (IL), but abnormalities in downstream metabolic pathways were dramatically different and associated with separate secondary biological effects. In the PrL, the neuroprotective branch of the kynurenine pathway was attenuated, as evidenced by a decrease in kynurenic acid and kynurenine aminotransferase II accompanied by defects in astrocytes, reflected by decreases in GFAP-positive cells and glial transporters and morphological damage. In the IL, the neurotoxic branch of the kynurenine pathway was enhanced, as evidenced by an increase in 3-hydroxy-kynurenine and kynurenine 3-monooxygenase paralleled by the overactivation of microglia, reflected by an increase in Iba1-positive cells and cytokines with morphological alterations. Synaptic plasticity was attenuated in both subregions. Additionally, a microinjection of the selective IDO inhibitor 1-MT in the PrL or IL alleviated depression-like behaviors by reversing these different abnormalities in the PrL and IL. These results suggest that the antidepressant effects of IDO inhibition in the PrL and IL occur through different pathways, namely by enhancing neuroprotective effects in the PrL and attenuating neurotoxic responses in the IL.

Two Cases of Anti-PIT-1 Hypophysitis Exhibited as a Form of Paraneoplastic Syndrome

Abstract Background: Anti-pituitary-specific transcription factor 1 (PIT-1) hypophysitis (anti-PIT-1 antibody syndrome) is a newly defined clinical entity, demonstrating an adult-onset hypopituitarism, and is a thymoma-associated autoimmune disease characterized by acquired GH, PRL, and TSH deficiencies due to autoimmunity against PIT-1 (1, 2). This disease is defined by an acquired specific GH, PRL, and TSH deficiencies and the presence of circulating anti-PIT-1 antibody and/or PIT-1-specific T cells (2). As the etiology, ectopic expression of PIT-1 in thymoma plays a causal role in the development of the disease (3); however, it is unknown whether this disease is involved in other conditions. Here, we report two PIT-1 hypophysitis cases, exhibiting as a form of paraneoplastic syndrome with malignancies other than thymoma. Clinical Case: A 79-year-old woman (case 1) and an 86-year-old man (case 2) were referred to us on suspicion of anti-PIT-1 hypophysitis because of acquired GH, PRL, and TSH deficiencies. In both patients, the endocrinological evaluation revealed extremely low basal levels and blunted responses of GH, PRL, and TSH to the provocative stimuli. In contrast, the secretion of HPA and HPG axis were preserved in both patients. Magnetic resonance imaging of the pituitary gland showed slight atrophy in case 1 and normal size in case 2. Interestingly, computed tomography imaging revealed no evidence for thymomas in both patients. On the other hand, case 1 was complicated with diffuse large B-cell lymphoma (DLBCL) of the bladder with multiple bilateral cervicals, axillary, para-aorta, and internal and external peri iliac lymphadenopathies. Case 2 was diagnosed with malignancy with multiple metastases of unknown origin with para-aortic and para-gastric lymphadenopathies, and vertebral body infiltrates. Because circulating anti-PIT-1 antibody was detected, both patients were diagnosed with anti-PIT-1 hypophysitis. Circulating PIT-1-reactive T cells were detected in case 1 using Enzyme-Linked Immunospot assay. Interestingly, the PIT-1 protein was ectopically expressed in the DLBCL tissue of case 1, while DLBCL tissues derived from control patients without anti-PIT-1 hypophysitis were negative for PIT-1. In case 2, the materials were not available because of the situation of the best supportive care. Conclusion: These data show that anti-PIT-1 hypophysitis is associated not only with thymoma but also with other malignancies. Additionally, the ectopic expression of PIT-1 in the DLBCL tissues and presence of PIT-1- reactive T cells suggested that the underlying mechanisms were similar to those observed in thymoma (3). Thus, anti-PIT-1 hypophysitis is defined as a form of paraneoplastic syndrome. Reference: (1) J Clin Invest. 2011;121(1):113-119., (2) Endocr Rev. 2020;41(2)., (3) Sci Rep. 2017;7:43060.

SAT-244 Inflammatory Rathke Cleft Cyst Caused Hypothalamic Panhypopituitarism

Background: Hypothalamic panhypopituitarism was a rare disease which was caused by brain tumors such as Rathke cyst, germinoma, malignant lymphoma and craniopharyngioma, and vascular accidents such as thrombosis and hemorrhage. We have found a rare case of hypothalamic panhypopituitarism occurred by the inflammation of Rathke cyst. Case presentation: A 77-year-old woman was admitted to our hospital because of severe headache, nausea, vomiting and fever. Hyponatremia (Na 131 meq/L) and increased CRP level (0.20 mg/dl) and no finding of gastroenterological examination and abdominal CT scanning were observed. Endocrinological examination revealed low levels of anterior pituitary hormones such as GH, LH, FSH and ACTH and increased PRL levels and low level of serum cortisol. Simultaneous CRH, TRH and LH-RH stimulations tests indicated low responses of TSH, LH, FSH and PRL and hyperesponse of ACTH (from 2.4 to 251 pg/ml). Radiological examination by enhanced MRI revealed high intensity of T2-weighted images and low and partial high intensities of T1-weighted images in swelling of pituitary gland and vanishment of high intensity of posterior lobe in T2-weighted images suggesting that the inflammatory wall of Rathke cyst. We searched previous data of ACTH and cortisol levels which showed normal level of ACTH (55.2 pg/ml) and cortisol 18.8 μ;g/dl) when headache and nausea arouse on 50 days before. Based on above results patient was diagnosed as hypothalamic hypopituitarism due to inflammatory Rathke cyst. Therefore, patient was treated with hormone replacement therapy by 20 mg of hydrocortisone. After these treatment, polyuria, urinary low osmotic pressure and hypernatremia appeared due to partial diabetes insipidus caused by the impairment of posterior lobe in pituitary gland, and diagnosed by the examination of vasopressin test. This patient was also treated by the oral desmopressin acetate hydrate (60 μ;g/day), and has been well-tolerated in the outpatient clinic. Conclusion: These results suggested that inflammatory Rathke cyst with inflammatory changes in hypothlamo-pituitary system raised a rare case of hypothalamic panhypopituitarism.Reference: Nishioka H. et al.: Clin Endocrinology (Oxf) 2006:64:184–188

Changes in Clinical Stage Identify Different Response Categories Among Patients in Iwcll PR: Analysis of CLL Patients on the Resonate Study

Background:In CLL/SLL, the iwCLL PR category is heterogeneous and complex to evaluate. Changes in clinical staging (Binet, Rai) have been proposed as a method to evaluate response in CLL (Montserrat, Cancer 1985; iwCLL, Ann Intern Med 1989). Ibrutinib (ibr), a first-in-class, once-daily inhibitor of Bruton's tyrosine kinase, is indicated by the FDA for the treatment of pts with CLL/SLL and allows for treatment without chemotherapy. Robust improvements in progression-free survival (PFS) and overall survival (OS) among ibr-treated pts in the phase 3 RESONATE trial demonstrated superiority of ibr over ofatumumab (ofa) in heavily pretreated CLL, regardless of prognostic features. As the majority of ibr pts achieved iwCLL PR or PR-L manifested by improved hematologic function and/or disease burden, we analyzed RESONATE pts with PR or PR-L by Binet stage to determine if clinical downstaging captures different, clinically meaningful subgroups among patients in iwCLL PR/PR-L.Methods:Among 391 previously treated CLL pts randomized to receive oral ibr (n=195) or intravenous ofa (n=196), those who achieved a best overall response of PR or PR-L were assessed for Binet Stage at time of first response. Stage A was defined as no anemia or thrombocytopenia and <3/5 sites of involvement (unilateral or bilateral cervical, axillary, and inguinal lymph nodes, liver, spleen); Stage B as no anemia or thrombocytopenia and ≥3/5 involved sites; and Stage C as anemia (hemoglobin <10 g/dL) and/or thrombocytopenia (platelets <100,000/µL) regardless of lymph node/organ site involvement. Binet stage data were considered missing if any one component of the staging criteria was not available. Kaplan-Meier analyses were performed based on Binet Stage at time of first response. Data were analyzed as of the interim analysis (Byrd, N Engl J Med 2014), and p-values are descriptive.Results:A total of 162 (83%) ibr pts and 45 (23%) ofa pts achieved PR/PR-L as best overall response as assessed by investigator; 53% of ibr responders were PR and 46% were PR-L at first response. Baseline characteristics (age, prior therapy, marrow infiltration, unmutated IGHV) were balanced between arms. A majority of PR/PR-L ibr pts were downstaged to Stage A reflecting improvement in lymphadenopathy/organomegaly and/or cytopenias with treatment. At time of first PR/PR-L, the proportion of Stage C pts decreased from 44% (n=72) at baseline to 27% (n=44) for the ibr arm and from 42% (n=19) to 33% (n=15) for the ofa arm. While maintaining PR/PR-L, 48% of ibr-treated and 40% of ofa-treated pts shifted from Stage C to A (or to B/A). The efficacy of ibr over ofa in PR/PR-L pts was similar to that observed in the intent-to-treat population for median PFS (not reached [NR] for ibr vs. 8.48 mo for ofa, P<0.0001). A treatment effect between ibr vs. ofa was also observed for duration of response (DOR) in PR/PR-L pts (NR for ibr vs. 5.52 mo for ofa, P<0.0001). Responders with PR/Stage A showed a longer PFS outcome than responders with PR/Stage C at time of first response to ibr (P=0.0314, Figure). The estimated median PFS for Stage C should be interpreted with caution as it occurred at the tail end of the curve with 2 pts at risk. Within the ofa arm, no difference in PFS between PR/Stage A vs. PR/Stage C was observed, although a limited sample size of responders prohibits robust analysis of this arm. For the ibr arm, both OS (P=0.0281) and DOR (P=0.0431) suggest a trend for improved outcome for PR/Stage A vs. PR/Stage C. Subset analysis (e.g., pts with del17p; PR vs PR-L outcomes) were not feasible because of the small number of pts in these categories.Conclusions:This ad-hoc analysis shows that changes in clinical stage break down the PR/PR-L (iwCLL) category into different, clinically meaningful subgroups, and reinforces the notion that improving cytopenias is a desirable goal of CLL therapy with ibrutinib (Barrientos, ASH 2014). Altogether, this study demonstrates that changes in clinical stage could be a useful and non-costly method to evaluate treatment response at different time points over the course of the disease, a concept with potential clinical implications that requires validation in prospective clinical trials. [Display omitted] DisclosuresDelgado:Janssen: Consultancy, Honoraria; Novartis/GSK: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Roche: Consultancy, Honoraria, Research Funding; Infinity: Research Funding. Suzuki:AbbVie: Equity Ownership; Pharmacyclics, LLC, an Abbie Company: Employment, Other: Leadership, travel, accommodations, expenses. Hsu:AbbVie: Equity Ownership; Pharmacyclics, LLC, an Abbie Company: Employment. James:Pharmacyclics, LLC, an AbbVie Company: Employment; AbbVie: Equity Ownership. Montserrat:Vivia Biotech: Equity Ownership; Pharmacyclics: Consultancy; Janssen: Honoraria, Other: travel, accommodations, expenses; Morphosys: Other: Expert Testimony; Gilead: Consultancy, Other: Expert Testimony.

Revealing the Neuroendocrine Response After Remoxipride Treatment Using Multi-Biomarker Discovery and Quantifying It by PK/PD Modeling

To reveal unknown and potentially important mechanisms of drug action, multi-biomarker discovery approaches are increasingly used. Time-course relationships between drug action and multi-biomarker profiles, however, are typically missing, while such relationships will provide increased insight in the underlying body processes. The aim of this study was to investigate the effect of the dopamine D2 antagonist remoxipride on the neuroendocrine system. Different doses of remoxipride (0, 0.7, 5.2, or 14 mg/kg) were administered to rats by intravenous infusion. Serial brain extracellular fluid (brainECF) and plasma samples were collected and analyzed for remoxipride pharmacokinetics (PK). Plasma samples were analyzed for concentrations of the eight pituitary-related hormones as a function of time. A Mann–Whitney test was used to identify the responding hormones, which were further analyzed by pharmacokinetic/pharmacodynamic (PK/PD) modeling. A three-compartment PK model adequately described remoxipride PK in plasma and brainECF. Not only plasma PRL, but also adrenocorticotrophic hormone (ACTH) concentrations were increased, the latter especially at higher concentrations of remoxipride. Brain-derived neurotropic factor (BDNF), follicle stimulating hormone (FSH), growth hormone (GH), luteinizing hormone (LH), and thyroid stimulating hormones (TSH) did not respond to remoxipride at the tested doses, while oxytocin (OXT) measurements were below limit of quantification. Precursor pool models were linked to brainECF remoxipride PK by Emax drug effect models, which could accurately describe the PRL and ACTH responses. To conclude, this study shows how a multi-biomarker identification approach combined with PK/PD modeling can reveal and quantify a neuroendocrine multi-biomarker response for single drug action.

A novel mutation of &lt;i&gt;IGSF1&lt;/i&gt; in a Japanese patient of congenital central hypothyroidism without macroorchidism [Rapid Communication

Congenital central hypothyroidism (C-CH) is a rare disease known to be caused by mutations of the genes encoding TSH β or the TRH receptor gene, although the cause of the disease in a number of patients has not yet been clarified. Recently, mutations and deletions of the immunoglobulin superfamily member 1 (IGSF1) gene have been reported to be the cause of C-CH. Here we report a Japanese male patient with C-CH due to a novel IGSF1 mutation. He was detected by neonatal mass screening of simultaneous TSH and free T4 measurements and levothyroxine was initiated. At 6 years of age he underwent ¹²³I scintigraphy after levothyroxine treatment had been discontinued for one month and his thyroid and pituitary function were evaluated. Since TSH and PRL responses after TRH stimulation were low, his diagnosis of C-CH was confirmed. During follow up, whereas onset of his puberty was delayed, his secondary sex characterization completed at 17 years old. In this patient we analyzed IGSF1 and TRHR. As results, we identified a novel insertion mutation in IGSF1 (c.3528-3529insC), resulting in a premature stop codon (p.Pro1082Trpfs39X). In conclusion, we identified a novel mutation of IGSF1 in a Japanese male patient with C-CH.

Oxytocin does not modify GH, ACTH, cortisol and prolactin responses to Ghrelin in normal men

In order to test the possible effect of Oxytocin (OT) on Ghrelin-stimulated GH, PRL, ACTH and cortisol, ten healthy normal men were studied. Ghrelin (0.2 μg/kg body weight (BW)) as an iv bolus; Ghrelin plus OT (2 IU as bolus plus 0.07 IU/min administered for 90 min). The administration of OT did not change GH, PRL, ACTH and cortisol release induced by Ghrelin. The data suggests that in humans OT did not modulate the GH, PRL, ACTH and cortisol response to Ghrelin.

Neuroendocrine effects of Citalopram, a selective serotonin re-uptake inhibitor, during lifespan in humans

Serotonergic system contributes to the regulation of hypothalamus-pituitary-adrenal axis. In humans, serotonergic agonists increase PRL, ACTH, and cortisol, while serotonin (5HT) influence on GH is controversial. Central 5HT activity and neuroendocrine function change during lifespan. To clarify the neuroendocrine response to 5HT across lifespan, we assessed ACTH, cortisol, DHEA, PRL, and GH responses to citalopram (CT) in young adults (YA) (no.=12, 29.2±1.7 yr mean±SEM), middle aged (MA) (no.=12, 54.3±0.9 yr), and elderly (ES) (no.=12, 69.3±0.9 yr) males. All the subjects received placebo (saline iv over 120 min) or CT (20 mg iv over 120 min). Blood samples were taken every 15 min up to 240 min. During placebo, ACTH, cortisol, GH, and PRL were similar in all groups while DHEA showed an age-dependent reduction from middle age (p<0.001). During CT, ACTH, and cortisol were higher than during placebo in YA (p<0.05) and even more in MA (p<0.01 vs placebo, p<0.05 vs YA); in ES, the increase of both ACTH and cortisol (p<0.05 vs placebo) was lower than in MA (p<0.05) and higher than in YA (p<0.05 for cortisol only). No changes were observed for DHEA, GH, and PRL in any group. Corticotrope response to CT is age-dependent in normal men, being amplified starting from middle age, suggesting precocious changes in the serotonergic neuroendocrine control during lifespan. CT is a useful tool to evaluate the age-dependent serotonergic function in humans.

Effect of ghrelin and metoclopramide on prolactin secretion in normal women

Administration of ghrelin to women stimulates the secretion of PRL but the mechanism is not known. The aim of the study was to investigate the effect of the dopamine receptor blocker, metoclopramide, on ghrelin-induced PRL release. Ten healthy normally cycling women were studied in the midluteal phase of 4 menstrual cycles. A single dose of normal saline (cycle 1), ghrelin (1 μg/kg) (cycle 2), metoclopramide (20 mg) (cycle 3), and ghrelin plus metoclopramide (cycle 4) was given to the women iv. Blood samples in relation to the iv injection (time 0) were taken at -15, 0, 15, 30, 45, 60, 75, 90, and 120 min. The response of PRL and GH was assessed. Following ghrelin administration (cycles 2 and 4), plasma ghrelin and serum PRL and GH levels increased rapidly, peaking at 30 min (p<0.001). PRL was also increased after the injection of metoclopramide (p<0.001, cycle 3), but the increase was much greater than after the administration of ghrelin. The combination of ghrelin and metoclopramide stimulated PRL secretion to the same extent with metoclopramide alone. No changes in GH and PRL levels were seen after saline injection. These results demonstrate that the stimulating effect of ghrelin on PRL secretion is not additive with that of metoclopramide, although a dose range study might provide further information.

Blockage of ghrelin-induced prolactin secretion in women by bromocriptine

To investigate the effect of bromocriptine on ghrelin-induced PRL secretion in women. Longitudinal study. University hospital. Ten healthy, normally cycling women. The women were injected IV on day 3 of three cycles with a single dose of normal saline (cycle 1) or ghrelin (1 microg/kg) after pretreatment for 2 days either with placebo (cycle 2) or with bromocriptine (cycle 3) per os. Blood samples were taken before and frequently after drugs administration for 120 minutes. The PRL and GH responses to ghrelin were assessed. Bromocriptine suppressed basal PRL levels significantly. The injection of ghrelin stimulated a significant increase in serum PRL levels in cycle 2 but not in cycle 3, in which PRL levels remained stable. The response of GH to gherlin was significantly attenuated in cycle 3 as compared with cycle 2. The present study demonstrates for the first time that bromocriptine blocked the stimulating effect of ghrelin on PRL release and attenuated the GH response to the same stimulus. The mechanism of these interactions needs to be clarified.

The Pituitary-Testicular Axis in Non-Professional Soccer Players

In European countries, football is one of the most popular forms of physical exercise. However, the possibility that endocrine changes can arise in football players has not been investigated completely. Therefore, the aim of the present study was to evaluate the effects of a training program and the consequences of a football match on the pituitary-testicular axis in ten trained non-professional soccer players. Basal levels of LH, FSH, PRL and T, as well as LH, FSH and PRL responses to an iv bolus of GnRH (0.1 mg) plus TRH (0.2 mg), were measured in each subject. The endocrine evaluation was performed before the beginning of the seasonal training (after a 30 days rest period), and repeated on 2 consecutive days at the end of a 3 months regular training program, 14-15 h from the end of both a customary 3 h training session and a 90 min strenuous soccer match. In 5 out of the 10 athletes a semen analysis was performed after each endocrine evaluation. Ten age-matched, healthy, sedentary men served as a control group. Basal serum levels of LH (10.4 +/- 1.3 mIU/ml), FSH (8.7 +/- 1.1 mIU/ml), PRL (9.7 +/- 1.6 ng/ml) and T (6.3 +/- 0.9 ng/ml) measured in the soccer players before the beginning of the seasonal training were similar to those found in the control subjects (LH = 9.2 +/- 1.7 mIU/ml, FSH = 8.5 +/- 1.4 mIU/ml, PRL = 8.8 +/- 1.8 ng/ml, T = 6.4 +/- 1.1 ng/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Opioid-dopaminergic interactions in primary empty sella.

Previous studies have indicated different abnormalities of PRL secretion in patients with primary empty sella (PES). Since it is known that endogenous opiates and dopamine interact in modulating PRL secretion, we have studied the effect of an opiate receptor blockade (with Naloxone, NAL, 1.6 mg/h as a continuous infusion) on anterior pituitary hormones and on PRL responsiveness to metoclopramide (MCP), in 10 premenopausal normoprolactinemic patients with PES, studied in follicular phase, in order to investigate neurotransmitter abnormalities present in such a syndrome. NAL failed to significantly affect LH and FSH basal levels; on the contrary, slight but significant increases in PRL and GH secretion were observed. NAL partially blunted the PRL responsiveness to the dopaminergic blockade, which was very marked when tested after MCP alone. These data confirm that the modulation of anterior pituitary hormone secretion is different in PES patients, when compared with normal subjects. The infusion of NAL induced a "paradoxical" increase in hormones (PRL and GH) which are normally stimulated by endogenous opiates; but, on the other side, it blocked the marked PRL responsiveness to the dopaminergic blockade, which is characteristic of PES syndrome. This phenomenon seems to indicate that the relationships between dopaminergic and opiatergic neurons could be modified by the neuroanatomic alteration which is present in this complex syndrome.

Pituitary Gonadal Function in Diabetic Male Patients with and without Impotence

Assessment of pituitary function was undertaken in diabetic male patients with and without impotence, and in normal subjects, using a combined gonadotropin releasing hormone (GnRH) and thyrotropin releasing hormone (TRH) test. Basal plasma levels of testosterone, gonadotropins, PRL and TSH were similar in the diabetic patients and controls. Following the administration of I.V. GnRH 150 microgram and TRH 500 microgram, diabetic patients with impotence demonstrated a lower LH response at 30 and 150 minutes and an increased PRL response at 20 minutes, which was statistically significant when compared to controls. FSH and TSH were similar in the diabetic patients and controls. The GnRH and TRH test was repeated in impotent diabetic patients while receiving 0.8-1 mU/kg/hr of insulin through an infusion pump. No difference in LH and PRL response could be demonstrated. These results demonstrate that following GnRH and TRH test, diabetic patients with impotence have a significantly different LH and PRL response than controls. In these patients acute control of hyperglycemia using an insulin infusion pump did not reverse the abnormal response.

Re-evaluation of the prolactin receptor expression in human breast cancer

The pituitary hormone PRL is involved in tumorigenesis in rodents and humans. PRL promotes proliferation, survival and migration of cancer cells acting via the PRL receptor (PRLR). Aiming to perform a large-scale immunohistochemical (IHC) screening of human mammary carcinomas for PRLR expression, we evaluated the specificity of commercially available anti-human PRLR antibodies (B6.2, U5, PRLRi pAb, 1A2B1, 250448 and H-300). The latter three antibodies were found to specifically recognise PRLR. The relative PRLR expression level detected with these antibodies closely reflected the level of (125)I-PRL binding to the cell surface. The monoclonal antibody (mAb) 250448 was specific for the N-()glycosylated form of PRLR and blocked PRL binding and signalling. The PRLRi polyclonal antibody recognised cytokeratin-18. The mAb B6.2, previously used in a number of studies, was found to lack specificity for PRLR and to rather recognise a PRLR-associated protein. The mAb U5 raised against the rat PRLR did not cross-react with the human receptor. Only one mAb, 1A2B1, was found useful for detection of PRLR in IHC applications. This antibody recognised PRLR expressed in human breast cancer cell lines and decidual cells in tissue sections of human placenta. Screening of 160 mammary adenocarcinomas demonstrated significant immunoreactivity in only four tumours, indicating that PRLR is generally not strongly upregulated in human breast cancer. However, even a very low level of PRLR expression was found to be sufficient to mediate PRL responsiveness in breast cancer cell lines.

Prolactin Stimulation of Iodide Uptake and Incorporation into Protein Is Polyamine-Dependent in Mouse Mammary Gland Explants

Abstract. Previous studies have demonstrated that the prolactin stimulation of most lactational processes (casein, lactose, and triglyceride synthesis) requires an earlier stimulating effect of prolactin on the synthesis of the polyamines. Spermidine appears to be the specific polyamine required for prolactin to enhance milk product synthesis. Inorganic iodide is present in milk at more than an order of magnitude higher concentration than that of the maternal plasma. Since prolactin stimulates iodide accumulation in milk, the goal of these studies was to determine the role of the polyamines in this hormone response. Two drugs were employed in these studies: DFMO (difluoromethylornithine), which inhibits ornithine decarboxylase, and MGBG [methylglyoxal bis(guanyl-hydrazone)], which inhibits S-adenosyl methionine decarboxylase. In mammary gland explants from midpregnant (10–14 days of pregnancy) mice, MGBG at 100 μM abolished the prolactin stimulation of iodide uptake and incorporation into milk proteins, whereas DFMO caused a concentration-dependent inhibition of the PRL response. Selected sensitivity of the MGBG and DFMO inhibitions was validated by a reversal of the drug inhibitions with the addition of 1 mM spermidine to the culture medium. These data suggest that the polyamine signaling pathway is involved in the prolactin stimulation of iodide uptake into milk.

Effects of Pantothenic Acid Supplementation on Adrenal Steroid Secretion from Male Rats

The effects of pantothenic acid-supplementation on the adrenal secretion of corticosterone and progesterone in male rats were investigated using an in vitro cell culture system. Male rats at 21 d of age were given 0.03% pantothenic acid in their drinking water for 9 weeks. After 9 weeks of treatment, the animals were decapitated, and adrenal cells were cultured in the absence or presence of rat adrenocorticotropic hormone (ACTH; 10(-15) to 10(-10) M) and/or ovine prolactin (oPRL; 10(-9) to 10(-7) M) for 4 h. Adrenal cells in pantothenic acid-treated rats exhibited higher basal levels of corticosterone and progesterone than control rats. The response of ACTH and/or PRL on corticosterone and progesterone release was higher in the pantothenic acid-treated rats than in the control rats. In addition, PRL increased the stimulatory effect of ACTH-induced corticosterone secretion in both normal and pantothenic acid-treated rats. These results clearly demonstrated that pantothenic acid supplementation stimulates the ability of adrenal cells in male rats to secrete corticosterone and progesterone. Additionally, these results also showed that pantothenic acid supplementation induced adrenal hyperresponsiveness to ACTH stimulation, and PRL further stimulated adrenal sensitivity to ACTH.

TRH Test in Patients with Diabetes Mellitus Type 1 and/or Autoimmune Thyroiditis. Changes in the Pituitary –Thyroid Axis, Reverse T3, Prolactin and Growth Hormone Levels

The response of the pituitary- thyroid axis, reverse triiodothyronine (rT3), prolactin, and growth hormone (GH) levels following TRH stimulus (Relefact TRH 200 microg 2 amp. i.v.) was examined in patients with autoimmune diabetes type 1 (DM1, n=30), with autoimmune thyroiditis (AT, n=25), and with concurrent DM1 and AT (n=22) to evaluate the influence of DM1 and AT of autoimmune pathogenesis on the above-mentioned hormonal parameters. Statistical analysis (ANOVA) showed that: a) the response of TSH did not differ from control groups (C); b) free triiodothyronine (fT3), free thyroxine (fT4) and their ratio in DM1, DM1+AT and C rose in 120 and 180 min, while a similar increase was not seen in AT (p<0.000001); c) rT3 was not present in any group, with rT3 levels higher in AT (p<0.00002) and lower in DM1 (p<0.02); d) the response of GH had a paradoxical character in some patients in all groups, most often in DM1 (52 %, DM1 vs C, p <0.01). The characteristic response difference was not in the peak GH level, but the delayed return to basal levels in DM1 (p<0.0001) and an abrupt one in AT (p<0.0001). The major findings in DM1 were the differences in GH response, while significant impairment of pituitary-thyroid axis and PRL response to TRH was absent. AT was associated with impairment of TRH stimulated fT3, fT4, fT3/fT4 response and changes in rT3 levels, in spite of preserved TRH-stimulated TSH secretion. GH response in AT patients was also altered.

Hormonal profile and reproductive performance in lactation deficient (OFA hr/hr) and normal (Sprague–Dawley) female rats

Lactation deficiency may have important consequences on infant health, particularly in populations of low socioeconomic status. The OFA hr/hr (OFA) strain of rats, derived from Sprague-Dawley (SD) rats, has deficient lactation and is a good model of lactation failure. We examined the reproductive performance and hormonal profiles in OFA and SD strains to determine the cause(s) of the lactation failure of the OFA strain. We measured hormonal (PRL, GH, gonadotropins, oxytocin, and progesterone) levels by RIA in cycling, pregnant, and lactating rats and in response to suckling. Dopaminergic metabolism was assessed by determination of mediobasal hypothalamic dopamine and dihydroxyphenylacetic acid (DOPAC) concentrations by HPLC and tyrosine hydroxylase expression by immunocytochemistry and western blot. OFA rats have normal fertility but 50% of the litters die of malnutrition on early lactation; only 6% of the mothers show normal lactation. The OFA rats showed lower circulating PRL during lactation, increased hypothalamic dopamine and DOPAC, and impaired milk ejection with decreased PRL and oxytocin response to suckling. Before parturition, PRL release and lactogenesis were normal, but dopaminergic metabolism was altered, suggesting activation of the dopaminergic system in OFA but not in SD rats. The number of arcuate and periventricular neurons expressing tyrosine hydroxylase was higher in SD rats, but hypothalamic expression of TH was higher in OFA rats at the end of pregnancy and early lactation. These results suggest that the OFA rats have impaired PRL release linked with an augmented dopaminergic tone which could be partially responsible for the lactational failure.

An Infant Case of Hyperprolactinemia Induced by a Functional Disorder of the Hypothalamus

Although functional hyperprolactinemia originating in the hypothalamus has been observed, there have so far been few reports of this condition occurring in children. This report describes a 1-yr-and-4-mo old boy with hyperprolactinemia due to functional disorder of the hypothalamic region. He was referred to our hospital because of left gynecomastia which had been observed for one month. His left breast development was stage II, right breast stage I, and pubic hair stage I by Tanner stages, and his bilateral testicular volume was 1 ml. Both his height and growth velocity were normal and his bone age was not advanced. The basal PRL level was high (40.4 ng/ml), but other sex steroids and adrenal androgen levels were normal. GnRH demonstrated the prepubertal stage. PRL response to TRH was normal and levodopa suppressed the increased basal PRL level. His chromosomal finding was 46, XY and macroprolactinemia was ruled out. Repeated MRI examinations did not demonstrate any organic lesions in the brain. He was diagnosed as having hyperprolactinemia induced by a functional disorder of the hypothalamus. His gynecomastia reduced and the high PRL level decreased without medication after 1 year.