Mean Prolactin Concentrations Research Articles

Effect size and inferential statistical techniques coupled with machine learning for assessing the association between prolactin concentration and metabolic homeostasis

Background and objectiveRecent guidelines classify low prolactin levels as low as <7 ng/mL and high levels as >25 ng/mL, while the “Homeostatically Functionally Increased Transient Prolactinemia” (HomeoFIT-PRL) range (25–100 ng/mL) suggests that a temporary increase in prolactin could be metabolically beneficial if no related health issues are present. The aim of this study was to investigate the association between mean prolactin concentrations and disturbances in glycidic and lipidic metabolism and to identify the gray zone associated with prolactin inflection points that correlate with these metabolic changes. MethodsThis cross-sectional study involved 65,795 adults who underwent HOMA-IR, glucose, insulin, total cholesterol, HDL-c, LDL-c, and triglyceride tests. Data was categorized into 106 partitions based on prolactin results. Employing an approach referred to in this study as “Hierarchical Multicriteria Analysis of Differences Between Groups - Statistical and Effect Size Approach” (HiMADiG-SESA) comparing the mean concentrations of metabolic tests across prolactin ranges. A machine learning model was utilized to determine inflection points and their corresponding confidence intervals (CIs). These CIs helped establish gray zones in mean prolactin results related to metabolic changes. ResultsStatistically and clinically, metabolic test means differed for prolactin <7 ng/mL, except insulin. In the HomeoFIT-PRL range, means were lower except for HDL-c. The gray zones of the mean prolactin results associated with changes in glycidic and lipidic metabolism were 9.58–12.87 ng/mL and 13.81–18.73 ng/mL, respectively. ConclusionA strong correlation was identified between mean prolactin concentrations and the results of metabolism tests below the gray zones associated with inflection points, indicating the potential role of prolactin in the appearance of metabolic disorders. Mean prolactin results can provide deeper insight into metabolic balance.

Prolactin secretion pattern among female flight attendants.

Epidemiological observations indicate that female flight attendants are exposed to some reproductive and endocrine system disturbances. The aim of the study was to determine the incidence of hyperprolactinemia among female flight attendants, and to identify factors affecting the secretion of prolactin in female flight attendants working within 1 time zone as well as on long-distance flights. The cross-sectional study covered 103 women aged 23-46 years. The study group (I) was divided into 2 subgroups: subgroup Ia comprising female flight attendants flying within 1 flight zone, and subgroup Ib composed of female flight attendants working on long-distance flights. The control group (II) included women of reproductive age who sought medical assistance due to marital infertility in whom the male factor was found to be responsible for problems with conception in the course of the diagnostic process. The assessment included: age, the body mass index, menstrual cycle regularity, the length of service, the frequency of flying, the prolactin, estradiol and progesterone concentrations, and the result of endometrial biopsy. Descriptive and inferential statistics methods were used to compile the data. The incidence of hyperprolactinemia in the female flight attendants (46%) was significantly higher than in the control group (9%), p < 0.001. Differences between subgroups Ia and Ib regarding individual concentrations were not statistically significant (p = 0.425). Hyperprolactinemia among the female flight attendants working ≥15 years is present slightly more often than in those working <15 years: 46% vs. 45% (p > 0.05). No significant difference was revealed in the secretion of prolactin between the study participants spending <60 h/month flying and those spending ≥60 h/month flying (p > 0.05). Hyperprolactinemia is more common in female flight attendants than in the general population. High values of prolactin concentration in flight attendants are rarely manifested in clinical symptoms. The frequency of flying and the length of service do not affect the development of hyperprolactinemia or the mean prolactin concentration. Int J Occup Med Environ Health. 2021;34(3):351-61.

104 Induction of cyclicity in seasonally anestrous recipient mares

Anestrous (AN) recipient mares’ natural cyclicity must be manipulated to produce foals from transferred embryos early in the year. One approach uses sulpiride to stimulate prolactin (PRL) that appears to have an important reproductive role effecting seasonality in mares. While previous research utilized sulpiride to induce ovulation (OV) in AN mares, few have transferred embryos after treatment. This study was designed to evaluate the effect of a treatment of estradiol cypionate (ECP) and sulpiride on inducing OV and subsequent pregnancy outcome in AN recipient mares of various reproductive status performed on a commercial embryo transfer farm. Anestrous recipient mares (n = 32) were randomly assigned to 4 treatment groups based on records of ovarian activity. Transitional (T, n = 8), AN (n = 11), and progesterone pre-treated (P, n = 9, received 4 mg altrenogest IM 3 wk prior) groups were treated January 20 with 50 mg of ECP IM and 3 g of sulpiride IM 24 h later. A control group (C, n = 4) of AN mares received the carrier. Jugular blood samples were collected at 0, 3, 6, 12, and 24 h post-treatment followed by daily collection for 10 d and collection every other day for 32 d thereafter and analyzed for luteinizing hormone (LH) and PRL. Ovaries were transrectally scanned every 2 to 3 d for 60 d. Embryos were transferred to 10 mares (5 T, 3 P, 2 AN) after at least the second estrous cycle up to the sixth cycle depending on their synchrony to the donor. Binomial data was analyzed via PROC GLIMMIX of SAS, and number of days to OV and hormonal data were analyzed via PROC MIXED with repeated measures. Nonparametric data were natural log-transformed and analyzed if normality was improved. Differences of least squares means were determined using the PDIFF option in SAS with ∝ ≤ 0.05 used to declare significance. There was an effect of treatment on the number of mares that achieved first OV ( P < 0.001) with 23 of 28 (82.1%) treated mares having a first OV within 22 d of treatment; and second OV ( P = 0.018) with 15 of the 23 (65.2%) mares that had a first OV achieving a second OV within 43 d. The mean number of days to first OV of T, AN, and P groups together were 32 ± 5 d earlier ( P < 0.001) than C. The transitional group ovulated sooner ( P = 0.05) than AN and tended ( P = 0.07) to ovulate sooner than P. There was an effect of the treatment-by-day interaction on plasma mean PRL ( P < 0.001) and LH ( P = 0.021) concentrations. Of the 10 embryos that were transferred, 7 (70%) resulted in a confirmed pregnancy at 60 d. Overall, the treatment protocol using ECP and sulpiride appeared to hasten OV and resulted in sustained pregnancy after embryo transfer.

19 Interaction of kisspeptin and the somatotropic and lactotropic axes in mares and geldings

Several experiments were conducted to investigate the interaction between kisspeptin and the somatotropic and lactotropic axes in mares and geldings. Light horse, diestrous mares and geldings, weighing approximately 500 kg and aged 6 to 24 years, were randomly assigned to treatment with 1 mg equine kisspeptin-10 (Kp10; n = 10) or 1 mL saline (n = 9), i.v. Blood samples were collected via jugular venipuncture −10, 0, 5, 10, 15, 20 and 30 min relative to treatment. Plasma concentrations of growth hormone (GH) and prolactin (PRL) were determined by RIA and means compared using ANOVA with repeated sampling. Neither GH nor PRL were stimulated by Kp10. In a second experiment, 30 mares and geldings were used to determine if pre-treatment with estradiol or progesterone would elicit a GH or PRL response to Kp10. Five mares and 5 geldings each were assigned to pre-treatment with 50 mg estradiol cypionate in oil (ECP), 600 mg long-acting progesterone, or oil only, i.m. Two days later, all horses received 1 mg Kp10 in saline, i.v., and blood sampling occurred 0, 5, 10, 15 and 20 min relative to Kp10 administration. Mean GH and PRL concentrations and area under the curve were compared by ANOVA. No stimulation of GH or PRL was observed. In a third experiment, 12 diestrous mares, confirmed by plasma progesterone and ultrasound findings, were randomly assigned to treatment with 1 mg Kp10 (n = 6) or 1 mL saline (n = 6) followed by the dopamine antagonist, sulpiride (0.01 mg/kg body weight), 5 min later. Blood sampling occurred 0, 5, 10 and 15 min relative to sulpiride administration. Sulpiride stimulated PRL ( P < 0.0001) in both groups of mares; however, PRL concentrations were lower ( P ≤ 0.01) in Kp10-treated mares compared with saline-treated mares. To determine if estrogen altered the PRL response to sulpiride, 12 seasonally anovulatory mares, confirmed by plasma progesterone and ultrasound findings, were used in a fourth experiment and randomly assigned to receive 50 mg ECP (n = 6) or oil (n = 6), i.m. The next day, mares were challenged with sulpiride. Treatment and blood sampling occurred as described in experiment 3. Plasma PRL was stimulated ( P < 0.001) in both groups of mares and responses were similar between treatments. In the described experiments, 1 mg Kp10 given as a bolus failed to stimulate circulating GH or PRL within 30 min in mares or geldings regardless of steroid milieu. This is in contrast to reports of GH stimulation in ruminants. Kp10 did alter the PRL response to sulpiride in diestrous mares, perhaps suggesting an interaction between Kp10 and dopaminergic input to the pituitary in a progesterone dominant environment.

Safety and Tolerability of Antipsychotic Drugs in Pediatric Patients: Data From a 1-Year Naturalistic Study.

Background: Antipsychotic drugs (APs) are increasingly used to treat a variety of psychiatric disorders in children and adolescents. However, their safety and tolerability profiles, when used in a developmental age context, show different characteristics from the ones observed in adult patients. Treatment with APs in pediatric patients is often long-term. However, the tolerability data regarding these patients mostly derive from short-term studies.Methods: Starting from April 2017, for a 1-year period, patients between 4 and 18 years of age followed by five units of developmental age neuropsychiatry, who initiated a treatment with at least an AP (ATC class N05A) were included into the study. Patient-related data have been collected at baseline and regularly thereafter, as allowed by the clinical routine. Changes to continuous variables over time have been analyzed using a linear mixed model in subsamples of our population treated with risperidone or aripiprazole.Results: During the observation period, 158 patients were initially enrolled, but only 116 completed 12 months of therapy with an AP. Risperidone was the most used AP (n = 52) followed by aripiprazole (n = 44) and olanzapine (n = 7). For both the aripiprazole and risperidone groups, the mean body mass index (BMI) (P < 0.001 for both groups) and heart rate (P = 0.026 for aripiprazole group and P < 0.001 for the risperidone one) values significantly increased over time. The mean prolactin concentration value significantly increased over time only in the risperidone group (P = 0.04). Eighty-six patients experienced at least one adverse drug reaction (ADR), accounting for a total of 238 specific reactions, with the most frequent being weight gain (n = 34), increased serum prolactin levels (n = 21), hyperphagia (n = 20), and hypercholesterolemia (n = 14). Among these, only 24 ADRs were classifiable as serious.Conclusions: The results of this study confirm that risperidone and aripiprazole are relatively well-tolerated therapeutic options for the treatment of a variety of psychiatric disorders in pediatric patients. However, in findings such as statistically significant increments of BMI and heart rate mean values, the variations over time in prolactin levels observed with risperidone and the differences between the two drugs remark the necessity of systematic monitoring.

UNDERSTANDING PROLACTIN REGULATION AND DETERMINING THE EFFICACY OF CABERGOLINE AND DOMPERIDONE TO MITIGATE PROLACTIN-ASSOCIATED OVARIAN CYCLE PROBLEMS IN ZOO AFRICAN ELEPHANTS (LOXODONTA AFRICANA ).

Perturbations in serum prolactin secretion, both over- and underproduction, are observed in zoo African elephants (Loxodonta africana) that exhibit abnormal ovarian cycles. Similar prolactin problems are associated with infertility in other species. Pituitary prolactin is held under constant inhibition by a hypothalamic-derived neurotransmitter, dopamine; thus, regulation by exogenous treatment with agonists or antagonists may be capable of reinitiating normal ovarian cycles. This study tested the efficacy of oral administration of cabergoline (agonist) and domperidone (antagonist) as possible treatments for hyperprolactinemia or chronic low prolactin, respectively. Hyperprolactinemic (overall mean prolactin, >30 ng/ml), acyclic elephants were administered oral cabergoline (2 mg, n = 4) or placebo (dextrose capsule, n = 4) twice weekly. Overall mean prolactin concentration decreased in treated females compared with controls (32.22 ± 14.75 vs 77.53 ± 0.96 ng/ml; P = 0.01). Interestingly, overall mean progestagen concentrations also increased slightly (P < 0.05) in treated females (0.15 ± 0.01 ng/ml) compared with controls (0.07 ± 0.01 ng/ml), but no reinitation of normal cyclic patterns was observed. Chronic low prolactin (overall mean prolactin, <10 ng/ml), acyclic females were orally administered domperidone (2 g/day, n = 4) or placebo (dextrose capsule, n = 4) for 4 wk, followed by 8 wk of no treatment (four cycles) to simulate the prolactin pattern observed in normal cycling elephants. Overall mean prolactin concentrations increased (P = 0.005) during domperidone treatment (21.77 ± 3.69 ng/ml) compared with controls (5.77 ± 0.46 ng/ml), but progestagen concentrations were unaltered. Prolactin regulation by dopamine was confirmed by expected responses to dopamine agonist and antagonist treatment. Although prolactin concentrations were successfully reduced by cabergoline, and domperidone initiated the expected cyclic prolactin pattern, neither treatment induced normal ovarian activity.

Maternal Pregnancy Hormone Concentrations in Countries with Very Low and High Breast Cancer Risk.

Background: Breast cancer rates in Asia are much lower than in Europe and North America. Within Asia, rates are lower in Mongolia than in neighboring countries. Variation in pregnancy exposure to endogenous hormone concentrations may explain the differences, but data are lacking. Methods: We measured maternal serum progesterone, prolactin, estradiol and estrone concentrations in the second half of pregnancy in a cross-sectional study of urban (n = 143–194 depending on the analyte) and rural (n = 150–193) Mongolian women, and U.S. women from Boston (n = 66–204). Medical records provided information on maternal and perinatal factors. Geometric mean hormones were estimated from standard linear models with the log-hormone as the dependent variable and country as the independent variable adjusted for maternal and gestational age at blood draw. Results: Mean concentrations of prolactin (5722 vs. 4648 uIU/mL; p < 0.0001) and estradiol (17.7 vs. 13.6 ng/mL; p < 0.0001) were greater in Mongolian than U.S. women, while progesterone (147 vs. 201 ng/mL; p < 0.0001) was lower. Mean hormone concentrations were similar in rural and urban Mongolian women. Results were generally similar, with additional adjustment for gravidity, parity, height, body mass index at blood draw, education and alcohol use during pregnancy, and when stratified by offspring sex or parity. Conclusions: Mongolian women had greater concentrations of prolactin and estrogen and lower concentrations of progesterone than U.S. women, while hormone concentrations were similar in rural and urban Mongolian pregnancies. Impact: These data do not support the hypothesis that estrogen concentrations in pregnant women are lower in Mongolian compared with Caucasian women.

Maternal Pregnancy Hormone Concentrations in Countries with Very Low and High Breast Cancer Risk

Background: Breast cancer rates in Asia are much lower than in Europe and North America. Within Asia, rates are lower in Mongolia than in neighboring countries. Variation in pregnancy exposure to endogenous hormone concentrations may explain the differences, but data are lacking. Methods: We measured maternal serum progesterone, prolactin, estradiol and estrone concentrations in the second half of pregnancy in urban and rural Mongolian, and U.S. women from Boston. Medical records provided information on maternal and perinatal factors. Geometric mean hormones were estimated from standard linear models with the log-hormone as the dependent variable and country as the independent variable adjusted for maternal and gestational age at blood draw. Results: Mean concentrations of prolactin (5722 vs. 4648 uIU/mL; p<0.0001) and estradiol (17.7 vs. 13.6 ng/mL; p<0.0001) were greater in Mongolian than U.S. women, while progesterone (147 vs. 201 ng/mL; p<00001) was lower. Mean hormone concentrations were similar in rural and urban Mongolian women. Results were generally similar with additional adjustment for gravidity, parity, height, body mass index at blood draw, education and alcohol use during pregnancy, and when stratified by offspring sex or parity. Conclusions: Mongolian women had greater concentrations of prolactin and estrogen and lower concentrations of progesterone than US women, while hormone concentrations were similar in rural and urban Mongolian pregnancies. Funding Statement: This research was supported by funding from the intramural program at the Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health. Declaration of Interests: None of the authors has a conflict of interest. Ethics Approval Statement: The study was approved by ethical review boards at Mongolia’s Ministry of Health, the National University of Mongolia, and in the United States (U.S.) at the National Cancer Institute (National Institutes of Health), and the Harvard School of Public Health and Brigham and Women’s Hospital in Boston. All participants provided written, informed consent.

Effect of Inhibin-B hormone and its relationship with a number of sex hormones in men with Azoospermia

Inhibin-B is produced by sertoli cells and acts as a negative feedback mechanism of follicular stimulation hormone (FSH). In order to evaluate the effect of Inhibin-B in men with Azoospermia, the study measured the concentrations of the following hormones: Inhibin-B, FSH, Luteinizing Hormone Prolactin (PRL), (LH) and Testosterone (Testo). Serum for 30 normal men semen and 50 men with Azoespermia (zero sperm count in sperm). The mean concentration of the hormone Inhibin-B in patients with Azoospermia was (135.7 ±87.6) pg/ml, while in normal men (175.6 ±47.9) Pg / ml with a significant value of the group of healthy patients at a significant level (p≤0.01). The mean serum FSH concentration in patients was (13.7 ± 12.27) lU / L whereas in normal men (4.1 ± 2.84) lU / L, the relationship was significant between patients and healthy at a significant level (P≤0.01) the correlation with the Inhibin-B hormone is reversible relationship. The mean concentration of LH in patients was (12.8±11.87) IU/L and in the healthy (7.9±5.57) IU/L and the relationship between them was significant (P≤0.05) and the correlation with the Inhibin-B hormone is positive relationship. The mean concentration of the Testosterone In the patients was (2.37 ± 1.22) IU / L and in the healthy (5.1 ± 1.96) IU/ L, the relationship was of significant value at P≤0.01 and the correlation with the Inhibin-B hormone is positive relationship, and there is a difference in the mean concentration of PRL between the patients and the healthy where it reaches (8.88 ±5.16) IU / L in patients and (8.03 ± 4.2) IU / L in the healthy. where the relationship was non-significant value between both patients and healthy and the correlation with the Inhibin-B hormone is positive relationship

Prolonged ovarian acyclicity is associated with a higher likelihood of developing hyperprolactinemia in zoo female African elephants.

Hyperprolactinemia is a common disorder of the hypothalamic-pituitary axis, and a cause of ovarian dysfunction in women. Currently, over half of non-cycling African elephant females in North America also are hyperprolactinemic, suggesting a similar link between these two conditions may exist. The objective of this study was to determine the relationship between acyclicity and prolactin status by comparing mean prolactin concentrations of bi-weekly samples collected over a 1-year period in 2012 with 20 years of historical weekly progestagen data to assess cyclicity. Females were categorized as: 1) non-cycling with an average prolactin concentration of 15 ng/ml or greater (HIGH; n = 17); 2) non-cycling with an average prolactin concentration below 15 ng/ml (LOW; n = 16); and 3) typical temporal patterns of progestagen and prolactin secretion (NORMAL; n = 45), and evaluated based on length of time (in years) they had experienced ovarian inactivity. Results showed that the majority of HIGH prolactin elephants had been acyclic for at least 5 years, and in a number of cases (n = 9) for over 10 years. By contrast, most of the LOW prolactin elephants had experienced acyclicity for less than 5 years. Finally, there was a positive association between duration of acyclicity and mean prolactin concentrations, with an increase in the likelihood of having higher prolactin concentrations the longer an individual was acyclic. This study highlights the importance of longitudinal hormonal datasets to examine temporal changes in biological functioning and better understand the etiology of infertility problems.

Reduced sexual dysfunction with aripiprazole once-monthly versus paliperidone palmitate: results from QUALIFY.

Sexual dysfunction, a common side effect of antipsychotic medications, may be partly caused by dopamine antagonism and elevation of prolactin. In QUALIFY, a randomized study, aripiprazole once-monthly 400 mg (AOM 400), a dopamine D2 receptor partial agonist, showed noninferiority and subsequent superiority versus paliperidone palmitate (PP), a dopamine D2 receptor antagonist, on the Heinrichs-Carpenter Quality-of-Life Scale (QLS) in patients with schizophrenia aged 18-60 years. Sexual dysfunction (Arizona Sexual Experience Scale) and serum prolactin levels were also assessed. Odds for sexual dysfunction were lower with AOM 400 versus PP [week 28 adjusted odds ratio (95% confidence interval), 0.29 (0.14-0.61); P=0.0012] in men [0.33 (0.13-0.86); P=0.023], women [0.14 (0.03-0.62); P=0.0099], and patients aged 18-35 years [0.04 (<0.01-0.34); P=0.003]. Among patients shifting from sexual dysfunction at baseline to none at week 28, there was a trend toward greater improvement in the QLS total score. The mean (SD) prolactin concentrations decreased with AOM 400 [-150.6 (274.4) mIU/l] and increased with PP [464.7 (867.5) mIU/l] in both men and women. Six PP-treated patients experienced prolactin-related adverse events. In addition to greater improvement on QLS, patients had a lower risk for sexual dysfunction and prolactin elevation with AOM 400 versus PP in QUALIFY.

Effects of Cabergoline on Thyroid Hormones and Semen Quality of Dog

In this study, the concentration of prolactin, FT4, and semen quality were investigated in 5 clinically healthy fertile mixed-breed dogs (1-3 years old) treated with cabergoline (5μg/kg) during 9 weeks. Semen analysis was performed for volume, live or dead, concentration, and motility factors every week. The results indicated that cabergoline administration caused a minor but significant reduction of the mean prolactin concentration (P < .05) and did not affect the secretion of FT4 (P > .05). Further, there was not a significant effect of cabergoline on semen quality, statistically. We could not find any relationship between prolactin and FT4 concentration and changes in semen characteristics.

Reproductive hormonal profile patterns among male partners of infertile couples at the University of Ilorin teaching hospital

Background: Seminal fluid analysis (SFA) is the most important investigation of the infertile males but limited in revealing the etiologies of the various spermatozoa abnormalities observed on microscopy. Increasing prevalence of male infertility and the challenges of diagnosis require biochemical investigations such as reproductive hormonal profile. Aims: The aim of this study is to determine the reproductive hormonal profile patterns among infertile males in Ilorin. Settings and Design: This was a descriptive, cross-sectional study. Materials and Methods: A total of 130 male partners of infertile couples served as subjects and 50 fertile males as controls. Serum reproductive hormonal assay was done using ELISA method. Statistical Analysis Used: Statistical Package for the Social Sciences (SPSS) version 20.0 (SPSS Inc., Chicago, IL, USA) was used. Normally distributed data were expressed as mean ± standard deviation. Results: The mean age of the subjects who were majorly civil servants was 38.6 ± 6.6 years. The prevalence of reproductive endocrinopathies in this study was 46.9%. Mean serum concentrations of follicle-stimulating hormone, luteinizing hormone, and prolactin were elevated in our subjects than control. Mean serum testosterone concentration was significantly lower in our infertile subjects. Patterns of hormonal profile abnormalities among our subjects were 2 (1.5%) with hypogonadotropic hypogonadism, 15 (11.5%) with hypergonadotropic hypogonadism, 23 (17.7%) with hypergonadotropic normogonadism, 21 (16.2%) with normogonadotropic hypogonadism, and 69 (53.1%) with normogonadotropic normogonadism. This showed 59 (45.4%) subjects with primary testicular failure/resistance and 2 (1.5%) with secondary testicular failure. Twenty (15.4%) of the subjects had hyperprolactinemia. Conclusions: Reproductive hormonal profiling of male partners of infertile couples is an important adjuvant to SFA, in diagnosis and monitoring responses to treatment.

Comparative studies on testicular and epididymal morphology, and serum hormone concentrations in foxes and the hybrids during the breeding season

The silver fox and the blue fox belong to different genera, and the hybrid males are fully or partially sterile. In the present study, the objective was to evaluate the causes of hybrid male sterility, and therefore analyze the differences in testicular, and epididymal morphology and serum hormone concentrations among silver foxes, blue foxes, and the hybrids during the breeding season. Samples were collected from 20 male silver foxes, 20 male blue foxes, 15 male HSBs (silver fox female×blue fox male hybrids) and 14 male HBSs (blue fox male×silver fox female hybrids), respectively. Seminal evaluation showed large numbers of sperm present in the semen of blue foxes and silver foxes, but no sperm present in the hybrids. Mean testicular volume and the diameter of seminiferous tubules in silver foxes and blue foxes were greater than in the hybrids; and there were many Sertoli cells, spermatogenic cells, and sperm in silver foxes and blue foxes, while spermatogenic cells decreased with no sperm in the hybrids. Mean serum LH and prolactin concentrations in silver foxes and blue foxes were less and testosterone was greater than in the hybrids (P<0.05). The results indicate that germ cell meioses in the hybrids were arrested at the prophase stage of meiosis, and that lesser concentrations of testosterone and greater concentrations of LH and prolactin can inhibit the completion of spermatogenesis.

Hyperprolactinemia diagnostics--dilemmas over optimal selection of prolactinemia time points.

Laboratory discrimination of pathologic hyperprolactinemia is an important step in the diagnosis of pathology influencing overall health and fertility. A major issue is the choice of time and circumstances for obtaining a blood sample for prolactin assay that would be representative for mean daily plasma concentration of a subject. The aim of the study was a comparison of reliability of single prolactin assessment on various time-points in a day with circadian prolactinemia profile in order to find the easiest, the least expensive, and the most reliable method of hyperprolactinemia diagnosis. The study was a retrospective analysis of 138 women, hospitalized in the Department of Endocrinology and Metabolic Diseases, Polish Mother`s Memorial Hospital - Research Institute, Lodz, Poland, in whom the circadian profile of prolactin (including assays at 8.00 am, 11.00 am, 2.00 pm, 5.00 pm, 8.00 pm, 11.00 pm, 2.00 am, 5.00 am and repeatedly at 8.00 am) had been assessed. On the basis of AUC (area under the curve) of prolactin concentrations, hyperprolactinemia was diagnosed in 34 subjects (24.6 % of the entire group). The attempts to diagnose hyperprolactinemia based on a single prolactin assay failed due to a high percentage of false negative and false positive results. Only significant hyperprolactinemia with mean prolactin concentration of about 100 µg/l or more appeared easy to diagnose. Combinations of several time points also appeared not reliable enough. The nine-point daily profile of prolactinemia in any patient with clinical suspicion of hyperprolactinemia seems the best mode for estimating mean circadian prolactin concentration.

Testicular Steroids, Prolactin, Relaxin and Prostate Gland Markers in Peripheral Blood and Seminal Plasma of Normal Dogs and Dogs with Prostatic Hyperplasia

Concentrations of 17β-oestradiol (E(2) ), testosterone (T), 5α-dihydrotestosterone, prolactin (PRL) and relaxin (RLN) were determined in peripheral blood serum or plasma and prostatic secretion of 77 physically healthy intact male dogs (19 Rhodesian Ridgebacks/RR, 58 dogs of other breeds, 1-9 years of age). Furthermore, the concentrations of acid phosphatase in prostatic secretion and canine prostate-specific esterase (CPSE) were measured in blood plasma. All dogs were submitted to a complete breeding soundness examination, including B-mode sonography. Prostatic volume was larger, and blood plasma levels of CPSE were higher in ageing dogs and in dogs with benign prostatic hyperplasia (BPH) compared with young dogs and dogs with normal prostate. Furthermore, a higher E(2) /T ratio was found in dogs with BPH. Despite missing significant differences in PRL concentrations, the slight increases in PRL concentrations in the prostatic secretion observed both with increasing age and in dogs with BPH and the observed correlations between concentrations of PRL and testicular steroids may possibly indicate a role of PRL in the pathogenesis of canine BPH. Serum RLN concentrations were at similar level in all dogs. Regarding breed differences, an appreciably larger prostatic volume and higher concentration of CPSE were verified in RR than in other pure-bred dogs, confirming our suspicion of a premature enlargement of the prostate gland, which may result from a genetic disposition for BPH in this breed.

Prolactin Secretion in Healthy Adults Is Determined by Gender, Age and Body Mass Index

BackgroundProlactin (PRL) secretion is quantifiable as mean, peak and nadir PRL concentrations, degree of irregularity (ApEn, approximate entropy) and spikiness (brief staccato-like fluctuations).HypothesisDistinct PRL dynamics reflect relatively distinct (combinations of) subject variables, such as gender, age, and BMI.LocationClinical Research Unit.SubjectsSeventy-four healthy adults aged 22–77 yr (41 women and 33 men), with BMI 18.3–39.4 kg/m2.MeasuresImmunofluorometric PRL assay of 10-min samples collected for 24 hours.ResultsMean 24-h PRL concentration correlated jointly with gender (P<0.0001) and BMI (P = 0.01), but not with age (overall R2 = 0.308, P<0.0001). Nadir PRL concentration correlated with gender only (P = 0.017) and peak PRL with gender (P<0.001) and negatively with age (P<0.003), overall R2 = 0.325, P<0.0001. Forward-selection multivariate regression of PRL deconvolution results demonstrated that basal (nonpulsatile) PRL secretion tended to be associated with BMI (R2 = 0.058, P = 0.03), pulsatile secretion with gender (R2 = 0.152, P = 0.003), and total secretion with gender and BMI (R2 = 0.204, P<0.0001). Pulse mass was associated with gender (P = 0.001) and with a negative tendency to age (P = 0.038). In male subjects older than 50 yr (but not in women) approximate entropy was increased (0.942±0.301 vs. 1.258±0.267, P = 0.007) compared with younger men, as well as spikiness (0.363±0.122 vs. 0463±2.12, P = 0.031). Cosinor analysis disclosed higher mesor and amplitude in females than in men, but the acrophase was gender-independent. The acrophase was determined by age and BMI (R2 = 0.186, P = 0.001).ConclusionIn healthy adults, selective combinations of gender, age, and BMI specify distinct PRL dynamics, thus requiring balanced representation of these variables in comparative PRL studies.

Evidence that hyperprolactinaemia is associated with ovarian acyclicity in female zoo African elephants

African elephants of reproductive age in zoos are experiencing high rates of ovarian cycle problems (>40%) and low reproductive success. Previously, our laboratory found that 1/3 of acyclic females exhibit hyperprolactinaemia, a likely cause of ovarian dysfunction. This follow-up study re-examined hyperprolactinaemia in African elephants and found the problem has increased significantly to 71% of acyclic females. Circulating serum progestagens and prolactin were analysed in 31 normal cycling, 13 irregular cycling and 31 acyclic elephants for 12 months. In acyclic females, overall mean prolactin concentrations differed from cycling females (P < 0.05), with concentrations being either higher (n = 22; 54.90 ± 13.31 ngmL(-1)) or lower (n = 9; 6.47 ± 1.73 ngmL(-1)) than normal. No temporal patterns of prolactin secretion were evident in elephants that lacked progestagen cycles. In cycling females, prolactin was secreted in a cyclical manner, with higher concentrations observed during nonluteal (34.38 ± 1.77 and 32.75 ± 2.61 ngmL(-1)) than luteal (10.51 ± 0.30 and 9.67 ± 0.42 ngmL(-1)) phases for normal and irregular females, respectively. Of most concern was that over two-thirds of acyclic females now are hyperprolactinemic, a dramatic increase over that observed 7 years earlier. Furthermore, females of reproductive age constituted 45% of elephants with hyperprolactinaemia. Until the cause of this problem is identified and a treatment is developed, reproductive rates will remain suboptimal and the population nonsustaining.

Stimulation of prolactin after estradiol pretreatment: Comparison of polymer formulations for domperidone and sulpiride and oral administration of sulpiride in horses

Stimulation of prolactin after estradiol pretreatment: Comparison of polymer formulations for domperidone and sulpiride and oral administration of sulpiride in horses

The modulatory role of cortisol on prolactin secretion in anestrus Iranian fat-tailed ewes

Release of prolactin, a milk-secreting hormone, is normally inhibited by the neurotransmitter dopamine. Numerous attempts have been made to explain the effects of environmental stress on the level of prolactin, proposing a basic role for cortisol in the modulation of the hormone secretion. The pharmacologic properties of antagonists in the release of prolactin, during the anovulatory early postpartum period, were examined in this research. This study included ten 3-year-old Mehraban ewes that gave birth to their third lambs, at least 2 weeks before the experiment. Each animal was randomly assigned to receive either a corresponding dose of either metoclopramide (0.3 mg/kg BW; im; n = 5) or haloperidol (0.1 mg/kg BW; im; n = 5). During the 2 weeks prior to the start of the study, all ewes were allowed to acclimatize to their environment with free access to food and tap water, in order to avoid stress-induced influences on hormone levels resulting from environmental factors. Blood samples were collected from each ewe through the jugular vein via intravenous catheter immediately at the time of study entry, 2 and 4 h before and after every injection, with a time interval of 30 min. The serum recovered was assayed for prolactin, cortisol, and progesterone. Animals were assumed to be anestrous if the mean serum level of progesterone was lower than 0.4 ng/mL and that of prolactin higher than 80 mIU/L. One-way ANOVA revealed that the mean serum concentrations of prolactin measured at 30 and 90 min after metoclopramide administration were statistically different compared with the control but showed no difference at other time points. The secretion of cortisol prior to the treatment and afterward was statistically similar; however, under haloperidol administration, it increased and the difference was statistically significant (p 0.05). In conclusion, the pharmacologic properties of an antagonist to release prolactin, during the anovulatory early postpartum period, may depend on the presence of dopaminergic D2 receptor subtypes. In addition to its specificity for D2 receptors, the bioactivity of that antagonist may also play a role in the control of the secretion.