Pulsatile secretion of prolactin and luteinizing hormone and their synchronous relationship during the human menstrual cycle

Serum prolactin and gonadal hormones in hemodialysis women: a meta-analysis

BACKGROUND

A meta-analysis followed by PRISMA 2020 statement was performed aiming to present a whole prolactin and sex hormone profile in hemodialysis women.

METHODS

Literatures were searched in PubMed, Cochrane library, Embase, and Web of science before March 11, 2023. Trial sequential analysis (TSA) was performed to test the conclusiveness of this meta-analysis. Egger's test and trim-and-fill analysis was used to test publication bias. We took standardized mean difference (SMD) as pool effect of hormones values including prolactin (PRL), follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2) and progesterone (P). This study was registered in PROSPERO and the number was CRD42023394503.

RESULTS

Twenty-two articles from 13 countries were analyzed. Combining the results of TSA and meta-analysis, we found that compared with healthy control, hemodialysis women had higher PRL, follicular FSH and LH values and lower P levels (PRL: I2 = 87%, SMD 1.24, 95% CI: 0.79-1.69, p < 0.00001; FSH: I2 = 0%, SMD 0.34, 95% CI: 0.13-0.55, p = 0.002; LH: I2 = 39%, SMD 0.64, 95% CI: 0.34-0.93, p < 0.00001; P: I2 = 30%, SMD - 1.62, 95% CI: -2.04 to -1.20, p < 0.00001). What's more, compared with women after renal transplantation, hemodialysis women had higher PRL levels (I2 = 0%, SMD 0.51, 95% CI: 0.25-0.78, p = 0.0001). There was not enough evidence to draw a conclusion on the comparison of hormones between regular and irregular menses hemodialysis women. Egger's test and trim-and-fill analysis didn't show significant publication bias.

CONCLUSIONS

Hemodialysis women had higher serum PRL, follicular phase FSH, LH and lower serum P values compared with healthy control. PRL values of hemodialysis women were also higher than that of women after renal transplantation.

Effects of Season and Estradiol on KNDy Neuron Peptides, Colocalization With D2 Dopamine Receptors, and Dopaminergic Inputs in the Ewe

Seasonal reproduction in sheep is primarily due to a dramatic increase in the ability of estradiol (E2) to inhibit the pulsatile secretion of gonadotropin-releasing hormone (GnRH) during the nonbreeding season [anestrus (ANS)]. Recent findings suggest that kisspeptin/neurokinin B/dynorphin (KNDy) neurons of the arcuate nucleus (ARC) play a key role in conveying this negative feedback influence, with dopaminergic projections from the retrochiasmatic area acting upon KNDy cells to decrease kisspeptin release and thus inhibit GnRH pulses. However, several questions remain unanswered: (1) Are the coexpressed KNDy peptides, neurokinin B (NKB) and dynorphin, under seasonal regulation similar to kisspeptin? (2) Are seasonal changes in these peptides and their colocalization of D2 dopamine receptors (D2Rs) steroid dependent? and (3) Do KNDy neurons receive direct input from dopaminergic terminals? We used dual- and triple-label immunofluorescence to analyze brain sections through the ARC of ovariectomized (OVX) and OVX plus E2 ewes perfused during either the breeding season or ANS. Results showed (1) steroid-dependent and steroid-independent seasonal changes in kisspeptin and NKB, but not dynorphin, immunoreactivity; (2) increased D2R coexpression during ANS that was dependent on the presence of E2; and (3) evidence that KNDy cells receive direct contact from dopaminergic terminals and that this input increases during ANS. These results support the hypothesis that dopamine acts to inhibit GnRH secretion in ANS by directly suppressing the activity of ARC KNDy neurons, and implicate NKB as well as kisspeptin in seasonal shifts in E2-negative feedback in the sheep.

Burnout is associated with elevated prolactin levels in men but not in women

OBJECTIVE

Prolactin levels have been shown to be increased by different types of psychosocial stress. Since burnout is a consequence of long-term psychosocial stress, prolactin levels might also be affected in burnout. The aim of this study was to investigate whether there are differences in prolactin levels between individuals who report burnout and others.

METHOD

Morning fasting serum prolactin levels were compared between individuals who reported burnout (24 men and 25 women) and individuals who reported no burnout (25 men and 13 women). Women were tested in the follicular phase of the menstrual cycle. Men and women were analysed separately.

RESULTS

Men who reported burnout exhibited significantly higher (34%) serum prolactin levels compared to men who reported no burnout. The prolactin levels in women who reported burnout were not different from the levels in the women who reported no burnout before or after adjusting for estradiol levels.

CONCLUSIONS

This study indicates that prolactin levels are higher in men with burnout than men without burnout but not affected in women with burnout. Why no association was seen in women needs to be further explored.

The acute and long-term effect of olanzapine compared with placebo and haloperidol on serum prolactin concentrations

Prolactin elevation is both a common and a persistent event with the currently marketed antipsychotics, excluding clozapine. Elevations have been associated with both acute (galactorrhea, amenorrhea) and chronic (predisposition to osteoporosis) treatment-emergent adverse events. One of the defining criteria for an atypical antipsychotic is the relative lack of persistent prolactinemia. A double-blind, placebo- (N = 68) and haloperidol- (Hal: 15 +/- 5 mg/day, N = 69) controlled trial of three dose ranges of olanzapine (Olz-L: 5 +/- 2.5 mg/day, N = 65; Olz-M: 10 +/- 2.5 mg/day, N = 64; Olz-H: 15 +/- 2.5 mg/day, N = 69) in the treatment of schizophrenia afforded the opportunity to assess the temporal course of the influence of olanzapine and haloperidol on serum prolactin concentration. Consistent with its potent D2 antagonism, haloperidol was associated with a statistically significantly higher incidence of treatment-emergent prolactin elevation (72%) than seen with placebo (8%; p < 0.001) at week 2 of therapy. Expectedly, this elevation was also persistent at weeks 4 and 6. In contrast, olanzapine-associated treatment-emergent prolactin elevations were both lower in magnitude and transient. At week 2, 38% of the Olz-H, 24% of the Olz-M, and 13% of the Olz-L treatment groups exhibited a treatment-emergent prolactin elevation, with a mean increase of 0.35, 0.52, and 0.61 nmol/l, respectively; for haloperidol the mean increase was 1.23 nmol/l. For only the Olz-M and the Olz-H treatment groups did the week 2 incidence of treatment-emergent prolactin elevations differ statistically significantly from placebo. Both the incidence of elevations and the mean increase, in prolactin concentration were less than that seen with haloperidol. Furthermore, by treatment week 6, all three olanzapine groups exhibited incidences of treatment-emergent prolactin elevation that were comparable to placebo and were statistically significantly less than observed with haloperidol. Rapid adaptation was observed in the temporal course of prolactin elevations associated with olanzapine based on both the categorical analysis of treatment-emergent high values and the analyses of temporal change in mean concentrations. In contrast to haloperidol, the magnitudes of the treatment-emergent elevations associated with olanzapine were minimal. The rates of elevation were approximately one-half to one-third those observed with haloperidol and were significantly more transient. Olanzapine, even at the highest doses (15 +/- 2.5 mg/day) used, was not associated with persistent elevations of prolactin, consistent with an 'atypical' pharmacologic profile.

Pulsatile secretion of gonadotropins and prolactin during the follicular and luteal phases of the menstrual cycle: analysis of instantaneous secretion rate and secretory concomitance

OBJECTIVE

To characterize the pulsatile secretions of luteinizing hormone (LH), follicle-stimulating hormone (FSH), and prolactin (PRL) during the menstrual cycle and to statistically evaluate their secretory concomitance.

DESIGN

Pulsatility study performed during the midfollicular and midluteal phases of a same menstrual cycle, blood samples being collected every 10 minutes for 6 hours.

SETTING

Participants investigated in the Division of Endocrinology, University Hospital.

PARTICIPANTS

Nine healthy women (22 to 38 years) with regular menstrual cycles.

MAIN OUTCOME MEASURES

Plasma LH, FSH, and PRL values were analyzed as raw and deconvoluted data, and the specific (nonrandom) secretory concomitance was evaluated statistically.

RESULTS

The pulsatile secretion of LH was confirmed, and that of FSH and PRL was clearly established during both phases of the cycle by characterization of peak frequency, period, and amplitude. A specific secretory concomitance was assessed between LH and FSH in the follicular but not the luteal phase, and a tight concomitance between LH and PRL was demonstrated during both phases.

CONCLUSIONS

These results are supportive of significant pulsatile secretions of the three hormones during the menstrual cycle, and they are demonstrative of a definite copulsatility of these hormones, suggestive of common regulatory factors in the complex temporal patterns of gonadotropin and PRL secretions along the cycle.