Prolactin hyperstimulation in response to thyrotropin-releasing hormone in patients with endometriosis

Prolactin and pain of endometriosis

Women experience chronic pain more often than men with some pain conditions being specific to women while others are more prevalent in women. Prolactin, a neuropeptide hormone with higher serum levels in women, has recently been demonstrated in preclinical studies to sensitize nociceptive sensory neurons in a sexually dimorphic manner. Dysregulation of prolactin and prolactin receptors may be responsible for increased pain especially in female predominant conditions such as migraine, fibromyalgia, and pelvic pain. In this review, we focus on the role of prolactin in endometriosis, a condition characterized by pelvic pain and infertility that affects a large proportion of women during their reproductive age. We discuss the symptoms and pathology of endometriosis and discuss how different sources of prolactin secretion may contribute to this disease. We highlight our current understanding of prolactin-mediated mechanisms of nociceptor sensitization in females and how this mechanism may apply to endometriosis. Lastly, we report the results of a systematic review of clinical studies conducted by searching the PubMed and EMBASE databases to identify association between endometriosis and blood levels of prolactin. The results of this search strongly indicate that serum prolactin levels are increased in patients with endometriosis and support the possibility that high levels of prolactin may promote pelvic pain in these patients and increase vulnerability to other comorbid pain conditions likely by dysregulating prolactin receptor expression. Targeting of prolactin and prolactin receptors may improve management of pain associated with endometriosis.

Role of hypothyroidism and associated pathways in pregnancy and infertility: Clinical insights

Thyroid disorders are the most common endocrine problems in women. In most of the cases, thyroid can lead to infertility or miscarriages. The etiology of infertility is multifactorial with thyroid disorders as the most common presenting factor, hypothyroidism in particular. Infertility in women can lead to emotional and psychological stress. The prevalence of hypothyroidism during pregnancy is estimated to be 0.3%–0.5%. Hypothyroidism and hyperthyroidism can result in menstrual irregularities and anovulatory cycles, thus affecting the fertility. There is a significant high prolactin (PRL) level in infertile women with hypothyroidism when compared to euthyroid patients, indicating the relation between hypothyroidism and hyperprolactinemia. The amount of thyrotropin releasing hormone (TRH) from the hypothalamus is markedly increased by inhibition of pyroglutamyl peptidase II, the enzyme catalyzing TRH. The increased TRH in hypothyroidism causes increased thyroid-stimulating hormone and PRL secretion by pituitary, leading to infertility and galactorrhea. In recent years, a neuropeptide called kisspeptin, encoded by Kiss1 gene, a potent stimulus for GnRH secretion, has been recognized, which suggests a future direction of treatment with kisspeptin and benefits the fertility induction among hyperprolactinemic infertile patients. Untreated hypothyroidism during pregnancy can lead to subfertility, fetal deaths, premature deliveries, and abortions. Therefore, women planning for pregnancy and infertile women should be assessed for thyroid hormones and serum PRL.

Ultrasound-guided percutaneous microwave ablation for adenomyosis: efficacy of treatment and effect on ovarian function

A total of 142 premenopausal women with symptomatic adenomyosis underwent ultrasound (US)-guided percutaneous microwave ablation (PMWA) at the Chinese PLA General Hospital. This study aimed to evaluate changes in serum pituitary, gonadal hormone and cancer antigen 125 (CA125) levels after US-guided PMWA. Therefore, estradiol (E₂), follicle-stimulating hormone (FSH), prolactin (PRL) and CA125 levels were evaluated before ablation and at 3, 6, 9 and 12 months after ablation. No significant differences were observed in the E₂ and FSH levels pre-ablation and during follow-up (E₂: p = 0.933, p = 0.987, p = 0.106, p = 0.936; FSH: p = 0.552, p = 0.295, p = 0.414, p = 0.760). The mean absolute values of serum CA125 and PRL were significantly decreased at 3, 6, 9 and 12 months after ablation (CA125: p < 0.001, p < 0.001, p < 0.001, p = 0.003; PRL: p < 0.001, p < 0.001, p < 0.001, p < 0.001). A significant correlation between changes in CA125 levels and uterine volume was found (p < 0.001). No evidence of a decline in ovarian function was observed after US-guided PMWA.

The role of prolactin- and endometriosis-associated infertility

This review will address the current understanding of the relationship between prolactin (PRL) and endometriosis-associated infertility. Although the exact mechanisms of action of hyperprolactinemia in patients with endometriosis-associated infertility have not been clearly established, this report reviews results from relevant studies in the literature. These include serum PRL levels in endometriosis-associated infertility, PRL receptors in ectopic endometriotic tissues, basal PRL levels after TSH and Danazol (isoxazolic derivative of the synthetic steroid 5alpha-ethinyl-testosterone) therapy, peritoneal fluid and nocturnal serum PRL levels in endometriosis, infertility, and luteal phase PRL concentrations in patients with endometriosis.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians.

LEARNING OBJECTIVES

After completion of this article, the reader should be able to explain the relationship between prolactin- and endometriosis-associated infertility, relate endometriosis with infertility, and summarize two ways in which prolactin and endometriosis may be linked in the pathophysiology of infertility.

Aromatase expression in endometriotic tissues and its relationship to clinical and analytical findings

OBJECTIVE

To study the relationship between aromatase expression in endometriotic tissues and clinical and laboratory findings.

DESIGN

Prospective basic and clinical research.

SETTING

University hospital.

PATIENT(S)

Sixty-two women with endometriosis, and 12 without endometriosis.

INTERVENTION(S)

Conservative surgery, or hysterectomy and adnexectomy, along with an immunohistochemical study of aromatase in endometriotic and nonendometriotic tissues.

MAIN OUTCOME MEASURE(S)

Symptoms of the disease, ultrasound and surgical findings, values of tumor markers, steroids and immunoglobulins, and recurrences after surgery.

RESULT(S)

We observed positive immunohistochemical expression for aromatase in endometriotic tissues from 38 patients (61.3%). Aromatase expression was negative in the rest of the tissues studied and in the 12 cases without endometriosis. Aromatase-positive patients had a higher number of endometriomas, more bilaterality, and more moderate-to-severe chronic pelvic pain. Also, infertility and associated leiomyomas were more frequent in these patients, though without significant differences. There were no differences in recurrence of the disease 1 year later. Estradiol and PRL levels were significantly higher, and IgG values lower, than in aromatase-negative patients. High values of blood sedimentation rate were more frequent in aromatase-negative patients.

CONCLUSION(S)

Molecular alterations such as the presence of aromatase in endometriotic tissues could be involved in the development or maintenance of endometriosis. Our findings suggest major severity, activity, and chronic pelvic pain in patients with aromatase in endometriotic tissue.

Influence of severe endometriosis on gene expression of vascular endothelial growth factor and interleukin-6 in granulosa cells from patients undergoing controlled ovarian hyperstimulation for in vitro fertilization-embryo transfer

OBJECTIVE

To evaluate how endometriosis affects expression of vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) in granulosa cells.

DESIGN

Prospective study.

SETTING

IVF-ET program at Osaka Medical College.

PATIENT(S)

Seventeen patients with revised American Fertility Society stage IV endometriosis and 17 patients with tubal infertility and no endometriosis.

INTERVENTION(S)

Granulosa cells obtained at oocyte retrieval were examined for VEGF and IL-6 gene expression.

MAIN OUTCOME MEASURE(S)

Serum E(2) and P levels at hCG administration, number of oocytes, fertilization rate, high-quality embryo rate, and pregnancy rate, and expression of VEGF and IL-6 genes.

RESULT(S)

Total hMG and FSH levels were statistically significantly higher in patients with endometriosis; however, the number of retrieved oocytes and the fertilization rate were lower compared with patients with tubal infertility. Serum E(2) levels and expression of VEGF in patients with tubal infertility were statistically significantly higher than those in patients with endometriosis. Interleukin-6 gene expression did not differ between the groups.

CONCLUSION(S)

In severe endometriosis, lower VEGF gene expression in granulosa cells may adversely affect oocyte development and maturation.

Endometrial quality in infertile women with endometriosis

Several analyses in our infertility (IVF) and oocyte donation programs were carried out to gain clinical knowledge of the factors involved in the etiology of endometriosis-associated infertility. We first compared the IVF outcomes in women with tubal infertility and endometriosis. The results indicated that patients with endometriosis had a poorer IVF outcome in terms of reduced pregnancy rate per cycle, per transfer, and reduced implantation rate per embryo replaced. We then evaluated embryo development in vitro in women with and without endometriosis who underwent IVF and embryo replacement 72 hours after oocyte retrieval. We observed that compared to controls, patients with endometriosis had a significantly reduced number of blastomeres per embryo as well as an increased incidence of arrested embryos in vitro. In subsequent studies we compared fertility parameters in patients receiving donor oocytes. We noted that when donor oocytes came from patients without known endometriosis, embryo development and implantation rates were similar in patients with and without endometriosis. However, when the results of oocyte donation were classified according to the nature of the oocytes donated, patients who received embryos derived from oocytes from women with endometriotic ovaries showed a significantly reduced implantation rate compared to the controls. Taken together, these observations suggest that IVF in patients with endometriosis may be related to alterations within the oocyte, which, in turn, result in embryos of lower quality with a reduced ability to implant.

Prolactin secretion in endometriotic patients

OBJECTIVE

To clarify a significance of prolactin (PRL) for infertility in endometriosis.

STUDY DESIGNS

For seventy endometriotic patients with or without infertility, serum PRL concentrations measured by radioimmunoassay before and 30 min after 500 micrograms of thyrotropin-releasing hormone (TRH) injection were analyzed in relation to the Revised American Fertility Society score in endometriosis as well as to the outcome of the treatment for endometriotic infertility.

RESULTS

While no significant relationship was found between the basal PRL levels and the stage of endometriosis or the outcome of the treatment for infertility, the PRL value after TRH injection was significantly greater in the patients who did not become pregnant than those who did (P < 0.05).

CONCLUSIONS

Occult hyperprolactinemia may be involved in infertility in endometriotic patients.

Provocative tests of prolactin before, during and after long-term danazol treatment in patients with endometriosis

Ten patients suffering from endometriosis were treated with danazol at a dose of 200 mg three times daily for 6 months. To evaluate prolactin secretion, a thyrotropin releasing hormone (TRH) test and an insulin challenge test were carried out in the follicular phase before treatment, during the 6th month of treatment and after the reappearance of the second menses. The same tests were also performed, only once, in the follicular phase of ten normal women. The absence of a significant difference in basal prolactin levels as well as the response to the TRH and insulin challenge tests between controls and patients with endometriosis, before and after danazol treatment, support the view that hyperprolactinemia should not be considered as a cause of infertility in endometriotic women. Furthermore, the significant reduction of prolactin response to provocative tests during danazol treatment may be associated with the low estrogen levels caused by the medication. Finally, the inadequate prolactin response to insulin-induced hypoglycemia in patients with endometriosis and in normal women shows that this provocative test is not so effective for hypothalamic stimulation of prolactin.

Endometriosis and infertility

The relationship of endometriosis, the most common benign gynaecological disease during reproductive life, to infertility is generally ill understood. The association between infertility and minimal to mild endometriosis, when no anatomical defect is evident, may be explained by the following possible mechanisms: alternations in peritoneal fluid (macrophages - immunoglobulins, Interleukin-1, protease inhibitors, prostanoids, an ovum capture inhibitor), ovulatory dysfunctions (anovulation, LUF syndrome), luteal phase defect, disturbed implantation, and spontaneous abortion. These possibilities are discussed. The latest prospective controlled studies offer strong evidence that endometriosis per se is not a direct cause of infertility. On the other hand, the disease usually deteriorates if not treated, and therefore medical or surgical interventions are often needed when expectant treatment or other infertility therapies, e.g., ovulation induction, fail to result in pregnancy. Women with minimal to mild endometriosis only should be diagnosed as having unexplained infertility, which today may be treated by in vitro fertilization.

Prolactin and its response to the luteinizing hormone-releasing hormone thyrotropin-releasing hormone test in patients with endometriosis before, during, and after treatment with danazol

Basal levels of prolactin (PRL) were studied in 16 normal women and in 60 women with endometriosis, 37 of whom were infertile. In addition, the authors studied the response to an intravenous (IV) injection of luteinizing hormone-releasing hormone (LH-RH) (100 micrograms) plus thyrotropin-releasing hormone (TRH) (300 micrograms) in the 16 normal women and in 18 endometriosis patients, examining the basal PRL and thyrotropin, and at 15, 30, 45, 60, and 120 minutes after the IV bolus. After laparoscopy and/or conservative surgery, the patients were treated with danazol for 6 months and a second laparoscopy was performed. The LH-RH/TRH test was carried out in the third month of danazol treatment in 6 endometriosis patients and before the second laparoscopy in 11 patients. The results show that there was both an increase in the mean basal levels of PRL and in the percentage of cases of moderate hyperprolactinemia in endometriosis patients. There also was a greater rise in PRL with the LH-RH/TRH test in moderate and severe endometriosis. The PRL response was significantly greater in endometriosis than in normal women, and was not related to TSH response. Danazol treatment reduced significantly the PRL response. The PRL response before treatment was significantly higher in patients who after treatment showed persistent endometriosis at the second laparoscopy. This could suggest a lower effectiveness of danazol in patients with endometriosis and a PRL hyper-response to LH-RH/TRH.

In vitro fertilization and embryo transfer (IVF/ET): an established and successful therapy for endometriosis

The purpose of this report is to present a 6-year experience in the management of endometriosis with in vitro fertilization and embryo transfer (IVF/ET). We divided 136 patients who underwent 280 cycles into three groups: (1) previous history of endometriosis but normal pelvis at the time of oocyte retrieval, (2) stages I-II endometriosis (revised AFS classification), and (3) stages III-IV endometriosis. The stimulation protocols, estradiol (E2) responses, and distribution of terminal E2 patterns were similar in all groups. Group 3 had significantly fewer preovulatory and immature oocytes retrieved and fewer embryos transferred. The fertilization rate and the per cycle/per transfer pregnancy rates were similar in all groups. The miscarriage rate was higher in group 3, and the ongoing pregnancy rate per cycle was lower. Luteal phase E2 and progesterone levels were comparable in all groups. No differences were found when groups 2 and 3 were analyzed for the presence of one or two ovaries or the presence/absence of ovarian endometriosis. The overall fertilization rate, the per cycle/per transfer pregnancy rates, and the miscarriage rate were similar to those of tubal factor patients. We underscore the excellent outcome of patients with minimal or mild endometriosis in IVF/ET. We conclude that patients with moderate or severe endometriosis have a compromised reproductive potential, probably because of a reduced oocyte recovery rate and poor embryo quality.

The role of in vitro fertilization in infertile patients with endometriosis

Thirty-nine cycles were studied in patients with a history of endometriosis who went through in vitro fertilization. In 15 cycles, there was no evidence of endometriosis; in 10 cycles, the patients had mild or moderate disease; in 14 cycles, severe or extensive endometriosis was found. The pregnancy rates per cycle were 33%, 60%, and 7%, respectively (groups I and II, no significant difference; groups II and III, P less than 0.01). The difference was due to the different number of oocytes aspirated at laparoscopy because of technical problems in the cases with severe and extensive disease. There was also a significant difference in the number of pregnancies per transferred cycles. There was no difference in the luteal phase in the three groups. The reproductive potential, which seemed to be similar in groups I and II, was severely impaired in the group with severe endometriosis.

Luteinizing hormone receptor disorder in endometriosis

Luteinizing hormone (LH) receptor concentrations in ovarian follicles and corpora lutea were measured in 51 patients with histologically proven endometriosis and in 41 control patients. The LH receptor concentrations in cases of endometriosis were lower during the early (0.43 +/- 0.11 [mean +/- standard error] versus 1.31 +/- 0.27 fmol/mg protein; P less than 0.001) and late (0.48 +/- 0.10 versus 1.59 +/- 0.22 fmol/mg protein; P less than 0.001) follicular phase, and during the late luteal phase (2.62 +/- 0.55 versus 4.62 +/- 0.65 fmol/mg protein; P less than 0.05) of the cycle than in control patients. In contrast to the control patients, the LH receptor concentration during the follicular phase remained constant in endometriosis, being lower in patients with extensive or severe disease than in patients with moderate or mild disease (0.28 +/- 0.07 versus 0.61 +/- 0.21 fmol/mg protein; P less than 0.05). Endometriosis-associated infertility might be a consequence of a defect in the mechanism mediating LH action in the ovaries.