Kiyohito Yano

Relationship between serum anti-Mullerian hormone and clinical parameters in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is an ovulatory disorder that affects 6-10% of women of reproductive age. Serum AMH level may be an additional factor, or surrogate of PCOM, in the diagnostic criteria of PCOS. We evaluated the correlations between the serum AMH level and various endocrine and metabolic features in PCOS using the latest fully automated assay. Serum AMH level was compared between 114 PCOS patient (PCOS group) and 95 normal menstrual cycle women (Control group). Correlations between serum AMH level and various endocrine and metabolic factors were analysed in PCOS group. The serum AMH level was significantly higher in the PCOS group (8.35±8.19 ng/mL) than in the Control group (4.99±3.23 ng/mL). The serum AMH level was independently affected by age and the presence of PCOS on multiple regression analysis. Ovarian volume per ovary (OPVO) showed the strongest positive correlation (r=0.62) with the serum AMH level among related factors. On receiver operating characteristic (ROC) curve analysis, the cut-off value of AMH for the diagnosis of PCOS was 7.33 ng/mL, but this value did not have high efficacy (sensitivity 44.7%, specificity 76.8%). A cut-off value of 10 ng/mL had a high specificity of 92.6%, although the sensitivity was low (24.6%). The serum AMH level was elevated and reflected ovarian size in PCOS patients. The serum AMH level could be a surrogate for ultrasound findings of the ovaries in PCOS and might be useful for estimating ovarian findings without transvaginal ultrasound in the diagnosis of PCOS.

Kisspeptin mRNA expression is increased in the posterior hypothalamus in the rat model of polycystic ovary syndrome

Hypersecretion of luteinizing hormone (LH) is a common endocrinological finding of polycystic ovary syndrome (PCOS). This derangement might have a close relationship with hypothalamic kisspeptin expression that is thought to be a key regulator of gonadotropin-releasing hormone (GnRH). We evaluated the relationship between the hypothalamic-pituitary-gonadal axis (HPG axis) and kisspeptin using a rat model of PCOS induced by letrozole. Letrozole pellets (0.4 mg/day) and control pellets were placed subcutaneously onto the backs of 3-week-old female Wistar rats. Body weight, vaginal opening and vaginal smear were checked daily. Blood and tissues of ovary, uterus and brain were collected at 12-weeks of age. An hypothalamic block was cut into anterior and posterior blocks, which included the anteroventral periventricular nucleus (AVPV) and the arcuate nucleus (ARC), respectively, in order to estimate hypothalamic kisspeptin expression in each area. The letrozole group showed a similar phenotype to human PCOS such as heavier body weight, heavier ovary, persistent anovulatory state, multiple enlarged follicles with no corpus luteum and higher LH and testosterone (T) levels compared to the control group. Kisspeptin mRNA expression in the posterior hypothalamic block including ARC was higher in the letrozole group than in the control group although its expression in the anterior hypothalamic block was similar between groups. These results suggest that enhanced KNDy neuron activity in ARC contributes to hypersecretion of LH in PCOS and might be a therapeutic target to rescue ovulatory disorder of PCOS in the future.

Gonadotropin-Inhibitory Hormone Plays Roles in Stress-Induced Reproductive Dysfunction

Physical and psychological stressors suppress hypothalamic–pituitary–gonadal axis activity and sexual behavior and consequently induce reproductive dysfunction. Recently, it has been shown that gonadotropin-inhibitory hormone (GnIH), also called RFamide-related peptide 3 (RFRP) in mammals, which is a potent inhibitory regulator of gonadotropin-releasing hormone (GnRH) and gonadotropin, is involved in stress-induced reproductive dysfunction. GnIH/Rfrp (the gene coding RFRP-3) expression and activity are increased by psychological and immune stress, and this alteration suppresses GnRH and gonadotropin secretion. Glucocorticoid acts as a mediator that interacts between stress and hypothalamic GnIH/RFRP-3. GnIH/RFRP-3 also plays important roles in stress-induced suppression of sexual behavior and infertility, and genetic silencing of GnIH/Rfrp completely recovers sexual behavior and fertility. This review summarizes what is currently known about the roles of GnIH in stress-induced reproductive dysfunction.

The effects of chronic testosterone administration on hypothalamic gonadotropin-releasing hormone regulatory factors (Kiss1, NKB, pDyn and RFRP) and their receptors in female rats

Abstract The effects of androgens on gonadotropin-releasing hormone (GnRH) secretion in females have not been fully established. To clarify the direct effects of androgens on hypothalamic reproductive factors, we evaluated the effects of chronic testosterone administration on hypothalamic GnRH regulatory factors in ovariectomized (OVX) female rats. Both testosterone and estradiol reduced the serum luteinizing hormone levels of OVX female rats, indicating that, as has been found for estrogen, testosterone suppresses GnRH secretion via negative feedback. Similarly, the administration of testosterone or estradiol suppressed the hypothalamic mRNA levels of kisspeptin and neurokinin B, both of which are positive regulators of GnRH, whereas it did not affect the hypothalamic mRNA levels of the kisspeptin receptor or neurokinin-3 receptor. On the contrary, the administration of testosterone, but not estradiol, suppressed the hypothalamic mRNA expression of prodynorphin, which is a negative regulator of GnRH. The administration of testosterone did not alter the rats’ serum estradiol levels, indicating that testosterone’s effects on hypothalamic factors might be induced by its androgenic activity. These findings suggest that as well as estrogen, androgens have negative feedback effects on GnRH in females and that the underlying mechanisms responsible for these effects are similar, but do not completely correspond, to the mechanisms underlying the effects of estrogen on GnRH.

Intra-follicular kisspeptin levels are related to oocyte maturation and gonadal hormones in patients who are undergoing assisted reproductive technology

To assess the kisspeptin concentrations in follicular fluid and their relationship with clinical outcomes during assisted reproductive technology.

Developmental changes in the hypothalamic mRNA expression levels of brain-derived neurotrophic factor and serum leptin levels: Their responses to fasting in male and female rats

The actions and responses of hypothalamic appetite regulatory factors change markedly during the neonatal to pre‐pubertal period in order to maintain appropriate metabolic and nutritional conditions. In this study, we examined the developmental changes in the hypothalamic mRNA levels of brain‐derived neurotrophic factor (BDNF), which is a potent anorectic factor and the changes in the sensitivity of the hypothalamic expression of this factor to fasting during the neonatal to pre‐pubertal period. Under fed conditions, hypothalamic BDNF mRNA expression decreased during development in both male and female rats. Similarly, the serum levels of leptin, which is a positive regulator of hypothalamic BDNF expression, also tended to fall during the developmental period. The serum leptin level and the hypothalamic BDNF mRNA level were found to be positively correlated in both sexes under the fed conditions. Hypothalamic BDNF mRNA expression was decreased by 24 h fasting (separating the rats from their mothers) in the early neonatal period (postnatal day 10) in both males and females, but no such changes were seen at postnatal day 20. Twenty‐four hours’ fasting (food deprivation) did not affect hypothalamic BDNF mRNA expression in the pre‐pubertal period (postnatal day 30). On the other hand, the rats’ serum leptin levels were decreased by 24 h fasting (separating the rats from their mothers at postnatal day 10 and 20, and food deprivation at postnatal day 30) throughout the early neonatal to pre‐pubertal period. The correlation between serum leptin and hypothalamic BDNF mRNA levels was not significant under the fasted conditions. It can be speculated that leptin partially regulates hypothalamic BDNF mRNA levels, but only in fed conditions. Such changes in hypothalamic BDNF expression might play a role in maintaining appropriate metabolic and nutritional conditions and promoting normal physical development. In addition, because maternal separation induces a negative energy balance and short‐ and long‐term stress responses, it is also possible that reductions in hypothalamic BDNF mRNA levels in the early neonatal period (postnatal day 10) may be partially induced by stress responses of the maternal deprivation.

Clinical outcome of various metformin treatments for women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is an ovulatory disorder and insulin resistance and diabetes are involved in its pathophysiology. Metformin, an anti‐diabetic agent, has been reported to be useful to induce ovulation.

Prenatal undernutrition disrupted the sexual maturation, but not the sexual behavior, in male rats

Exposure to various stressors, including psychological, metabolic, and immune, in the perinatal period induces long‐lasting effects in physiological function and increase the risk of metabolic disorders in later life. In the present study, sexual maturation and sexual behavior were assessed in prenatally undernourished mature male rats.

The effects of prenatal undernutrition and a high-fat postnatal diet on central and peripheral orexigenic and anorexigenic factors in female rats

Prenatal undernutrition and postnatal overnutrition increase the risk of some peripheral and central metabolic disorders in adulthood. We speculated that disturbances of appetite/metabolic regulatory factors might already have been established in the early stages of life and contribute to obesity later in life. The effects of a high-fat diet on the levels of peripheral and central appetite/metabolic regulatory factors were compared between the offspring of normally nourished dams and those of undernourished dams in the peri-pubertal period. In the offspring of the normally nourished dams (control), the consumption of the high-fat diet resulted in lower hypothalamic mRNA levels of orexigenic factors (neuropeptide Y (NPY) and prepro-orexin (pporexin)), whereas no such changes were seen in the offspring of the undernourished dams (subjected to intrauterine growth restriction). These results indicate that in high-energy conditions either the adaptive response does not function properly or has not been established in the offspring of undernourished dams. Because NPY and pporexin are negatively regulated by leptin, these findings suggest that in the intrauterine growth restriction group, the leptin resistance of hypothalamic functions, which is usually caused by diet-induced obesity in adulthood, had already been established in the peri-pubertal period.

Pilot study of the optimal protocol of low dose step-up follicle stimulating hormone therapy for infertile women

To evaluate the optimized protocol of low dose follicle‐stimulating hormone (FSH) therapy that has a starting dose of 50 IU/62.5 IU with a small increment dose (12.5 IU) for women with World Health Organization (WHO) II ovulatory disorder and unexplained infertility.