dynorphins and Polycystic-Ovary-Syndrome

To investigate the relationship between elevated luteinizing hormone (LH), hyperinsulinemia and neuropeptides in patients with polycystic ovarian syndrome (PCOS).. An oral glucose (100g) tolerance test (OGTT) was performed in 15 normally menstruating women (control) and 30 PCOS women with LH/follicle stimulating hormone (FSH) ratio greater than 3 (group 1) and 25 PCOS subjects with the ratio < 3 (group 2). The responses of insulin, somatostatin (SS), beta-endorphin (beta-EP) and dynorphin A (Dyn A) during OGTT were measured by RIA.. In basal state, significant negative correlations were found between LH and SS (r = -0.51, P < 0.05) in group 1 and between LH and beta-EP (r = -0.49, P < 0.05) in group 2. During OGTT, PCOS women had a greater beta-EP and Dyn A responses in group 1 and an impaired SS response in group 2 as compared with the control.. These data suggested lower endogenous SS, higher beta-EP and Dyn A may lead to elevation of LH and insulin secretions in patients with PCOS.

Topics: Adult; beta-Endorphin; Dynorphins; Female; Follicle Stimulating Hormone; Glucose Tolerance Test; Humans; Insulin; Luteinizing Hormone; Peptide Fragments; Polycystic Ovary Syndrome; Somatostatin

Polycystic ovary syndrome (PCOS) is characterized by hyperandrogenism, anovulation, and polycystic ovaries. Electroacupuncture (EA) can effectively improve hyperandrogenism and increase ovulation frequency in patients with PCOS. Pieces of suggest that androgen activity in the brain is associated with impaired steroid negative feedback in such patients. Studies have shown that EA regulated androgen receptor (AR) expression and local factor levels (such as anti-Müllerian hormone and inhibin B) in the ovary of PCOS rats. However, few studies have explored the effect of EA on androgen activity in the brain.. This study investigated the effect of EA on the kisspeptin-gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) neural circuit and sex hormone receptor expression in the hypothalamus of PCOS rats.. PCOS signs were induced by letrozole administration, and the induced rats were treated with low-frequency EA at Guan Yuan acupoint (CV4). The effect of EA on PCOS-like signs was evaluated by observing changes in the body weight, ovarian quality, ovarian morphology, and serum sex hormone levels in rats. To explore the mechanism of the effect of EA on PCOS-like signs, the neuropeptide content of the kisspeptin-GnRH/LH neural circuit was assessed using enzyme-linked immunosorbent assay(ELISA); AR and estrogen receptor α (ERα) coexpression on kisspeptin/neurokinin B/dynorphin (KNDy) neurons was determined via triple-label immunofluorescence; and protein and mRNA expression of Kiss1, Ar, Esr1, and kisspeptin receptor (Kiss1r) was evaluated via western blotting and Reverse Transcription-Polymerase Chain Reaction (RT-PCR).. The results revealed that the estrous cycle of rats in the EA treatment group recovered, and their body and ovary weight reduced; ovarian morphology improved; serum testosterone and LH levels significantly decreased; and kisspeptin, GnRH, and dynorphin levels in hypothalamic arcuate nucleus significantly decreased. Compared with controls, the number of AR/Kiss1-positive cells increased, number of ERα/Kiss1-positive cells decreased, and protein and mRNA expression of Kiss1, Ar, and Kiss1r significantly increased in PCOS rats. However, EA treatment reversed these changes and reduced the expression of Kiss1, Ar, and Kiss1r significantly.. Improvement in the reproductive hallmarks of PCOS rats via EA may be achieved by regulating the kisspeptin-GnRH/LH circuit via androgen activity attenuation. Thus, the results provide an experimental basis for acupuncture as an adjuvant medical therapy on PCOS.

Topics: Androgens; Animals; Dynorphins; Electroacupuncture; Estrogen Receptor alpha; Female; Gonadal Steroid Hormones; Gonadotropin-Releasing Hormone; Humans; Hyperandrogenism; Kisspeptins; Luteinizing Hormone; Neurokinin B; Neurons; Polycystic Ovary Syndrome; Rats; Rats, Sprague-Dawley; Receptors, Androgen; Receptors, Kisspeptin-1; RNA, Messenger

To explore the effects and mechanism of action of electroacupuncture (EA) in a rat model of pubertal polycystic ovary syndrome (PCOS).. Female offspring of Sprague-Dawley rats receiving dihydrotestosterone (DHT) during pregnancy (days 16-19), as a model of prenatal androgenization, were divided randomly into three groups: model group (M), EA group, and sham acupuncture (SA) group (n = 8 each). A normal (N) group comprising female offspring of healthy pregnant rats not receiving DHT (n = 8) was added. EA was administered at CV6 and bilateral SP6/ST36 with 2 Hz frequency and 2 mA intensity. SA consisted of superficial needling at different locations without electrical stimulation.. EA improved the disturbed estrous cycles, while it could not be concluded that SA was effective in this respect. EA improved ovarian morphology including the number of corpora lutea and area of the ovary, whereas SA did not. However, both EA and SA attenuated the increased luteinizing hormone and decreased estradiol and gonadotropin-releasing hormone levels in the serum of PCOS model rats. Levels of testosterone, follicle-stimulating hormone, and progesterone did not significantly differ between groups. EA and SA alleviated the upregulation of kisspeptin protein and mRNA levels in the hypothalamus and kisspeptin protein level in the arcuate nucleus (ARC). No differences were found between groups in protein or mRNA expression of dynorphin (DYN) or neurokinin B (NKB) in the hypothalamus. Co-expression of kisspeptin, NKB, and DYN were observed in ARC. The GnRH level in the median eminence decreased and could be rescued by EA and SA. Intriguingly, kisspeptin levels in the granulosa cells of the ovary decreased in the model group and could be rescued by EA but not SA. Levels of kisspeptin, NKB, and DYN protein and mRNA in the ovary did not differ between any groups.. Both EA and SA appeared to improve symptoms of PCOS at puberty by modulating the kisspeptin system in the hypothalamus. EA also had an effect on ovarian kisspeptin expression and a more comprehensive effect with respect to improving PCOS at puberty than SA.

Topics: Acupuncture Points; Animals; Dynorphins; Electroacupuncture; Estrous Cycle; Female; Follicle Stimulating Hormone; Humans; Hypothalamus; Kisspeptins; Luteinizing Hormone; Neurokinin B; Ovary; Polycystic Ovary Syndrome; Pregnancy; Puberty; Rats; Rats, Sprague-Dawley

Polycystic ovarian syndrome (PCOS), the most common endocrinopathy affecting women worldwide, is characterized by elevated luteinizing hormone (LH) pulse frequency due to the impaired suppression of gonadotrophin-releasing hormone (GnRH) release by steroid hormone negative feedback. Although neurons that co-express kisspeptin, neurokinin B, and dynorphin (KNDy cells) were recently defined as the GnRH/LH pulse generator, little is understood about their role in the pathogenesis of PCOS. We used a prenatal androgen-treated (PNA) mouse model of PCOS to determine whether changes in KNDy neurons or their afferent network underlie altered negative feedback. First, we identified elevated androgen receptor gene expression in KNDy cells of PNA mice, whereas progesterone receptor and dynorphin gene expression was significantly reduced, suggesting elevated androgens in PCOS disrupt progesterone negative feedback via direct actions upon KNDy cells. Second, we discovered GABAergic and glutamatergic synaptic input to KNDy neurons was reduced in PNA mice. Retrograde monosynaptic tract-tracing revealed a dramatic reduction in input originates from sexually dimorphic afferents in the preoptic area, anteroventral periventricular nucleus, anterior hypothalamic area and lateral hypothalamus. These results reveal 2 sites of neuronal alterations potentially responsible for defects in negative feedback in PCOS: changes in gene expression within KNDy neurons, and changes in synaptic inputs from steroid hormone-responsive hypothalamic regions. How each of these changes contribute to the neuroendocrine phenotype seen in in PCOS, and the role of specific sets of upstream KNDy afferents in the process, remains to be determined.

Topics: Afferent Pathways; Androgens; Animals; Disease Models, Animal; Dynorphins; Female; Kisspeptins; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Neurokinin B; Neurons; Neurons, Afferent; Neurosecretory Systems; Polycystic Ovary Syndrome; Pregnancy; Prenatal Exposure Delayed Effects

Polycystic ovary syndrome (PCOS), a common reproductive disorder in women, is characterized by hyperandrogenemia, chronic anovulation, cystic ovarian follicles, and luteinizing hormone (LH) hyper-pulsatility, but the pathophysiology isn't completely understood. We recently reported a novel mouse model of PCOS using chronic letrozole (LET; aromatase inhibitor). Letrozole-treated females demonstrate multiple PCOS-like phenotypes, including polycystic ovaries, anovulation, and elevated circulating testosterone and LH, assayed in "one-off" measures. However, due to technical limitations, in vivo LH pulsatile secretion, which is elevated in PCOS women, was not previously studied, nor were the possible changes in reproductive neurons. Here, we used recent technical advances to examine in vivo LH pulse dynamics of freely moving LET female mice versus control and ovariectomized (OVX) mice. We also determined whether neural gene expression of important reproductive regulators such as kisspeptin, neurokinin B (NKB), and dynorphin, is altered in LET females. Compared to controls, LET females exhibited very rapid, elevated in vivo LH pulsatility, with increased pulse frequency, amplitude, and basal levels, similar to PCOS women. Letrozole-treated mice also had markedly elevated Kiss1, Tac2, and Pdyn expression and increased Kiss1 neuronal activation in the hypothalamic arcuate nucleus. Notably, the hyperactive LH pulses and increased kisspeptin neuron measures of LET mice were not as elevated as OVX females. Our findings indicate that LET mice, like PCOS women, have markedly elevated LH pulsatility, which likely drives increased androgen secretion. Increased hypothalamic kisspeptin and NKB levels may be fundamental contributors to the hyperactive LH pulse secretion in the LET PCOS-like condition and, perhaps, in PCOS women.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Aromatase Inhibitors; Disease Models, Animal; Dynorphins; Female; Gene Expression; Kisspeptins; Letrozole; Luteinizing Hormone; Mice; Neurokinin B; Neurons; Polycystic Ovary Syndrome

Prenatal testosterone (T)-treated female sheep display reproductive deficits similar to women with polycystic ovarian syndrome (PCOS), including an increase in LH pulse frequency due to actions of the central GnRH pulse generator. In this study, we used multiple-label immunocytochemistry to investigate the possibility of changes in the γ-aminobutyric acid (GABA) neurotransmitter system at two key components of the GnRH pulse generator in prenatal T-treated sheep: kisspeptin/neurokinin B/dynorphin (KNDy) neurons of the arcuate nucleus, and GnRH neurons in the preoptic area (POA) and mediobasal hypothalamus (MBH). We observed a significant decrease and increase, respectively, in the number of GABAergic synapses onto POA and MBH GnRH neurons in prenatal T-treated ewes; additionally, there was a significant increase in the number of GABAergic inputs onto KNDy neurons. To determine the actions of GABA on GnRH and KNDy neurons, we examined colocalization with the chloride transporters NKCC1 and KCC2, which indicate stimulatory or inhibitory activation of neurons by GABA, respectively. Most GnRH neurons in both POA and MBH colocalized NKCC1 cotransporter whereas none contained the KCC2 cotransporter. Most KNDy neurons colocalized either NKCC1 or KCC2, and 28% of the KNDy population contained NKCC1 alone. Therefore, we suggest that, as in the mouse, GABA in the sheep is stimulatory to GnRH neurons, as well as to a subset of KNDy neurons. Increased numbers of stimulatory GABAergic inputs to both MBH GnRH and KNDy neurons in prenatal T-treated animals may contribute to alterations in steroid feedback control and increased GnRH/LH pulse frequency seen in this animal model of PCOS.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Disease Models, Animal; Dynorphins; Female; GABAergic Neurons; Gonadotropin-Releasing Hormone; K Cl- Cotransporters; Kisspeptins; Neurokinin B; Polycystic Ovary Syndrome; Pregnancy; Prenatal Exposure Delayed Effects; Preoptic Area; Sheep; Solute Carrier Family 12, Member 2; Symporters; Testosterone

Prenatal testosterone (T)-treated ewes display a constellation of reproductive defects that closely mirror those seen in PCOS women, including altered hormonal feedback control of GnRH. Kisspeptin/neurokinin B/dynorphin (KNDy) neurons of the arcuate nucleus (ARC) play a key role in steroid feedback control of GnRH secretion, and prenatal T treatment in sheep causes an imbalance of KNDy peptide expression within the ARC. In the present study, we tested the hypothesis that prenatal T exposure, in addition to altering KNDy peptides, leads to changes in the morphology and synaptic inputs of this population, kisspeptin cells of the preoptic area (POA), and GnRH cells. Prenatal T treatment significantly increased the size of KNDy cell somas, whereas POA kisspeptin, GnRH, agouti-related peptide, and proopiomelanocortin neurons were each unchanged in size. Prenatal T treatment also significantly reduced the total number of synaptic inputs onto KNDy neurons and POA kisspeptin neurons; for KNDy neurons, the decrease was partly due to a decrease in KNDy-KNDy synapses, whereas KNDy inputs to POA kisspeptin cells were unaltered. Finally, prenatal T reduced the total number of inputs to GnRH cells in both the POA and medial basal hypothalamus, and this change was in part due to a decreased number of inputs from KNDy neurons. The hypertrophy of KNDy cells in prenatal T sheep resembles that seen in ARC kisspeptin cells of postmenopausal women, and together with changes in their synaptic inputs and projections to GnRH neurons, may contribute to defects in steroidal control of GnRH observed in this animal model.

Topics: Animals; Arcuate Nucleus of Hypothalamus; Disease Models, Animal; Dynorphins; Female; Gonadotropin-Releasing Hormone; Kisspeptins; Neurokinin B; Neurons; Polycystic Ovary Syndrome; Pregnancy; Prenatal Exposure Delayed Effects; Preoptic Area; Sheep; Testosterone

To investigate the relationship between elevated LH, hyperinsulinemia and neuropeptides in polycystic ovarian syndrome (PCOS), we measured the endogenous levels of insulin, somatostatin (SS), beta-endorphin (beta-EP) and dynorphin A (Dyn A) before and after a glucose load in three groups: group 1 (LH/ FSH > or = 3, n = 30); group 2 (LH/FSH < 3, n = 25), and controls (n = 15). In the basal state, significantly negative correlations were found between LH and SS (r = -0.51, p < 0.05) in group 1 and between LH and beta-EP (r = -0.49, p < 0.05) in group 2. After a glucose load, PCOS women had greater beta-EP and Dyn A responses in group 1 and impaired SS response in group 2 as compared with the control. The data suggest endogenously lower SS, higher beta-EP and Dyn A may contribute to the elevation of LH and insulin secretions in PCOS.

Topics: Adult; beta-Endorphin; Catheterization; Catheters, Indwelling; Cohort Studies; Dynorphins; Female; Glucose; Humans; Insulin; Luteinizing Hormone; Polycystic Ovary Syndrome; Reference Values; Somatostatin; Time Factors