Effect of long-term naltrexone treatment on endocrine profile, clinical features, and insulin sensitivity in obese women with polycystic ovary syndrome

Restoring function to inactivating G protein-coupled receptor variants in the hypothalamic-pituitary-gonadal axis1

G protein-coupled receptors (GPCRs) are central to the functioning of the hypothalamic-pituitary-gonadal axis (HPG axis) and include the rhodopsin-like GPCR family members, neurokinin 3 receptor, kappa-opioid receptor, kisspeptin 1 receptor, gonadotropin-releasing hormone receptor, and the gonadotropin receptors, luteinizing hormone/choriogonadotropin receptor and follicle-stimulating hormone receptor. Unsurprisingly, inactivating variants of these receptors have been implicated in a spectrum of reproductive phenotypes, including failure to undergo puberty, and infertility. Clinical induction of puberty in patients harbouring such variants is possible, but restoration of fertility is not always a realisable outcome, particularly for those patients suffering from primary hypogonadism. Thus, novel pharmaceuticals and/or a fundamental change in approach to treating these patients are required. The increasing wealth of data describing the effects of coding-region genetic variants on GPCR function has highlighted that the majority appear to be dysfunctional as a result of misfolding of the encoded receptor protein, which, in turn, results in impaired receptor trafficking through the secretory pathway to the cell surface. As such, these intracellularly retained receptors may be amenable to 'rescue' using a pharmacological chaperone (PC)-based approach. PCs are small, cell permeant molecules hypothesised to interact with misfolded intracellularly retained proteins, stabilising their folding and promoting their trafficking through the secretory pathway. In support of the use of this approach as a viable therapeutic option, it has been observed that many rescued variant GPCRs retain at least a degree of functionality when 'rescued' to the cell surface. In this review, we examine the GPCR PC research landscape, focussing on the rescue of inactivating variant GPCRs with important roles in the HPG axis, and describe what is known regarding the mechanisms by which PCs restore trafficking and function. We also discuss some of the merits and obstacles associated with taking this approach forward into a clinical setting.

Opioid-induced hypogonadism in opioid use disorder, its role in negative reinforcement, and implications for treatment and retention

Hypogonadism is a highly prevalent complication of chronic opioid use associated with a constellation of affective, algesic, and cognitive symptoms as well as decreased quality of life. Given that the mainstays of pharmacologic opioid use disorder (OUD) treatment - methadone and buprenorphine - are themselves agonists or partial agonists at the mu opioid receptor, opioid-induced hypogonadism (OIH) remains an underappreciated clinical concern throughout the course of OUD treatment. Prominent theoretical frameworks for OUD emphasize the importance of negative reinforcement and hyperkatifeia, defined as the heightened salience of negative emotional and motivational states brought on by chronic opioid use. In this perspective article, we highlight the striking parallels between the symptom domains of hyperfakifeia and hypogonadism in males, who comprise the vast majority of existing clinical research on OIH. By extension we propose that future research and ultimately clinical care should focus on the identification and treatment of OIH in OUD patients to help address the longstanding paradox of poor treatment retention despite efficacious therapies, particularly in the setting of the current opioid overdose epidemic driven by high potency synthetic opioids such as fentanyl. We then review evidence from chronic pain patients that testosterone replacement provides clinically significant benefits to men with OIH. Finally, using this framework, we compare extant OUD therapeutics and discuss critical gaps in the clinical literature-including the relative dearth of data regarding hypothalamic-pituitary-gonadal function in females who use opioids-where future study should be focused.

Prenatal Origins of Endometriosis Pathology and Pain: Reviewing the Evidence of a Role for Low Testosterone

Endometriosis is a polygenic, estrogen-dependent, inflammatory disorder of uncertain aetiology associated with pain, infertility and reduced quality of life. While the positive association between endometriosis and estrogen is established, a suite of recent studies has demonstrated an inverse association between the presence of endometriosis lesions and levels of testosterone both prenatally and postnatally. The following narrative review provides new insights into the roles of testosterone in the aetiology, diagnosis, and management of endometriosis and associated symptoms, especially pain. A relatively short anogenital distance (AGD) is indicative of lower levels of testosterone during fetal development. A shorter AGD has recently been correlated with both a higher risk of developing endometriosis in adult life, and with known correlates of endometriosis including earlier onset of reproductive cycling, lower ovarian follicle number, lower postnatal testosterone, and premature ovarian insufficiency. During adult life, lower levels of testosterone are positively associated with key comorbidities of endometriosis, including days per month of pelvic pain and increased pain sensitivity. Biochemically, lower levels of testosterone are associated with higher levels of pro-inflammatory IL-1β and lower levels of β-endorphin. In rodents, prenatal administration of testosterone to females reduces their pain sensitivity in adulthood. The emerging convergent links of endometriosis with low prenatal and postnatal testosterone provide evidence of a centrally mediated effect beginning in early prenatal development, and persisting through adult life, with notable effects on pain sensitivity. They generate a novel conceptual framework for understanding, studying and treating this disorder, whereby endometriosis is mediated by a combination of high estrogen in endometrial tissue with low systemic and ovarian testosterone.

Assessment of Eating Disorders and Eating Behavior to Improve Treatment Outcomes in Women with Polycystic Ovary Syndrome

The essential role of the frequent coexistence of mental disorders and polycystic ovary syndrome (PCOS) is being increasingly recognized in the management of PCOS patients since it influences the success of weight loss interventions. Patients frequently experience disrupted eating behaviors, evidenced by the high prevalence of eating disorders in this population. Therefore, assessment and potential modification of eating disorders and eating-related behavior might be especially relevant to improve obesity treatment outcomes in this population, which remains the most efficient causal treatment in PCOS patients with high metabolic risk. Following a literature overview on common eating disorders and eating behaviors in PCOS, the aim of this review was to explore the prevalence and underlying mechanisms behind those occurrences. Understanding the clinical relevance of those associations and the addition of the assessments of eating disorders as well as eating phenotypes, eating chronotypes, and eating content as essential determinants of eating behavior could aid in the successful management of women with PCOS. In addition, the review also covers the potential of using eating disorders and eating behavior as a tool for the personalization of obesity treatment in PCOS.

Opioid antagonism mitigates antipsychotic-associated weight gain: focus on olanzapine

BACKGROUND

The endogenous opioid system affects metabolism, including weight regulation. Evidence from preclinical and clinical studies provides a rationale for targeting this system to mitigate weight-related side effects of antipsychotics. This review describes the role of the opioid system in regulating weight and metabolism, examines the effects of opioid receptor antagonism on those functions, and explores the use of opioid antagonists to mitigate antipsychotic-associated weight gain and/or metabolic effects.

METHODS

A PubMed literature search was conducted to identify representative opioid antagonists and associated preclinical and clinical studies examining their potential for the regulation of weight and metabolism.

RESULTS

The mu opioid receptor (MOR), delta opioid receptor (DOR), and kappa opioid receptor (KOR) types have overlapping but distinct patterns of central and peripheral expression, and each contributes to the regulation of body weight and metabolism. Three representative opioid antagonists (eg, naltrexone, samidorphan, and LY255582) were identified for illustration. These opioid antagonists differed in their receptor binding and pharmacokinetic profiles, including oral bioavailability, systemic clearance, and half-life, and were associated with varying effects on food intake, energy utilization, and metabolic dysregulation.

CONCLUSIONS

Preclinical and clinical data suggest that antagonism of the endogenous opioid system is a mechanism to address antipsychotic-associated weight gain and metabolic dysregulation. However, evidence suggests that the differing roles of MOR, DOR, and KOR in metabolism, together with the differences in receptor binding, pharmacokinetic, and functional activity profiles of the opioid receptor antagonists discussed in this review, likely contribute to their differential pharmacodynamic effects and clinical outcomes observed regarding antipsychotic-associated weight gain.

From Pharmacology to Physiology: Endocrine Functions of μ-Opioid Receptor Networks

The steady rise in opioid users and abusers has uncovered multiple detrimental health consequences of perturbed opioid receptor signaling, thereby creating the need to better understand the biology of these systems. Among endogenous opioid networks, μ-receptors have received special attention due to their unprecedented biological complexity and broad implications in homeostatic functions. Here, we review the origin, molecular biology, and physiology of endogenous opioids with a special focus on μ-opioid receptor networks within the endocrine system. Moreover, we summarize the current evidence supporting an involvement of the latter in regulating distinct endocrine functions. Finally, we combine these insights to present an integrated perspective on μ-opioid receptor biology and provide an outlook on future studies and unresolved questions in this field.

Weight management strategies for patients with PCOS: current perspectives

INTRODUCTION

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder of reproductive-aged women. Overweight and obesity commonly accompany the syndrome at the clinic and are significant concerns for women with PCOS.

AREAS COVERED

Herein, we provide an overview of the relevant literature on weight management strategies in women with PCOS. We performed an electronic-based search using PubMed until February 2021. We aimed to summarize available evidence of different weight-reducing interventions in PCOS and outline the gaps in our current knowledge and recommend areas for further research.

EXPERT OPINION

PCOS is closely linked to obesity and increased adiposity enhances severity and expression of PCOS phenotype. Current data suggest that weight loss is associated with improved metabolic, endocrine, reproductive, cardiovascular and psychological features in overweight and obese women with PCOS. Lifestyle interventions including diet and exercise, anti-obesity medications and bariatric surgery have been used as therapeutic approaches for short-term management of obesity in PCOS with varying success rates. Large and sufficiently powered studies are required in order to determine long-term effects of weight management strategies and potential benefits beyond weight loss in the syndrome. This would allow informing the guidelines to make PCOS specific evidence-based recommendations.

Successive treatment with naltrexone induces epithelial-mesenchymal transition and facilitates the malignant biological behaviors of bladder cancer cells

Naltrexone is widely used for alleviating opioid-related side effects in cancer patients. However, the effects of naltrexone on cancer progression are controversial in the literature. The present study was carried out to investigate the effects of successive treatment with clinically relevant doses of naltrexone on the malignant biological behaviors of bladder cancer cells. The human bladder cancer T24 cells and mouse bladder cancer MB49 cells were treated with naltrexone. Cell proliferation, migration, and invasion abilities were analyzed. Morphological changes of the cells were confirmed by F-actin immunofluorescence staining. Epithelial-mesenchymal transition (EMT)-related markers and transcriptional factors, as well as activation of the phosphatidylinositol 3 kinase (PI3K)/AKT signaling pathway, were analyzed. Results showed that, compared with the control group, successive treatment with naltrexone significantly promoted the proliferation and decreased the apoptosis of bladder cancer cells, together with increase in cell migration and invasion ability. Continuous treatment with naltrexone also significantly reduced the expression of epithelial markers (E-cadherin and cytokeratin 19), increased the expression of mesenchymal markers (N-cadherin and vimentin) and EMT-inducing transcription factors (Snail and Slug), and further shifted the morphological phenotype of bladder cancer cells to a mesenchymal phenotype. The PI3K/AKT signaling pathway was activated by successive treatment with naltrexone. Notably, incubation with the specific PI3K inhibitor LY294002 together with naltrexone reversed the naltrexone-induced EMT progression. In conclusion, successive treatment with naltrexone may be favorable for the progression of bladder tumors by activating the PI3K/AKT signaling pathway and inducing EMT. Long-term exposure to naltrexone should be used cautiously in patients with bladder cancer.

β-Edorphin predict pregnancy outcome of PCOS and DOR women after IVF-ET

PURPOSE

The present study aims to explore whether β-EP in serum (sβ-EP) and follicular fluid (ffβ-EP) could predict the in vitro fertilization (IVF) outcomes of patients with polycystic ovary syndrome (PCOS) and diminished ovarian reserve (DOR).

METHODS

90 PCOS women, 50 DOR women, and 100 women with normal ovarian function (control group), who were all undergoing an IVF-embryo transfer trial, were included in the study. Biochemical characteristics, anti-Mullerian hormone (AMH), sβ-EP, ffβ-EP, embryo formation, and pregnancy indicators were assessed in all women. The correlations of AMH and β-EP with oocyte quality were analyzed. Population-based and age-category stratified receiver operating characteristic (ROC) curve analysis of AMH and β-EP for predicting pregnancy and live birth were performed.

RESULTS

Compared with the control group, the PCOS group had higher antral follicle count, testosterone, luteinizing hormone, AMH, sβ-EP, and ffβ-EP, which were lower in the DOR group. Meanwhile, the PCOS and DOR groups had higher cycle cancellation and miscarriage rates, and lower high quality embryo numbers. Correlation analysis showed that the oocyte quality were positively correlated with AMH, sβ-EP, and ffβ-EP. The population-based and age-stratified ROC curve analysis showed that sβ-EP and ffβ-EP had high sensitivity and specificity to predict pregnancy and live birth. Meanwhile, age-stratified AMH enhanced the sensitivity for prediction of live birth after IVF.

CONCLUSION

sβ-EP and ffβ-EP are different among women with PCOS, DOR, and normal ovarian function. β-EP can be used as a good predictor of clinical pregnancy and live birth after IVF.

Role of Bupropion and Naltrexone in Managing Depression With Polycystic Ovary Syndrome: A Case Report and Literature Review

Polycystic ovary syndrome (PCOS) is a common endocrine disorder that affects women of reproductive age. Women with PCOS may present with obesity, amenorrhea, oligomenorrhea, infertility, or androgenic features. Studies have shown the association of psychiatric disorders with endocrine disorders, including PCOS. We present a case of a PCOS patient with no prior psychiatric history who presented with suicidal ideation. We emphasize the importance of screening women for PCOS when presented with mental disorders through this clinical case. It is crucial to rule out any medical causes in patients predominantly presented with psychiatric symptoms. We highlight the possible role of bupropion and naltrexone in managing PCOS symptoms, depression with suicidal ideation, and trichotillomania through this unique and rare case.

Beta endorphin in serum and follicular fluid of PCOS- and non-PCOS women

PURPOSE

To compare the concentrations of beta endorphin in serum and follicular fluid (FF) of PCOS- and non-PCOS women. Secondarily, to investigate associations between beta endorphin and other parameters.

METHODS

Fifty-nine women undergoing in vitro fertilization (IVF) were included in the study. Sixteen were stratified to the PCOS group using the Rotterdam criteria. The remaining 43 women served as controls. Follicular fluid was collected during oocyte retrieval and peripheral blood sampling was performed on the same day. Beta endorphin concentrations in serum and follicular fluid, serum levels of insulin, glucose, LH, estradiol and progesterone were measured. Additionally, testosterone was measured before starting the stimulation protocol.

RESULTS

There was no difference in beta endorphin levels between PCOS- and non-PCOS women. The concentration of the peptide was higher in serum than in FF, likely due to collection of FF after ovulation induction and corresponding to the early luteal phase. We found a significant correlation between the number of mature Metaphase II (MII) oocytes retrieved and beta endorphin concentration in FF. In women with biochemical hyperandrogenemia, beta endorphin levels in FF correlated with testosterone levels.

CONCLUSION

Beta Endorphin concentrations in serum and FF do not differ between PCOS- and non PCOS-women undergoing IVF. However, together with sex hormones, beta endorphin might play a key role in oocyte maturation.

Polycystic ovary syndrome: effect and mechanisms of acupuncture for ovulation induction

Polycystic ovary syndrome (PCOS), the most common endocrine disorder among women of reproductive age, is characterized by the coexistence of hyperandrogenism, ovulatory dysfunction, and polycystic ovaries (PCO). PCOS also represents the largest part of female oligoovulatory infertility, and the management of ovulatory and menstrual dysfunction, comprises a third of the high costs of PCOS treatment. Current pharmacological and surgical treatments for reproductive symptoms are effective, however, associated with negative side effects, such as cardiovascular complications and multiple pregnancies. For menstrual irregularities and ovulation induction in women with PCOS, acupuncture has indicated beneficial effects. This review will focus on the results from randomized controlled acupuncture trials for regulation of menstrual dysfunction and for inducing ovulation in women with PCOS although there are uncontrolled trials with nonetheless interesting results. Animal experimental studies will be further discussed when they can provide a more mechanistic explanatory view.

Hypothetical physiological and molecular basis for the effect of acupuncture in the treatment of polycystic ovary syndrome

Clinical and experimental evidence indicates that acupuncture may be a safe alternative or complement in the treatment of endocrine and reproductive function in women with polycystic ovary syndrome (PCOS). This review describes potential etiological factors of PCOS with the aim to support potential mechanism of action of acupuncture to relieve PCOS related symptoms. The theory that increased sympathetic activity contributes to the development and maintenance of PCOS is presented, and that the effects of acupuncture are, at least in part, mediated by modulation of sympathetic outflow. While there are no relevant randomized controlled studies on the use of acupuncture to treat metabolic abnormalities in women with PCOS, a number of experimental studies indicate that acupuncture may improve metabolic dysfunction. For each aspect of PCOS, it is important to pursue new treatment strategies that have fewer negative side effects than drug treatments, as women with PCOS often require prolonged treatment.

Effects of naltrexone on food intake and body weight gain in olanzapine-treated rats

Blockade of opioidergic neurotransmission contributes to reduction in body weight. However, how such blockade affects body weight gain (BWG) attributed to second generation antipsychotic agents (SGAs) has not yet been established. Here we examined the effects of an opioid receptor antagonist, naltrexone (NTX), on food intake and BWG associated with an SGA, olanzapine (OL). Four groups of Wistar Han IGS rats were treated for 28 days with either OL (2 mg/kg twice daily, intraperitoneal (IP)), a combination of OL (2 mg/kg twice daily, IP) + extended-release NTX (50 mg/kg, one-time, intramuscular (IM)), extended-release NTX (50 mg/kg, one-time, IM) or vehicle and their food intake and body weight were measured daily for the first nine days and every other day thereafter. Food intake and BWG that were increased by OL were decreased by the added NTX while NTX alone had no significant effects on food intake or on BWG. Plasma leptin concentrations were significantly elevated in the three groups receiving pharmacological agents, but did not differ among each other, suggesting that changes in leptin secretion and/or clearance alone would not explain the food intake and the body weight findings. Our results extend prior reports on anorexigenic effects of opioid antagonists by demonstrating that such effects may generalize to food intake increases and BWG arising in the context of OL pharmacotherapy.

Medical management of metabolic dysfunction in PCOS

Polycystic ovary syndrome (PCOS) is associated with metabolic derangements including insulin resistance, dyslipidemia, systemic inflammation and endothelial dysfunction. There is a growing need to develop pharmacologic interventions to improve metabolic function in women with PCOS. Medications that have been tested in patients with PCOS include metformin, thiazolidinediones, acarbose, naltrexone, orlistat, vitamin D and statins. Metformin decreases hepatic gluconeogenesis and free fatty acid oxidation while increasing peripheral glucose uptake. Early studies in PCOS suggested that metformin indirectly reduces insulin level, dyslipidemia and systemic inflammation; however, recent placebo-controlled trials failed to demonstrate significant metabolic benefit. Thiazolidinediones act primarily by increasing peripheral glucose uptake. Most studies in PCOS have demonstrated that thiazolidinediones reduce insulin resistance; however, effects on dyslipidemia were disappointing. Use of thiazolidinediones is associated with weight gain and major complications. Acarbose reduces digestion of polysaccharides. Studies in PCOS yielded inconsistent effects of acarbose on insulin sensitivity and no significant improvement of dyslipidemia. Naltrexone reduces appetite and modulates insulin release; its use in PCOS may reduce hyperinsulinemia. Orlistat decreases absorption of dietary fats; studies in PCOS suggest beneficial effects on insulin sensitivity. Vitamin D may improve insulin sensitivity but mixed results on lipid profile in PCOS have been reported. Statins are competitive inhibitors of the key enzyme regulating the mevalonate pathway; their effects are related to reduced cholesterol production as well as anti-inflammatory and anti-oxidant properties. In women with PCOS, statins reduce hyperandrogenism, improve lipid profile and reduce systemic inflammation while the effects on insulin sensitivity are variable. Use of statins is contraindicated in pregnancy.

The physiological basis of complementary and alternative medicines for polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine disorder that is characterized by chronic hyperandrogenic anovulation leading to symptoms of hirsutism, acne, irregular menses, and infertility. Multiple metabolic and cardiovascular risk factors are associated with PCOS, including insulin resistance, obesity, type 2 diabetes, hypertension, inflammation, and subclinical atherosclerosis. However, current treatments for PCOS are only moderately effective at controlling symptoms and preventing complications. This article describes how the physiological effects of major complementary and alternative medicine (CAM) treatments could reduce the severity of PCOS and its complications. Acupuncture reduces hyperandrogenism and improves menstrual frequency in PCOS. Acupuncture's clinical effects are mediated via activation of somatic afferent nerves innervating the skin and muscle, which, via modulation of the activity in the somatic and autonomic nervous system, may modulate endocrine and metabolic functions in PCOS. Chinese herbal medicines and dietary supplements may also exert beneficial physiological effects in PCOS, but there is minimal evidence that these CAM treatments are safe and effective. Mindfulness has not been investigated in PCOS, but it has been shown to reduce psychological distress and exert positive effects on the central and autonomic nervous systems, hypothalamic-pituitary-adrenal axis, and immune system, leading to reductions in blood pressure, glucose, and inflammation. In conclusion, CAM treatments may have beneficial endocrine, cardiometabolic, and reproductive effects in PCOS. However, most studies of CAM treatments for PCOS are small, nonrandomized, or uncontrolled. Future well-designed studies are needed to further evaluate the safety, effectiveness, and mechanisms of CAM treatments for PCOS.

Insulin resistance influences central opioid activity in polycystic ovary syndrome

This pilot study describes a relationship between insulin resistance and μ-opioid neurotransmission in limbic appetite and mood-regulating regions in women with polycystic ovary syndrome (PCOS), suggesting that insulin-opioid interactions may contribute to behavioral and reproductive pathologies of PCOS. We found that [1] patients with PCOS who are insulin-resistant (n = 7) had greater limbic μ-opioid receptor availability (nondisplaceable binding potential) than controls (n = 5); [2] receptor availability was correlated with severity of insulin resistance; and [3] receptor availability normalized after insulin-regulating treatment.

The role of opioid system and its interaction with sympathetic nervous system in the processing of polycystic ovary syndrome modeling in rat

BACKGROUND

This study was conducted to evaluate the effect of interaction of sympathetic and opioid systems in the processing of polycystic ovary syndrome modeling in rat.

METHODS

Ninety adult female rats (7-8 weeks of age) were treated with EV for 60 days for induction of follicular cysts (PCO modeling). Clonidine and yohimbine were used for sympathic agonist and antagonist and nalterxone was used for opioid system inhibition. Interactions of two systems were studied.

RESULTS

Our results indicate that both systems and interaction of two systems are effective in processing modeling of PCOS in rat. Interaction of two system drugs decreased estradiol (P < 0.05). Qualitative analysis showed that the bulk of cysts and corpus lutea and dominant follicles were increased in PCO rats in comparison with control group.

CONCLUSION

Therefore there could been an alternative in the treatment of the polycystic ovary syndrome in the rat by using adrenergic agonist and antagonists in combination with naltrexone.

Intense electroacupuncture normalizes insulin sensitivity, increases muscle GLUT4 content, and improves lipid profile in a rat model of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is associated with hyperandrogenism and insulin resistance, possibly reflecting defects in skeletal muscle and adipocyte insulin signaling. Low-frequency (2 Hz) electroacupuncture (EA) increases insulin sensitivity in female rats with dihydrotestosterone (DHT)-induced PCOS, but the mechanism is unclear. We hypothesized that low-frequency EA regulates mediators involved in skeletal muscle glucose uptake and metabolism and alters the lipid profile in rats with DHT-induced PCOS. To test this hypothesis, we implanted in prepubescent female rats 90-day continuous-release pellets containing DHT (PCOS). At 70 days of age, the rats were randomly subdivided into two groups: one received low-frequency EA (evoking muscle twitches) for 20-25 min five times/wk for 4-5 wk; the other did not. Controls were implanted with pellets containing vehicle only. All three groups were otherwise handled similarly. Lipid profile was measured in fasting blood samples. Insulin sensitivity was determined by euglycemic hyperinsulinemic clamp, soleus muscle protein expression of glucose transporter 4 (GLUT4), and phosphorylated and nonphosphorylated Akt, and Akt substrate of 160 kDa was determined by Western blot analysis and GLUT4 location by immunofluorescence staining. PCOS EA rats had normalized insulin sensitivity, lower levels of total high-density lipoprotein and low-density lipoprotein cholesterol, and increased expression of GLUT4 in different compartments of skeletal muscle compared with PCOS rats. Total weight and body composition did not differ in the groups. Thus, in rats with DHT-induced PCOS, low-frequency EA has systemic and local effects involving intracellular signaling pathways in muscle that may, at least in part, account for the marked improved insulin sensitivity.

Hedonic and motivational roles of opioids in food reward: implications for overeating disorders

Food reward can be driven by separable mechanisms of hedonic impact (food 'liking') and incentive motivation (food 'wanting'). Brain mu-opioid systems contribute crucially to both forms of food reward. Yet, opioid signals for food 'liking' and 'wanting' diverge in anatomical substrates, in pathways connecting these sites, and in the firing profiles of single neurons. Divergent neural control of hedonic and motivational processes raises the possibility for joint or separable modulation of food intake in human disorders associated with excessive eating and obesity. Early findings confirm an important role for 'liking' and 'wanting' in human appetitive behaviors, and suggest the intriguing possibility that exaggerated signals for 'wanting,' and perhaps 'liking,' may contribute to forms of overeating.

Metformin, naltrexone, or the combination of prednisolone and antiandrogenic oral contraceptives as first-line therapy in hyperinsulinemic women with polycystic ovary syndrome

To compare the short-term effects of metformin (M), naltrexone (N), and a combination of OC and prednisolone (OC/Pr) on the metabolic state and the ovarian function of PCOS women, we randomized 29 women to a 3-month course of therapy. We observed significant improvements in hyperandrogenemia and ovulation rates in PCOS women of all three groups, in the absence of changes in the metabolic state, suggesting that insulin resistance in PCOS patients is only one of several factors leading to hyperandrogenemic ovarian failure.

From taste hedonics to motivational drive: central μ-opioid receptors and binge-eating behaviour

Endogenous opioids and μ-opioid receptors (MORs) have long been implicated in the mechanism of appetite control and, in particular, hedonic processes associated with food evaluation, consumption and orosensory reward processes. In animal models of binge eating, selective MOR antagonists suppress food consumption. In humans, non-selective opioid receptor antagonists reduce hedonic taste preferences and food intake, particularly for palatable foods, and cause short-term weight loss. These effects have been linked to direct stimulation of MORs and modulation of dopamine release within the reward circuitry including the nucleus accumbens. These findings suggest that reduction of MOR-mediated hedonic and motivation processes driving consumption of highly palatable foods may be a promising therapeutic approach and provide a strong rationale for developing safer and more selective MOR antagonists or inverse agonists for disorders of 'appetitive motivation' including obesity and binge-eating disorder.

The role of the endogenous opioid system in polycystic ovary syndrome

OBJECTIVE

To review the complex role of the opioid system in reproduction and carbohydrate metabolism, abnormalities in the opioid system in women with polycystic ovary syndrome (PCOS), and the role of opioid antagonists in the management of PCOS-related infertility.

DESIGN

Pertinent articles were identified through a computer PubMed search. References of selected articles were hand searched for additional citations.

CONCLUSION(S)

Endogenous opioids are generally considered inhibitory central neurotransmitters. Peripherally, opioids are involved in the regulation of pancreatic islet function, hepatic insulin clearance, and glucose metabolism, potentially contributing to the pathogenesis of hyperinsulinemia and insulin resistance in PCOS. The presence of sex steroids is required for normal function of the opioid system in both GnRH secretion and carbohydrate metabolism. In women with PCOS, growing evidence suggests dysregulation of the opioid system both centrally and peripherally, with complex interactions. The opioid system effects on carbohydrate metabolism appear to be modulated by obesity. Finally, naltrexone has been demonstrated to successfully augment traditional ovulation induction regimens, but has limited support as a single ovulation induction agent for PCOS.

Acupuncture and exercise restore adipose tissue expression of sympathetic markers and improve ovarian morphology in rats with dihydrotestosterone-induced PCOS

Altered activity of the sympathetic nervous system, which innervates adipose and ovarian tissue, may play a role in polycystic ovary syndrome (PCOS). We hypothesize that electro-acupuncture (EA) and physical exercise reduce sympathetic activity by stimulating ergoreceptors and somatic afferent pathways in muscles. Here we investigated the effects of low-frequency EA and physical exercise on mRNA expression of sympathetic markers in adipose tissue and on ovarian morphology in female rats that received dihydrotestosterone (DHT) continuously, starting before puberty, to induce PCOS. At age 11 wk, rats with DHT-induced PCOS were randomly divided into three groups: PCOS, PCOS plus EA, and PCOS plus exercise. The latter two groups received 2-Hz EA (evoking muscle twitches) three times/week or had free access to a running wheel for 4-5 wk. In mesenteric adipose tissue, expression of beta(3)-adrenergic receptor (ADRB3), nerve growth factor (NGF), and neuropeptide Y (NPY) mRNA was higher in untreated PCOS rats than in controls. Low-frequency EA and exercise downregulated mRNA expression of NGF and NPY, and EA also downregulated expression of ADRB3, compared with untreated rats with DHT-induced PCOS. EA and exercise improved ovarian morphology, as reflected in a higher proportion of healthy antral follicles and a thinner theca interna cell layer than in untreated PCOS rats. These findings support the theory that increased sympathetic activity contributes to the development and maintenance of PCOS and that the effects of EA and exercise may be mediated by modulation of sympathetic outflow to the adipose tissue and ovaries.

Adipokines--targeting a root cause of cardiometabolic risk

Obesity often co-presents with other cardiometabolic risk factors such as dyslipidaemia, insulin resistance and hypertension. Less well appreciated is that dysregulation of adipokine production by excess adipose tissue also promotes a state of low-level systemic chronic inflammation and a prothrombotic state, implicated in the development of both atherosclerosis and subsequently cardiovascular events. Lifestyle modification and pharmacological therapy can reduce cardiometabolic risk, a benefit that may be partly due to their effects on adipokine levels.

Naltrexone treatment in clomiphene resistant women with polycystic ovary syndrome

BACKGROUND

Endogenous opiates may affect various aspects of reproductive and metabolic function in patients with polycystic ovary syndrome (PCOS). This study evaluated long-term inhibition of the opioid system using naltrexone in clomiphene citrate (CC)-resistant women with PCOS.

METHODS

A group of 30 infertile females with PCOS were evaluated; all subjects were obese, hyperandrogenic and hyperinsulinemic; 16 patients were amenorrhic and 14 were oligomenorrhic. All subjects received natrexone (50 mg p.o. daily) for 6 months. Patients who did not ovulate after 12 weeks of naltrexone monotherapy, also received CC (starting at 50 mg/day for 5 days and, for non-responders, increasing it up to 150 mg/day).

RESULTS

Of the 30 women, 3 ovulated during naltrexone monotherapy and 19 of the remaining 27 ovulated during naltrexone + CC therapy. There were no conceptions during naltrexone monotherapy, but 9 of 27 women (33.3%) conceived during naltrexone + CC; there was one missed abortion at 9 weeks, one preterm delivery at 34 weeks and seven term live births. Naltrexone therapy was also followed by significant reductions in BMI, fasting serum insulin, luteinizing hormone (LH), LH/follicle-stimulating hormone ratio and testosterone.

CONCLUSIONS

In this preliminary trial, naltrexone improved endocrine and metabolic function in women with CC-resistant PCOS. Furthermore, naltrexone restored CC sensitivity in the majority of subjects, resulting in a significant number of pregnancies.

Food intake and reward mechanisms in patients with schizophrenia: implications for metabolic disturbances and treatment with second-generation antipsychotic agents

Obesity is highly prevalent among patients with schizophrenia and is associated with detrimental health consequences. Although excessive consumption of fast food and pharmacotherapy with such second-generation antipsychotic agents (SGAs) as clozapine and olanzapine has been implicated in the schizophrenia/obesity comorbidity, the pathophysiology of this link remains unclear. Here, we propose a mechanism based on brain reward function, a relevant etiologic factor in both schizophrenia and overeating. A comprehensive literature search on neurobiology of schizophrenia and of eating behavior was performed. The collected articles were critically reviewed and relevant data were extracted and summarized within four key areas: (1) energy homeostasis, (2) food reward and hedonics, (3) reward function in schizophrenia, and (4) metabolic effects of the SGAs. A mesolimbic hyperdopaminergic state may render motivational/incentive reward system insensitive to low salience/palatability food. This, together with poor cognitive control from hypofunctional prefrontal cortex and enhanced hedonic impact of food, owing to exaggerated opioidergic drive (clinically manifested as pain insensitivity), may underlie unhealthy eating habits in patients with schizophrenia. Treatment with SGAs purportedly improves dopamine-mediated reward aspects, but at the cost of increased appetite and worsened or at least not improved opiodergic capacity. These effects can further deteriorate eating patterns. Pathophysiological and therapeutic implications of these insights need further validation via prospective clinical trials and neuroimaging studies.

Normalization of hyperinsulinemia by chronic opioid receptor blockade in hyperandrogenemic women

OBJECTIVE

Evaluation of the effects of naltrexone on hyperinsulinemia and hyperandrogenemia in hyperandrogenemic, hyperinsulinemic women.

DESIGN

Controlled clinical study.

SETTING

Department of Gynecologic Endocrinology and Reproductive Medicine, Center of Obstetrics and Gynecology, Medical University of Innsbruck, Austria.

PATIENT(S)

Thirty-nine hyperandrogenemic, hyperinsulinemic women were studied.

INTERVENTION(S)

Women were treated with naltrexone (50 mg/d) for >or=3 weeks.

MAIN OUTCOME MEASURE(S)

Body mass index (BMI), gonadotropin (LH, FSH) and androgen (T, free T, DHEAS) levels, and plasma levels of glucose, insulin, and C-peptide, during a standard 75-g oral glucose tolerance test (OGTT), were determined before and during chronic opiate receptor blockade.

RESULT(S)

The BMI did not change during therapy. When OGTT was repeated after treatment with naltrexone, glucose levels were not different from those before treatment. Insulin response, however, had dramatically declined. We also observed a significant decrease in the levels of serum androgens.

CONCLUSION(S)

Hyperinsulinemia associated with hyperandrogenemia can be improved or completely abolished by chronic opiate receptor blockade. This observation suggests that endogenous opiates play a critical role in the process leading to hyperinsulinemia in hyperandrogenemia.

Failure of the homeostatic model assessment calculation score for detecting metabolic deterioration in young patients with polycystic ovary syndrome

OBJECTIVE

To verify whether the homeostatic model assessment (HOMA) test is a suitable method for the identification of metabolic deterioration in normal-weight patients affected by polycystic ovary syndrome (PCOS).

DESIGN

Prospective clinical study.

SETTING

Academic clinic and research environment in Cagliari, Italy.

PATIENT(S)

Forty-nine PCOS normal-weight adolescent subjects, and 50 eumenorrheic, normal-weight, nonhirsute controls matched for age and body mass index (BMI).

INTERVENTION(S)

History and physical examination, oral glucose tolerance test (OGTT) and blood sampling, ultrasound.

MAIN OUTCOME MEASURE(S)

The HOMA score and integrated secretory area under the curve of insulin values (I-AUC) during the OGTT were calculated.

RESULT(S)

Normal insulin sensitivity was defined as upper control 95th percentile by HOMA values <65.6, I-AUC at 180 minutes <16,921, and I-AUC at 120 minutes <11,817. When applying the calculated I-AUC cutoff, 27 PCOS patients were classified as normoinsulinemic and 22 as hyperinsulinemic, whereas using the calculated HOMA cutoff, only 9 PCOS patients could be classified as insulin resistant (IR). Thirteen of the 40 non-IR PCOS patients presented with hyperinsulinemia; fasting glucose and insulin levels and HOMA scores were not sufficient to identify these subjects. Thus, the HOMA test displayed a low sensitivity (41%) and specificity (100%) in the diagnosis of the metabolic disorder disclosed by I-AUC. Moreover, analysis of I-AUC after 120 and 180 minutes revealed how the shorter evaluation period did not suffice for identification of all hyperinsulinemic subjects, implying an unrecognized condition in 11 of 22 subjects.

CONCLUSION(S)

In young, normal-weight patients with PCOS, the prevalence of hyperinsulinemia is not detectable by HOMA studies. The prevalence of IR was 18% according to HOMA evaluation, whereas hyperinsulinemia was found in 44% of subjects examined by I-AUC. Normal-weight, young PCOS patients should undergo a 3-hour OGTT to detect early metabolic abnormalities.

Resistance to diet-induced obesity in mu-opioid receptor-deficient mice: evidence for a "thrifty gene"

Using pharmacological tools, a role for opioid receptors in the regulation of food intake has been documented. However, the involvement of specific receptor subtypes remains questionable, and little information is available regarding a role for opioid receptors in energy metabolism. Using adult male mice lacking the mu-opioid receptor (MOR) gene (MOR-/-), we show that the MOR is not essential for the maintenance of normal levels of ad libitum food intake but does modulate the efficiency of energy storage during high-fat diets through the regulation of energy partitioning. When fed a regular diet, MOR-/- mice displayed only subtle alterations in energy homeostasis, suggesting a relative overuse of fat as a fuel source in the fed state. When fed a high-fat diet, MOR-/- mice were resistant to obesity and impaired glucose tolerance, despite having similar energy intake to wild-type mice. This resistance to obesity was associated with a strong induction of the expression of key mitochondrial enzymes involved in fatty acid oxidation within skeletal muscle. This metabolic role of the MOR, which is consistent with the properties of a "thrifty gene," suggests that the MOR pathway is a potential target for pharmacological intervention in the treatment of obesity associated with the intake of fatty diets.

Is ovulation induction still a therapeutic problem in patients with polycystic ovary syndrome?

Polycystic ovary syndrome (PCOS) is one of the most common endocrine diseases affecting women of fertile age, and is characterized by hyperandrogenism, chronic anovulatory cycles and oligomenorrhea or amenorrhea. Given the repercussions of chronic anovulation on sterility, PCOS is a heavy social burden. Here we describe the procedures used to induce ovulation in PCOS patients, the surgical approach and medical treatments that are still being experimented.

The Management of Polycystic Ovary Syndrome

It is well known that subjects with polycystic ovary syndrome (PCOS) show very variable clinical and biochemical aspects. Considering long-term repercussions, two main disturbances, not always strictly related, need to be countered: hyperandrogenism and insulin resistance, with compensatory hyperinsulinemia. The aim of this review is to summarize therapeutic perspectives for PCOS, starting from basic approach, such as weight reduction and changes in lifestyle. The benefits of long-term use of oral contraceptives and the criteria of choice of the estro-progestin combinations are discussed. With severe hyperandrogenism, a pure antiandrogen should be added. The experiences with insulin-sensitizing drugs, especially metformin, are reviewed; while their beneficial role as an adjuvant to treatment of ovulatory infertility has been well established, the effects of a long-term treatment, especially in very young patients, are still under debate. Current studies are testing the results of combinations of different treatments at low dosage; randomized comparative trials on the long-term efficacy of these approaches have yet to be scheduled.