Genetic variants associated with insulin signaling and glucose homeostasis in the pathogenesis of insulin resistance in polycystic ovary syndrome: a systematic review

Therapeutic effects of stevia aqueous extract alone or in combination with metformin in induced polycystic ovary syndrome rats: Gene expression, hormonal balance, and metabolomics aspects

OBJECTIVES

This study aimed to assess the individual and combined effects of SAE and Met on the expression of genes related to insulin signaling, oxidative stress, hormonal imbalance, insulin resistance, and dyslipidemia in rats with induced PCOS.

METHODS

The estrous cycle of 50 adult Wistar female rats was monitored through vaginal smears. Subsequently, the rats were randomly assigned into five groups of 10, including control (receiving 1ml of carboxymethyl cellulose for 49 days), induction (letrozole at 1mg/kg/d for 21 days), SAE, Met, and SAE/Met. SAE and Met were orally administered at doses of 400mg/kg/d and 250mg/kg/d on day 22 and continued for an additional 28 days. Vaginal smears were analyzed, and gene expression levels of GLUT4, SIRT1, TNF-α, and INSR were evaluated using RT-qPCR. Antioxidant parameters were assessed using detection kits.

RESULTS

Treatment with SAE and Met restored a regular estrous cycle pattern in PCOS rats. Furthermore, SAE and Met treatment improved hormonal balance, dyslipidemia, and hyperglycemia in the rats. Administration of SAE and Met significantly elevated levels of antioxidant enzymes SOD and GPx in ovarian tissue (P<0.001). Additionally, mRNA levels of GLUT4, SIRT1, and INSR were significantly increased in ovarian tissue following SAE and Met treatment, while TNF-α gene expression decreased significantly (P<0.0001).

CONCLUSION

The findings suggest that SAE and Met aqueous extract exert protective effects on letrozole-induced PCOS in rats by modulating gene expression associated with insulin signaling and oxidative stress.

Pterostilbene Ameliorates Cognitive Impairment in Polycystic Ovary Syndrome Rat Model through Improving Insulin Resistance via the IRS-1/PI3K/Akt/GSK-3β Pathway: A Comparative Study with Metformin

Polycystic ovary syndrome (PCOS) is an intricate endocrine disorder that targets millions of women globally. Recent research has drawn attention to its association with cognitive impairment and Alzheimer's disease (AD) risk, yet the exact mechanism remains elusive. This study aimed to explore the potential role of PCOS-associated insulin resistance (IR) and inflammation in linking PCOS to AD pathogenesis. It additionally investigated the therapeutic merits of pterostilbene (PTS) in ameliorating PCOS and associated cognitive deficits in comparison to metformin (MET). Rats were divided into five groups; vehicle group, PTS group [30 mg/kg, per os (p.o.) for 13 days], and the remaining three groups received letrozole (1 mg/kg, p.o. for 21 days) to represent the PCOS, PCOS + MET (300 mg/kg, p.o. for 13 days), and PCOS + PTS groups, respectively. Behavioral tests were conducted, along with a histopathological investigation of brains and ovaries. Assessment of serum hormonal profile and hippocampal IRS-1/PI3K/AKT/GSK-3β insulin signaling pathway components were performed. PTS rats exhibited improved insulin sensitivity and hormonal profile, besides enhanced neurobehavioral tests performance and histopathological findings. These effects may be attributed to modulation of the IRS-1/PI3K/AKT/GSK-3β pathway, reducing GSK-3β activity, and mitigating Tau hyperphosphorylation and Aβ accumulation in the brain. Likewise, PTS attenuated nuclear factor kappa B-mediated inflammation and reversed AChE elevation, suggesting multifaceted neuroprotective effects. Comparatively, PTS showed outcomes similar to those of MET in most parameters. The obtained findings validated that dysregulated insulin signaling in PCOS rats detrimentally affects cognitive function, which is halted by PTS, unveiling the potential of PTS as a novel therapy for PCOS and related cognitive deficits.

Relationship between polycystic ovary syndrome and high periostin level

OBJECTIVE

There is growing evidence suggesting a relationship between periostin levels, inflammation, and ovarian dysfunction. In this prospective case-control study, we aimed to investigate serum periostin levels and their relationship with metabolic parameters in patients with polycystic ovary syndrome.

METHODS

We conducted a prospective case-control study involving 45 polycystic ovary syndrome patients and 45 control subjects, matched in a 1:1 ratio. Serum samples collected from both study and control groups were analyzed using enzyme-linked immunosorbent assay.

RESULTS

The demographic characteristics were similar between the polycystic ovary syndrome and control groups (p>0.05). Periostin levels were significantly higher in patients with polycystic ovary syndrome compared with the control group (4.67±2.46 vs. 2.60±1.41 ng/mL, respectively; p=0.000).

CONCLUSION

Our study revealed a significant elevation in periostin levels among polycystic ovary syndrome patients compared with controls. These findings suggest that periostin could serve as a potential marker for assessing disease severity in polycystic ovary syndrome patients.

Comparative effects of acupuncture and metformin on insulin sensitivity in overweight/obese and lean women with polycystic ovary syndrome and insulin resistance: a post hoc analysis of a randomized trial

Objective

This study explored the efficacy of acupuncture and metformin in enhancing insulin sensitivity among women with polycystic ovary syndrome (PCOS) and insulin resistance (IR), distinguishing between overweight/obese and lean groups.

Methods

A post-hoc analysis of a randomized trial (NCT02491333) was undertaken. Participants were women aged 18-40 with PCOS and IR. They were randomized to receive true acupuncture with a placebo, metformin with sham acupuncture, or sham acupuncture with a placebo for 4 months, with follow-up visits over 3 months. Our study, involving 339 women, assessed the differential impact of acupuncture and metformin on insulin sensitivity in overweight/obese [body mass index (BMI) ≥ 24] versus lean women (BMI < 24). Primary outcomes measured changes in the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) at 4 and 7 months. Secondary outcomes assessed changes in glucose area under the curve (glucoseAUC) during the oral glucose tolerance test (OGTT) and BMI changes at 4 months.

Results

Overweight/obese participants were generally older with higher measurements in various health metrics, but lower levels in specific hormonal metrics compared to lean women (p < 0.05). Among overweight/obese women, metformin outperformed acupuncture in reducing HOMA-IR levels (p = 0.004) and showed a significant drop from the baseline after 4 months (p < 0.05). In contrast, acupuncture's effect on HOMA-IR did not significantly differ from sham acupuncture at 4 and 7 months. For lean women, metformin and acupuncture showed comparable improvements in HOMA-IR, with notable declines at 4 and 7 months (p < 0.05). Acupuncture proved more beneficial for lean women than their overweight/obese counterparts after 4 months (p = 0.021).

Conclusion

In overweight/obese women with PCOS and IR, acupuncture was less effective than metformin in enhancing insulin sensitivity. However, in lean women, acupuncture's efficacy was comparable to metformin. Further studies are required to validate these observations.

Effect of Wenshentiaojing Decoction on Hormone Level and Follicular Number in Patients with Menstrual Disorder of Polycystic Ovary Syndrome

Objective

To explore the curative effect of Wenshentiaojing Decoction on the treatment of menstrual disorder caused by PCOS.

Methods

Patients with menstrual disorders caused by PCOS admitted to our department from January 2020 to January 2021 were selected as the research objects and were divided into a control group and observation group according to the random number table method. The control group was treated with Western medicine, and the observation group was treated with Wenshentiaojing Decoction on the basis of Western medicine. The clinical efficacy of the two groups was compared. Before and after treatment, sex hormones (LH, FSH, LH/FSH, and testosterone (T)), ovarian volume, endometrial thickness, cervical mucus score, follicular number, menstrual conditions (menstrual duration, menstrual cycle, and menstrual volume), and other indicators in both groups were recorded.

Results

After treatment, the total effective rate of the observation group (91.1% (41/45)) was higher than that of the control group (77.8% (35/45)), and the difference was statistically significant (P < 0.05). After treatment, the LH, LH/FSH, and T levels in the observation group were lower than those in the control group, while the FSH level was higher than that in the control group (P < 0.05). After treatment, the ovarian volume, endometrial thickness, cervical mucus score, and follicle number in the observation group were higher than those in the control group (P < 0.05). After treatment, the menstrual duration and menstrual volume in the observation group were longer than those in the conventional group, and the menstrual cycle was shorter than that in the conventional group (P < 0.05).

Conclusion

For patients with menstrual disorders caused by PCOS, the treatment effect of Wenshentiaojing Decoction assisted with Western medicine is better, which can effectively improve the level of sex hormones, cervical mucus, and menstrual conditions, increase the ovarian volume, endometrial thickness, and follicle number, and improve the treatment effect, with fewer adverse reactions, which is worthy of further promotion and application.

The Treatment with Complementary and Alternative Traditional Chinese Medicine for Menstrual Disorders with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a frequent gynecological female endocrinopathy, characterized by chronic anovulation, hyperandrogenism, and insulin resistance (IR). Menstrual disorders are one of the main clinical manifestations of PCOS. Other symptoms include hirsutism and/acne. At present, the treatment of PCOS with irregular menstruation is mainly based on oral contraceptives, but there are some side effects and adverse reactions. In recent years, more and more attention has been paid to the complementary and alternative medicine (CAM), which has been widely used in clinical practice. Modern Western medicine is called "conventional medicine" or "orthodox medicine," and the complementary and alternative medicine is called "unconventional medicine" or "unorthodox medicine." CAM includes traditional medicine and folk therapy around the world. Around 65-80% of world health management business is classified into traditional medicine by the World Health Organization, which is used as alternative medicine in Western countries. In our country, Chinese medicine, acupuncture, and other therapies are commonly used due to their significant efficacy and higher safety. Therefore, this review aims to summarize and evaluate the mechanisms and the effect of current complementary replacement therapy in the treatment of menstrual disorders caused by PCOS, so as to provide guidance for the following basic and clinical research.

Metabolomic Biomarkers in Polycystic Ovary Syndrome: A Review of the Evidence

Polycystic ovary syndrome (PCOS) is an endocrinologic condition affecting one in five women of reproductive age. PCOS is often characterized by disruptions to the menstrual cycle, development of male-pattern hair growth (hirsutism), and polycystic ovary morphology. Recently, PCOS has been linked to metabolic dysfunction, with 40 to 80% of women characterized as overweight or obese. Despite these well-known negative health effects of PCOS, 75% of sufferers remain undiagnosed. This is most likely due to the variability in symptom presentation and the lack of a definitive test for the condition. Metabolomics, which is a platform used to analyze and characterize a large number of metabolites, has recently been proposed as a potential tool for investigating the metabolic pathways that could be involved in the pathophysiology of PCOS. In doing so, novel biomarkers could be identified to improve diagnosis and treatment of PCOS. This review aims to summarize the findings of recent metabolomic studies that highlight metabolic-specific molecules which are deranged in PCOS, to identify potential biomarkers for the condition. Current limitations for metabolomic studies are discussed, as well as future directions to progress the field toward further validation and integration into clinical practice.

Paeoniflorin attenuates DHEA-induced polycystic ovary syndrome via inactivation of TGF-β1/Smads signaling pathway in vivo

Polycystic ovarian syndrome (PCOS) is one of the most common reproductive endocrine disorders which are involved in complicated and unknown pathogenic mechanisms. Paeoniflorin (PAE) plays a significant anti-fibrotic role according to previous studies. The aim of the present study was to investigate the effect of PAE on ovarian fibrosis and its underlying mechanism in PCOS development. An animal model of PCOS was established by subcutaneous injection of 60mg/kg/d dehydroepiandrosterone (DHEA) for 35 consecutive days. Rats in PAE-L, PAE-M and PAE-H groups were administrated by gavage with PAE (20, 40, 80 mg/kg/d) for 4 weeks. Our results indicated that DHEA-induced PCOS rats showed similar phenotypes with PCOS patients. PAE could significantly block the DHEA-induced decline of ovary weight and organ coefficient, shorten the prolonged diestrus period, and regulate the irregular estrous cycle of PCOS rats. Moreover, PAE regulated reproductive hormone levels and improved ovarian fibrosis induced by DHEA. PAE treatment could also reduce the expression levels of TGF-β1 and Smad3, and increase the expression levels of Smad7 and MMP2. In conclusion, PAE significantly attenuated the ovarian fibrosis in PCOS, which could be mediated by TGF-β1/Smads signaling pathway. Herein, PAE can be used for the treatment of ovarian fibrosis in PCOS progression.

Adenovirus-36 infection and obesity: A case control study of Turkish women with polycystic ovary syndrome

BACKGROUND AND AIMS

Adenovirus-36 (Ad-36) seropositivity has been shown to be involved in the aetiology of obesity. The aim of this study was to examine Ad-36 positivity in obese and normal-weight patients with polycystic ovary syndrome (PCOS).

METHODS

There were two groups including 92 and 110 subjects. This study was a prospective case-control study. The enzyme-immunoassay method was used to quantitatively determine antibodies (Abs) specific to human Ad-36 in the serum samples. Age, body mass index (BMI), fasting glucose levels and insulin levels of the participants were recorded. The PCOS and control group patients were divided into two groups: the overweight group with BMI ≥25 kg/m² and non-obese group with BMI <25 kg/m².

RESULTS

Ad-36 Ab positivity in the PCOS group was found to be significantly higher than that in the control group (p < 0.001). Ad-36 Ab positivity was significantly higher in the PCOS obese group than in the control obese group (p < 0.001). Ad-36 Ab positivity and BMI ≥25 kg/m² were identified as independent predictors of PCOS in logistic regression analysis.

CONCLUSION

Ad-36 Ab positivity was significantly higher in the obese/overweight PCOS patients. Obesity can be prevented in patients with PCOS by treating Ad-36.

Glucose, insulin, and cortisol concentrations and glucose tolerance test in Holstein cows with inactive ovaries

A total of 60 healthy (the control group) and 30 anestrous Holstein cows with inactive ovaries (the case group) from three dairy farms around Tehran were randomly selected and diagnosed to determine the concentrations of glucose, insulin, and cortisol, and the rate of the insulin resistance disorder in them. Primarily, serum samples were obtained from all animals, and the concentrations of glucose, insulin, and cortisol were measured in a laboratory. Thereupon, the glucose tolerance test (GTT) was implemented. Before the implementation of the GTT, the median of serum glucose levels (62 mg/dl), insulin (7.16 μIU/ml), and cortisol (2.5 μg/dl) was estimated in healthy cows. The median of serum glucose levels (68.5 mg/dl, p = 0.00009) was higher, and serum insulin (6.1 μIU/ml, p = 0.025) and cortisol (1.1 μg/dl, p = 0.00029) levels were lesser in the anestrous cows when estimated simultaneously. After the implementation of GTT, the median of serum glucose concentrations in one (120 mg/dl), two (73.5 mg/dl), and three (63.5 mg/dl) hours after the glucose injection was estimated in healthy cows. The findings also showed that the median of serum glucose levels was lesser in one (100 mg/dl, p = 0.015), similar in two (77.5 mg/dl, p = 0.9), and higher in three (70 mg/dl, p = 0.012) hours after the glucose injection in anestrous cows. In conclusion, higher serum glucose, lesser insulin and cortisol concentrations, and the different correlation between serum glucose and insulin levels before the GTT were detected in anestrous cows. The pattern of glucose changes also differed in anestrous cows after the GTT.

Possible Link Between Stress-related Factors and Altered Body Composition in Women with Polycystic Ovarian Syndrome

Background

Stress is an invisible factor affecting modern day living and is strongly associated with many disease pathogenesis including polycystic ovarian syndrome (PCOS) in women. PCOS is the most frequent endocrinological disorder that affects women of reproductive age, leading to metabolic dysfunction and body composition alterations. Salivary amylase and cortisol are major stress mediators that have been implicated in PCOS. However, their role in altering body composition in PCOS is yet to be deciphered.

Aim

The present study aimed at understanding the relation between stress-associated factors and alterations in body composition among PCOS patients.

Design

This study enrolled a total of 100 patients (PCOS) and 60 age-matched controls. The female patients were of ages between 13 and 30 years.

Materials and Methods

Standard assay kits were used to evaluate the α-amylase activity and cortisol level in saliva. The participants were chosen on the basis of the Rotterdam American Society for Reproductive Medicine/European Society of Human Reproduction criteria. Saliva was collected from each participant as per the protocol of Salimetrics, USA.

Statistical Analysis

Statistical analysis was performed using SPSS version 20 for Windows. The quantitative variables are described as mean ± standard deviation. P < 0.05 was considered significant.

Results

Increased salivary cortisol level and α-amylase activity were seen in the PCOS population as compared to age-matched controls suggesting patients a sustained stress scenario in their system. Moreover, overweight PCOS participants reflected higher amylase activity than the lean patients participants. Pulse rate, body mass index (BMI), visceral adiposity, and waist-hip ratio (WHR) was considerably higher in the PCOS patients participants compared to controls. A significant correlation could be drawn between the α-amylase activity and BMI or WHR, respectively, among PCOS patients. These observations indicate a strong link between the stress marker and alterations in the body composition parameters of PCOS patients participants.

Conclusion

Higher prevalence of stress in PCOS patients participants has a critical role in their altered body composition.

Effect of omega-3 fatty acids supplementation on insulin resistance in women with polycystic ovary syndrome: Meta-analysis of randomized controlled trials

BACKGROUND

Several studies have shown that omega-3 polyunsaturated fatty acids (PUFA) may improve insulin resistance in various diseases. However, the possible effect of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation on insulin resistance in PCOS still remains unclear. We evaluated the effect of omega-3 PUFA supplementation on insulin resistance in women with PCOS in a meta-analysis.

METHODS

Literature searches of MEDLINE, PubMed Central and EMBASE for publications in English were conducted up to December 2015. We included all randomized controlled trials (RCTs) that investigated effects of omega-3 fatty acids supplements on insulin resistance in women with PCOS. Results are summarized as mean differences (MD) with 95% confidence intervals (CI). Effect sizes of eligible studies were pooled using random-effects models (the DerSimonian-Laird estimator). We assessed the potential sources of heterogeneity using the standard χ2 test.

RESULTS

Of 1202 papers, three RCTs were eligible for inclusion which involved 72 cases and 73 controls. The dose range for omega3 supplement was 1.2g to 3.6g and the duration of follow-up was from 6 to 8 weeks. There was no significant effect of omega-3 fatty acids supplements compared to placebo on insulin resistance (MD: 6.18; CI; -3.347, 15.382; p=0.208) and HOMA -IR (MD: 0.276; 95% CI=-1.428, 1.981; p=0.751) in women with PCOS.

CONCLUSION

The results provide an evidence that supplementation with omega-3 fatty acids may not have a beneficial effect on improving insulin resistance in women with PCOS.

Acupuncture treatment for insulin sensitivity of women with polycystic ovary syndrome and insulin resistance: a study protocol for a randomized controlled trial

BACKGROUND

Our prospective pilot study of acupuncture affecting insulin sensitivity on polycystic ovary syndrome (PCOS) combined with insulin resistance (IR) showed that acupuncture had a significant effect on improving the insulin sensitivity of PCOS. But there is still no randomized controlled trial to determine the effect of acupuncture on the insulin sensitivity in women with PCOS and IR. In this article, we present the protocol of a randomized controlled trial to compare the effect of true acupuncture on the insulin sensitivity of these patients compared with metformin and sham acupuncture. Acupuncture may be an effective therapeutic alternative that is superior to metformin and sham acupuncture in improving the insulin sensitivity of PCOS combined with IR.

METHODS

This study is a multi-center, controlled, double-blind, and randomized clinical trial aiming to evaluate the effect of acupuncture on the insulin sensitivity in PCOS combined with IR. In total 342 patients diagnosed with PCOS and IR will be enrolled. Participants will be randomized to one of the three groups: (1) true acupuncture + metformin placebo; (2) sham acupuncture + metformin, and (3) sham acupuncture + metformin placebo. Participants and assessors will be blinded. The acupuncture intervention will be given 3 days per week for a total of 48 treatment sessions during 4 months. Metformin (0.5 g per pill) or placebo will be given, three times per day, and for 4 months. Primary outcome measures are changes in homeostasis model assessment of insulin resistance (HOMA-IR) and improvement rate of HOMA-IR by oral glucose tolerance test (OGTT) and insulin releasing test (Ins). Secondary outcome measures are homeostasis model assessment-β (HOMA-β), area under the curve for glucose and insulin, frequency of regular menstrual cycles and ovulation, body composition, metabolic profile, hormonal profile, questionnaires, side effect profile, and expectation and credibility of treatment. Outcome measures are collected at baseline, at the end of treatments, and 3 months after the last acupuncture treatment. On completion of the screening visit, randomization will be conducted using a central randomization system.

DISCUSSION

This study will investigate the effects of acupuncture on the insulin sensitivity of PCOS and IR women compared with metformin and sham acupuncture. We will test whether true acupuncture with needles placed in skeletal muscles and stimulated manually and by electrical stimulation is more effective than metformin and sham acupuncture with superficial needle placement with no manual or electrical stimulation in improving the insulin sensitivity in PCOS women with IR.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02491333 ; Chinese Clinical Trial Registry, ChiCTR-ICR-15006639. Registered on 24 June 2015.

The endocrine disruptor bisphenol A may play a role in the aetiopathogenesis of polycystic ovary syndrome in adolescent girls

AIM

Experimental in vitro studies have shown that bisphenol A affects steroidogenesis, folliculogenesis and ovarian morphology. The aim of this study was to investigate the role of the endocrine disruptor bisphenol A in the aetiopathogenesis of polycystic ovary syndrome (PCOS) in adolescents and its relationship with metabolic parameters, insulin resistance and obesity in this population.

METHODS

A total of 112 girls with PCOS and 61 controls between 13 and 19 years of age were enrolled in the study. Serum bisphenol A levels were measured by high-pressure liquid chromatography. An oral glucose tolerance test was also performed.

RESULTS

Adolescents with PCOS had markedly increased serum bisphenol A levels (mean: 1.1 ng/mL 95% CI: 1.0-1.2) than controls (mean: 0.8 ng/mL 95% CI: 0.6-0.9, p = 0.001). When we compared the subgroups according to obesity, the main factor determining the significant increase in bisphenol A was the presence of PCOS, but not obesity (p = 0.029). Bisphenol A was significantly correlated with total testosterone (r = 0.52), free testosterone (r = 0.44), dehydroepiandrosterone sulphate (r = 0.37) and Ferriman-Gallwey score (r = 0.43) (p < 0.05).

CONCLUSION

Adolescents with PCOS had higher serum bisphenol A levels than controls, independent of obesity. Bisphenol A concentrations were significantly correlated with androgen levels, leading us to consider that bisphenol A might play a role in the aetiopathogenesis of PCOS in adolescents.

New insights into the genetic basis of infertility

Infertility is a disease of the reproductive system characterized by inability to achieve pregnancy after 12 or more months of regular unprotected sexual intercourse. A variety of factors, including ovulation defects, spermatogenic failure, parental age, obesity, and infections have been linked with infertility, in addition to specific karyotypes and genotypes. The study of genes associated with infertility in rodent models has expanded the field of translational genetics in identifying the underlying cause of human infertility problems. Many intriguing aspects of the molecular basis of infertility in humans remain poorly understood; however, application of genetic knowledge in this field looks promising. The growing literature on the genetics of human infertility disorders deserves attention and a critical concise summary is required. This paper provides information obtained from a systematic analysis of the literature related to current research into the genetics of infertility affecting both sexes.

Importance of the interdisciplinary, evidence-based diagnosis of polycystic ovary syndrome

Polycystic ovary syndrome is recognized as the most common hormonal and metabolic disorder of women. This heterogeneous endocrinopathy characterized by clinical and/or biochemical hyperandrogenism, oligo- or amenorrhoea, anovulatory infertility, and polycystic ovarian morphology. The prevalence, clinical feature and the risk of co-morbidity vary depending on the accuracy of the diagnosis and the criteria used. Evidence suggests that those women are at high risk who fulfil the criteria based on National Institute of Health. The complex feature of the syndrome and the considerable practice heterogenity that is present with regards to diagnostic testing of patients who are suspected to have polycystic ovary syndrome require an interdisciplinary, evidence-based diagnostic approach. Such a method can ensure the patient safety and the effectiveness and efficiency of the diagnosis. This paper summarises the highest available evidence provided by well-designed studies, meta-analysis and systematic reviews of the clinical feature and the clinical implications of the diagnostic criteria of polycystic ovary syndrome. Orv. Hetil., 2014, 155(30), 1175–1188.

Insulin: its role in the central control of reproduction

Insulin has long been recognized as a key regulator of energy homeostasis via its actions at the level of the brain, but in addition, plays a role in regulating neural control of reproduction. In this review, we consider and compare evidence from animal models demonstrating a role for insulin for physiological control of reproduction by effects on GnRH/LH secretion. We also review the role that insulin plays in prenatal programming of adult reproduction, and consider specific candidate neurons in the adult hypothalamus by which insulin may act to regulate reproductive function. Finally, we review clinical evidence of the role that insulin may play in adult human fertility and reproductive disorders. Overall, while insulin appears to have a significant impact on reproductive neuroendocrine function, there are many unanswered questions regarding its precise sites and mechanisms of action, and their impact on developing and adult reproductive neuroendocrine function.