Evaluation of hypothalamic-pituitary-adrenal axis in amenorrhoeic women with insulin-dependent diabetes

Development of a nutrition screening tool to identify need for dietetic intervention in female infertility

BACKGROUND

One in seven couples are impacted by infertility in the UK, and female infertility is often associated with several health conditions impacted by nutrition. Despite many studies aimed at identifying the critical role of nutrition in infertility, there is currently no screening tool that identifies nutritional risk factors for infertility.

AIM

To propose a self-administered screening tool to identify women who would benefit from nutritional intervention to promote fertility.

METHODS

A narrative review was carried out to identify and summarise modifiable nutritional risk factors that can influence female fertility, including comorbidities that can influence nutrition intake, absorption, and metabolism.

KEY FINDINGS

A nutrition screening tool outlining modifiable nutrition risk factors potentially improving female fertility has been proposed, comprising of BMI, medical history and quality of diet and lifestyle which would aid in designing evidence based dietetic services for female infertility.

Taurine Improves Sexual Function in Streptozotocin-Induced Diabetic Rats

Previous studies have identified that diabetic erectile dysfunction is associated with androgen and nitric oxide deficiency resulting from hyperglycemia. It has been demonstrated that taurine can stimulate testosterone secretion, increase nitric oxide synthase (NOS) activity and nitric oxide (NO) production, and reduce blood glucose levels in the diabetic animals. Furthermore, recent studies have found that taurine relaxes both the corpus cavernosum and the vasculature. Accordingly, we hypothesized that taurine might exert beneficial effects on erectile function of the diabetic rats. Here, we assessed the effects of taurine on sexual function in streptozotocin (STZ) -induced diabetic male rats. We observed that taurine treatment could markedly increase sexual response and mating ability of STZ-diabetic rats. The serum concentration of gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone (T) were also significantly increased by taurine administration. Importantly, taurine supplementation notably increased mRNA levels and activity of endothelial NOS (eNOS) and neuronal NOS (nNOS), as well as NO and cGMP content, in the corpus cavernosum of the diabetic rats. In conclusion, the present data indicate that taurine can increase sexual function of STZ-induced diabetic male rats mainly by correcting the diabetes, increasing sexual desire, which is implicated in ameliorating the hypothalamic-pituitary-testicular axis function, and by improving penile erection, which requires increased signaling from the penile endothelial- and neuronal-dependent NO-cGMP pathway.

Neuroactive steroids and diabetic complications in the nervous system

Important complications of diabetes mellitus in the nervous system are represented by diabetic peripheral neuropathy and diabetic encephalopathy. In this context, an important link is represented by neuroactive steroids (i.e., steroids coming from peripheral glands and affecting nervous functionality as well as directly synthesized in the nervous system). Indeed, diabetes does not only affect the reproductive axis and consequently the levels of sex steroid hormones, but also those of neuroactive steroids. Indeed, as will be here summarized, the levels of these neuromodulators present in the central and peripheral nervous system are affected by the pathology in a sex-dimorphic way. In addition, some of these neuroactive steroids, such as the metabolites of progesterone or testosterone, as well as pharmacological tools able to increase their levels have been demonstrated, in experimental models, to be promising protective agents against diabetic peripheral neuropathy and diabetic encephalopathy.

Review: Diabetes and assisted reproductive technology

Patients with a range of medical disorders, including diabetes mellitus, are increasingly seeking access to assisted reproductive technology (ART). With appropriate patient selection, monitoring and counselling, these technologies may be applied successfully. Diabetes in the female is associated with disturbed ovarian function but strict metabolic control may encourage resumption of ovulation and allow ovarian stimulation for ART. Insulin metabolism appears intimately involved with ovarian function, through mechanisms encompassing the actions of insulin-like growth factors, but is not yet fully understood. Diabetes has minimal effects on spermatogenesis but may severely disrupt erectile and/or ejaculatory function; the techniques of epididymal sperm aspiration and intracytoplasmic sperm injection (ICSI) are particularly useful in such cases. Well-controlled diabetes is not associated with recurrent miscarriage but diabetes is a risk factor for pregnancy-induced hypertension and, poorly controlled, is associated with neonatal macrosomia. In reproduction, as in general health, good metabolic control is key to a successful outcome.

Female reproduction and type 1 diabetes: from mechanisms to clinical findings

BACKGROUND

The functional reproductive alterations seen in women with type 1 diabetes (T1D) have changed as therapy has improved. Historically, patients with T1D and insufficient metabolic control exhibited a high prevalence of amenorrhea, hypogonadism and infertility. This paper reviews the impact of diabetes on the reproductive axis of female T1D patients treated with modern insulin therapy, with special attention to the mechanisms by which diabetes disrupts hypothalamic-pituitary-ovarian function, as documented mainly by animal model studies.

METHODS

A comprehensive MEDLINE search of articles published from 1966 to 2012 was performed. Animal model studies on experimental diabetes and human studies on T1D were examined and cross-referenced with terms that referred to different aspects of the gonadotropic axis, gonadotrophins and gonadal steroids.

RESULTS

Recent studies have shown that women with T1D still display delayed puberty and menarche, menstrual irregularities (especially oligomenorrhoea), mild hyperandrogenism, polycystic ovarian syndrome, fewer live born children and possibly earlier menopause. Animal models have helped us to decipher the underlying basis of these conditions and have highlighted the variable contributions of defective leptin, insulin and kisspeptin signalling to the mechanisms of perturbed reproduction in T1D.

CONCLUSIONS

Despite improvements in insulin therapy, T1D patients still suffer many reproductive problems that warrant specific diagnoses and therapeutic management. Similar to other states of metabolic stress, T1D represents a challenge to the correct functioning of the reproductive axis.

Functional state of the hypothalamic-pituitary-gonadal axis in diabetes mellitus

Diabetic patients present with a wide variety of reproductive disorders supposed to be underlain by changes in the functional activity of the hypothalamic-pituitary-gonadal axis (HPGA) and sensitivity of the reproductive system tissues to the regulatory hormonal action. The objective of the present review is to analyse the literature data and the results of original studies pertinent to the biosynthesis and secretion of hypothalamic LH releasing factor, pituitary gonadotropic hormones, steroid hormones, and susceptibility of their target tissues in patients with types 1 and 2 diabetes mellitus. It is concluded that the improvement of control over blood glucose levels constitutes a most efficacious approach to the correction and normalization of reproductive function in diabetic patients.

Fertility Issues in Women with Diabetes

Diabetes mellitus Type 1 and Type 2 should be considered in the differential diagnosis of menstrual abnormalities and infertility. The reproductive period of diabetic women may be reduced due to delayed menarche and premature menopause. During the reproductive years, diabetes has been associated with menstrual abnormalities, such as oligomenorrhea and secondary amenorrhea. It was found that better glycemic control and prevention of diabetic complications improves these irregularities and increases fertility rates close to those that are seen in the general population. Women with persistent menstrual abnormalities despite adequate treatment need to be approached by broader evaluation, which will include the examination of the hypothalamic–pituitary–ovarian axis and the hormonal status, presence of autoimmune thyroid disease and antiovarian autoantibodies, and hyperandrogenism.

Pituitary-testicular axis function, biological to immunological ratio and charge isoform distribution of pituitary LH in male rats with experimental diabetes

Men with insulinopenic diabetes mellitus frequently present hypogonadism and exhibit circulating luteinizing hormone (LH) molecules with increased biological activity. To further study this latter issue, we analyzed the pattern of isoform distribution and the impact of changes in terminal glycosylation of pituitary LH on the bioactivity of this gonadotropin in experimental diabetes. Adult male rats were treated with streptozotocin or vehicle and euthanized on days 30, 60, or 90 posttreatment. All diabetic groups exhibited a significant decrease in serum insulin and testosterone levels as well as in sperm count; serum gonadotropins and 17beta-estradiol decreased only after 90 days of insulinopenia. Both the immunoreactive concentrations and the biological to immunological ratio of intrapituitary LH significantly increased in all experimental groups, as assessed by an in vitro homologous bioassay in HEK-293 cells expressing a recombinant LH receptor. Chromatofocusing of pituitary extracts revealed the presence of multiple LH charge isoforms; the pH distribution profile of LH in diabetic and control rats was indistinguishable on days 30 and 60 posttreatment. By contrast, the abundance of more basic isoforms (pH 9.99-9.0) decreased and that of isoforms with pH values 8.99-8.0 increased in rats with long-standing diabetes compared to controls. It is concluded that experimental diabetes alters the function of the pituitary-testicular axis, resulting in reduced sex steroids levels and hypogonadotropism. Long-standing insulinopenia leads to a paradoxical accumulation of intrapituitary LH molecules enriched in bioactivity with altered terminal glycosylation, which are apparently subserved by distinct mechanisms involving altered hypothalamic and/or gonadal inputs on the gonadotrope.

Reproductive history and hormonal birth control use are associated with coronary calcium progression in women with type 1 diabetes mellitus

CONTEXT

Coronary artery disease is increased in women with type 1 diabetes (T1D), compared with nondiabetic (Non-DM) women. Women with T1D have more menstrual dysfunction and are less likely to use hormonal birth control (BC) than Non-DM women.

OBJECTIVE

The purpose of this study was to determine whether coronary artery calcium (CAC) is associated with menstrual dysfunction and BC use in women with T1D.

MATERIALS AND METHODS

This was a prospective cohort study, and participants were followed up for an average of 2.4 yr.

PATIENTS

Patients included 612 women (293 T1D, 319 Non-DM) between the ages of 19 and 55 yr who had CAC measured twice by electron beam tomography.

RESULTS

Irregular menses and amenorrhea were more common in T1D than Non-DM women (22.1 vs. 14.9%, P < 0.05 and 16.6 vs. 7.0%, P < 0.001). T1D women reported less BC use than Non-DM women (79.8 vs. 89.9%, P < 0.001) and reached menarche at an older age (13.1 +/- 1.8 vs. 12.8 +/- 1.5 yr, P < 0.05). Use of BC was associated with less CAC progression in all women, but this association was stronger in T1D women (P value for interaction = 0.02). Irregular menses were associated with greater CAC progression only among T1D women.

CONCLUSIONS

A prior history of BC use is associated with reduced CAC progression among all women, with a stronger association in T1D than in Non-DM women. Women with T1D who report irregular menses have increased CAC progression, compared with those with regular menses.

In vitro evidence of glucose-induced toxicity in GnRH secreting neurons: high glucose concentrations influence GnRH secretion, impair cell viability, and induce apoptosis in the GT1-1 neuronal cell line

OBJECTIVE

To evaluate for direct toxic effects of high glucose concentrations on cellular physiology in GnRH secreting immortalized GT1-1 neurons.

DESIGN

Prospective experimental design.

SETTING

In vitro experimental model using a cell culture system.

INTERVENTION(S)

GT1-1 cells were cultured in replicates in media with two different glucose concentrations (450 mg/dL and 100 mg/dL, respectively) for varying time intervals (24, 48, and 72 hours).

MAIN OUTCOME MEASURE(S)

Effects of glucose concentrations on GnRH secretion by the GT1-1 neurons were evaluated using a static culture model. Cell viability, cellular apoptosis, and cell cycle events in GT1-1 neurons maintained in two different glucose concentrations were assessed by flow cytometry (fluorescence-activated cell sorter) using Annexin V-PI staining.

RESULT(S)

Adverse influences of high glucose concentrations on GnRH secretion and cell viability were noted in cultures maintained in high glucose concentration (450 mg/dL) culture medium for varying time intervals. A significantly higher percentage of cells maintained in high glucose concentration medium demonstrated evidence of apoptosis by a fluorescence-activated cell sorter.

CONCLUSION(S)

We provide in vitro evidence of glucose-induced cellular toxicity in GnRH secreting GT1-1 neurons. Significant alterations in GnRH secretion, reduced cell viability, and a higher percentage of apoptotic cells were observed in GT1-1 cells maintained in high (450 mg/dL) compared with low (100 mg/dL) glucose concentration culture medium.

Energy balance of pregnant diabetic rats

Pregnancy and diabetes lead to metabolic alterations in the energy balance that may not be completely independent. The objective of the present study was to look at the alterations induced by type 1 diabetes mellitus on the energy balance of pregnant rats and the offspring. Diabetes was induced by streptozotocin injection 15 d before the starting of pregnancy. The rats had their energy balance variables followed for 21 d. Protein, fat and energy content of dams was determined from samples of the carcasses. Pregnancy led to increased energy intake, energy gain and energy expenditure as well as higher gross food efficiency than non-pregnant counterparts. Diabetes increased metabolizable energy intake but not the energy gain of the animals: they had very high energy expenditure, so that diabetes blocked the improvement in gross food efficiency shown during pregnancy. Offspring from diabetic dams were born with lower body weight. Pregnant animals did not present the usual energy storage as seen by lower energy gain of diabetic dams as well as by the lower fat content in the carcasses of pregnant diabetic rats. It is concluded that diabetes impairs the energy variables usually enhanced by pregnancy alone.

Somatotropic and gonadotropic axes linkages in infancy, childhood, and the puberty-adult transition

Integrative neuroendocrine control of the gonadotropic and somatotropic axes in childhood, puberty, and young adulthood proceeds via multiple convergent and divergent pathways in the human and experimental animal. Emerging ensemble concepts are required to embody independent, parallel, and interacting mechanisms that subserve physiological adaptations and pathological disruption of reproduction and growth. Significant advances in systems biology will be needed to address these challenges.

The hypothalamus–pituitary–ovary axis and type 1 diabetes mellitus: a mini review

A high prevalence of menstrual cycle and fertility disturbances has long been associated with diabetes mellitus. However, rationalization of the intrinsic mechanisms of these alterations is controversial and even contradictory. This review considers (i) the relationship between diabetes mellitus, especially type 1 diabetes mellitus (T1DM), and the hypothalamus-pituitary-ovary (HPO) axis, (ii) the state of our knowledge concerning neuroendocrine control and its relationship with dopaminergic and opioid tonus, and (iii) the influence of the hypothalamus-pituitary-adrenal axis on ovarian function. Functional disturbances that occur as a consequence of diabetes are also discussed, but some T1DM-related diseases of autoimmune origin, such as oophoritis, are not further analysed. Although there are clear indications of a relationship between menstrual and fertility alterations and glycaemic control, in many instances the improvement of the latter is not sufficient to reverse such alterations. It appears that the oligoamenorrhoea and amenorrhoea associated with T1DM is mainly of hypothalamic origin (i.e. failure of the GnRH pulse generator) and may be reversible. The importance of the evaluation of the HPO axis in T1DM women with menstrual irregularities, even in the presence of adequate metabolic control, is emphasized.

Impaired fertility caused by endocrine dysfunction in women

Infertility can be frustrating for patients and physicians. Endocrine dysfunction can impair fertility and alter pregnancy outcome. Once the diagnosis is secured, most endocrine disorders are reversible or can be adequately managed to restore fertility and decrease associated pregnancy complications. Improved understanding of the subtleties and intricacies of mechanisms by which endocrinopathies can hinder fertility and influence the course of a pregnancy is vital, more so in the era of assisted reproductive technology, because pregnancy in an abnormal endocrine environment can be disastrous. The role of autoimmunity in infertility and pregnancy loss is less clear; in this context, there are limited management options to improve fertility and overall pregnancy outcomes.