An appraisal of serum preptin levels in PCOS

[Neuroendocrine features of the pathogenesis of polycystic ovary syndrome (literature review)]

Polycystic ovary syndrome (PCOS) is one of the most pressing problems in endocrine gynecology. The main signs of the disease are hyperandrogenism, menstrual and/or ovulatory dysfunction, and polycystic ovarian structure according to ultrasound. Women with PCOS are at risk for developing metabolic syndrome, type 2 diabetes, cardiovascular disease, and endometrial cancer. In this connection, the pathogenetic mechanisms of the occurrence of this syndrome are continuously studied and new methods of treatment are being sought. PCOS is characterized by a wide range of various disorders of the neuroendocrine regulation of the reproductive system. The main focus of the review is aimed at summarizing information about the etiological role of neuropeptides and neurotransmitters, such as phoenixin, galanins, orexins, GABA, in the pathophysiology of PCOS and about the possibility of their use for diagnostic and therapeutic purposes. In recent decades, the interest of scientists has been focused on the study of KNDy neurons, because it is the kisspeptin synthesized by them that is one of the main regulators of the hypothalamic-pituitary-ovarian axis. This article discusses data on the significance of KNDy neurons in the pathogenesis of the syndrome. Information is provided on the effect of elevated levels of androgens and anti-Müllerian hormone on GnRH neurons. Also analyzed are studies on functional and structural disorders in the hypothalamus in PCOS. Literature search was carried out in national (eLibrary, CyberLeninka.ru) and international (PubMed, Cochrane Library) databases in Russian and English. The priority was free access to the full text of articles. The choice of sources was prioritized for the period from 2018 to 2023.However, taking into account the insufficient knowledge of the chosen topic, the choice of sources dates back to 1998.

Preptin: A New Bone Metabolic Parameter?

Preptin is a 34-aminoacid peptide derived from the E-peptide of pro-insulin-like growth factor 2 (pro-IGF2) that is co-secreted with insulin and upregulates glucose-mediated insulin secretion. High serum preptin levels were described in conditions associated with insulin resistance, such as polycystic ovary syndrome and type 2 diabetes mellitus (T2M). Insulin and also IGF2 are known to be anabolic bone hormones. The "sweet bone" in T2M usually associates increased density, but altered microarchitecture. Therefore, preptin was proposed to be one of the energy regulatory hormones that positively impacts bone health. Experimental data demonstrate a beneficial impact of preptin upon the osteoblasts. Preptin also appears to regulate osteocalcin secretion, which in turn regulates insulin sensitivity. Preptin is greatly influenced by the glucose tolerance status and the level of physical exercise, both influencing the bone mass. Clinical studies describe low serum preptin concentrations in osteoporosis in both men and women, therefore opening the way towards considering preptin a potential bone anabolic therapy. The current review addresses the relationship between preptin and bone mass and metabolism in the experimental and clinical setting, also considering the effects of preptin on carbohydrate metabolism and the pancreatic-bone loop.

Preptin Deficiency Does Not Protect against High-Fat Diet-Induced Metabolic Dysfunction or Bone Loss in Mice

Preptin is derived from the cleavage of the E-peptide of pro-insulin-like growth factor (IGF)-II and is an insulin secretagogue. Observational studies have linked elevated circulating preptin to metabolic dysfunction in humans; however, a causal role for preptin in metabolic dysfunction has not been established. Additionally, preptin can promote osteoblast proliferation and differentiation, suggesting a link with skeletal health. We previously described a global preptin knockout (KO) model. In this study, we sought to uncover the impact of preptin KO in mice on the response to a moderately high-fat diet (HFD) and low-fat diet (LFD). HFD groups had higher weight and fat mass gain, lower trabecular and cortical bone volume and fracture load, and higher liver triglycerides. In males, preptin deficiency led to lower blood glucose than wild-type (WT) mice under LFD conditions. This was accompanied by differences in bone microarchitecture, including lower trabecular bone volume fraction, trabecular number, and lower cortical thickness. These differences were absent in female mice, although KO females had a HFD-driven increase in fat mass and liver triglycerides that was absent in WT mice. Female WT mice had increased glucose-stimulated insulin secretion under HFD conditions that was absent in female KO mice. Overall, preptin may have a detrimental impact on metabolism and a positive impact on bone health in male mice and may protect against liver fat storage in females while enabling islet compensation under HFD conditions. When we consider that serum preptin levels are elevated in humans of both sexes in pathological states in which insulin levels are elevated, the impact of preptin on comorbidity risk needs to be better understood. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Genetic ablation of the preptin-coding portion of Igf2 impairs pancreatic function in female mice

Preptin is a 34-amino acid peptide derived from the E-peptide of pro-insulin-like growth factor 2 and is co-secreted with insulin from β-cells. Little is understood about the effects of endogenous preptin on whole body glucose metabolism. We developed a novel mouse model in which the preptin portion of Igf2 was genetically ablated in all tissues, hereafter referred to as preptin knockout (KO), and tested the hypothesis that the removal of preptin will lead to a decreased insulin response to a metabolic challenge. Preptin KO and wild-type (WT) mice underwent weekly fasting blood glucose measurements, intraperitoneal insulin tolerance tests (ITT) at 9, 29, and 44 wk of age, and an oral glucose tolerance test (GTT) at 45 wk of age. Preptin KO mice of both sexes had similar Igf2 exon 2-3 mRNA expression in the liver and kidney compared with WT mice, but Igf2 exon 3-4 (preptin) expression was not detectable. Western blot analysis of neonatal serum indicated that processing of pro-IGF2 translated from the KO allele may be altered. Preptin KO mice had similar body weight, body composition, β-cell area, and fasted glucose concentrations compared with WT mice in both sexes up to 47 wk of age. Female KO mice had a diminished ability to mount an insulin response following glucose stimulation in vivo. This effect was absent in male KO mice. Although preptin is not essential for glucose homeostasis, when combined with previous in vitro and ex vivo findings, these data show that preptin positively impacts β-cell function.NEW & NOTEWORTHY This is the first study to describe a model in which the preptin-coding portion of the Igf2 gene has been genetically ablated in mice. The mice do not show reduced size at birth associated with Igf2 knockout suggesting that IGF2 functionality is maintained, yet we demonstrate a change in the processing of mature Igf2. Female knockout mice have diminished glucose-stimulated insulin secretion, whereas the insulin response in males is not different to wild type.

Follicular fluid 25-hydroxyvitamin D levels determine fertility outcome in patients with polycystic ovary syndrome

OBJECTIVE

To determine the possible relationship between follicular fluid 25-hydroxyvitamin D [25(OH)D] levels and fertility outcome of women who underwent IVF/ICSI with the diagnosis of lean polycystic ovary syndrome.

MATERIALS AND METHODS

Thirty patients who were diagnosed with PCOS according to the Rotterdam criteria and decided on IVF/ICSI were included in the study. Thirty patients who were scheduled for IVF/ICSI for reasons other than PCOS and matched in terms of age and BMI were taken as the control group (non-PCOS). According to BMI values, patients in both PCOS and non-PCOS groups were lean. Women in both groups were aged 21-35 years with a normal BMI (18.5-24.9 kg/m2) and first IVF/ICSI attempt. Both groups of patients were followed up using the antagonist protocol. Vit D levels were measured in serum and follicular fluid (FF) samples taken on the day of oocyte collection. The correlation between FF vit D levels, the number of total oocytes, MII oocytes and 2 PN zygotes, HOMA-IR, hormonal and demographic parameters, clinical pregnancy rate (CPR), live birth rate (LBR), and miscarriage rate were evaluated.

RESULTS

At the time of oocyte retrieval women with PCOS had similar serum Vitamin D compared to non-PCOS women (21.8 (12.6-24.8) ng/ml vs 22.3 (11.5-25.1) ng/ml, p < 0.54). In FF, assessed on the day of oocyte retrieval, the concentration of Vitamin D was similar in women with PCOS when compared to non-PCOS women (11.2 (9.2-14.4) ng/ml vs 13.3 (11.1-17.4) ng/ml, p < 0.06). For both groups, Vitamin D levels were lower in FF compared to serum vit D. A positive correlation was found between serum and FF Vitamin D concentrations in the full cohort. A positive and significant correlation was found between FF-vit D levels and the number of total oocyte (r = 0.344, p < 0.04) and MII oocyte (r = 0.404, p < 0.02) in the PCOS group. The number of total oocyte, MII oocyte and 2 PN zygotes of the PCOS group were significantly higher than the non-PCOS group. Positive pregnancy test rate, clinical pregnancy and live birth rates were similar in both groups. The miscarriage rates in the non-PCOS group were significantly higher than in the PCOS group. A positive and significant correlation was also found between FF vit D levels and positive pregnancy test (r = 0.566, p < 0.03) and CPR (r = 0.605, p < 0.02) in PCOS group. There was no correlation between FF-vit D levels and live birth and miscarriage rates in neither the PCOS nor the non-PCOS group.

CONCLUSIONS

Both serum and FF 25-hydroxyvitamin D level of women with PCOS at the time of oocyte retrieval are similar to non-PCOS controls. While FF 25-hydroxyvitamin D levels correlate with total and MII oocyte counts, positive pregnancy test and CPR, it does not correlate with miscarriage and live birth rates.

Functional stapled fragments of human preptin of minimised length

Preptin is a 34-amino-acid-long peptide derived from the E-domain of a precursor of insulin-like growth factor 2 (pro-IGF2) with bone-anabolic and insulin secretion amplifying properties. Here, we describe the synthesis, structures, and biological activities of six shortened analogues of human preptin. Eight- and nine-amino-acid-long peptide amides corresponding to the C-terminal part of human preptin were stabilised by two types of staples to induce a higher proportion of helicity in their secondary structure. We monitored the secondary structure of the stapled peptides using circular dichroism. The biological effect of the structural changes was determined afterwards by the ability of peptides to stimulate the release of intracellular calcium ions. We confirmed the previous observation that the stabilisation of the disordered conformation of human preptin has a deleterious effect on biological potency. However, surprisingly, one of our preptin analogues, a nonapeptide stabilised by olefin metathesis between positions 3 and 7 of the amino acid chain, had a similar ability to stimulate calcium ions' release to the full-length human preptin. Our findings could open up new ways to design new preptin analogues, which may have potential as drugs for the treatment of diabetes and osteoporosis.

Review of Novel Potential Insulin Resistance Biomarkers in PCOS Patients—The Debate Is Still Open

Research on proteins and peptides that play roles in metabolic regulation, which may be considered potential insulin resistance markers in some medical conditions, such as diabetes mellitus, obesity and polycystic ovarian syndrome (PCOS), has recently gained in interest. PCOS is a common endocrine disorder associated with hyperandrogenemia and failure of ovulation, which is often accompanied by metabolic abnormalities, including obesity, dyslipidemia, hyperinsulinemia, and insulin resistance. In this review, we focus on less commonly known peptides/proteins and investigate their role as potential biomarkers for insulin resistance in females affected by PCOS. We summarize studies comparing the serum fasting concentration of particular agents in PCOS individuals and healthy controls. Based on our analysis, we propose that, in the majority of studies, the levels of nesfastin-1, myonectin, omentin, neudesin were decreased in PCOS patients, while the levels of the other considered agents (e.g., preptin, gremlin-1, neuregulin-4, xenopsin-related peptide, xenin-25, and galectin-3) were increased. However, there also exist studies presenting contrary results; in particular, most data existing for lipocalin-2 are inconsistent. Therefore, further research is required to confirm those hypotheses, as well as to elucidate the involvement of these factors in PCOS-related metabolic complications.

New Peptides as Potential Players in the Crosstalk Between the Brain and Obesity, Metabolic and Cardiovascular Diseases

According to the World Health Organization report published in 2016, 650 million people worldwide suffer from obesity, almost three times more than in 1975. Obesity is defined as excessive fat accumulation which may impair health with non-communicable diseases such as diabetes, cardiovascular diseases (hypertension, coronary artery disease, stroke), and some cancers. Despite medical advances, cardiovascular complications are still the leading causes of death arising from obesity. Excessive fat accumulation is caused by the imbalance between energy intake and expenditure. The pathogenesis of this process is complex and not fully understood, but current research is focused on the role of the complex crosstalk between the central nervous system (CNS), neuroendocrine and immune system including the autonomic nervous system, adipose tissue, digestive and cardiovascular systems. Additionally, special attention has been paid to newly discovered substances: neuropeptide 26RFa, preptin, and adropin. It was shown that the above peptides are synthesized both in numerous structures of the CNS and in many peripheral organs and tissues, such as the heart, adipose tissue, and the gastrointestinal tract. Recently, particular attention has been paid to the role of the presented peptides in the pathogenesis of obesity, metabolic and cardiovascular system diseases. This review summarizes the role of newly investigated peptides in the crosstalk between brain and peripheral organs in the pathogenesis of obesity, metabolic, and cardiovascular diseases.

Insulin-like growth factor-II and bioactive proteins containing a part of the E-domain of pro-insulin-like growth factor-II

Insulin-like growth factor (IGF)-II is considered to function as an important fetal growth factor, which is structurally and functionally related to IGF-I and proinsulin. At least in vitro, IGF-II actions are mediated through the IGF-I receptor and to a lesser extent the insulin receptor. After birth, the function of IGF-II is less clear although in adults the serum level of IGF-II exceeds that of IGF-I several fold. The IGF-II gene is maternally imprinted, with exception of the liver and several parts of the brain, where it is expressed from both alleles. The regulation, organization, and translation of the IGF-II gene is complex, with five different putative promotors leading to a range of noncoding and coding mRNAs. The 180-amino acid pre-pro-IGF-II translation product can be divided into five domains and include a N-terminal signal peptide of 24 amino acid residues, the 67 amino acid long mature protein, and an 89 residues extension at the COOH terminus, designated as the E-domain. After removal of the signal peptide, the processing of pro-IGF-II into mature IGF-II requires various steps including glycosylation of the E-domain followed by the action of endo-proteases. Several of these processing intermediates can be found in the human circulation. There is increasing evidence that, besides IGF-II, several incompletely processed precursor forms of the protein, and even a 34-amino acid peptide (preptin) derived from the E-domain of pro-IGF-II, exhibit distinct biological activities. This review will focus on the current insights regarding the specific roles of the latter proteins in cancer, glucose homeostasis, and bone physiology. To address this topic clearly in the right context, a concise overview of the biological and biochemical properties of IGF-II and several relevant aspects of the IGF system will be provided.

Alterations of irisin, adropin, preptin and BDNF concentrations in coronary heart disease patients comorbid with depression

Background

Depression is a well-known co-morbidity of coronary heart disease (CHD) and these two diseases share common risk mechanisms. Here, the aim of this study was to investigate the possible link between energy homeostasis regulation and CHD patients comorbid with depression.

Methods

Two hundred and nine CHD patients and 101 matched healthy individuals were included. Demographic, clinical data were collected, serum irisin, adropin, preptin and brain-derived neurotrophic factor (BDNF) levels were determined by a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), and the depression was scored by Patient Health Questionnaire-9 (PHQ-9). Correlation analysis as well as multiple linear regression was used to assess the relationship between the three peptides, BDNF serum levels and PHQ-9 scores.

Results

Irisin serum level was significantly lower in CHD patients without depression as compared with healthy controls (P=0.002), as well as adropin (P=0.000), preptin (P=0.000) and BDNF (P=0.000). Furthermore, similar trends were observed in CHD patients with depression in terms of irisin, adropin and BDNF as compared with CHD patients without depression (P=0.006; P=0.003; P=0.002; respectively). Multiple logistic regression results confirmed the contribution of irisin and BDNF to the occurrence of depression in CHD. Interestingly, correlations analysis revealed significant negative correlations between PHQ-9 scores and irisin, adropin, BDNF level (r=-0.43, P<0.01; r=-0.29, P<0.05; r=-0.45, P<0.001 respectively), and irisin serum level was positively correlated with BDNF (r=0.38, P<0.01).

Conclusions

Our study firstly identified the role of energy homeostasis in the susceptibility to depression in CHD patients, and the interaction between irisin and BDNF could trigger the imbalance of energy homeostasis that occurs in depression of CHD patients.

Preptin promotes proliferation and osteogenesis of MC3T3-E1 cells by upregulating β-catenin expression

Preptin, an oligopeptide secreted by pancreatic β-cell, plays a significant role in glycometabolism and bone metabolism. Preptin strengthens proliferation and differentiation of osteoblasts, but the mechanism is unclear. Here, we explored the role of the Wnt/β-catenin signaling pathway which is well known to affect bone development and remodelling in the function of preptin. We found that preptin promoted the cell proliferative activity and osteoblastic differentiation in osteoblast-like MC3T3-E1 cells in a dose-independent manner, as evidenced by elevation in osteogenic genes, alkaline phosphatase activity and alizarin red staining in a dose-independent manner. Additionally, our findings demonstrated that the β-catenin expression level and runt-related transcription factor 2, which is the key downstream target of this pathway, were increased. The Wnt/β-catenin signalling pathway antagonist DKK1 abrogated the proliferative effect and differentiation function of preptin in MC3T3-E1 cells. These data indicated that preptin may be a potential therapeutic target for the treatment of osteoporosis and that osteogenic impact of preptin in MC3T3-E1 cells might be mediated by the Wnt/β-catenin signalling pathway. © 2019 IUBMB Life, 9999(9999):1-9, 2019.

Serum Preptin and Amylin Levels with Respect to Body Mass Index in Polycystic Ovary Syndrome Patients

Background

Preptin and amylin are pancreatic hormones which participate in glucose homeostasis. This study aimed to evaluate how serum preptin and amylin levels are altered in polycystic ovary syndrome (PCOS) patients and healthy women based on BMI groups (<25 kg/m² and ≥25 kg/m²).

Material/Methods

This was a prospective randomized control study of 40 PCOS patients and 40 healthy women who were matched with respect to BMI (<25 kg/m² and ≥25 kg/m²).

Results

When compared to the healthy women, PCOS patients had significantly higher ovarian volumes, Ferriman-Gallwey scores, and free and total testosterone levels, but significantly lower amylin concentrations (p=0.001, p=0.001, p=0.049, p=0.021, and p<0.001, respectively). Both the normal-weight and overweight PCOS patients had significantly lower amylin levels than the normal-weight and overweight controls (p<0.001, p=0.009, p=0.001, and p=0.001, respectively). Amylin levels were negatively and significantly correlated with the Ferriman-Gallwey scores (r=−0.272, p=0.001) and ovarian volume (r=−0.206, p=0.007). Serum preptin levels were not elevated in either group.

Conclusions

Serum preptin levels are statistically similar in PCOS patients and BMI-matched healthy controls. Serum amylin levels are significantly higher in healthy controls than PCOS patients whether they are slim or overweight. These findings suggest the presence of mechanisms that can prevent the elevation in serum amylin concentrations that can occur in response to the impaired glucose metabolism in PCOS patients.

Preptin in women with polycystic ovary syndrome

INTRODUCTION

Polycystic ovary syndrome (PCOS) patients, frequently develop metabolic complications, such as insulin resistance (IR), impaired carbohydrate metabolism, dyslipidemia, obesity. Among the new markers responsible for metabolic disorders, preptin seems to be of great significance.

MATERIAL

One hundred and thirty-four women aged 17-45 were enrolled. PCOS was diagnosed in 73 women on the basis of ESHRE-ASRM criteria. Non-PCOS group consisted of 61 women with regular menstruation matched for nutritional status.

METHODS

All women underwent anamnesis, physical examination, anthropometric measurements, the abdominal ultrasound examination, and dual energy X-ray absorptiometry (DXA). Serum adropin levels were determined by ELISA. Biochemical and hormonal (testosterone, androstenedione, LH, FSH, estradiol) measurements were also performed. Insulin resistance indices (HOMA, QUICKI, Matsuda) and free androgen index (FAI) were calculated with the test results according to the standard formula. For all comparisons, statistical significance was defined by p ≤ .05.

RESULTS

Serum preptin levels were significantly higher in the PCOS group. No significant correlations between preptin level and metabolic and hormonal markers were observed. The logistic regression analysis demonstrated that serum preptin level was an independent factor differentiating the two groups.

CONCLUSIONS

Serum preptin levels were significantly higher in women with PCOS compared with controls. This peptide might be an independent predictor of PCOS in the future.

Pathogenesis of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is the most common and important chronic liver disease in the world. As the prevalence of obesity increases in adults and children, the incidence of NAFLD has increased rapidly, reaching 17% to 33%. NAFLD is clinically divided into two forms: simple fatty liver (SFL) and non-alcoholic steatohepatitis (NASH), with NASH accounting for 1/3-1/2 of all NAFLD cases. The probability of developing cirrhosis is 0.6%-3.0% in patients with SFL for 10-20 years, and as high as 15%-25% in patients with NASH for 10-15 years. Approximately 1% of cirrhosis cases develop hepatocellular carcinoma each year. The pathogenesis of NAFLD is still not completely clear. It is generally believed that age, sex, obesity, insulin resistance, cytokines, gene polymorphism, and intestinal microflora are involved in the pathogenesis of NAFLD. An in-depth understanding of the pathogenesis of NAFLD can provide a basis for treatment of this disease. In recent years, cytokines or genes have been reported as targets for NAFLD treatment with appreciated effects. Since there is currently no specific treatment for NAFLD, targeted therapy may have a profound impact on the prognosis of the disease.

Relationships between preptin and osteocalcin in obese, overweight, and normal weight adults

Preptin is an endocrine peptide secreted from pancreatic β cells; it acts as a physiological amplifier of glucose-mediated insulin secretion. Osteocalcin, secreted by osteoblasts, is also involved in the regulation of body energy in that it modulates fat and glucose metabolism. The aim of this study was to investigate circulating preptin and osteocalcin levels and the possible association between them in obese and overweight adults. A total of 100 obese-overweight adults and 50 healthy controls matched for age and sex were enrolled in this study. Anthropometric measurements were taken and fasting glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), lipid profile, preptin, and osteocalcin were assessed. Preptin was significantly higher in obese and overweight subjects than in controls, whereas osteocalcin was significantly lower. In multiple regression analysis, preptin was independently influenced by waist circumference (WC) (β = 3.75, P = 0.03), fasting insulin (β = 4.77, P = 0.01), HOMA-IR (β = 8.21, P = 0.003), and osteocalcin (β = -28.41, P = 0.04). Osteocalcin was independently influenced by body mass index (β = -1.46, P = 0.05), WC (β = -2.04, P = 0.03), fasting insulin (β = -2.69, P = 0.02), HOMA-IR (β = -0.19, P = 0.006), and triglyceride (β = -4.54, P = 0.001). In conclusion, elevated serum preptin and decreased osteocalcin concentrations, together with insulin resistance, are associated with obesity and overweight. Serum preptin is also independently associated with osteocalcin, which may explain, at least in part, the crosstalk between bone and the β cells of the pancreas.

Serum Preptin and Amylin Values in Psoriasis Vulgaris and Behçet's Patients

BACKGROUND

Insulin resistance is found in both psoriasis and Behçet's disease. No study has yet explored whether preptin and amylin, two hormones associated with insulin resistance, are involved in the insulin resistance observed in patients with psoriasis and Behçet's disease.

OBJECTIVES

We aimed to explore how the amounts of preptin and amylin change in psoriasis and Behçet's disease and whether they are involved in the etiopathology of these two diseases, by comparing hormone levels in patients and healthy controls.

METHODS

The study registered 30 patients with psoriasis, 30 patients with Behçet's disease, and 30 healthy volunteers (as a control group). Fasting blood sugar, triglyceride, LDL, VLDL, HDL, total cholesterol, HbA1c, C-peptide, insulin, and serum preptin and amylin levels were measured in all subjects.

RESULTS

Serum preptin and amylin levels were significantly lower in the patients with psoriasis and Behçet's disease than in the control group (P < 0.001, P = 0.004, and P = 0.008, respectively). A comparison of the serum preptin and amylin levels between the patients with psoriasis and Behçet's disease did not reveal a statistically significant difference. Serum insulin level and The homeostasis model assessment of insulin resistance (HOMA-IR) index were significantly lower in the psoriasis patient group relative to the control group (P = 0.02 and P = 0.03, respectively), while the values for the Behçet's disease group did not differ significantly from those for the control group

CONCLUSIONS

Serum levels of preptin and amylin were significantly lower in patients with psoriasis and Behçet's disease, indicating that these hormones may be a factor for development of metabolic syndrome in these two diseases.

Insulin-like growth factor-II: its role in metabolic and endocrine disease

Insulin-like growth factor-II (IGF-II) is a widely expressed 7·5 kDa mitogenic peptide hormone. Although it is abundant in serum, understanding of its physiological role is limited compared with that of IGF-I. IGF-II regulates foetal development and differentiation, but its role in adults is less well understood. Evidence suggests roles in a number of tissues including skeletal muscle, adipose tissue, bone and ovary. Altered IGF-II expression has been observed in metabolic conditions, notably obesity, diabetes and the polycystic ovary syndrome. This article summarizes what is known about the actions of IGF-II and its dysregulation in metabolic and endocrine diseases. The possible causes and consequences of dysregulation are discussed along with the implications for diagnostic tests and future research.

Three new players in energy regulation: preptin, adropin and irisin

Homeostasis of energy is regulated by genetic factors, food intake, and energy expenditure. When energy input is greater than expenditure, the balance is positive, which can lead to weight gain and obesity. When the balance is negative, weight is lost. Regulation of this homeostasis is multi-factorial, involving many orexigenic (appetite-stimulating) and anorexigenic (appetite-suppressing) peptide hormones. Peripheral tissues are now known to be involved in weight regulation and research on its endocrine characteristics proceeds apace. Preptin with 34 amino acids (MW 3948 Da), adropin with 43 amino acids and a molecular weight of (4999 Da), and irisin with 112 amino acids (12587 Da), are three newly discovered peptides critical for regulating energy metabolism. Preptin is synthesized primarily in pancreatic beta cells, and adropin mainly in the liver and brain, and many peripheral tissues. Irisin, however, is synthesized principally in the heart muscle, along with peripheral tissues, including salivary glands, kidney and liver. The prime functions of preptin and adropin include regulating carbohydrate, lipid and protein metabolisms by moderating glucose-mediated insulin release. Irisin is an anti-obesitic and anti-diabetic hormone regulating adipose tissue metabolism and glucose homeostasis by converting white to brown adipose tissue. This review offers a historical account of these discovery and function of these peptides, including their structure, and physiological and biochemical properties. Their roles in energy regulation will be discussed. Their measurement in biological fluids will be considered, which will lead to further discussion of their possible clinical value.

Serum orexin-A (OXA) level decreases in polycystic ovarian syndrome

AIM

In the current study, we aimed to investigate whether serum orexin-A (OXA) levels are different in polycystic ovary syndrome (PCOS) subjects.

MATERIALS AND METHODS

Thirty-six women with PCOS and 40 healthy, age and body mass index-matched controls were included in the prospective cross-sectional study. All subjects underwent venous blood draws during the early follicular phase after overnight fasting. Serum OXA levels were measured with an enzyme immunoassay (EIA). The relationships between the serum OXA levels and the anthropometric and metabolic parameters were also assessed.

RESULTS

The serum OXA levels were lower in the women with PCOS compared to the control group. The serum OXA levels were correlated negatively with systolic blood pressure, the Ferriman-Gallway score and LH and free testosterone levels.

CONCLUSION

Our results indicate that serum OXA levels decrease in the serum of women with PCOS.

Salusins, newly identified regulators of hemodynamics and mitogenesis, increase in polycystic ovarian syndrome

In the current study, we aimed to investigate whether serum salusin α and β levels are different in PCOS subjects. Fifty women with PCOS and 50 healthy, age- and body mass index matched controls were included to the prospective cross-sectional study. All subjects underwent venous blood drawing on the early follicular phase after an overnight fasting. Serum salusin α and β levels were measured with EIA, and ELISA respectively. The relationships between serum salusin levels and anthropometric and metabolic parameters were also assessed. Plasma salusin α and β levels were higher in women with PCOS compared to control group. Serum salusin α level correlated positively with salusin β and fasting serum insulin levels. The serum salusin β levels were correlated positively with HOMA-IR, TG, LDL-C, LH, FSH, and total testosterone levels. Our results indicate that salusins, newly identified regulators of hemodynamics and mitogenesis, are increased within the serum of women with PCOS.

Acylated and desacylated ghrelin, preptin, leptin, and nesfatin-1 Peptide changes related to the body mass index

This study examines the levels of acylated and desacylated ghrelin, preptin, leptin, and nesfatin-1 peptide changes related to the body mass index (BMI). The subjects were allocated to 5 groups depending on their BMIs as follows: Group I (BMI <18.5 kg/m(2)); Group II (BMI 18.5-24.9 kg/m(2)); Group III (BMI 25-29.9 kg/m(2)); Group IV (BMI 30-39.9 kg/m(2)); Group V (BMI >40 kg/m(2)). Serum acylated and desacylated ghrelin, preptin, and leptin levels were measured by the enzyme-linked immunosorbent assay (ELISA) and nesfatin-1 was measured by the enzyme immunoassay (EIA). Desacylated ghrelin levels showed a gradual and statistically significant drop from Group I to Group V, while preptin and leptin levels exhibited a gradual and significant increase from Group I to Group IV. Serum nesfatin-1 levels gradually, but not significantly, increased from Group I to Group III and showed a significant decrease in Groups IV and V. In conclusion, leptin, preptin, and acylated ghrelin (AG) levels increased with higher BMI, whereas desacylated ghrelin (DAG) decreased and nesfatin-1 showed no clear relationship to BMI.

The relationship between polycystic ovary syndrome, glucose tolerance status and serum preptin level

BACKGROUND

Polycystic ovary syndrome (PCOS) is linked to obesity, impaired glucose tolerance and diabetes. Recently, studies have found that preptin enhances insulin secretion in rats and might play a role in the pathogenesis of diabetes and PCOS in humans. The aim of this study was to evaluate the relationship between PCOS, glucose tolerance status, and serum preptin level.

METHODS

This study was conducted in a university-affiliated hospital from October 2010 to August 2011. Anthropometric parameters, sex hormone concentrations, blood pressure, lipid profiles, fasting glucose and insulin, 2-h blood glucose after glucose overloaded (2hOGTT), glycosylated haemoglobin (HbA1c), homeostasis model assessment-insulin resistance index (HOMA-IR), and serum preptin of the samples were analyzed.

RESULTS

Sixty-three PCOS patients, including 33 women with normal glucose tolerance (NGT) and 30 women with impaired glucose tolerance (IGT), and 63 patients without PCOS, including 35 women with NGT and 28 women with IGT were recruited in this study. For patients with and without PCOS, women with IGT had higher serum preptin levels compared with women with NGT. Preptin levels in PCOS patients were higher compared with patients without PCOS, but the difference was not significant. Fasting serum preptin levels correlated positively with TG, SBP, DBP, FBG, 2hOGTT, and HOMA-IR in simple regression analysis of the pooled data. While in multiple stepwise regression analysis, preptin levels were independently related with glucose tolerance, but not with PCOS.

CONCLUSIONS

Irrespective of PCOS status, women with IGT had higher serum preptin levels compared with women with NGT. Preptin levels are related with glucose tolerance status, but not with PCOS status.