Normalization of hyperinsulinemia by chronic opioid receptor blockade in hyperandrogenemic women

Blood pressure response to extended-release naltrexone in heroin and prescription opioid users and its implications for cardiovascular morbidity

BACKGROUND

Consuming opioid agonists is a risk factor for cardiovascular disease particularly in intravenous heroin users. The monthly injectable extended-release opioid antagonist, naltrexone (XR-NTX) is an effective treatment for opioid use disorder. The impact of opioid receptor blockade through XR-NTX on blood pressure, a critical risk factor for cardiovascular morbidity, has not yet been characterized.

METHODS

The study evaluated the change in blood pressure during XR-NTX treatment among 14 patients who predominately used intravenous heroin and 24 patients who used prescription oral opioids, all with opioid use disorder. Blood pressure was measured in each patient immediately before the first XR-NTX injection and ∼two weeks after the first injection. The change in diastolic and systolic pressure was compared between the heroin users and the prescription opioids users using analysis of variance.

RESULTS

XR-NTX treatment was associated with significant decreases in diastolic blood pressure in the heroin group, but not in the prescription opioids group. Systolic blood pressure values in the heroin users showed a decline at trend level only.

CONCLUSIONS

Further research is warranted to replicate our findings and to determine whether XR-NTX effect is relatively specific to blood pressure or generalizes to other components of metabolic syndrome. Distinguishing between heroin and prescription opioid users could shed light on the unique clinical and pharmacological profiles of opioid drugs, particularly regarding their cardiovascular safety. This information can be useful in developing personalized therapeutic strategies based on the route of opioid administration.

The immune-opioid axis in prediabetes: predicting prediabetes with insulin resistance by plasma interleukin-10 and endomorphin-2 to kappa-opioid receptors ratio

BACKGROUND

Prediabetes is characterized by a hemoglobin A1c of 5.7-6.4% and fasting blood glucose of 100-125 mg/dl. A high percentage of prediabetes subjects develop type 2 diabetes mellitus in the next years. The effects of opioid peptides and their receptors, in addition to immunological cytokines, on prediabetes are not well understood. Therefore, molecular, physiological, and clinical studies are required to link the opioid system, immune system, and insulin resistance (IR) in prediabetes. We hypothesize that opioid peptides (endomorphin-2 (EM2), and β-endorphin (βEP)), and their receptors (µ-opioid receptors (MOR) and κ-opioid receptors (KOR)), in addition to the inflammatory cytokines (IL-6) and anti-inflammatory cytokine (IL-10), affect IR parameters in patients with prediabetes.

METHODS

Sixty prediabetes patients with IR (prediabetes+IR) and sixty prediabetes patients without IR (prediabetes-IR), in addition to 58 controls, have participated in the study. IL-6, IL-10, EM2, βEP, MOR, and KOR were measured by the ELISA technique.

RESULTS

In general, most prediabetes subjects have dyslipidemia. The IL-6, IL-10, β-endorphin, MOR, and endomorphin-2 were higher in the prediabetes subgroups than the control group. The immune system was activated in the prediabetes in an IR-dependent manner. Prediabetes+IR can be predicted by the increased levels of IL-10, βEP, and EM2 and by the combination of IL-10 and EM2/KOR with good sensitivity and specificity.

CONCLUSION

Opioid peptides and their receptors were upregulated in patients with prediabetes, depending on the significance of IR and the immune cytokines. The intercorrelation between the immune system, EOS, and insulin in prediabetes was confirmed.

Neurotransmitter, neuropeptide and gut peptide profile in PCOS-pathways contributing to the pathophysiology, food intake and psychiatric manifestations of PCOS

Polycystic ovary syndrome (PCOS) is a major health problem with a heterogeneous hormone-imbalance and clinical presentation across the lifespan of women. Increased androgen production and abnormal gonadotropin-releasing hormone (GnRH) release and gonadotropin secretion, resulting in chronic anovulation are well-known features of the PCOS. The brain is both at the top of the neuroendocrine axis regulating ovarian function and a sensitive target of peripheral gonadal hormones and peptides. Current literature illustrates that neurotransmitters regulate various functions of the body, including reproduction, mood and body weight. Neurotransmitter alteration could be one of the reasons for disturbed GnRH release, consequently directing the ovarian dysfunction in PCOS, since there is plenty evidence for altered catecholamine metabolism and brain serotonin or opioid activity described in PCOS. Further, the dysregulated neurotransmitter and neuropeptide profile in PCOS could also be the reason for low self-esteem, anxiety, mood swings and depression or obesity, features closely associated with PCOS women. Can these altered central brain circuits, or the disrupted gut-brain axis be the tie that would both explain and link the pathogenesis of this disorder, the occurrence of depression, anxiety and other mood disorders as well as of obesity, insulin resistance and abnormal appetite in PCOS? This review intends to provide the reader with a comprehensive overview of what is known about the relatively understudied, but very complex role that neurotransmitters, neuropeptides and gut peptides play in PCOS. The answer to the above question may help the development of drugs to specifically target these central and peripheral circuits, thereby providing a valuable treatment for PCOS patients that present to the clinic with GnRH/LH hypersecretion, obesity or psychiatric manifestations.

Metformin induces a prompt decrease in LH-stimulated testosterone response in women with PCOS independent of its insulin-sensitizing effects

BACKGROUND

The use of insulin-sensitizing drugs has been shown to improve both the reproductive and the metabolic aspects of PCOS. However, the mechanisms by which metformin exerts its effects in PCOS are still not completely understood. There is growing evidence of a direct effect of metformin on ovarian steroidogenesis, independent of its effects on insulin sensitivity.

METHODS

We evaluated the short-term effects of metformin compared to placebo on basal and LH- stimulated androgen secretion as well as on hormonal and metabolic parameters in 19 women with PCOS during a four-day randomized, double-blinded placebo-controlled clinical trial. In a three month follow-up evaluation, we investigated the longer-term therapeutic effects of metformin on ovulation, metabolic and endocrine parameters.

RESULTS

Compared to placebo, 2 days of metformin was associated with a borderline significant reduction in the free androgen index (FAI) (p = 0.05) and with a reduction in the serum concentration of LH-stimulated testosterone (T) (p = 0.03). Following three months of use, a decline in serum T was observed, independent of changes in weight, metabolic parameters, or insulin sensitivity.

CONCLUSIONS

In women with PCOS, Metformin induces a prompt decrease in LH-stimulated T secretion after only several days of use. This action precedes the medication's effects on insulin sensitivity or weight loss.

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.

Accurate screening for insulin resistance in PCOS women using fasting insulin concentrations

The aims of this cross-sectional study were to evaluate the relative agreement of both static and dynamic methods of diagnosing IR in women with polycystic ovary syndrome (PCOS) and to suggest a simple screening method for IR. All participants underwent serial blood draws for hormonal profiling and lipid assessment, a 3 h, 75 g load oral glucose tolerance test (OGTT) with every 15 min measurements of glucose and insulin, and an ACTH stimulation test. The prevalence of IR ranged from 12.2% to 60.5%, depending on the IR index used. Based on largest area under the curve on receiver operating curve (ROC) analyses, the dynamic indices outperformed the static indices with glucose to insulin ratio and fasting insulin (fInsulin) demonstrating the best diagnostic properties. Applying two cut-offs representing fInsulin extremes (<7 and >13 mIU/l, respectively) gave the diagnosis in 70% of the patients with high accuracy. Currently utilized indices for assessing IR give highly variable results in women with PCOS. The most accurate indices based on dynamic testing can be time-consuming and labor-intensive. We suggest the use of fInsulin as a simple screening test, which can reduce the number of OGTTs needed to routinely assess insulin resistance in women with PCOS.

Ultrasonographic assessment of skin thickness in patients with PCOS - a case-control study

OBJECTIVE

To measure skin thickness in patients with polycystic ovary syndrome (PCOS) in comparison to controls and to examine a possible association with sex steroids, body mass index, lipid profile and hyperinsulinemia.

METHODS

Thirty patients with confirmed PCOS were compared to thirty-two women presenting for infertility workup. Skin thickness was measured using high-resolution ultrasound in a standardized area, blood samples were collected once at presentation.

RESULTS

Patients with PCOS showed a statistically significant thicker skin than women in the control group (0.95 mm (±0.093 mm) versus 0.85 mm (±0.077 mm, p < 0.0001)). LH, estradiol, testosterone, the free androgen index, triglycerides, cholesterol, LDL-cholesterol and body mass index were significantly increased in PCOS - patients. No correlation between hyperinsulinemia and skin thickness was seen.

CONCLUSIONS

PCOS - patients showed a greater skin thickness in comparison to women without PCOS. This might be due to proliferative effects of sex steroids such as estrogens and testosterone and metabolic derangements on skin thickness.

Adiposopathy, diabetes mellitus, and primary prevention of atherosclerotic coronary artery disease: treating "sick fat" through improving fat function with antidiabetes therapies

Both obesity and type 2 diabetes mellitus (DM) are worldwide epidemics, an association that is neither incidental nor coincidental. Adipose tissue is as an active endocrine and immune organ whose dysfunction (adiposopathy or "sick fat") is promoted by excessive caloric balance in genetically and environmentally susceptible patients. The resultant adiposopathic responses directly and indirectly contribute to pathologies leading to hyperglycemia, high blood pressure, and dyslipidemia--all major cardiovascular risk factors--as well as to cardiovascular disease (CVD) itself. Toward the goal of primary prevention of CVD among DM patients, clinical trial outcomes evidence support the use of antihypertensive agents, lipid-altering drugs, and antiplatelet agents. Some of the most proactive measures to reduce the onset of cardiovascular risk factors and potentially prevent the onset of DM are early and aggressive nutritional, physical activity, and lifestyle interventions. Such measures improve the functionality of adipose tissue, reduce adiposopathic responses, and thus improve glycemic, blood pressure, and lipid parameters--all of which would be expected to reduce CVD risk. Finally, if nutritional, physical activity, and lifestyle interventions are not successful, and if DM pharmacologic therapies are indicated, then the choice of anti-DM medications should take into consideration the effects of such agents on adipose tissue function and dysfunction, which in turn, affects major CVD risk factors and CVD.

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.

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.

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.

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.

Endogenous opiates and behavior: 2006

This paper is the 29th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning 30 years of research. It summarizes papers published during 2006 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior (Section 2), and the roles of these opioid peptides and receptors in pain and analgesia (Section 3); stress and social status (Section 4); tolerance and dependence (Section 5); learning and memory (Section 6); eating and drinking (Section 7); alcohol and drugs of abuse (Section 8); sexual activity and hormones, pregnancy, development and endocrinology (Section 9); mental illness and mood (Section 10); seizures and neurological disorders (Section 11); electrical-related activity and neurophysiology (Section 12); general activity and locomotion (Section 13); gastrointestinal, renal and hepatic functions (Section 14); cardiovascular responses (Section 15); respiration and thermoregulation (Section 16); and immunological responses (Section 17).