Effect of methadone addiction on glucose metabolism in rats

Metabolic profiles associated with opioid use and opioid use disorder: a narrative review of the literature

Purpose of Review

Opioid use disorder (OUD) is a chronic, relapsing condition that is epidemic in the USA. OUD is associated with serious adverse consequences, including higher incarceration rates, impaired medical and mental health, and overdose-related fatalities. Several medications with demonstrated clinical efficacy in reducing opioid use are approved to treat OUD. However, there is evidence that medications for OUD cause metabolic impairments, which raises concerns over the long-term metabolic health of individuals recovering from OUD. Here, we summarize the scientific literature on the metabolic effects of the use of opioids, including medications for treating OUD.

Recent Findings

Our findings showed lower body weight and adiposity, and better lipid profiles in individuals with OUD. In individuals with diabetes mellitus, opioid use was associated with lower blood glucose levels. In contrast, among individuals without underlying metabolic conditions, opioids promoted insulin resistance. Treatment of OUD patients with the agonists methadone or buprenorphine caused weight gain, increased liking and intake of sugar, and impaired lipid profile and glucose metabolism, whereas treatment with the antagonist naltrexone demonstrated evidence for reduced sweet preferences.

Summary

Our findings highlighted a gap in knowledge regarding the safety of medications for OUD. Further research is needed to determine how best to reduce the risk of metabolic disorder in the treatment of OUD with opioid agonists versus antagonists.

The therapeutic effect of N-acetylcysteine as an add-on to methadone maintenance therapy medication in outpatients with substance use disorders: A randomized, double-blind, placebo-controlled clinical trial

OBJECTIVE

Patients with substance use disorders (SUD) under methadone maintenance therapy (MMT) are susceptible to a number of complications (psychological and metabolic disorders). Evidence studies have shown the roles of the glutamatergic system in addiction. N-Acetylcysteine (NAC) enhances extracellular glutamate, and is effective in the treatment of neuropsychiatric disorders. We assessed oral NAC as an add-on to MMT medication for the treatment of SUD.

METHODS

In the current randomized, double-blind, placebo-controlled clinical trial, outpatients with SUD under MMT who were 18-60 years old received 2400 mg/day NAC (n = 30) or placebo (n = 30) for 12 weeks. Psychological status and metabolic biomarkers were assessed at baseline and the end of the trial.

RESULTS

Compared with the placebo group, NAC treatment resulted in a significant improvement in depression score (β -2.36; 95% CI, -3.97, -0.76; p = .005), and anxiety score (β -1.82; 95% CI, -3.19, -0.44; p = .01). Furthermore, NAC treatment resulted in a significant elevation in total antioxidant capacity levels (β 72.28 mmol/L; 95% CI, 11.36, 133.19; p = .02), total glutathione (GSH) levels (β 81.84 μmol/L; 95% CI, 15.40, 148.28; p = .01), and a significant reduction in high-sensitivity C-reactive protein levels (β -0.89 mg/L; 95% CI, -1.50, -0.28; p = .005), and homeostasis model of assessment-insulin resistance (β -0.33; 95% CI, -0.65, -0.009; p = .04), compared with the placebo group.

CONCLUSION

In the current study, improvement in depression and anxiety symptoms as well as some metabolic profiles with NAC treatment for 12 weeks in outpatients with SUD under MMT was detected.

Genetic liability for prescription opioid use and risk of cardiovascular diseases: a multivariable Mendelian randomization study

BACKGROUND AND AIMS

Observational studies have yielded conflicting results on the association of prescription opioid use (POU) with the risk of cardiovascular diseases (CVD). Residual confounding and potential reverse causality are inevitable in such conventional observational studies. This study used Mendelian randomization (MR) design to estimate the causal effect of POU on the risk of CVD, including coronary heart disease (CHD), myocardial infarction (MI) and ischemic stroke (IS), as well as their common risk factors.

DESIGN

We estimated the causal effect of genetic liability for POU on CVD in a two-sample MR framework. Complementary sensitivity analyses were conducted to test the robustness of our results.

SETTING

Genome-wide association studies (GWAS) that were based on predominantly European ancestry.

PARTICIPANTS

The sample sizes of the GWAS used in this study ranged from 69 033 to 757 601 participants.

MEASUREMENTS

Genetic variants predictive of the POU and their corresponding summary-level information in the outcomes were retrieved and extracted from the respective GWAS.

FINDINGS

Using univariable MR, we found evidence for a causal effect of genetic liability for POU on an increased risk of CHD [odds ratio (OR) = 1.09; 95% confidence interval (CI) = 1.02-1.16; P = 0.008] and MI (OR = 1.13; 95% CI = 1.04-1.22; P = 0.002). In multivariable MR, the association remained after accounting for comorbid pain conditions, but was attenuated with adjustment for potential mediators, including body mass index (BMI), waist circumference (WC) and type 2 diabetes (T2D).

CONCLUSION

Mendelian randomization estimates provide robust evidence for the causal effects of genetic liability for prescription opioid use on an increased risk of coronary heart disease and myocardial infarction, which might be mediated by obesity-related traits.

Codeine exerts cardiorenal injury via upregulation of adenine deaminase/xanthine oxidase and caspase 3 signaling

AIMS

Codeine treatment has been shown to be associated with glucolipid deregulation, though data reporting this are inconsistent and the mechanisms are not well understood. Perturbation of glutathione-dependent antioxidant defense and adenosine deaminase (ADA)/xanthine oxidase (XO) signaling has been implicated in the pathogenesis of cardiometabolic disorders. We thus, hypothesized that depletion of glutathione contents and upregulation of ADA/XO are involved in codeine-induced glucolipid deregulation. The present study also investigated whether or not codeine administration would induce genotoxicity and apoptosis in cardiac and renal tissues.

MATERIALS AND METHODS

Male New Zealand rabbits received per os distilled water or codeine, either in low dose (4 mg/kg) or high dose (10 mg/kg) for 6 weeks.

KEY FINDINGS

Codeine treatment led to reduced absolute and relative cardiac and renal mass independent of body weight change, increased blood glucose, total cholesterol (TC), triglycerides (TG), and low-density lipoprotein (LDL-C), as well as increased atherogenic indices and triglyceride-glucose index (TyG). Codeine administration significantly increased markers of cardiac and renal injury, as well as impaired cardiorenal functions. Codeine treatment also resulted in increased cardiac and renal malondialdehyde, Advanced Glycation Endproducts (AGE) and 8-hydroxydeoxyguanosine (8-OH-dG), and myeloperoxidase (MPO), ADA, XO, and caspase 3 activities. These observations were accompanied by impaired activities of cardiac and renal proton pumps.

SIGNIFICANCE

Findings of this study demonstrate that upregulation of ADA/XO and caspase 3 signaling are, at least partly, contributory to the glucolipid deregulation and cardiorenal injury induced by codeine.

The effect of methadone on blood glucose, lipids and glucose-modulating hormones in methadone-dependent Wistar rats

A growing body of evidence indicates that opioids regulate mechanisms activated during the stress response. This study was aimed to investigate the effect of methadone dependency on blood glucose, lipids and glucose-modulating hormones in male and female Wistar rats.This study was performed on 40 Wistar rats weighing 150-350 g, in four methadone exposure and control groups of both males and females. All rats were weighed at the beginning and end of the study and their fasting blood glucose was measured using a glucometer. In order to induce addiction, methadone was injected intraperitoneal for 10 consecutive days at 5 mg/kg dose. The control group received the same volume of only normal saline. At the end of the study, the rats were sacrificed and their blood serum collected to measure cortisol, glucagon, adrenaline and lipid profile levels.There was a significant decrease in the mean final blood glucose of methadone-treated versus control male rats (p = 0.02). There was no significant glucose difference, however, in female rats. Furthermore, a decrease in the mean serum levels of triglyceride, cortisol, and adrenaline occurred in male rats of methadone-dependent compared with control animals, but there was no significant difference in these values in female rats. Our results showed that methadone significantly reduced serum glucose as well as triglyceride levels only in male rats, this being associated with a reduction in the level of counter-regulating hormones of carbohydrate metabolism. Changes in lipid profiles, however, occurred independently of gender.

Metabolic and Addiction Indices in Patients on Opioid Agonist Medication-Assisted Treatment: A Comparison of Buprenorphine and Methadone

Metabolic hormones stabilize brain reward and motivational circuits, whereas excessive opioid consumption counteracts this effect and may impair metabolic function. Here we addressed the role of metabolic processes in the course of the agonist medication-assisted treatment for opioid use disorder (OUD) with buprenorphine or methadone. Plasma lipids, hemoglobin A1C, body composition, the oral glucose tolerance test (oGTT) and the Sweet Taste Test (STT) were measured in buprenorphine- (n = 26) or methadone (n = 32)- treated subjects with OUD. On the whole, the subjects in both groups were overweight or obese and insulin resistant; they displayed similar oGTT and STT performance. As compared to methadone-treated subjects, those on buprenorphine had significantly lower rates of metabolic syndrome (MetS) along with better values of the high-density lipoproteins (HDL). Subjects with- vs. without MetS tended to have greater addiction severity. Correlative analyses revealed that more buprenorphine exposure duration was associated with better HDL and opioid craving values. In contrast, more methadone exposure duration was associated with worse triglycerides-, HDL-, blood pressure-, fasting glucose- and hemoglobin A1C values. Buprenorphine appears to produce beneficial HDL- and craving effects and, contrary to methadone, its role in the metabolic derangements is not obvious. Our data call for further research aimed at understanding the distinctive features of buprenorphine metabolic effects vis-à-vis those of methadone and their potential role in these drugs' unique therapeutic profiles.

The effects of melatonin supplementation on mental health, metabolic and genetic profiles in patients under methadone maintenance treatment

This investigation was designed to determine the effect of melatonin supplementation on mental health parameters, metabolic and genetic profiles in patients under methadone maintenance treatment (MMT). This randomized, double-blind, placebo-controlled, clinical trial was conducted among 54 patients under MMT. Participants were randomly allocated to receive either 10 mg melatonin (2 melatonin capsules, 5 mg each) (n = 26) or placebo (n = 28) once a day, 1 hour before bedtime for 12 weeks. Melatonin supplementation significantly decreased Pittsburgh Sleep Quality Index (β -4.08; 95 percent CI, -5.51, -2.65; P < 0.001), Beck Depression Inventory index (β -5.46; 95% CI, -8.92, -2.00; P = 0.003) and Beck Anxiety Inventory index (β -3.87; 95% CI, -5.96, -1.77; P = 0.001) and significantly increased International Index of Erectile Functions (β 5.59; 95% CI, 1.76, 9.42; P = 0.005) compared with the placebo. Subjects who received melatonin supplements had significantly lower serum insulin levels (β -2.53; 95% CI, -4.48, -0.59; P = 0.01), homeostasis model of assessment-insulin resistance (β -0.56; 95% CI, -1.03, -0.09; P = 0.01) and higher quantitative insulin sensitivity check index (β 0.01; 95% CI, 0.004, 0.02; P = 0.009) and HDL-cholesterol levels (β 3.71; 95% CI, 1.77, 5.64; P = 0.002) compared to placebo. Additionally, melatonin intake resulted in a significant reduction in serum high sensitivity C-reactive protein (β -0.15; 95% CI, -0.27, -0.02; P = 0.02), malondialdehyde (β -0.31; 95% CI, -0.57, -0.05; P = 0.02) and protein carbonyl (β -0.06; 95% CI, -0.09, -0.04; P < 0.001). This trial indicated that taking melatonin supplements for 12 weeks by patients under MMT had beneficial effects on their mental health metabolic profiles.

Clinical trial of the effects of vitamin D supplementation on psychological symptoms and metabolic profiles in maintenance methadone treatment patients

BACKGROUND

Vitamin D deficiency may be associated with some complications including nonspecific musculoskeletal pain and periodontal disease in maintenance methadone treatment (MMT) patients. This study was designed to determine the effect of vitamin D supplementation on psychological symptoms and metabolic profiles in MMT patients.

METHODS

This randomized, double-blind, placebo-controlled, clinical trial was carried out among 68 MMT patients. Participants were randomly allocated to receive either 50,000IU vitamin D supplements (n=34) or placebo (n=34) every 2weeks for 12weeks. Fasting blood samples were taken at baseline and post-intervention to evaluate relevant variables.

RESULTS

After the 12-week intervention, serum 25(OH) vitamin D levels significantly increased in the intervention group compared with the placebo group (+8.1±4.9 vs. -0.4±3.0, P<0.001). In addition, vitamin D supplementation significantly improved Pittsburgh Sleep Quality Index (-1.5±2.2 vs. -0.2±2.3, P=0.02) and Beck Depression Inventory (-4.8±7.3 vs. -1.5±6.1, P=0.04) compared with the placebo. Patients who received vitamin D supplements had significantly decreased fasting plasma glucose (-7.5±10.6 vs. +0.3±10.7mg/dL, P=0.004), serum insulin levels (-3.6±5.3 vs. -0.9±3.5 μIU/mL, P=0.01), homeostasis model of assessment-insulin resistance (-1.0±1.3 vs. -0.2±0.7, P=0.003), serum triglycerides (-9.6±30.8 vs. +15.6±30.2mg/dL, P=0.001), total- (-8.7±20.9 vs. +11.0±27.4mg/dL, P=0.001) and LDL-cholesterol (-11.1±17.9 vs. +5.9±27.5mg/dL, P=0.004) compared with the placebo. Additionally, vitamin D intake resulted in a significant decrease in serum high sensitivity C-reactive protein (-2.2±4.2 vs. +2.0±3.7mg/L, P<0.001), and significant increases plasma total antioxidant capacity (+26.2±99.8 vs. -86.3±127.5mmol/L, P<0.001) and glutathione levels (+292.3±172.4 vs. +48.9±208.9μmol/L, P<0.001) compared with the placebo. There was no significant effect of vitamin D supplementation on serum HDL-cholesterol, and other markers of insulin metabolism, inflammation and oxidative stress.

CONCLUSIONS

Totally, taking 50,000IU vitamin D supplement every 2weeks for 12weeks in MMT patients had beneficial effects on psychological symptoms and few metabolic profiles.

Beneficiary effect of Commiphora mukul ethanolic extract against high fructose diet induced abnormalities in carbohydrate and lipid metabolism in wistar rats

The present study was proposed to elucidate the effect of Commiphora mukul gum resin elthanolic extract treatment on alterations in carbohydrate and lipid metabolisms in rats fed with high-fructose diet. Male Wistar rats were divided into four groups: two of these groups (group C and C+CM) were fed with standard pellet diet and the other two groups (group F and F+CM) were fed with high fructose (66 %) diet. C. mukul suspension in 5% Tween-80 in distilled water (200 mg/kg body weight/day) was administered orally to group C+CM and group F+CM. At the end of 60-day experimental period, biochemical parameters related to carbohydrate and lipid metabolisms were assayed. C. mukul treatment completely prevented the fructose-induced increased body weight, hyperglycemia, and hypertriglyceridemia. Hyperinsulinemia and insulin resistance observed in group F decreased significantly with C. mukul treatment in group F+CM. The alterations observed in the activities of enzymes of carbohydrate and lipid metabolisms and contents of hepatic tissue lipids in group F rats were significantly restored to near normal values by C. mukul treatment in group F+CM. In conclusion, our study demonstrated that C. mukul treatment is effective in preventing fructose-induced insulin resistance and hypertriglyceridemia while attenuating the fructose induced alterations in carbohydrate and lipid metabolisms by the extract which was further supported by histopathological results from liver samples which showed regeneration of the hepatocytes. This study suggests that the plant can be used as an adjuvant for the prevention and/or management of insulin resistance and disorders related to it.

Substance Use Disorders among Patients with Type 2 Diabetes: a Dangerous but Understudied Combination

PURPOSE OF REVIEW

This paper reviews research on substance use and disorders (SUDs) among adults with diabetes. It describes epidemiological data on SUDs in persons with type 2 diabetes, overviews effects of substance use on diabetes outcomes, and discusses treatments for SUDs in patients with diabetes.

RECENT FINDINGS

Rates of current smoking range from 10 to 26% and alcohol use disorders are 0-5%. Rates of illicit SUDs are 3-4%, but there are no population-based studies using nationally representative samples. Smoking increases the risk for long-term diabetes complications and premature death. Alcohol and illicit drug use can also impact long-term diabetes complications by impairing glucose homeostasis and adversely influencing self-management behaviors. There is mixed evidence about psychosocial smoking cessation interventions in adults with diabetes and little on alcohol and illicit SUD interventions. Limited data exist on pharmacotherapies for SUDs in this population, but a recent study suggests that varenicline is safe and effective for treating smoking in patients with diabetes. Substance use is an understudied problem in type 2 diabetes, and addressing substance use holds potential for improving outcomes. Additional large population-based epidemiological studies in those with type 2 diabetes are needed, particularly for alcohol and illicit SUDs. Longitudinal studies should be conducted to better understand the time course of diabetes onset and outcomes in relation to SUDs. Randomized controlled trials are needed to assess safety and efficacy of promising psychosocial and pharmacological interventions.

The Impact of Opium Consumption on Blood Glucose, Serum Lipids and Blood Pressure, and Related Mechanisms

Aim: Substance abuse has become a universal crisis in our modern age. Among illegal substances, opium and its derivatives have been ranked second in terms of usage after cannabis in the world. In many Asian regions, the use of opium enjoys a high social acceptance; hence, some common people and even medical practitioners believe that opium lowers blood glucose and pressure and treat dyslipidemia. How much this belief is scientifically justified?

Method: The results of available studies on both humans and animals searched in different search engines up to mid-2016 were integrated (78 articles). Upon the findings we try to offer a more transparent picture of the effects of opium on the mentioned factors along with the probable underlying mechanisms of its action.

Results: Taken together, a variety of evidences suggest that the consumption of opium has no scientific justification for amendment of these biochemical variables. The mechanisms proposed so far for the action of opium in the three above disorders are summarized at the end of the article. Short term effects seems to be mostly mediated through central nervous system (neural and hormonal mechanisms), but long term effects are often due to the structural and functional alterations in some body organs.

Conclusion: Although opium may temporarily reduce blood pressure, but it increases blood glucose and most of blood lipids. Moreover its long term use has negative impacts and thus it aggravates diabetes, dyslipidemia and hypertension. Accordingly, it is necessary to inform societies about the potential disadvantages of unauthorized opium consumption.

Effect of the co-administration of glucose with morphine on glucoregulatory hormones and causing of diabetes mellitus in rats

BACKGROUND

Morphine is related to dysregulation of serum hormone levels. In addition, addict subjects interest to sugar intake. Therefore, this study investigated the effect of co-administration of glucose with Mo on the glucoregulatory hormones and causing of diabetes mellitus in rats.

MATERIALS AND METHODS

Male rats were randomly divided into four groups including, control, morphine, Morphine-Glucose and diabetes groups. Morphine was undergone through doses of 10, 20, 30, 40, 50, and 60 mg/kg, respectively on days 1, 2, 3, 4, 5, and 6. Then, dose of 60 mg/kg was used repeated for 20 extra days. The Morphine-Glucose group received the same doses of morphine plus 1 g/kg glucose per day. Diabetes was induced by intraperitoneal injection of 65 mg/kg streptozotocin. At the end of experiment, the serum insulin, glucagon, growth hormone (GH), cortisol, and glucose levels were measured. The homeostasis model assessment (HOMA) indexes concluding the HOMA-insulin resistance (HOMA-IR) and HOMA-β were evaluated.

RESULTS

Morphine insignificantly induced a hyperglycemia condition and insulin resistance. Whereas, the beta-cell functions significantly (P < 0.05) decreased only in morphine group. The co-administration of glucose slightly increased the GH, and increased insulin and cortisol levels significantly (P < 0.05 and P < 0.01; respectively) in the Morphine-Glucose group. Furthermore, the co-administration of glucose with morphine could nearly modulate the morphine effects on body weight, glucose, and glucagon levels.

CONCLUSION

It is probable that the co-administration of glucose with morphine modulate the serum glucose levels by stimulating the beta-cell functions and to increase insulin secretion.

The effect of naltrexone on body fat mass in olanzapine-treated schizophrenic or schizoaffective patients: a randomized double-blind placebo-controlled pilot study

Olanzapine (OLZ), a commonly prescribed second generation antipsychotic drug, is associated with obesity and metabolic syndrome and may contribute to increased cardiovascular morbidity and mortality. Opioidergic neurotransmission may be implicated in the development of these metabolic disturbances. The objective of this study was to assess the effects of opioid blockade on OLZ-treated patients' metabolic status. Patients with schizophrenia or schizoaffective disorder (n=30) on a stable dose of OLZ were randomized in a double-blind fashion to receive an opioid receptor antagonist, naltrexone (NTX), (n=14) or placebo (n=16). The primary outcome measure was the change in body mass index (BMI) at 12 weeks. Secondary measures included body fat and fat-free mass, along with homeostasis model assessment-estimated insulin resistance (HOMA-IR), plasma lipids and liver function tests (LFTs). There was no significant change in BMI between the treatment arms. However, in comparison to the OLZ + placebo combination, the OLZ + NTX group displayed a significant decrease in the fat and increase in fat-free mass along with a trend towards improvement in HOMA-IR values. There were no significant differences in plasma lipids and LFTs. These findings suggest that addition of NTX to OLZ may attenuate OLZ-induced body fat mass gain. A larger study of longer duration will be needed to confirm these results.

Methadone-induced hypoglycemia

To determine if recent observations of hypoglycemia in patients receiving high-dose methadone extended to an animal model, we explored the effects of methadone and other mu-opioids on blood glucose levels in mice. Methadone lowered blood glucose in a dose-dependent manner with 20 mg/kg yielding a nadir in average glucose levels to 55 ± 6 mg/dL from a baseline of 172 ± 7 mg/dL, an effect that was antagonized by naloxone and mu selective antagonists β-funaltrexamine and naloxonazine. The effect was stereoselective and limited to only the l-isomer, while the d-isomer was ineffective. Despite the robust decrease in blood glucose produced by methadone, a series of other mu-opioids, including morphine, fentanyl, levorphanol, oxycodone or morphine-6β-glucuronide failed to lower blood glucose levels. Similar differences among mu-opioid agonists have been observed in other systems, suggesting the possible role of selected splice variants of the mu-opioid receptor gene Oprm1. This mouse model recapitulates our clinical observations and emphasizes the need to carefully monitor glucose levels when using high methadone doses, particularly intravenously, and the need for controlled clinical trials.

Metabolic plasticity and the energy economizing effect of ibogaine, the principal alkaloid of Tabernanthe iboga

ETHNOPHARMACOLOGICAL RELEVANCE

The root bark of iboga plant-Tabernanthe iboga has been used traditionally in Central Africa as a psychoactive substance in religious rituals, while in smaller doses it is appreciated due to its stimulant properties. The iboga root bark, iboga extract or pure ibogaine are being recognized in the West as an anti-addiction remedy and their use is increasing.

AIM OF THE STUDY

Our previous studies have demonstrated a transient ATP pool reduction under ibogaine accompanied by the induction of energy metabolism related enzymes. The present study aimed to find the cause of this energy deprivation and to foresee its immediate and long-term impact on metabolism. The overall project is designed to disclose the common mechanism of action at these seemingly diverse indications for iboga use, to predict eventual adverse effects and to build the grounds for its safe and beneficial utilization.

MATERIALS AND METHODS

The rate of carbon dioxide (CO(2)) as a marker of energy metabolism in stationary yeast model under aerobic conditions in the presence of ibogaine at concentration of 1, 4 and 20mg/l was measured for 5h by gas chromatography. The overall oxidative load was determined fluorimetrically by 2',7'-dichlorofluorescein diacetate (H(2)DCFDA) and in vitro antioxidant properties of ibogaine were defined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) test.

RESULTS

The CO(2) production under ibogaine was temporarily increased in a dose dependent manner. The increased energy consumption as an early effect of ibogaine was proven by the fact that in spite of energy mobilization, the ATP pool has been simultaneously decreased. Although increased cellular respiration co-produces reactive oxygen species (ROS), the overall oxidative load was significantly lowered by ibogaine. Since ibogaine does not show any significant in vitro antioxidant properties, the results indicate its stimulating influence on physiological oxidative stress defence system.

CONCLUSION

Ibogaine triggers remodeling of the housekeeping metabolism. Under the initial energy cost it results in increased efficacy of physiological antioxidative systems, which reduce oxidative damage and lowers basal metabolic needs. Together with induced catabolic enzymes they set a new metabolic equilibrium that saves energy and makes it easily available in case of extra needs. While healthy organism profits from improved fitness and mental performance and can withstand higher stress without risking a disease, due to the same principle ibogaine provides beneficial support at the recovery after diseases including addiction syndrome.

Depot naltrexone decreases rewarding properties of sugar in patients with opioid dependence

BACKGROUND

Opioid neurotransmission mediates hedonic value of sweet tastants; their intake may be exaggerated by the consumption of exogenous opioids (e.g., opioid dependence). Sweet Taste Test (STT) is a validated quantitative instrument assessing taste perception and hedonic features of sugar (sucrose) using a randomized and double-blind administration at five different sucrose concentrations ranging from 0.05 to 0.83 M.

METHODS

The STT and cue-induced craving procedure were administered to opioid-dependent patients (n = 15) before and 1 week after the injection of a long-acting depot naltrexone (XRNT) preparation.

RESULTS

Analyses of covariance, employing sucrose concentration and its perceived taste as covariates, showed that XRNT therapy significantly reduced the self-reported hedonic and motivational characteristics of sucrose. Greater reductions in both these characteristics were associated with more diminution in the cue-induced opioid craving.

CONCLUSIONS

Opioid antagonism in opioid-dependent subjects leads to a smaller sweet taste reward, which, in turn, may be proportional to decreased opioid craving. These pilot results support the heuristic value of the STT as a potential marker of the XRNT treatment response and call for further inquiry into potential clinical applications of the test.

Opioid-induced biochemical alterations of the neuroendocrine axis

Exogenous opioids have been used for decades to palliate cancer-related pain and other cancer-related manifestations and, more recently, to treat patients with pain not related to oncologic disease. While the goal of opioid treatment is symptomatic relief and improved quality of life, these patients often suffer from adverse side effects, including endocrine system abnormalities, of which hypogonadism is the best known. Opioids may interact with other hypothalamic-pituitary pathways and endocrine end organs, and in most cases these interactions are subtle and the effects unclear. The long-term effects of these agents on the endocrine system are still largely unknown. This article discusses the various effects of opioid agents on the endocrine system and provides information that allows early recognition of side effects that may alter the quality of life of patients affected by pain, awareness of the potential complications in opioid addicts, and detection and treatment of side effects in participants of an opioid detoxification program.

The relationship between opioid and sugar intake: review of evidence and clinical applications

Opioid dependence poses significant public health risks arising from associated morbidity and mortality caused by accidents, infectious diseases, and social ramifications of crime and unemployment, among other complications. Opioid use, acute and chronic, is also associated with weight gain, glycemic dysregulation, and dental pathology. The literature supporting the connection between opiate use and development of preference for sweet tastes is reviewed, and further association with dental pathology, weight gain, and loss of glycemic control are considered. Additionally, the impact of sweet tastes on the endogenous opioid system, as pertaining to analgesia, is also discussed. The authors discuss the clinical implications in relation to the aforementioned conditions while treating the opiate-dependent patient.

The effects of opiate use and hepatitis C virus infection on risk of diabetes mellitus in the Women's Interagency HIV Study

BACKGROUND

Opiate use is common in HIV-infected and hepatitis C virus (HCV)-infected individuals, however, its contribution to the risk of diabetes mellitus is not well understood.

METHODS

Prospective study of 1713 HIV-infected and 652 HIV-uninfected participants from the Women's Interagency HIV Study between October 2000 and March 2006. Diabetes defined as fasting glucose > or =126 mg/dL, self report of diabetes medication use, or confirmed diabetes diagnosis. Opiate use determined using an interviewer-administered questionnaire. Detectable plasma HCV RNA confirmed HCV infection.

RESULTS

Current opiate users had a higher prevalence of diabetes (15%) than nonusers (10%, P = 0.03), and a higher risk of incident diabetes (adjusted relative hazard: 1.58, 95% confidence interval: 1.01 to 2.46), after controlling for HCV infection, HIV/antiretroviral therapy status, and diabetes risk factors including age, race/ethnicity, family history of diabetes, and body mass index. HCV infection was also an independent risk factor for diabetes (adjusted relative hazard: 1.61, 95% confidence interval: 1.02 to 2.52). HCV-infected women reporting current opiate use had the highest diabetes incidence (4.83 cases per 100 person-years).

CONCLUSIONS

Among women with or at-risk for HIV, opiate use is associated with increased diabetes risk independently of HCV infection. Diabetic screening should be part of care for opiate users and those infected with HCV.

Antihyperglycemic activity of Catharanthus roseus leaf powder in streptozotocin-induced diabetic rats

Catharanthus roseus Linn (Apocynaceae), is a traditional medicinal plant used to control diabetes, in various regions of the world. In this study we evaluated the possible antidiabetic and hypolipidemic effect of C. roseus (Catharanthus roseus) leaf powder in diabetic rats. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ, 55 mg/kg body wt) to male Wistar rats. The animals were divided into four groups: Control, control-treated, diabetic, and diabetic-treated group. Diabetic-treated and control-treated rats were treated with C. roseus leaf powder suspension in 2 ml distilled water, orally (100 mg/kg body weight/day/60 days). In diabetic rats (D-group) the plasma glucose was increased and the plasma insulin was decreased gradually. In the diabetic-treated group lowering of plasma glucose and an increase in plasma insulin were observed after 15 days and by the end of the experimental period the plasma glucose had almost reached the normal level, but insulin had not. The significant enhancement in plasma total cholesterol, triglycerides, LDL and VLDL-cholesterol, and the atherogenic index of diabetic rats were normalized in diabetic-treated rats. Decreased hepatic and muscle glycogen content and alterations in the activities of enzymes of glucose metabolism (glycogen phosphorylase, hexokinase, phosphofructokinase, pyruvate kinase, and glucose-6-phosphate dehydrogenase), as observed in the diabetic control rats, were prevented with C. roseus administration. Our results demonstrated that C. roseus with its antidiabetic and hypolipidemic properties could be a potential herbal medicine in treating diabetes.

The effects of opioids and opioid analogs on animal and human endocrine systems

Opioid abuse has increased in the last decade, primarily as a result of increased access to prescription opioids. Physicians are also increasingly administering opioid analgesics for noncancer chronic pain. Thus, knowledge of the long-term consequences of opioid use/abuse has important implications for fully evaluating the clinical usefulness of opioid medications. Many studies have examined the effect of opioids on the endocrine system; however, a systematic review of the endocrine actions of opioids in both humans and animals has, to our knowledge, not been published since 1984. Thus, we reviewed the literature on the effect of opioids on the endocrine system. We included both acute and chronic effects of opioids, with the majority of the studies done on the acute effects although chronic effects are more physiologically relevant. In humans and laboratory animals, opioids generally increase GH and prolactin and decrease LH, testosterone, estradiol, and oxytocin. In humans, opioids increase TSH, whereas in rodents, TSH is decreased. In both rodents and humans, the reports of effects of opioids on arginine vasopressin and ACTH are conflicting. Opioids act preferentially at different receptor sites leading to stimulatory or inhibitory effects on hormone release. Increasing opioid abuse primarily leads to hypogonadism but may also affect the secretion of other pituitary hormones. The potential consequences of hypogonadism include decreased libido and erectile dysfunction in men, oligomenorrhea or amenorrhea in women, and bone loss or infertility in both sexes. Opioids may increase or decrease food intake, depending on the type of opioid and the duration of action. Additionally, opioids may act through the sympathetic nervous system to cause hyperglycemia and impaired insulin secretion. In this review, recent information regarding endocrine disorders among opioid abusers is presented.

Induction of energy metabolism related enzymes in yeast Saccharomyces cerevisiae exposed to ibogaine is adaptation to acute decrease in ATP energy pool

Ibogaine has been extensively studied in the last decades in relation to its anti-addictive properties that have been repeatedly reported as being addiction interruptive and craving eliminative. In our previous study we have already demonstrated induction of energy related enzymes in rat brains treated with ibogaine at a dose of 20mg/kg i.p. 24 and 72 h prior to proteomic analysis. In this study a model organism yeast Saccharomyces cerevisiae was cultivated with ibogaine in a concentration of 1mg/l. Energy metabolism cluster enzymes glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, enolase and alcohol dehydrogenase were induced after 5h of exposure. This is a compensation of demonstrated ATP pool decrease after ibogaine. Yeast in a stationary growth phase is an accepted model for studies of housekeeping metabolism of eukaryotes, including humans. Study showed that ibogaine's influence on metabolism is neither species nor tissue specific. Effect is not mediated by binding of ibogaine to receptors, as previously described in literature since they are lacking in this model.

Proteomic analysis of striatal neuronal cell cultures after morphine administration

Using primary neuronal cell culture assays, combined with 2-D gel electrophoresis and capillary LC-MS, we identified differences in proteomes between control and morphine-treated cells. Statistically significant differences were observed among 26 proteins. Nineteen of them were up-regulated, while seven were down-regulated in morphine-treated cell populations. The identified proteins belong to classes involved in energy metabolism, associated with oxidative stress, linked with protein biosynthesis, cytoskeletal ones, and chaperones. The detected proteins demand further detailed studies of their biological roles in morphine addiction. It is crucial to confirm observed processes in vivo in order to reveal the nature and importance of the biological effect of proteome changes after morphine administration. Further investigations may lead to the discovery of new proteome-based effects of morphine on living organisms.

Expression changes of hippocampal energy metabolism enzymes contribute to behavioural abnormalities during chronic morphine treatment

Dependence and impairment of learning and memory are two well-established features caused by abused drugs such as opioids. The hippocampus is an important region associated with both drug dependence and learning and memory. However, the molecular events in hippocampus following exposure to abused drugs such as opioids are not well understood. Here we examined the effect of chronic morphine treatment on hippocampal protein expression by proteomic analyses. We found that chronic exposure of mice to morphine for 10 days produced robust morphine withdrawal jumping and memory impairment, and also resulted in a significant downregulation of hippocampal protein levels of three metabolic enzymes, including Fe-S protein 1 of NADH dehydrogenase, dihydrolipoamide acetyltransferase or E2 component of the pyruvate dehydrogenase complex and lactate dehydrogenase 2. Further real-time quantitative PCR analyses confirmed that the levels of the corresponding mRNAs were also remarkably reduced. Consistent with these findings, lower ATP levels and an impaired ability to convert glucose into ATP were also observed in the hippocampus of chronically treated mice. Opioid antagonist naltrexone administrated concomitantly with morphine significantly suppressed morphine withdrawal jumping and reversed the downregulation of these proteins. Acute exposure to morphine also produced robust morphine withdrawal jumping and significant memory impairment, but failed to decrease the expression of these three proteins. Intrahippocampal injection of D-glucose before morphine administration significantly enhanced ATP levels and suppressed morphine withdrawal jumping and memory impairment in acute morphine-treated but not in chronic morphine-treated mice. Intraperitoneal injection of high dose of D-glucose shows a similar effect on morphine-induced withdrawal jumping as the central treatment. Taken together, our results suggest that reduced expression of the three metabolic enzymes in the hippocampus as a result of chronic morphine treatment contributes to the development of drug-induced symptoms such as morphine withdrawal jumping and memory impairment.

Disorders of glucose metabolism among HIV-infected women

BACKGROUND

Abnormal glucose metabolism in HIV-infected patients has largely been attributed to the use of protease inhibitors. However, most studies of glucose metabolism in HIV-infected patients have focused on men or have lacked appropriate control groups.

METHODS

We assessed the factors associated with previously diagnosed diabetes among 620 middle-aged women with or at risk for HIV infection. For a subset of 221 women without previously diagnosed diabetes, we performed an oral glucose tolerance test (OGTT) to measure glucose and insulin levels, and we assessed factors associated with abnormal glucose tolerance, insulin resistance, and insulin secretion.

RESULTS

Thirteen percent of the women in the present study had previously diagnosed diabetes. Among women without previously diagnosed diabetes who underwent an OGTT, 6% had previously undiagnosed diabetes, and 12% had impaired glucose tolerance (IGT). According to multivariate analysis, factors that were associated with previously diagnosed diabetes included current methadone treatment, body mass index of > or =25, family history of diabetes, and physical inactivity. Factors that were independently associated with an abnormal result of an OGTT (i.e., a result consistent with IGT or diabetes) included age > or =50 years, family history of diabetes, physical inactivity, and a high number of pack-years of smoking. Factors independently associated with insulin resistance included waist circumference, Hispanic ethnicity, physical inactivity, and, among HIV-infected women, use of HAART that did not include protease inhibitors. Factors associated with lower levels of insulin secretion included current opiate use (i.e., methadone or heroin) and older age.

CONCLUSIONS

Abnormal glucose metabolism is highly prevalent among middle-aged women with or at risk for HIV infection, particularly women who use opiates. Screening for diabetes in the HIV primary care setting should occur for women who have classic risk factors for diabetes, rather than solely for women who are taking PIs. Interventions that target modifiable risk factors, including obesity and physical inactivity, are also warranted.

Proteomic analysis of phosphotyrosyl proteins in morphine-dependent rat brains

Morphine has been used as a potent analgesic, having a high propensity to induce tolerance and physical dependence following their repeated administration. Although the mechanisms that underlie the development of dependence on morphine remain unclear, previous studies suggested that phosphorylations of diverse types of cellular proteins are crucial determinants of the neuroadaptive mechanisms associated with morphine dependence. Thus, understanding global phosphorylation events induced by chronic morphine administration is essential for understanding the complex signaling mechanisms of morphine dependence. This study characterized the alteration of tyrosine phosphorylation of frontal cortical proteins in morphine-dependent rat brains using a proteomic approach. Dependence was produced by continuous intracerebroventricular (i.c.v.) infusion of morphine (26 nmol/microl/h) for 72 h via osmotic minipumps in rats. Phosphotyrosyl (p-Tyr) protein spots in brain frontal cortical regions were detected by two-dimensional electrophoresis (2-DE) and immunoblotting with anti-p-Tyr-specific antibodies. The protein spots showing significant changes in tyrosine phosphorylation were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Similar patterns of protein expression were detected by 2-DE gels in morphine-dependent and saline-treated control rat brains. However, phosphotyrosine 2-DE images of the frontal cortical proteins from saline-treated control and morphine-dependent rat brains were apparently different. The densities of most matched p-Tyr protein spots were increased in morphine-dependent rat brains compared with that of control samples. Additional p-Tyr protein spots were detected in 2-DE image of morphine-dependent rat brains. Fifty of p-Tyr protein spots, corresponding to 40 different proteins, were identified from 2-DE gels of morphine-dependent rat brains. The identified proteins include enzymes, cytoskeletal proteins, cell signaling molecules, and other proteins. In conclusion, the first available phosphotyrosine proteomic resources of morphine dependence were established using an animal model. The findings illustrate the potential of proteomics as an effective technique for studying phosphorylation events of morphine dependence in brains.

Morphine induces desensitization of insulin receptor signaling

Morphine analgesia is mediated principally by the micro -opioid receptor (MOR). Since morphine and other opiates have been shown to influence glucose homeostasis, we investigated the hypothesis of direct cross talk between the MOR and the insulin receptor (IR) signaling cascades. We show that prolonged morphine exposure of cell lines expressing endogenous or transfected MOR, IR, and the insulin substrate 1 (IRS-1) protein specifically desensitizes IR signaling to Akt and ERK cascades. Morphine caused serine phosphorylation of the IR and impaired the formation of the signaling complex among the IR, Shc, and Grb2. Morphine also resulted in IRS-1 phosphorylation at serine 612 and reduced tyrosine phosphorylation at the YMXM p85-binding motifs, weakening the association of the IRS-1/p85 phosphatidylinositol 3-kinase complex. However, the IRS-1/Grb2 complex was unaffected by chronic morphine treatment. These results suggest that morphine attenuates IR signaling to Akt by disrupting the IRS-1-p85 interaction but inhibits signaling to ERK by disruption of the complex among the IR, Shc, and Grb2. Finally, we show that systemic morphine induced IRS-1 phosphorylation at Ser612 in the hypothalamus and hippocampus of wild type, but not MOR knockout, mice. Our results demonstrate that opiates can inhibit insulin signaling through direct cross talk between the downstream signaling pathways of the MOR and the IR.

Effect of chronic morphine administration on glucose tolerance and insulin binding to isolated rat adipocytes

Morphine addiction was induced in six male Wistar rats. Improved glucose tolerance (peak value less by 28%, p<0.01) was observed in chronically morphinized rats as compared to the control rats, injected with saline. An increase in the maximal specific binding of 125I-labeled insulin to unit membrane area of adipocytes was observed in the experimental group (p < 0.01). The changes in insulin receptor number could be responsible for the improved glucose tolerance observed during morphine addiction.