Plasma epinephrine predicts fasting glucose in centrally obese African-American women

Is the Brain a Key Player in Glucose Regulation and Development of Type 2 Diabetes?

Ever since Claude Bernards discovery in the mid 19th-century that a lesion in the floor of the third ventricle in dogs led to altered systemic glucose levels, a role of the CNS in whole-body glucose regulation has been acknowledged. However, this finding was later overshadowed by the isolation of pancreatic hormones in the 20th century. Since then, the understanding of glucose homeostasis and pathology has primarily evolved around peripheral mechanism. Due to scientific advances over these last few decades, however, increasing attention has been given to the possibility of the brain as a key player in glucose regulation and the pathogenesis of metabolic disorders such as type 2 diabetes. Studies of animals have enabled detailed neuroanatomical mapping of CNS structures involved in glucose regulation and key neuronal circuits and intracellular pathways have been identified. Furthermore, the development of neuroimaging techniques has provided methods to measure changes of activity in specific CNS regions upon diverse metabolic challenges in humans. In this narrative review, we discuss the available evidence on the topic. We conclude that there is much evidence in favor of active CNS involvement in glucose homeostasis but the relative importance of central vs. peripheral mechanisms remains to be elucidated. An increased understanding of this field may lead to new CNS-focusing pharmacologic strategies in the treatment of type 2 diabetes.

Optimism, pessimism, cynical hostility, and biomarkers of metabolic function in the Women's Health Initiative

BACKGROUND

Psychological attitudes reflecting expectations about the future (optimism, pessimism) and people (cynical hostility) independently predict incident cardiovascular disease and possibly diabetes, but underlying biologic pathways are incompletely understood. Herein we examined the cross-sectional relationship between optimism, pessimism, and cynicism and biomarkers of metabolic function in the Women's Health Initiative.

METHODS

Among 3443 postmenopausal women, biomarkers of metabolic function (fasting insulin [FINS] and glucose) were measured at baseline and used to calculate insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR]) and pancreatic β-cell activity (homeostasis model assessment of β-cell function [HOMA-B]). Psychological attitudes were assessed by the Life Orientation Test, Revised (full scale, and optimism and pessimism subscales) and the Cook-Medley cynicism subscale. Multivariable linear regression modeled the association of psychological attitudes with biomarker levels, adjusting for sociodemographics, health conditions, and health behaviors. Because obesity promotes insulin resistance and obese individuals tend to report higher levels of pessimism and cynical hostility, an interaction with body mass index (BMI) was explored.

RESULTS

In fully adjusted models, only pessimism remained independently associated with higher FINS and insulin resistance (HOMA-IR). Scoring 1 point higher on the pessimism subscale was associated with a 1.2% higher FINS, whereas scoring 1 SD higher was associated with a 2.7% higher FINS (P = 0.03); results were similar for HOMA-IR. An interaction term with BMI was not significant.

CONCLUSIONS

In multivariable models, higher dispositional pessimism was associated with worse metabolic function; these findings were not modified by obesity status. Results extend prior work by linking pessimism to an objective biomarker of insulin resistance in elderly women.

How fast monoamine oxidases decompose adrenaline? Kinetics of isoenzymes A and B evaluated by empirical valence bond simulation

This work scrutinizes kinetics of decomposition of adrenaline catalyzed by monoamine oxidase (MAO) A and B enzymes, a process controlling the levels of adrenaline in the central nervous system and other tissues. Experimental kinetic data for MAO A and B catalyzed decomposition of adrenaline are reported only in the form of the maximum reaction rate. Therefore, we estimated the experimental free energy barriers form the kinetic data of closely related systems using regression method, as was done in our previous study. By using multiscale simulation on the Empirical Valence Bond (EVB) level, we studied the chemical reactivity of the MAO A catalyzed decomposition of adrenaline and we obtained a value of activation free energy of 17.3 ± 0.4 kcal/mol. The corresponding value for MAO B is 15.7 ± 0.7 kcal/mol. Both values are in good agreement with the estimated experimental barriers of 16.6 and 16.0 kcal/mol for MAO A and MAO B, respectively. The fact that we reproduced the kinetic data and preferential catalytic effect of MAO B over MAO A gives additional support to the validity of the proposed hydride transfer mechanism. Furthermore, we demonstrate that adrenaline is preferably involved in the reaction in a neutral rather than in a protonated form due to considerably higher barriers computed for the protonated adrenaline substrate. The results are discussed in the context of chemical mechanism of MAO enzymes and possible applications of multiscale simulation to rationalize the effects of MAO activity on adrenaline level.

Obesity and the dysregulation of fatty acid metabolism: implications for healthy aging

The population of the world is aging. In 2010, an estimated 524 million people were aged 65 years or older representing eight percent of the global population. By 2050, this number is expected to nearly triple to approximately 1.5 billion, 16 percent of the world's population. Although people are living longer, the quality of their lives are often compromised due to ill-health. Areas covered: Of the conditions which compromise health as we age, obesity is at the forefront. Over half of the global older population were overweight or obese in 2010, significantly increasing the risk of a range of metabolic diseases. Although, it is well recognised excessive calorie intake is a fundamental driver of adipose tissue dysfunction, the relationship between obesity; intrinsic aging; and fat metabolism is less understood. In this review we discuss the intersection between obesity, aging and the factors which contribute to the dysregulation of whole-body fat metabolism. Expert commentary: Being obese disrupts an array of physiological systems and there is significant crosstalk among these. Moreover it is imperative to acknowledge the contribution intrinsic aging makes to the dysregulation of these systems and the onset of disease.

Depression Amplifies the Influence of Central Obesity on 10-Year Incidence of Diabetes: Findings from MIDUS

BACKGROUND

Central obesity is a major risk factor for diabetes but many obese individuals never develop diabetes, suggesting the presence of important effect modifiers. Depression has emerged as a key risk factor for poor glycemic control, but to our knowledge, no previous work has investigated whether depression amplifies the effect of central obesity on glucoregulation.

METHODS AND FINDINGS

We used a national sample of adults without prevalent diabetes (MIDUS; N = 919) to test for synergy between central obesity and depression in the development of diabetes 10 years later. We found that depression amplified the association of waist-to-hip ratio (WHR) with incident diabetes adjusted for age, race, gender, education, physical activity, and sleep problems (p = 0.01 for test of interaction). The relative risk for incident diabetes per every 0.1 increment in WHR was 1.75 (95% CI: 1.31; 2.33) in those without depression and 3.78 in those with depression (95% CI: 2.14; 6.66).

CONCLUSIONS

These results confirm the role of depression as a robust risk factor for the development of diabetes and for the first time, demonstrate a synergy between depression and central obesity. Identifying and addressing depression could prove to be an effective approach to preventing diabetes in at risk individuals. Ultimately, elucidating the interplay among risk factors from different domains will be key to understanding multifactorial diseases such as diabetes and informing theory-based, patient-centered interventions aimed at reducing diabetes risk.

Associations between central nervous system serotonin, fasting glucose, and hostility in African American females

BACKGROUND

Previous research has shown an association between hostility and fasting glucose in African American women. Central nervous system serotonin activity is implicated both in metabolic processes and in hostility related traits.

PURPOSE

The purpose of this study is to determine whether central nervous system serotonin influences the association between hostility and fasting glucose in African American women.

METHODS

The study consisted of 119 healthy volunteers (36 African American women, 27 White women, 21 White males, and 35 African American males, mean age 34 ± 8.5 years). Serotonin related compounds were measured in cerebrospinal fluid. Hostility was measured by the Cook-Medley Hostility Scale.

RESULTS

Hostility was associated with fasting glucose and central nervous system serotonin related compounds in African American women only. Controlling for the serotonin related compounds significantly reduced the association of hostility to glucose.

CONCLUSIONS

The positive correlation between hostility and fasting glucose in African American women can partly be explained by central nervous system serotonin function.

Anger, adiposity, and glucose control in nondiabetic adults: findings from MIDUS II

Anger has been linked to cardiovascular disease, but few studies have examined the relationship between anger and type 2 diabetes. The aim was to investigate associations among different indicators of anger expression, adiposity, and nondiabetic glucose metabolism in a national survey of adults. Participants were 939 adults without diabetes in the Midlife in the US study (MIDUS II). Glucose metabolism was characterized by fasting glucose, insulin, insulin resistance, and glycosylated hemoglobin (HbA1c). Spielberger's Anger Expression inventory was used to measure suppressed anger (anger-in), expressed anger (anger-out), and controlled anger (anger-control). We investigated the relationship between anger and glucose metabolism, and whether anger amplified the adverse relationship between body weight distribution (body mass index = BMI and waist-to-hip ratio = WHR) and glucose metabolism. Multivariate-adjusted analyses revealed an association between anger-out and both insulin and insulin resistance. As predicted, anger-in amplified the relationships between BMI and insulin and insulin resistance, while anger-out amplified the association between WHR and insulin and insulin resistance. Low anger-control was associated with higher glucose. None of the three anger measures was significantly associated with HbA1c. Our findings extend previous research on anger as a potential risk factor for type 2 diabetes by demonstrating that anger expression is associated with clinical indicators of glycemic control, especially among those with pre-existing risk due to obesity and high central adiposity.

Trait anxiety and glucose metabolism in people without diabetes: vulnerabilities among black women

AIMS

We examined whether the relationship between anxiety and indicators of glucose metabolism in people without diabetes varies by race and gender.

METHODS

Participants were 914 adults (777 white, 137 black) without diabetes in the MIDUS (Midlife in the USA) II study. Glucose metabolism was characterized by fasting glucose, insulin, HOMA-IR (homeostasis model of assessment--insulin resistance), and HbA(1c). Hierarchical linear regressions stratified by race and gender examined whether anxiety was associated with glucose metabolism.

RESULTS

After adjustment for potential confounders, positive relationships between anxiety and fasting glucose (P = 0.04), insulin (P = 0.01), and HOMA-IR (P = 0.02) but not HbA(1c), were observed in black women only.

CONCLUSIONS

Our findings extend previous evidence for the links between psychosocial vulnerabilities and impaired glucose metabolism in black women, by documenting significant associations between anxiety and clinical indicators of glycaemic control among black women without diabetes. Thus, anxiety might constitute an intervention target in black women, a subgroup disproportionately affected by Type 2 diabetes, its complications, and premature mortality.