Moderate alcohol consumption, glucose metabolism and lipolysis: the effect on adiponectin and tumor necrosis factor alpha

Glial abnormalities in substance use disorders and depression: does shared glutamatergic dysfunction contribute to comorbidity?

OBJECTIVES

Preclinical and clinical research in neuropsychiatric disorders, particularly mood and substance use disorders, have historically focused on neurons; however, glial cells-astrocytes, microglia, and oligodendrocytes - also play key roles in these disorders.

METHODS

Peer-reviewed PubMed/Medline articles published through December 2012 were identified using the following keyword combinations: glia, astrocytes, oligodendrocytes/glia, microglia, substance use, substance abuse, substance dependence, alcohol, opiate, opioid, cocaine, psychostimulants, stimulants, and glutamate.

RESULTS

Depressive and substance use disorders are highly comorbid, suggesting a common or overlapping aetiology and pathophysiology. Reduced astrocyte cell number occurs in both disorders. Altered glutamate neurotransmission and metabolism - specifically changes in the levels/activity of transporters, receptors, and synaptic proteins potentially related to synaptic physiology - appear to be salient features of both disorders. Glial cell pathology may also underlie the pathophysiology of both disorders via impaired astrocytic production of neurotrophic factors. Microglial/neuroinflammatory pathology is also evident in both depressive and substance use disorders. Finally, oligodendrocyte impairment decreases myelination and impairs expression of myelin-related genes in both substance use and depressive disorders.

CONCLUSIONS

Glial-mediated glutamatergic dysfunction is a common neuropathological pathway in both substance use and depression. Therefore, glutamatergic neuromodulation is a rational drug target in this comorbidity.

Lipid accumulation in overweight type 2 diabetic subjects: relationships with insulin sensitivity and adipokines

Adipokines are known to play a fundamental role in the etiology of obesity, that is, in the impaired balance between increased feeding and decreased energy expenditure. While the adipokine-induced changes of insulin resistance in obese diabetic and nondiabetic subjects are well known, the possible role of fat source in modulating insulin sensitivity (IS) remains controversial. The aim of our study was to explore in overweight type 2 diabetic patients (T2DM) with metabolic syndrome IS in different energy storage conditions (basal and dynamic) for relating it to leptin and adiponectin. Sixteen T2DM (5/11 F/M; 59 ± 2 years; 29.5 ± 1.1 kg/m(2)) and 16 control (CNT 5/11; 54 ± 2; 29.1 ± 1.0) underwent an oral glucose tolerance test. Fasting IS was measured by QUICKI, while the dynamic one with OGIS. The insulinogenic index (IGI) described beta cell function. Also, the lipid accumulation product parameter (LAP) was assessed. LAP accounts for visceral abdominal fat and triglycerides, and it is known to be related to IS. Possible interrelationships between LAP and adipokines were explored. In T2DM and CNT, adiponectin (7.4 ± 0.5 vs. 7.8 ± 0.9 μg/mL), leptin (13.3 ± 3.0 vs. 12.4 ± 2.6 ng/mL), and QUICKI (0.33 ± 0.01 vs. 0.33 ± 0.01) were not different (P > 0.40), at variance with OGIS (317 ± 11 vs. 406 ± 13 mL/min/m(2); P = 0.006) and IGI (0.029 ± 0.005 vs. 0.185 ± 0.029 × 10(3) pmolI/mmolG; P = 0.00001). LAP was 85 ± 15 cm × mg/dL in T2DM and 74 ± 10 in CNT (P > 0.1), correlated with OGIS in all subjects (R = -0.42, P = 0.02) and QUICKI (R = -0.56, P = 0.025) in T2DM. Leptin correlated with QUICKI (R = -0.45, P = 0.009), and adiponectin correlated with OGIS (R = 0.43, P = 0.015). In overweight T2DM, insulin sensitivity in basal condition appears to be multifaceted with respect to the dynamic one, because it should be more fat-related. Insulin sensitivity appears to be incompletely described by functions of fasting glucose and insulin values alone and the use of other indices, such as LAP could be suggested.

Modifying effects of alcohol on the postprandial glucose and insulin responses in healthy subjects

BACKGROUND

Moderate alcohol consumption associates with lower risk of type 2 diabetes, but in postprandial studies, alcohol induced impaired insulin sensitivity. The measurement of the glycemic index (GI) for beer has been considered challenging because of its low carbohydrate content. Therefore, imputed GI values from 36 to 95 on the basis of carbohydrate-rich beverages have been used for beer in epidemiologic studies.

OBJECTIVES

We investigated the acute effects of alcohol on glucose and insulin responses and measured GIs and insulinemic indexes (IIs) of nonalcoholic and alcoholic beers.

DESIGN

In a crossover design, 10 healthy volunteers were served beer with 4.5% alcohol by volume, nonalcoholic beer, and a glucose solution with alcohol once and the reference glucose solution twice. Each portion contained 25 g available carbohydrate, and the beer and glucose solution with alcohol contained 21 g alcohol. Capillary blood samples were collected up to 2 h after ingestion, and the incremental AUCs (IAUCs), GIs, and IIs were calculated.

RESULTS

Compared with the reference glucose solution, the glucose solution with alcohol produced an 18% higher postprandial glucose IAUC (P = 0.03) and had no significant effect on the insulin IAUC. Compared with the reference glucose solution, beer had no significant effect on glucose or insulin IAUCs, and nonalcoholic beer tended to reduce the glucose IAUC (P = 0.06) but not the insulin IAUC. GIs of beer and nonalcoholic beer were 119 and 80, and IIs were 130 and 88, respectively.

CONCLUSIONS

Alcohol increases the postprandial glucose response, probably through impaired insulin sensitivity. GI values published for alcohol-containing beers have underestimated the true glycemic effects.

Alterations in total and high-molecular-weight adiponectin after 3 weeks of moderate alcohol consumption in premenopausal women

Moderate alcohol consumption is associated with increased concentrations of adiponectin. Whether this is the case for both total and high-molecular-weight (HMW) adiponectin is uncertain. Furthermore, the rate at which this increase occurs is unclear. Therefore, we examined the effect of moderate alcohol consumption on total and HMW adiponectin. In a randomized, crossover trial, 24 premenopausal women who were regular alcohol consumers received beer (∼26 g alcohol) or alcohol-free beer daily for 3 weeks preceded by a 1-week washout. Blood samples were collected weekly after an overnight fast for measurement of total and HMW adiponectin and markers of glucose and lipid metabolism. There was a significant interaction (P < .05) between the 2 treatments over time for both plasma HMW and total adiponectin concentrations. Within 3 weeks, plasma total (8.2%, P = .01) and HMW (8.2%, P = .02) adiponectin levels were higher after moderate alcohol consumption compared with abstention. Changes over time in total adiponectin were positively associated with changes in HMW adiponectin during the nonalcoholic beer (r = 0.80; 95% confidence interval, 0.55-0.92) and beer (r = 0.82; 0.58-0.93) intervention. Alcohol consumption did not affect the ratio of HMW to total adiponectin or the serum glucose, insulin, hemoglobin A(1c), or triglyceride levels compared with abstention during the intervention periods. Both total and HMW adiponectin concentrations are higher after moderate alcohol consumption compared with abstention in premenopausal women. These effects were evident after at least 3 weeks of consumption and occurred concomitantly.

Ageing and plasma adiponectin concentration in apparently healthy males and females

OBJECTIVE

It is well known that ageing is associated with several hormonal alterations. However, the consequence of ageing on the endocrine function of adipose tissue is not fully elucidated. Adiponectin is a new anti-inflammatory protein secreted exclusively by adipocytes and plays a protective role against insulin resistance and atherosclerosis. Therefore, the aim of present study was to estimate plasma adiponectin concentration in apparently healthy elderly subjects.

SUBJECTS

Fifty-eight women and 67 men aged 20-93 years were included in this study. Subjects were divided into three groups: younger than 50 years, between 50 and 70 years and older than 70 years of age.

MEASUREMENTS

Plasma adiponectin concentration was estimated by an enzyme-linked immunosorbant assay in blood samples withdrawn in the morning after overnight fasting. In males plasma testosterone and dehydroepiandrostendione sulphate concentrations were assessed by a radioimmunoassay method.

RESULTS

Plasma adiponectin concentration only tended to be higher in all elderly subjects (above 70 years) than in the group of all subjects aged between 50 and 70 and the group younger than 50 years of age (12.8 +/- 5.7; 9.9 +/- 5.7 and 10.7 +/- 5.4 microg/ml, respectively). Plasma adiponectin concentration was of similar magnitude in female subjects of these three groups (11.2 +/- 5.7; 11.2 +/- 6.8 and 11.7 +/- 4.9 microg/ml, respectively). In contrast, males over 70 years old are characterized by significantly higher plasma adiponectin (14.0 +/- 5.4 microg/ml) concentration than males between 50 and 70 years of age (8.9 +/- 4.7 microg/ml, P < 0.01) and males younger than 50 years of age (9.6 +/- 5.7 microg/ml, P < 0.05). In the entire studied group a significant but weak, positive correlation was found between plasma adiponectin concentration and age (tau = 0.12; P = 0.04). Additionally, significant correlation was found between plasma adiponectin concentration and age in males when analysed separately (tau = 0.28; P = 0.0007). Such correlation was not significant in females (tau = -0.06; P = 0.5).

CONCLUSIONS

Plasma adiponectin concentration in females did not change significantly with age. In contrast to females, elderly males over 70 years of age are characterized by significantly higher plasma adiponectin concentration than younger ones.