Chronic Alcohol Consumption Results in Greater Damage to the Pancreas Than to the Liver in the Rats

Alcohol-induced increase in BMP levels promotes fatty liver disease in male prediabetic stage Otsuka Long-Evans Tokushima Fatty rats

Alcohol consumption exacerbates liver abnormalities in animal models, but whether it increases the severity of liver disease in early diabetic or prediabetic rats is unclear. To investigate the molecular mechanisms underlying alcohol-induced liver steatosis or hepatitis, we used a prediabetic animal model. Otsuka Long-Evans Tokushima Fatty (OLETF) and Long-Evans Tokushima Fatty (LETO) rats were pair-fed with an ethanol-containing liquid diet for 6 weeks. Compared with controls, OLETF and LETO rats displayed more pronounced liver steatosis and higher plasma levels of serum glutamic oxaloacetic transaminase (SGOT) and serum glutamate pyruvate transaminase (SPGT), indicating liver injury. Ethanol-fed LETO (Pd-L-E) rats showed mild liver steatosis and no inflammation compared with ethanol-fed OLETF (Pd-O-E) rats. Although precursor and active SREBP-1 levels in the liver of ethanol-fed OLETF rats significantly increased compared with control diet-fed OLETF rats (Pd-O-C), those of Pd-L-E rats did not. Bone morphogenetic protein (BMP) and TGF-β1 balance in Pd-O-E rats was significantly altered because BMP signaling was upregulated by inducing BMP2, BMP4, BMP7, BMP9, Smad1, and Smad4, whereas TGF-β1, Smad3, and Erk were downregulated. Activation of TGF-β/Smad signaling inhibited BMP2 and BMP9 expression and increased epithelial-mesenchymal transition (EMT) marker levels (Hepcidin, Snail, and Twist) in the liver of LETO rats. Livers of ethanol-fed OLETF rats showed increased levels of vimentin, FSP-1, α-SMA, MMP1, MMP13, and collagen III compared with rats of other groups, whereas EMT marker levels did not change. Thus, BMP exerted anti- and/or pro-fibrotic effects in ethanol-fed rats. Therefore, BMP and TGF-β, two key members of the TGF-β superfamily, play important but diverse roles in liver steatosis in young LETO and OLETF rats.

Chronic binge alcohol and ovariectomy-mediated impaired insulin responsiveness in SIV-infected female rhesus macaques

Aging people living with HIV (PLWH), especially postmenopausal women may be at higher risk of comorbidities associated with HIV, antiretroviral therapy (ART), hypogonadism, and at-risk alcohol use. Our studies in simian immunodeficiency virus (SIV)-infected male macaques demonstrated that chronic binge alcohol (CBA) reduced acute insulin response to glucose (AIRG), and at-risk alcohol use decreased HOMA-β in PLWH. The objective of this study was to examine the impact of ovariectomy (OVX) on glucose-insulin dynamics and integrity of pancreatic endocrine function in CBA/SIV-infected female macaques. Female macaques were administered CBA (12-15 g/kg/wk) or isovolumetric water (VEH) intragastrically. Three months after initiation of CBA/VEH administration, all macaques were infected with SIVmac251, and initiated on antiretroviral therapy (ART) 2.5 mo postinfection. After 1 mo of ART, macaques were randomized to OVX or sham surgeries (n = 7 or 8/group), and euthanized 8 mo post-OVX (study endpoint). Frequently sampled intravenous glucose tolerance tests (FSIVGTT) were performed at selected time points. Pancreatic gene expression and islet morphology were determined at study endpoint. There was a main effect of CBA to decrease AIRG at Pre-SIV and study endpoint. There were no statistically significant OVX effects on AIRG (P = 0.06). CBA and OVX decreased the expression of pancreatic markers of insulin docking and release. OVX increased endoplasmic stress markers. CBA but not OVX impaired glucose-insulin expression dynamics in SIV-infected female macaques. Both CBA and OVX altered integrity of pancreatic endocrine function. These findings suggest increased vulnerability of PLWH to overt metabolic dysfunction that may be exacerbated by alcohol use and ovarian hormone loss.

The Association Between Age at Initiation of Alcohol Consumption and Type 2 Diabetes Mellitus: A Cohort Study of 0.5 Million Persons in China

It is well known that alcohol consumption is associated with type 2 diabetes mellitus. However, the association of age at initiation of alcohol consumption and duration of alcohol drinking with type 2 diabetes mellitus among Chinese adults is not fully understood. This study was based on data from the China Kadoorie Biobank, which included 512,712 participants aged 30-79 years who were living in China in 2004-2008. A Cox proportional hazards model was used to estimate the association of AAI and drinking duration with type 2 diabetes. After adjustment for potential covariates, ages at alcohol initiation (AAIs) of 18.1-29.0 years, 29.1-39.0 years, and >39.0 years were associated with 22% (95% confidence interval (CI): 14, 30), 25% (95% CI: 17, 33), and 32% (95% CI: 24, 39) lower hazards of type 2 diabetes compared with abstaining, respectively. Drinking durations of <10.1 years, 10.1-20.0 years, and 20.1-30.0 years were associated with a lower risk of type 2 diabetes, compared with abstaining. Among current (weekly) drinkers, AAI <18.1 years and drinking duration >30.0 years were associated with 18% (95% CI: 4, 33) and 20% (95% CI: 3, 40) higher hazards of type 2 diabetes, compared with AAI 18.1-29.0 years and drinking duration <10.1 years, respectively. In conclusion, late AAI and a short drinking duration were associated with a lower risk of type 2 diabetes in this large prospective cohort study of Chinese adults, but early AAI and long drinking duration were not.

Joint and separate exposure to alcohol and ∆9-tetrahydrocannabinol produced distinct effects on glucose and insulin homeostasis in male rats

Cannabis and alcohol co-use is common, and the trend may increase further given the current popularity of cannabis legalization. However, the metabolic consequences of such co-use are unclear. Here, we investigated how co-administration of alcohol and ∆9-tetrahydrocannabinol (THC), the main psychoactive constituent of cannabis, affects body weight and visceral adiposity, and glucose and insulin homeostasis in rats. For 16 consecutive days during adolescence, male rats drank saccharin or alcohol after receiving subcutaneous oil or THC injections in Experiment 1 and voluntarily consumed alcohol, THC edible, or both drugs in Experiment 2. Experiment 1 showed that following abstinence, drug co-exposure reduced visceral fat and the amount of insulin required to clear glucose during an oral glucose tolerance test (OGTT). In Experiment 2, rats received a high-fat diet (HFD) after 3-week abstinence. Although adolescent drug use did not interact with the HFD to worsen hyperglycemia and hyperinsulinemia during an OGTT, HFD-fed rats that co-used alcohol and THC had the lowest insulin levels 75 min after an insulin injection, suggesting an altered rate of insulin secretion and degradation. These results suggest that THC and alcohol co-exposure can distinctly alter the physiology of glucose and insulin homeostasis in a rodent model.

Chronic moderate alcohol drinking alters insulin release without affecting cognitive and emotion-like behaviors in rats

Because the consumption of alcoholic beverages prevails in society, its effects on diabetes risk is a subject of interest. Extant literature on this issue often disagrees. Here, we probed the effects of chronic moderate ethanol consumption on glucose metabolism in rats. The effect of chronic moderate alcohol drinking on depression- and anxiety-like behaviors and memory was also explored. Adolescent male and female Long-Evans rats consumed saccharin-sweetened 5% (1 week) and 10% ethanol (7 weeks) under a 7.5-h/day (Monday-Friday) access schedule. This exposure was followed by sucrose preference and elevated plus maze (EPM) tests during an intervening week, before a 6-week intermittent-access (Monday, Wednesday, Friday) to 20% unsweetened ethanol in a 2-bottle choice drinking paradigm was implemented (EtOH). A free-feeding control group received water (Water). Our prior work revealed that voluntary ethanol consumption decreases food intake in rats. Hence, a second control group that received water was mildly food-restricted (FR), and their average body weight was matched to that of the EtOH group. During the week following week 6 of intermittent-access to 20% ethanol, rats were submitted to sucrose preference, EPM, and novel object recognition (NOR) tests. Insulin response to a glucose load was subsequently assessed via an oral glucose tolerance test (OGTT). Rats attained and maintained blood ethanol concentrations of ∼55 mg/dL that correlated with the dose of sweetened 10% ethanol ingested. Relative to intake by Water controls, EtOH rats consumed less chow. There was no body weight difference between both groups. Neither sex of EtOH rats showed increased depression- and anxiety-like behaviors, as respectively measured by sucrose preference and EPM, nor did they show deficit in object recognition memory during abstinence. Male EtOH rats, however, showed signs of reduced general activity on the EPM. During OGTT, male EtOH rats showed a time-dependent potentiation of insulin release for proper glucose clearance. Such an effect was not observed in females. This landmark study shows that chronic moderate alcohol consumption can have negative metabolic consequences in the absence of overt behavioral deficits, especially in males.

Short- and medium-term effects of light to moderate alcohol intake on glycaemic control in diabetes mellitus: a systematic review and meta-analysis of randomized trials

BACKGROUND

People with diabetes are told that drinking alcohol may increase their risk of hypoglycaemia.

AIMS

To report the effects of alcohol consumption on glycaemic control in people with diabetes mellitus.

METHODS

Medline, EMBASE and the Cochrane Library databases were searched in 2015 to identify randomized trials that compared alcohol consumption with no alcohol use, reporting glycaemic control in people with diabetes. Data on blood glucose, HbA_1c and numbers of hypoglycaemic episodes were pooled using random effects meta-analysis.

RESULTS

Pooled data from nine short-term studies showed no difference in blood glucose concentrations between those who drank alcohol in doses of 16-80 g (median 20 g, 2.5 units) compared with those who did not drink alcohol at 0.5, 2, 4 and 24 h after alcohol consumption. Pooled data from five medium-term studies showed that there was no difference in blood glucose or HbA_1c concentrations at the end of the study between those who drank 11-18 g alcohol/day (median 13 g/day, 1.5 units/day) for 4-104 weeks and those who did not. We found no evidence of a difference in number of hypoglycaemic episodes or in withdrawal rates between randomized groups.

CONCLUSIONS

Studies to date have not provided evidence that drinking light to moderate amounts of alcohol, with or without a meal, affects any measure of glycaemic control in people with Type 2 diabetes. These results suggest that current advice that people with diabetes do not need to refrain from drinking moderate quantities of alcohol does not need to be changed; risks to those with Type 1 diabetes remain uncertain.

Chronic saponin treatment attenuates damage to the pancreas in chronic alcohol-treated diabetic rats

Background

Chronic heavy alcohol consumption may raise the risk of developing type 2 diabetes mellitus. Saponins inhibit apoptosis of pancreatic islet cells and reduce lipid parameters. The present study was designed to investigate the effect of saponin on chronic ethanol-treated diabetic rats.

Methods

Long–Evans Tokushima Fatty (LETO) and Otsuka Long–Evans Tokushima Fatty (OLETF) rats were pair-fed a Lieber–DeCarli diet with and without 5% ethanol for 12 wks. Two weeks after starting the pair-feeding with the Lieber–DeCarli diet, intraperitoneal injection of saponin was performed for 10 wks. To perform the experiments, rats were divided as follows: LETO-Control (LC), LETO-Ethanol (LE), LETO-Ethanol-Saponin (LES), OLETF-Control (OC), OLETF-Ethanol (OE), and OLETF-Ethanol-Saponin (OES).

Results

The weights of epididymal and mesenteric fat tissue in LES and OES rats were the lightest from among the LETO and OLETF groups, respectively. The secretion of alanine aminotransferase and cholesterol in OES rats decreased significantly compared to their secretion in OC and OE rats, respectively. The islets of the pancreas in LE and OE rats showed clean, unclear, and smaller morphology compared to those of LC, LES, OC, and OES rats. In addition, the expression of insulin in the islets of the pancreas in LC, LES, OC, and OES rats was higher than in LE and OE rats.

Conclusion

Saponin may not only be helpful in alleviating the rapid progress of diabetes due to chronic alcohol consumption in diabetic patients, but may also show potential as an antidiabetic drug candidate for diabetic patients who chronically consume alcohol.

Alcoholic Beverage Consumption and Chronic Diseases

Epidemiological and experimental studies have consistently linked alcoholic beverage consumption with the development of several chronic disorders, such as cancer, cardiovascular diseases, diabetes mellitus and obesity. The impact of drinking is usually dose-dependent, and light to moderate drinking tends to lower risks of certain diseases, while heavy drinking tends to increase the risks. Besides, other factors such as drinking frequency, genetic susceptibility, smoking, diet, and hormone status can modify the association. The amount of ethanol in alcoholic beverages is the determining factor in most cases, and beverage types could also make an influence. This review summarizes recent studies on alcoholic beverage consumption and several chronic diseases, trying to assess the effects of different drinking patterns, beverage types, interaction with other risk factors, and provide mechanistic explanations.