Academic journal article Alcohol Research: Current Reviews

Alcohol and Other Endocrine Tissues

Academic journal article Alcohol Research: Current Reviews

Alcohol and Other Endocrine Tissues

Article excerpt

In addition to the brain areas and organs involved in the main hormone axes in the body that are discussed in this article, several other tissues also produce and secrete hormones that regulate crucial body functions, including the pancreas and fat (i.e., adipose) tissue. Alcohol exposure also can interfere with diese hormonal systems.

The Endocrine Pancreas

The pancreas, which lies behind the stomach, serves two major functions. First, acinar cells secrete digestive enzymes into the small intestine, thereby supporting digestion. Second, islet cells dispersed throughout the whole pancreas have an endocrine activity by producing hormones (i.e., insulin and glucagon) that regulate blood glucose levels. These islet cells can be further subdivided into [alpha]- and [beta]-cells. The [alpha]-cells produce glucagon, which raises blood glucose levels by stimulating the liver to metabolize glycogen into glucose molecules and to release the glucose into the blood. In addition, glucagon stimulates the adipose tissue to metabolize triglycerides into glucose, which then is released into the blood. Conversely, the [beta]-cells of the pancreas produce insulin, which lowers blood glucose levels after a meal by stimulating the absorption of glucose by liver, muscle, and adipose tissues and promoting the storage of glucose in the form of glycogen in these tissues. The endocrine function of the pancreas primarily is controlled by both the sympathetic and the parasympathetic divisions of the autonomic nervous system.

Alcohol's Effects on the Endocrine Pancreas

Heavy alcohol drinking can induce the development of inflammation of the pancreas (i.e., pancreatitis), most commonly in acinar cells. However, the inflammatory aspect of this disease also can damage islet cells and, therefore, the endocrine pancreas (Apte et al. 1997). Chronic alcohol consumption also is a risk factor for the development of pancreatic cancer, with moderate to heavy consumption increasing the risk both alone and in combination with other risk factors, such as tobacco and obesity (de Menezes et al. 2013; Haas et al. 2012). One type of pancreatic cancer called ductal adenocarcinoma has a very aggressive behavior with a 5-year survival rate of less than 4 percent (Welsch et al. 2006).

Chronic alcohol consumption also is a known independent risk factor for the development of type 2 diabetes (Hodge et al. 1993; Holbrook et al. 1990; Wei et al. 2000). This syndrome is characterized by impaired glucose metabolism with high blood glucose levels (i.e., hyperglycemia) and peripheral insulin resistance. The relationship between alcohol consumption and the risk of type 2 diabetes is "U" shaped--that is, risk is lower with moderate alcohol consumption than with either abstention or high alcohol consumption. Thus, the risk was reduced by 30 percent in moderate drinkers compared with abstainers, whereas no risk reduction was observed in heavy drinkers consuming 48 grams of ethanol (i.e., 3 to 4 drinks) per day or more (Koppes et al. 2005). Moderate alcohol use may have protective effects by enhancing peripheral insulin sensitivity (Conigrave et al. 2001; Tomie Furuya et al. 2005).

Some studies have shown that moderate alcohol consumption improves peripheral insulin sensitivity without affecting insulin secretion from pancreatic [beta]-cells (Avogaro et al. 2004), whereas others determined a reduced basal insulin secretion rate associated with a lower fasting plasma glucagon concentration (Bonnet et al. 2012). The beneficial metabolic effects of moderate alcohol use on insulin sensitivity and glucose homeostasis therefore might explain the significant reduction in the risk of development of type 2 diabetes and of cardiovascular disorders (Avogaro et al. 2004; Bande et al. 2008).

Heavy alcohol consumption, in contrast, has several detrimental effects resulting in impaired control of blood glucose levels. In addition to its effects on peripheral tissues, such as adipose tissue and the liver, where it induces insulin resistance, heavy drinking also negatively affects pancreatic [beta]-cell function. …

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