"The human body, like many other mammals and some bacteria, displays changes in functions and behavior that wax and wane through the cycle of day and night," said Dipak K. Sarkar, director of the endocrinology program and biomedical division of the Center of Alcohol Studies at Rutgers University, and corresponding author for the study, in a news release.
"These rhythms are not simply a response to 24-hour changes in the physical environment but instead arise from a timekeeping system or 'biological clock' within the body. An individual has more than 100 circadian rhythms that are unique and influence various aspects of body functions, including heart rate, blood pressure, body temperature, hormone levels, pain threshold and even the ability to fight against harmful invaders like bacteria and virus. Almost no area of our body is unaffected by these rhythms."
"This review shows that alcohol exposure can alter biological rhythmicity and, as a result, have deleterious consequences on a number of important physiological systems," noted Robert J. Handa, professor of neuroscience at Colorado State University. "The fact that alcohol intake may influence the molecular underpinnings of circadian rhythmicity is an emerging concept with potentially important biomedical ramifications. Although a majority of these studies have been performed in rodent models... observations of humans correlate with the animal studies and imply that similar types of pathology are associated with alcohol intake."
Key Study Findings
Some of the review's key findings were:- The chronobiological disruptions observed in human alcoholics appear to be partially due to alcohol-induced disruption of fundamental biological timing processes, and partially due to genetic associations.
- Chronic alcohol administration appears to significantly alter central and internal clocks that govern neuroendocrine functions.
- Alcohol consumption may influence immune function by altering an individual's central and internal clock activities.
- There may be a molecular basis for greater alcohol consumption among shift workers and people suffering from jet lag.
- Alcohol may interact with different human physiological systems that are subject to circadian rhythmicity.
Synchronizing Signals Altered
"Alcohol can directly alter the molecular clock machinery in different cell types, such as neuroendocrine cells and immune cells, and the molecular components of the central clock in the hypothalamus that coordinates the circadian rhythms in physiology and behavior," said Sarkar. "In addition, chronic alcohol consumption may also affect the synchronizing signals by which clocks in different tissues talk to each other."Sarkar said alcohol consumption has long-term adverse effects on the body's internal clocks and that chronic drinking may increase the risk for sleep disturbances, depression, compromised immune function, and increased incidence of certain forms of cancers.
"We are now conducting studies using laboratory animals to understand how alcohol drinking in the adult alters the molecular machinery governing the body's biological clock," said Sarkar. "We are also determining the negative health consequences of maternal alcohol abuse on the offspring's circadian neuroendocrine and immune system functions."
Source: Sarkar's review was published in the August 2005 issue of Alcoholism: Clinical & Experimental Research.
