Hormone Important in Smokers

A new study evaluated the potential role an antioxidant hormone plays in the prevention of adverse physiological changes due to tobacco smoke. Currently, approximately 20 percent of American adults, totaling 43.4 million people, smoke tobacco. Cigarette smoking is the leading preventable cause of death and is responsible for an estimated one in five deaths annually in the United States. Tobacco smoke is known to increase the risk of diseases such as cancer and cardiovascular disease. Furthermore, nicotine has been shown to promote the development of atherosclerosis, thrombosis (clots) and changes in the microvasculature (the smallest blood vessels known as capillaries).

A new study investigated the interaction between vascular damage caused by tobacco smoke and the protective activity of the hormone melatonin. Melatonin is a hormone secreted from the pineal gland that is responsible for regulation of circadian rhythms. In addition, melatonin exhibits significant antioxidant activity, particularly protecting DNA from free radical damage.

In this study, rats received nicotine alone, melatonin alone, nicotine plus melatonin or no treatment. After 28 days, the rats were evaluated for vascular changes involved in nicotine-induced atherosclerosis and hypertension. These included the marker of cellular stress known as extracellular signal-regulated kinase (ERK1/2); molecules involved in fibrosis formation called transforming growth factor (TGF-beta-1) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappaB); and the molecules involved in recruitment of white blood cells to the vessels called intercellular adhesion molecule-1 (ICAM-1) and vascular cellular adhesion molecule-1 (VCAM-1).

The results showed that nicotine caused significant structural and functional changes in the aorta of the rats. Nicotine was shown to activate ERK 1/2, which then activated both TGF-beta-1 and NF-kappaB, which, in turn, stimulated ICAM-1 and VCAM-1 and fibrosis formation by collagen. Melatonin blocked the activation of ERK1/2 and thereby inhibited the activation of the pathway that caused nicotine-induced vascular changes.

The study authors stated, “Based on these findings, melatonin is able to minimize the negative effects of nicotine by blocking the activation of ERK and the other signaling pathways in which this enzyme is involved.”

Reference:

Rodella LF, Filippini F, Bonomini F, Bresciani R, Reiter RJ, Rezzani R. Beneficial effects of melatonin on nicotine-induced vasculopathy. J Pineal Res. 2009 Dec 30. Published Online Ahead of Print.