Melatonin in Bacterial and Viral Infections with Focus on Sepsis: A Review

Abstract

Melatonin is a versatile molecule, synthesized not only by the pineal gland, but also in small amounts by many other organs like retina, gastrointestinal tract, thymus, bone marrow, lymphocytes etc. It plays an important role in various functions of the body like sleep and circadian rhythm regulation, immunoregulatory mechanism, free radical scavenger, antioxidant functions, oncostatic actions, control of reproductive functions, regulation of mood etc. Melatonin has also been found to be effective in combating various bacterial and viral infections. Its administration has been shown to be effective in controlling chlamydial infections, infections induced by Mycobacterium tuberculosis, and also in many viral infections. Molecular mechanisms of anti microbial actions of melatonin have suggested to be due to effects on free radical formation, direct regulation of duplication of bacteria, depletion of intracellular substrates like iron etc. Besides, it is effective in sepsis as demonstrated in various animal models of septic shock. Melatonin's protective action against sepsis is suggested to be due to its antioxidant, immunomodulating and inhibitory actions against the production and activation of pro-inflammatory mediators. Use of melatonin has been beneficial in treating premature infants suffering from severe respiratory distress syndrome and septic shock. It has a potential therapeutic value in treating septic shock and associated multi organ failure in critically ill patients in addition to its antimicrobial and antiviral actions. The patents related to melatonin's use for treatment of bacterial infections and its use in clinical disorders are included.

Role of Mitochondrial Oxidative Stress in Sepsis

“…Melatonin is the major hormone secreted by pineal gland predominantly at night. Melatonin has significant anti-inflammatory and antiapoptotic effects, but it can also act as an antioxidant scavenger for radical oxygen and nitrogen species [108,109]. There are several animal studies depicting these beneficial antioxidant properties of melatonin in LPS or cecal ligation and puncture-(CLP-) induced septic shock [110][111][112].…”

The Beneficial Effects of Agomelatine in Experimental Model of Sepsis Related Acute Kidney Injury

“…[13] In several experimental studies, beneficial effects of melatonin have been demonstrated with sepsis models. [13][14][15][16] Although the exact mechanism is not clear, it is thought that the antioxidant, anti-apoptotic, anti-inflammatory, and immunomodulating effects of melato-…”

Microbial Source of Melatonin and Its Clinical Aspects

“…Mice infected with VEE causes hyper-excitation, coma, and paralysis, which results into death (Bonilla et al 1997). The regulation of the inflammatory response, scavenging nature of the free radicals like reactive oxygen species, and related antioxidative property of melatonin are gaining a strong pharmacological significance to explore the mechanism for host pathogen reactions during viral pathogenesis and future consequences (Srinivasan et al 2010(Srinivasan et al , 2012. Although very few weakness of melatonin is short half-life, and their concentration varies with duration of light (Currier et al 2000).…”