Research ArticleInt J Complement Alt Med 2016, 4(2): 00115
IntroductionAmmonia neurotoxicity is considered responsible for development of a serious nervous system disorder called hepatic encephalopathy (HE). This situation arises mainly due to liver dysfunction led hyperammonemia (HA). HE is characterized by the neuropsychiatric manifestations related to motor dysfunction, memory impairment, and deranged sleep-awake cycle [1,2]. Since HE affects the quality of life of the patients, it is important to develop effective therapeutic strategy against HE. This necessitates understanding the neuro-chemistry of HA pathogenesis.Since ammonia crosses the blood brain barrier easily, prolonged HA condition, a common situation during chronic liver failure (CLF), is likely to maintain increased ammonia concentration in brain [3,4]. The information, mainly derived from the cell culture system and from animal models with acute HE, suggest that the increased brain ammonia level mainly drives astrocytes to undergo significant morpho-pathological changes and also over activates glutamate-NMDA receptor (N-Methyl-D-Aspartate Receptor) pathway in the post-synaptic neurons [1,[5][6][7]. Moreover, NMDAR inhibition could not be translated into prevention of ammonia neurotoxicity, mainly because threshold glutamate-NMDAR activation is necessary for normal neurological functions including higher order brain functions and normal synaptic activity.During recent past, "TNF theory" (Tumor necrosis factor) of HE pathogenesis could draw much attention due to a close association between the level of TNF-α and ammonia in the brain of CLF patients with HE [8]. Later studies have also emphasized significant involvement of TNF-α and other cytokines in HE to the extent that these cytokines could be used as markers for encephalopathy grading [4,[9][10][11][12][13].It is now evident that the microglia and astroglia cells in brain synthesize TNF-α to regulate higher order brain functions and astrocyte induced synaptic strengthening [14][15][16][17]. However, when produced in higher amounts during neuropathology, they are known to potentiate glutamate induced cytotoxicity by inhibiting glutamate transport to the glial cells from the synaptic cleft [12,[16][17][18][19]. Even development of MHE has been described to be dependent more on enhanced inflammatory markers than the severity of CLF or HA in the CLF patients [20]. Moreover, some findings from in vitro studies suggest that resveratrol treatment could prevent ammonia toxicity in astroglial cells by normalizing ROS/RNS level [12,21,22]. Thus, hinting towards a significant role of resveratrol in ameliorating ammonia toxicity. However, the mechanism by which resveratrol does so is unclear.Resveratrol (3, 3, 4'-trihydroxy-Trans stilbene), a natural polyphenol, is found in a number of dietary sources such as grapes, berries, and red wine [23][24][25]. It acts as an effective cardioprotector,
AbstractChronic liver failure (CLF) led hyperammonemia (HA) is known to develop a metabolic brain disorder known a...
