Induction of Inducible Nitric Oxide Synthase by Lipopolysaccharide and the Influences of Cell Volume Changes, Stress Hormones and Oxidative Stress on Nitric Oxide Efflux from the Perfused Liver of Air-Breathing Catfish, Heteropneustes fossilis

Abstract

The air-breathing singhi catfish (Heteropneustes fossilis) is frequently being challenged by bacterial contaminants, and different environmental insults like osmotic, hyper-ammonia, dehydration and oxidative stresses in its natural habitats throughout the year. The main objectives of the present investigation were to determine (a) the possible induction of inducible nitric oxide synthase (iNOS) gene with enhanced production of nitric oxide (NO) by intra-peritoneal injection of lipopolysaccharide (LPS) (a bacterial endotoxin), and (b) to determine the effects of hepatic cell volume changes due to anisotonicity or by infusion of certain metabolites, stress hormones and by induction of oxidative stress on production of NO from the iNOS-induced perfused liver of singhi catfish. Intra-peritoneal injection of LPS led to induction of iNOS gene and localized tissue specific expression of iNOS enzyme with more production and accumulation of NO in different tissues of singhi catfish. Further, changes of hydration status/cell volume, caused either by anisotonicity or by infusion of certain metabolites such as glutamine plus glycine and adenosine, affected the NO production from the perfused liver of iNOS-induced singhi catfish. In general, increase of hydration status/cell swelling due to hypotonicity caused decrease, and decrease of hydration status/cell shrinkage due to hypertonicity caused increase of NO efflux from the perfused liver, thus suggesting that changes in hydration status/cell volume of hepatic cells serve as a potent modulator for regulating the NO production. Significant increase of NO efflux from the perfused liver was also observed while infusing the liver with stress hormones like epinephrine and norepinephrine, accompanied with decrease of hydration status/cell volume of hepatic cells. Further, oxidative stress, caused due to infusion of t-butyl hydroperoxide and hydrogen peroxide separately, in the perfused liver of singhi catfish, resulted in significant increase of NO efflux accompanied with decrease of hydration status/cell volume of hepatic cells. However, the reasons for these cell volume-sensitive changes of NO efflux from the liver of singhi catfish are not fully understood with the available data. Nonetheless, enhanced or decreased production of NO from the perfused liver under osmotic stress, in presence of stress hormones and oxidative stress reflected its potential role in cellular homeostasis and also for better adaptations under environmental challenges. This is the first report of osmosensitive and oxidative stress-induced changes of NO production and efflux from the liver of any teleosts. Further, the level of expression of iNOS in this singhi catfish could also serve as an important indicator to determine the pathological status of the external environment.

Applications of microalga Chlorella vulgaris in aquaculture

“…Effects of microalgae on intestinal immunity is an area that has not been much exploited yet. However, Zahran and Risha (2014) have reported a positive effect of C. vulgaris on nitric oxide production, which is known to act as a mediator of different cell functions (Choudhury & Saha 2016). An enzyme responsible for nitric oxide synthesis, called inducible nitric oxide synthase (iNOS) is the key protein in intestinal immunity, as it controls inflammatory cytokines such as TNFa (Kousoulaki et al 2015).…”

Hydroethanolic Extract of Buchholzia coriacea Seeds Alleviates LPS Induced Liver Injury in Rat via Antioxidant and Anti-inflammatory Actions

“…he hepatoprotective potential of orally administered hydroethanolic seeds (HEBCS) in a rat induced acute liver injury is a wellestablished model to investigate the liver function atoprotective role of potential drug candidates. LPS induced hepatotoxicity is known to be associated with severe inflammatory responses and hepatic oxidative stress [34]. These are due to the involvement of the liver in the regulation of entry, metabolism, and clearance of LPS during exposure [35].…”

“…It has been reported that the hepatic and systemic toxicities exhibited by LPS have been due mainly to the release of pro-inflammatory cytokines, including TNF-α, IL-1β, and IL cytokines are produced following the binding of LPS to the CD14/LPS-binding protein and Toll like receptor-4 (TLR4) on the surface of Kupffer cells [36,37]. Subsequent interactions cause an increase in the expression of inducible enzymes/ proteins including COX-2, iNOS, and CRP an production of chemical oxidants such as superoxide radical anion ( Ÿ [34,38,39]. All these contribute to the hepatic injury in LPS -induced toxicity characterized by elevation of serum activities of ALP, AST, and ALT [40].…”

“…These llowing the binding of binding protein and Toll-4 (TLR4) on the surface of Kupffer cells [36,37]. Subsequent interactions cause an increase in the expression of inducible enzymes/ 2, iNOS, and CRP and production of chemical oxidants such as ,) and NO [34,38,39]. All these contribute to the hepatic induced toxicity characterized by elevation of serum activities of ALP, AST, and have reported that cytokines 6 are secreted from activated Kupffer cells during LPS endotoxicity [36].…”

“…We also observed a significant increase in the expression of CRP in the liver of rats, six hours after LPS administration. LPS signalling been linked to an elevation of acute proteins, most especially the CRP [34,44]. CRP is an acute-phase protein produced by hepatocytes and it plays a vital role in liver innate immunity [44].…”