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Hepatic nitric oxide production following acute endotoxemia in rats is mediated by increased inducible nitric oxide synthase gene expression.
Hepatology. 1995 Jul; 22(1):223-34.Hep

Abstract

In the present studies, we analyzed the effects of acute endotoxemia on hepatocyte nitric oxide production and functional activity. Treatment of rats with 5 mg/kg of lipopolysaccharide (LPS), which induces acute endotoxemia, caused an increase in nitric oxide production in the liver, as measured by electron paramagnetic spin trapping, which was evident within 6 hours. This was associated with expression of inducible nitric oxide synthase (iNOS) messenger (m) RNA in hepatocytes and in sinusoidal cells throughout the liver lobule. Acute endotoxemia also caused alterations in hepatic structure, including hypertrophy, vacuolization, and chromosomal emargination, however these changes were not apparent for 24 to 48 hours. Hepatocytes isolated from endotoxemic rats released increased amounts of nitric oxide, measured by nitrite production, in response to interferon gamma (gamma-IFN) alone or in combination with LPS, tumor necrosis factor alpha, macrophage-colony stimulating factor, granulocyte/macrophage-colony stimulating factor, or hepatocyte growth factor. These results show that hepatocytes are sensitized by acute endotoxemia to respond to inflammatory mediators and growth factors. Increased nitrite production by hepatocytes was due to increased expression of iNOS mRNA and protein and was correlated with the time following induction of acute endotoxemia. Thus, cells isolated 48 hours after induction of acute endotoxemia released significantly more nitrite than cells recovered after 6 hours, a response that was not due to alterations in hepatocyte viability. Hepatocytes isolated from endotoxemic rats also exhibited a marked increase in proliferative capacity when compared with cells from control rats. Nitric oxide production by hepatocytes in vitro was associated with inhibition of cell growth and protein synthesis, which was reversed by the nitric oxide synthase inhibitor, NG-monomethyl-l-arginine (L-NMMA). Agarose gel electrophoresis showed extensive cytoplasmic DNA fragmentation in hepatocytes treated with LPS and gamma-IFN, a characteristic of apoptosis, which was also reversed by L-NMMA. These results, together with our findings that treatment of rats with an inhibitor of nitric oxide synthase partially reversed the structural alterations in the liver associated with acute endotoxemia suggest that nitric oxide may contribute to the pathophysiologic response to this bacterially derived toxin.

Authors+Show Affiliations

Environmental and Occupational Health Sciences Institute, Rugers University, Piscataway, NJ 08855-0789, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

7541386

Citation

Laskin, D L., et al. "Hepatic Nitric Oxide Production Following Acute Endotoxemia in Rats Is Mediated By Increased Inducible Nitric Oxide Synthase Gene Expression." Hepatology (Baltimore, Md.), vol. 22, no. 1, 1995, pp. 223-34.
Laskin DL, Rodriguez del Valle M, Heck DE, et al. Hepatic nitric oxide production following acute endotoxemia in rats is mediated by increased inducible nitric oxide synthase gene expression. Hepatology. 1995;22(1):223-34.
Laskin, D. L., Rodriguez del Valle, M., Heck, D. E., Hwang, S. M., Ohnishi, S. T., Durham, S. K., Goller, N. L., & Laskin, J. D. (1995). Hepatic nitric oxide production following acute endotoxemia in rats is mediated by increased inducible nitric oxide synthase gene expression. Hepatology (Baltimore, Md.), 22(1), 223-34.
Laskin DL, et al. Hepatic Nitric Oxide Production Following Acute Endotoxemia in Rats Is Mediated By Increased Inducible Nitric Oxide Synthase Gene Expression. Hepatology. 1995;22(1):223-34. PubMed PMID: 7541386.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Hepatic nitric oxide production following acute endotoxemia in rats is mediated by increased inducible nitric oxide synthase gene expression. AU - Laskin,D L, AU - Rodriguez del Valle,M, AU - Heck,D E, AU - Hwang,S M, AU - Ohnishi,S T, AU - Durham,S K, AU - Goller,N L, AU - Laskin,J D, PY - 1995/7/1/pubmed PY - 1995/7/1/medline PY - 1995/7/1/entrez SP - 223 EP - 34 JF - Hepatology (Baltimore, Md.) JO - Hepatology VL - 22 IS - 1 N2 - In the present studies, we analyzed the effects of acute endotoxemia on hepatocyte nitric oxide production and functional activity. Treatment of rats with 5 mg/kg of lipopolysaccharide (LPS), which induces acute endotoxemia, caused an increase in nitric oxide production in the liver, as measured by electron paramagnetic spin trapping, which was evident within 6 hours. This was associated with expression of inducible nitric oxide synthase (iNOS) messenger (m) RNA in hepatocytes and in sinusoidal cells throughout the liver lobule. Acute endotoxemia also caused alterations in hepatic structure, including hypertrophy, vacuolization, and chromosomal emargination, however these changes were not apparent for 24 to 48 hours. Hepatocytes isolated from endotoxemic rats released increased amounts of nitric oxide, measured by nitrite production, in response to interferon gamma (gamma-IFN) alone or in combination with LPS, tumor necrosis factor alpha, macrophage-colony stimulating factor, granulocyte/macrophage-colony stimulating factor, or hepatocyte growth factor. These results show that hepatocytes are sensitized by acute endotoxemia to respond to inflammatory mediators and growth factors. Increased nitrite production by hepatocytes was due to increased expression of iNOS mRNA and protein and was correlated with the time following induction of acute endotoxemia. Thus, cells isolated 48 hours after induction of acute endotoxemia released significantly more nitrite than cells recovered after 6 hours, a response that was not due to alterations in hepatocyte viability. Hepatocytes isolated from endotoxemic rats also exhibited a marked increase in proliferative capacity when compared with cells from control rats. Nitric oxide production by hepatocytes in vitro was associated with inhibition of cell growth and protein synthesis, which was reversed by the nitric oxide synthase inhibitor, NG-monomethyl-l-arginine (L-NMMA). Agarose gel electrophoresis showed extensive cytoplasmic DNA fragmentation in hepatocytes treated with LPS and gamma-IFN, a characteristic of apoptosis, which was also reversed by L-NMMA. These results, together with our findings that treatment of rats with an inhibitor of nitric oxide synthase partially reversed the structural alterations in the liver associated with acute endotoxemia suggest that nitric oxide may contribute to the pathophysiologic response to this bacterially derived toxin. SN - 0270-9139 UR - https://www.unboundmedicine.com/medline/citation/7541386/Hepatic_nitric_oxide_production_following_acute_endotoxemia_in_rats_is_mediated_by_increased_inducible_nitric_oxide_synthase_gene_expression_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0270913995002217 DB - PRIME DP - Unbound Medicine ER -