Attenuation of the induction of nitric oxide synthase by endogenous glucocorticoids accounts for endotoxin tolerance in vivo

Csaba Szabo, Christoph Thiemermann, Chin Chen Wu, Mauro Perretti, John R. Vane

Research output: Contribution to journalArticle

197 Citations (Scopus)

Abstract

An enhanced formation of nitric oxide (NO) due to induction of a calcium- independent (inducible) NO synthase (iNOS) contributes importantly to the cardiovascular failure caused by bacterial endotoxin. Repeated challenges with small doses of endotoxin result in tolerance to both peripheral vascular failure and death caused by subsequent injection of a higher dose of endotoxin. Here we investigate whether tolerance to endotoxin is associated with a lack of induction of iNOS in vivo and whether endogenous glucocorticoids play a role in the development of endotoxin tolerance. In anesthetized rats, i.v. administration of Escherichia coli endotoxin [lipopolysaccharide (LPS); 2 mg · kg-1] resulted in a prolonged decrease in mean arterial blood pressure (MAP) and hyporeactivity to the contractile responses elicited by norepinephrine (NE; 10 nM) in aortic rings ex vivo. Hyporeactivity to NE was partially reversed by N(G)-nitro-L-arginine methyl ester (0.3 mM) in vitro, suggesting that an enhanced formation of NO contributes to this hyporeactivity. There was a substantial increase in the activity of iNOS in the lung 3 h after i.v. injection of LPS (0.2 ± 0.1 to 6.6 ± 0.6 pmol · mg-1 · min-1; n = 5; P < 0.01). Rats injected i.p. with LPS (0.5 mg · kg-1) for 4 consecutive days became tolerant to an i.v. injection of LPS (2 mg · kg-1) in that both hypotension and vascular hyporeactivity to NE were significantly attenuated. Moreover, in these endotoxin-tolerant rats, the induction of iNOS by LPS in the lung was attenuated by 63% ± 6%. Injection of LPS caused a 9-fold increase in plasma corticosterone (CCS) levels within 2 h and CCS levels remained significantly elevated 6 and 24 h after LPS. Animals rendered tolerant to endotoxin by administration of a low dose of LPS (0.5 mg · kg-1, i.p.) for 4 days still had a 6-fold increase in plasma CCS levels 24 h after the last injection of LPS. When endotoxin-tolerant rats were treated with the glucocorticoid receptor antagonist RU 486 (50 mg · kg-1, p.o. 3 h prior to LPS), there was a restoration of the effects of LPS (2 mg · kg-1, i.v.) in causing hypotension, vascular hyporeactivity to NE, and iNOS induction in the lung. However, in control rats RU 486 enhanced neither the decrease in MAP nor the induction of iNOS in response to LPS (2 mg · kg-1, i.v.). Thus, cardiovascular tolerance to endotoxin is accompanied and explained by reduced induction of iNOS in vivo due to the elevation of endogenous glucocorticoid levels.

Original languageEnglish (US)
Pages (from-to)271-275
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume91
Issue number1
DOIs
StatePublished - Jan 4 1994
Externally publishedYes

Fingerprint

Endotoxins
Nitric Oxide Synthase
Glucocorticoids
Lipopolysaccharides
Arterial Pressure
Corticosterone
Injections
Mifepristone
Hypotension
Lung
Nitric Oxide
NG-Nitroarginine Methyl Ester
Glucocorticoid Receptors
Nitric Oxide Synthase Type II
Blood Vessels
Norepinephrine
Calcium

Keywords

  • contraction
  • endotoxin shock
  • RU 486
  • tumor necrosis factor
  • vasodilatation

ASJC Scopus subject areas

  • Genetics
  • General

Cite this

Attenuation of the induction of nitric oxide synthase by endogenous glucocorticoids accounts for endotoxin tolerance in vivo. / Szabo, Csaba; Thiemermann, Christoph; Wu, Chin Chen; Perretti, Mauro; Vane, John R.

In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 91, No. 1, 04.01.1994, p. 271-275.

Research output: Contribution to journalArticle

@article{8c791b72ba4d4c6cb8e497fa2350e756,
title = "Attenuation of the induction of nitric oxide synthase by endogenous glucocorticoids accounts for endotoxin tolerance in vivo",
abstract = "An enhanced formation of nitric oxide (NO) due to induction of a calcium- independent (inducible) NO synthase (iNOS) contributes importantly to the cardiovascular failure caused by bacterial endotoxin. Repeated challenges with small doses of endotoxin result in tolerance to both peripheral vascular failure and death caused by subsequent injection of a higher dose of endotoxin. Here we investigate whether tolerance to endotoxin is associated with a lack of induction of iNOS in vivo and whether endogenous glucocorticoids play a role in the development of endotoxin tolerance. In anesthetized rats, i.v. administration of Escherichia coli endotoxin [lipopolysaccharide (LPS); 2 mg · kg-1] resulted in a prolonged decrease in mean arterial blood pressure (MAP) and hyporeactivity to the contractile responses elicited by norepinephrine (NE; 10 nM) in aortic rings ex vivo. Hyporeactivity to NE was partially reversed by N(G)-nitro-L-arginine methyl ester (0.3 mM) in vitro, suggesting that an enhanced formation of NO contributes to this hyporeactivity. There was a substantial increase in the activity of iNOS in the lung 3 h after i.v. injection of LPS (0.2 ± 0.1 to 6.6 ± 0.6 pmol · mg-1 · min-1; n = 5; P < 0.01). Rats injected i.p. with LPS (0.5 mg · kg-1) for 4 consecutive days became tolerant to an i.v. injection of LPS (2 mg · kg-1) in that both hypotension and vascular hyporeactivity to NE were significantly attenuated. Moreover, in these endotoxin-tolerant rats, the induction of iNOS by LPS in the lung was attenuated by 63{\%} ± 6{\%}. Injection of LPS caused a 9-fold increase in plasma corticosterone (CCS) levels within 2 h and CCS levels remained significantly elevated 6 and 24 h after LPS. Animals rendered tolerant to endotoxin by administration of a low dose of LPS (0.5 mg · kg-1, i.p.) for 4 days still had a 6-fold increase in plasma CCS levels 24 h after the last injection of LPS. When endotoxin-tolerant rats were treated with the glucocorticoid receptor antagonist RU 486 (50 mg · kg-1, p.o. 3 h prior to LPS), there was a restoration of the effects of LPS (2 mg · kg-1, i.v.) in causing hypotension, vascular hyporeactivity to NE, and iNOS induction in the lung. However, in control rats RU 486 enhanced neither the decrease in MAP nor the induction of iNOS in response to LPS (2 mg · kg-1, i.v.). Thus, cardiovascular tolerance to endotoxin is accompanied and explained by reduced induction of iNOS in vivo due to the elevation of endogenous glucocorticoid levels.",
keywords = "contraction, endotoxin shock, RU 486, tumor necrosis factor, vasodilatation",
author = "Csaba Szabo and Christoph Thiemermann and Wu, {Chin Chen} and Mauro Perretti and Vane, {John R.}",
year = "1994",
month = "1",
day = "4",
doi = "10.1073/pnas.91.1.271",
language = "English (US)",
volume = "91",
pages = "271--275",
journal = "Proceedings of the National Academy of Sciences of the United States of America",
issn = "0027-8424",
number = "1",

}

TY - JOUR

T1 - Attenuation of the induction of nitric oxide synthase by endogenous glucocorticoids accounts for endotoxin tolerance in vivo

AU - Szabo, Csaba

AU - Thiemermann, Christoph

AU - Wu, Chin Chen

AU - Perretti, Mauro

AU - Vane, John R.

PY - 1994/1/4

Y1 - 1994/1/4

N2 - An enhanced formation of nitric oxide (NO) due to induction of a calcium- independent (inducible) NO synthase (iNOS) contributes importantly to the cardiovascular failure caused by bacterial endotoxin. Repeated challenges with small doses of endotoxin result in tolerance to both peripheral vascular failure and death caused by subsequent injection of a higher dose of endotoxin. Here we investigate whether tolerance to endotoxin is associated with a lack of induction of iNOS in vivo and whether endogenous glucocorticoids play a role in the development of endotoxin tolerance. In anesthetized rats, i.v. administration of Escherichia coli endotoxin [lipopolysaccharide (LPS); 2 mg · kg-1] resulted in a prolonged decrease in mean arterial blood pressure (MAP) and hyporeactivity to the contractile responses elicited by norepinephrine (NE; 10 nM) in aortic rings ex vivo. Hyporeactivity to NE was partially reversed by N(G)-nitro-L-arginine methyl ester (0.3 mM) in vitro, suggesting that an enhanced formation of NO contributes to this hyporeactivity. There was a substantial increase in the activity of iNOS in the lung 3 h after i.v. injection of LPS (0.2 ± 0.1 to 6.6 ± 0.6 pmol · mg-1 · min-1; n = 5; P < 0.01). Rats injected i.p. with LPS (0.5 mg · kg-1) for 4 consecutive days became tolerant to an i.v. injection of LPS (2 mg · kg-1) in that both hypotension and vascular hyporeactivity to NE were significantly attenuated. Moreover, in these endotoxin-tolerant rats, the induction of iNOS by LPS in the lung was attenuated by 63% ± 6%. Injection of LPS caused a 9-fold increase in plasma corticosterone (CCS) levels within 2 h and CCS levels remained significantly elevated 6 and 24 h after LPS. Animals rendered tolerant to endotoxin by administration of a low dose of LPS (0.5 mg · kg-1, i.p.) for 4 days still had a 6-fold increase in plasma CCS levels 24 h after the last injection of LPS. When endotoxin-tolerant rats were treated with the glucocorticoid receptor antagonist RU 486 (50 mg · kg-1, p.o. 3 h prior to LPS), there was a restoration of the effects of LPS (2 mg · kg-1, i.v.) in causing hypotension, vascular hyporeactivity to NE, and iNOS induction in the lung. However, in control rats RU 486 enhanced neither the decrease in MAP nor the induction of iNOS in response to LPS (2 mg · kg-1, i.v.). Thus, cardiovascular tolerance to endotoxin is accompanied and explained by reduced induction of iNOS in vivo due to the elevation of endogenous glucocorticoid levels.

AB - An enhanced formation of nitric oxide (NO) due to induction of a calcium- independent (inducible) NO synthase (iNOS) contributes importantly to the cardiovascular failure caused by bacterial endotoxin. Repeated challenges with small doses of endotoxin result in tolerance to both peripheral vascular failure and death caused by subsequent injection of a higher dose of endotoxin. Here we investigate whether tolerance to endotoxin is associated with a lack of induction of iNOS in vivo and whether endogenous glucocorticoids play a role in the development of endotoxin tolerance. In anesthetized rats, i.v. administration of Escherichia coli endotoxin [lipopolysaccharide (LPS); 2 mg · kg-1] resulted in a prolonged decrease in mean arterial blood pressure (MAP) and hyporeactivity to the contractile responses elicited by norepinephrine (NE; 10 nM) in aortic rings ex vivo. Hyporeactivity to NE was partially reversed by N(G)-nitro-L-arginine methyl ester (0.3 mM) in vitro, suggesting that an enhanced formation of NO contributes to this hyporeactivity. There was a substantial increase in the activity of iNOS in the lung 3 h after i.v. injection of LPS (0.2 ± 0.1 to 6.6 ± 0.6 pmol · mg-1 · min-1; n = 5; P < 0.01). Rats injected i.p. with LPS (0.5 mg · kg-1) for 4 consecutive days became tolerant to an i.v. injection of LPS (2 mg · kg-1) in that both hypotension and vascular hyporeactivity to NE were significantly attenuated. Moreover, in these endotoxin-tolerant rats, the induction of iNOS by LPS in the lung was attenuated by 63% ± 6%. Injection of LPS caused a 9-fold increase in plasma corticosterone (CCS) levels within 2 h and CCS levels remained significantly elevated 6 and 24 h after LPS. Animals rendered tolerant to endotoxin by administration of a low dose of LPS (0.5 mg · kg-1, i.p.) for 4 days still had a 6-fold increase in plasma CCS levels 24 h after the last injection of LPS. When endotoxin-tolerant rats were treated with the glucocorticoid receptor antagonist RU 486 (50 mg · kg-1, p.o. 3 h prior to LPS), there was a restoration of the effects of LPS (2 mg · kg-1, i.v.) in causing hypotension, vascular hyporeactivity to NE, and iNOS induction in the lung. However, in control rats RU 486 enhanced neither the decrease in MAP nor the induction of iNOS in response to LPS (2 mg · kg-1, i.v.). Thus, cardiovascular tolerance to endotoxin is accompanied and explained by reduced induction of iNOS in vivo due to the elevation of endogenous glucocorticoid levels.

KW - contraction

KW - endotoxin shock

KW - RU 486

KW - tumor necrosis factor

KW - vasodilatation

UR - http://www.scopus.com/inward/record.url?scp=0028117232&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0028117232&partnerID=8YFLogxK

U2 - 10.1073/pnas.91.1.271

DO - 10.1073/pnas.91.1.271

M3 - Article

C2 - 7506416

AN - SCOPUS:0028117232

VL - 91

SP - 271

EP - 275

JO - Proceedings of the National Academy of Sciences of the United States of America

JF - Proceedings of the National Academy of Sciences of the United States of America

SN - 0027-8424

IS - 1

ER -