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Arachidonic Acid’s Role in Stress and Shock

Also see:
Resuscitation: Benefits of ATP, Glucose, and Sodium
Trauma & Resuscitation: Toxicity of Lactated Ringer’s Solution
Sunburn, PUFA, Prostaglandins, and Aspirin
Phospholipases, PUFA, and Inflammation
Dietary PUFA Reflected in Human Subcutaneous Fat Tissue
Toxicity of Stored PUFA
PUFA – Accumulation and Aging
Brain Swelling Induced by Polyunsaturated Fats (PUFA)
Fish Oil Toxicity
Estrogen’s Role in Asthma
PUFA Decrease Cellular Energy Production
Benefits of Aspirin
Protective “Essential Fatty Acid Deficiency”
Anti-Inflammatory Omega -9 Mead Acid (Eicosatrienoic acid)
Unsaturated Fats and Lung Function

“In adults, prostaglandins are known to be involved in many of the harmful effects of inflammation. They are formed from the polyunsaturated fats, linoleic acid and arachidonic acid, which we are unable to synthesize ourselves, so the adult’s exposure to the prostaglandins is influenced by diet.” -Ray Peat, PhD

“The remarkable resistance of “essential fatty acid deficient” animals to shock (Cook, et al., 1981; Li et al., 1990; Autore, et al., 1994) shows that the polyunsaturated fats are centrally involved in the maladaptive reactions of shock. The cellular changes that occur in shock–calcium retention, leakiness, reduced energy production–are seen in aging and the degenerative diseases; the stress hormones and free fatty acids tend to be chronically higher in old age, and an outstanding feature of old age is the reduced ability to tolerate stress and to recover from injuries…” -Ray Peat, PhD

Adv Shock Res. 1981;6:83-91.
Implications for thromboxane A2 in the pathogenesis of endotoxic shock.
Wise WC, Cook JA, Halushka PV.
During endotoxemia there is increased synthesis of arachidonic-acid-derived metabolites. We investigated the potential deleterious role of the proaggregatory vasoconstrictor, thromboxane A2, an arachidonic acid metabolite, in the endotoxic shocked rat. Plasma levels of thromboxane B2, the stable metabolite of thromboxane A2, 6-keto-PGF1 alpha, the stable metabolite of PGI2, and PGE were measured via radioimmunoassay. We also investigated the therapeutic efficacy of the fatty acid cyclo-oxygenase imidazole and 7(1-imidazolyl)-heptanoic acid (7-IHA), in endotoxic shocked rats. Thirty minutes after intravenous (IV) administration of Salmonella enteritidis endotoxin (20 mg/kg), plasma immunoreactive thromboxane B2 (TxB2) was increased from nondetectable levels (less than 200 pg/ml) in normal nonshocked rats to 2207 +/- 282 pg/ml (N = 16). The 6-keto-PGF1 alpha level was increased from nondetectable levels to 840 +/- 59 pg/ml (N = 8), and prostaglandin E rose from 146 +/- 33 to 2160 +/- 606 pg/ml (N = 5). Ibuprofen (3.75 mg/kg) or indomethacin (10 mg/kg) administered IV 30 min prior to endotoxin (20 mg/kg) improved the survival rate to 81% (N = 15, P less than 0.001) and 78% (N = 17, P less than 0.001), respectively, compared to the 24-hr survival of 8% (N = 26) in the vehicle-treated rats. Ibuprofen also inhibited the endotoxin-induced elevation of TxB2, 6-keto-PGF1 alpha, and fibrinogen/fibrin degradation products. Imidazole (30 mg/kg) or 7-IHA (30 mg/kg), IV, 30 min prior to endotoxin improved survival 65% (N = 11) and 81% (N = 15), respectively. These drugs also inhibited endotoxin-induced elevations in TxB2 and fibrinogen/fibrin degradation products, but did not inhibit endotoxin-induced elevations in plasma PGE. These results are consistent with the suggestion that TxA2 plays a role in the pathogenesis of endotoxic shock.

J Clin Invest. 1980 Jan;65(1):227-30.
Elevated thromboxane levels in the rat during endotoxic shock: protective effects of imidazole, 13-azaprostanoic acid, or essential fatty acid deficiency.
Cook JA, Wise WC, Halushka PV.
The potential deleterious role of the proaggregatory vasoconstrictor, thromboxane A(2), in endotoxic shock was investigated in rats. Plasma thromboxane A(2) was determined by radioimmunoassay of its stable metabolite thromboxane B(2). After intravenous administration of Salmonella enteritidis endotoxin (20 mg/kg), plasma thromboxane B(2) levels increased from nondetectable levels (<375 pg/ml) in normal control rats to 2,054+/-524 pg/ml (n = 8), within 30 min to 2,071+/-429 at 60 min, and decreased to 1,119+/-319 pg/ml, at 120 min. Plasma levels of prostaglandin E also increased from 146+/-33 pg/ml in normal controls (n = 5) to 2,161+/-606 pg/ml 30 min after endotoxin (n = 5). In contrast to shocked controls, rats pretreated with imidazole, a thromboxane synthetase inhibitor, or essential fatty acid-deficient rats, which are deficient in arachidonate and its metabolites, did not exhibit significant elevations in plasma levels of thromboxane B(2). Imidazole did not however inhibit endotoxin-induced elevations in plasma prostaglandin E. Essential fatty acid deficiency significantly reduced mortality to lethal endotoxic shock. This refractoriness could be duplicated in normal rats pretreated with the fatty acid cyclo-oxygenase inhibitor, indomethacin (10 mg/kg), intravenously 30 min before endotoxin injection. Imidazole (30 mg/kg) administered intraperitoneally 1 h before or intravenously 30 min before endotoxin, also significantly (P < 0.01) reduced mortality from lethal endotoxin shock to 40% compared to a control mortality of 95% at 24 h. Likewise pretreatment with 13-azaprostanoic acid (30 mg/kg), a thromboxane antagonist, reduced mortality from endotoxic shock at 24 h from 100% in control rats to only 50% (P < 0.01). The results suggest that endotoxin induces increased synthesis of thromboxane A(2) that may contribute to the pathogenesis of endotoxic shock.

Adv Shock Res. 1981;6:93-105.
Essential fatty acid deficient rats: a new model for evaluating arachidonate metabolism in shock.
Cook JA, Wise WC, Knapp DR, Halushka PV.
Essential fatty acid deficient (EFAD) rats are significantly more resistant to the lethal effects of S. enteritidis endotoxin (20 mg/kg, IV) than normal control rats. Compared to endotoxin-treated normal rats, EFAD rats also manifested less severe alterations of hepatic and lysosomal integrity and became less hypoglycemic. Administration of the ethyl ester of the essential fatty acid, arachidonic acid (100 mp, IP) two days prior to challenge with S. enteritidis endotoxin (20 mg/kg) in EFAD rats restored their sensitivity to endotoxin, as denoted by a 100% mortality compared to a 24% mortality (P less than 0.01) in EFAD rats.Treatment of EFAD rats with the fatty acid docosahexaenoic acid, a non-prostaglandin and thromboxane precursor, (100 mg, IP) produced significantly less (less than 0.01) mortality than ethyl-arachidonate-treated groups (ie, 40% vs 100%). The arachidonate metabolite, thromboxane B2 (TxB2), increased from nondetectable plasma levels (less than 200 pg/ml) to 2285 +/- 449 pg/ml (N = 10) at 30 min and remained elevated for 180 minutes after endotoxin administration in nondeficient rats. However, plasma TxB2 was not detectable in endotoxin-treated EFAD rats and was only slightly elevated in groups supplemented with docosahexaenoic acid (273 +/- 104 pg/ml, N = 6) after 30 minutes. In ethyl arachidonate (100 mg, IP) supplemented EFAD rats, plasma TxB2 rose to 873 +/- 204 pg/ml (N = 8), 30 min after endotoxin. Pretreatment of the ethyl-arachidonate-supplemented EFAD group with a specific thromboxane synthetase inhibitor, 7-(1-imidazolyl)-heptanoic acid (30 mg/kg, IV), significantly reduced mortality 100% to 50% (P less than 0.05) from endotoxic shock. These observations suggest a deleterious role for arachidonic acid and its conversion to TxA2 in the pathogenesis of endotoxic shock.

Circ Shock. 1990 Jun;31(2):159-70.
Resistance of essential fatty acid-deficient rats to endotoxin-induced increases in vascular permeability.
Li EJ, Cook JA, Spicer KM, Wise WC, Rokach J, Halushka PV.
Resistance to endotoxin in essential fatty acid-deficient (EFAD) rats is associated with reduced synthesis of certain arachidonic acid metabolites. It was hypothesized that EFAD rats would manifest decreased vascular permeability changes during endotoxemia as a consequence of reduced arachidonic acid metabolism. To test this hypothesis, changes in hematocrit (HCT) and mesenteric localization rate of technetium-labeled human serum albumin (99mTc-HSA) and red blood cells (99mTc-RBC) were assessed in EFAD and normal rats using gamma-camera imaging. Thirty minutes after Salmonella enteritidis endotoxin, EFAD rats exhibited less hemoconcentration as determined by % HCT than normal rats (47 +/- 2% vs. 54 +/- 1% respectively, P less than 0.01). Endotoxin caused a less severe change in permeability index in the splanchnic region in EFAD rats than in normal rats (1.2 +/- 0.6 x 10(-3)min-1 vs. 4.9 +/- 1.7 x 10(-3)min-1 respectively, P less than 0.05). In contrast to 99mTc-HSA, mesenteric localization of 99mTc-RBC was not changed by endotoxin in control or EFAD rats. Supplementation with ethyl-arachidonic acid did not enhance susceptibility of EFAD rats to endotoxin-induced splanchnic permeability to 99mTc-HSA. Leukotrienes have been implicated as mediators of increased vascular permeability in endotoxin shock. Since LTC3 formation has been reported to be increased in EFA deficiency, we hypothesized that LTC3 may be less potent than LTC4. Thus the effect of LTC3 on mean arterial pressure and permeability was compared to LTC4 in normal rats. LTC3-induced increases in peak mean arterial pressure were less than LTC4 at 10 micrograms/kg (39 +/- 5 mm Hg vs. 58 +/- 4 mm Hg respectively, P less than 0.05) and at 20 micrograms/kg (56 +/- 4 mm Hg vs. 75 +/- 2 mm Hg respectively, P less than 0.05). LY171883 (30 mg/kg), an LTD4/E4 receptor antagonist, attenuated the pressor effect of LTC4, LTD4, and LTC3. Infusion of LTC4 (4 micrograms/kg/min) in normal rats induced a rise in HCT from 44 +/- 1% to 51 +/- 1% (P less than 0.01), which was greater (P less than 0.05) than the rise induced by LTC3 (47 +/- 1% to 49 +/- 1%). The results showing that EFAD rats are resistant to endotoxin-induced increases in HCT and vascular permeability raise the possibility that this may, in part, be a result of preferential LTC3 production that is less potent than LTC4.

Journal of Applied Physiology August 1989 vol. 67 no. 2 811-816
Essential fatty acid-deficient rats are resistant to oleic acid-induced pulmonary injury
H. A. Ball, J. A. Cook, K. M. Spicer, W. C. Wise, and P. V. Halushka
Because leukotrienes and prostaglandins are inflammatory mediators derived from arachidonic acid, their potential role in oleic acid-induced lung injury was evaluated in control and in essential fatty acid-deficient (EFAD) rats depleted of arachidonic acid substrate. In control rats, oleic acid (0.06 ml/kg iv) increased the pulmonary permeability index (measured by scintigraphy) from -10 +/- 13 x 10(-6) s-1 to 217 +/- 20 x 10(-6) s-1 and 118 +/- 13 x 10(-6) s-1 at 5 and 50 min (P less than 0.05), respectively. It also caused arterial hypoxemia at 30 min (P less than 0.05). Compared with saline controls, oleic acid increased bronchoalveolar lavage fluid levels of immunoreactive (i) LTC4/D4, iLTB4, (P less than 0.01), and 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha) (P less than 0.05). In EFAD rats, oleic acid failed to significantly increase the lung permeability index at 5 and 50 min. In contrast to control rats, oleic acid failed to cause hypoxemia in the EFAD rats. Bronchoalveolar lavage levels of iLTB4 and i6-keto-PGF1 alpha after oleic acid in EFAD rats were lower compared with oleic acid controls, whereas iLTC4/D4 in the oleic acid EFAD group was not decreased. Treatment with intraperitoneal ethyl arachidonate (400 mg over 2 wk) reversed the resistance of EFAD rats such that the pulmonary edema (P less than 0.05) was evident after oleic acid. This latter group also manifested a significant (P less than 0.05) rise in the bronchoalveolar lavage levels of iLTB4 and i6-keto-PGF1 alpha. These results suggest that arachidonic acid metabolites contribute to oleic acid-induced pulmonary permeability.

INTENSIVE CARE MEDICINE Volume 12, Number 3, 116-126
Role of thromboxane, prostaglandins and leukotrienes in endotoxic and septic shock
H. A. Ball, J. A. Cook, W. C. Wise and P. V. Halushka
Intravenous bolus endotoxin elicits a marked but transient increase in plasma TxB2 and 6-keto-PGF1 in a large number of species. A smaller, delayed and more prolonged increase in TxB2 and 6-keto-PGF1 are reported in animals with septic shock, i.e., those with fecal peritonitis or cecal ligation. Thromboxane synthetase inhibitors or antagonists attenuate endotoxin-induced acute cardiopulmonary changes, the delayed increase in serum lysosomal enzymes, fibrin/fibrinogen degradation products and the thrombocytopenia in a number of species. While these drugs increase survival of rats or mice following endotoxin they do not alter survival of rats in septic shock. These results support the hypothesis that TxA2 exerts a pathophysiologic effect in shock following bolus endotoxin. In contrast, nonsteroidal antiinflammatory drugs (NSAID) and dietary essential fatty acid deficiency increase survival of rats subjected to endotoxin shock, and survival time in models of septic shock. These results also suggest that some other cyclooxygenase product(s) is involved in septic shock due to fecal peritonitis or cecal ligation. Preliminary experimental studies indicate salutary effects of leukotriene inhibitors and antagonists in endotoxin shock and in models of acute pulmonary injury. Clinical studies have demonstrated elevated plasma TxB2 and 6-keo-PGF1 concentrations in patients with septic shock, and elevated LTD4 in pulmonary edema fluid of patients with the adult respiratory distress syndrome. In view of these clinical and experimental results, clinical trials of NSAID and/or leukotriene inhibitors/antagonists should be considered.

Am J Vet Res. 2008 Feb;69(2):199-207.
Roles of thromboxane A2 and 5-hydroxytryptamine in endotoxin-induced digital vasoconstriction in horses.
Menzies-Gow NJ, Sepulveda MF, Bailey SR, Cunningham FM, Elliott J.
OBJECTIVE:
To evaluate the roles of 5-hydroxytryptamine (5-HT), thromboxane A2 (TxA2), and platelet-activating factor (PAF) in endotoxin-induced digital hypoperfusion in horses.
ANIMALS:
6 healthy adult Thoroughbreds.
PROCEDURES:
Horses were treated with IV administration of saline (0.9% NaCl) solution (control treatment) or the 5-HT 1B/D selective antagonist, GR55562 (0.3 mg/kg), prior to tryptamine infusion (1.6 microg/kg/min for 30 minutes) to establish an effective GR55562 dose. In a crossover study, horses were treated with IV administration of saline solution (control treatment), aspirin (4 mg/kg, 2 hours or 4 days before lipopolysaccharide [LPS] infusion), GR55562 (0.3 mg/kg), the PAF antagonist WEB2086 (3 mg/kg), or aspirin plus GR55562 prior to LPS infusion (30 ng/kg for 30 minutes). Digital blood flow was measured by use of Doppler ultrasonography. Concomitant measurements of hoof wall and coronary band surface temperatures were made. Serial blood samples were collected and plasma 5-HT and TxA2 concentrations determined.
RESULTS:
GR55562 abolished tryptamine-induced digital hypoperfusion. Neither WEB2086 nor GR55562 affected LPS-induced alterations in digital perfusion or plasma mediator concentrations. Aspirin given 2 hours before LPS administration abolished the increase in plasma TxA2 concentration and significantly attenuated LPS-induced digital hypoperfusion. Aspirin given 4 days before LPS significantly attenuated the increase in plasma TxA2 concentration and digital hypothermia. Aspirin plus GR55562 had a greater effect on LPS-induced digital hypothermia than aspirin alone.
CONCLUSIONS AND CLINICAL RELEVANCE:
Thromboxane A2 and 5-HT played a role in mediating LPS-induced digital hypoperfusion in horses. Platelet-activating factor appeared unimportant in mediating LPS-induced 5-HT or TxA2 release or digital hypoperfusion.

Prostaglandins, Leukotrienes and Medicine Volume 11, Issue 2, June 1983, Pages 179–188
Protective effects of thromboxane A2 on endotoxin shock
Sumio Fukumoto, Kenzo Tanaka
To elucidate the role of thromboxane A2 in the development of endotoxin shock following administration of endotoxin, the effects of three thromboxane A2 synthetase inhibitors, (E)-3-(4-(l-imidazolyl)phenyl)-2-propenoic acid hydrochloride monohydrate (OKY-046), sodium (E)-3-(4-(3-pyridylmethyl)phenyl)-2-methylacrylate (OKY-1581) and imidazole were examined. Intravenous administration of E. Coli endotoxin (3 mg/kg) produced shock and all rats died within ten hours. Pretreatment with thromboxane A2 synthetase inhibitors markedly improved the survival rates. The untreated endotoxin shock group showed marked increase in thromboxane B2 levels in the venous blood, while no such changes were seen in the pretreated groups. There were no statistically significant differences in 6-keto prostaglandin F1α levels in the venous blood. In the untreated shock group, micrathrombi were observed in 64 % of the glomeruli in the kidneys two hours after endotoxin injection. In the groups pretreated with OKY-046, OKY-1581 and imidazole, microthrombi were seen only in 22, 19 and 24%, respectively. Thus, thromboxane A2 plays an important role in the development of endotoxin shock and thromboxane A2 synthetase inhibitors, in particular OKY-046 and -1581, are prophylactic.

Am J Physiol. 1989 Oct;257(4 Pt 2):H1192-9.
Lung injury caused by cobra venom factor is reduced in rats raised on an essential fatty acid-deficient diet.
Morganroth ML, Schoeneich SO, Till GO, Pickett W, Ward PA.
Arachidonate metabolites appear to be involved in lung injury caused by cobra venom factor (CVF)-induced complement and polymorphonuclear leukocyte (PMN) activation. These studies were designed to assess the effects of a dietary-induced deficiency of arachidonic acid on CVF-induced lung injury. Rats raised on an essential fatty acid-deficient (EFAD) diet exhibited the expected changes in fatty acid composition including decreased plasma levels of arachidonic acid and increased levels of 5,8,11-eicosatrienoic acid. In intact rats raised on the EFAD diet, CVF-induced lung injury was attenuated. When blood and excised lungs from rats raised on the normal diet were used, CVF caused pulmonary vascular constriction and acute lung injury, as evidenced by increased 125I-labeled bovine serum albumin accumulation in lung parenchyma and alveolar lavage fluid. The CVF-induced pulmonary artery pressor response and lung injury were reduced when blood perfusate or blood perfusate and excised lungs were obtained from rats raised on the EFAD diet. The pulmonary vascular constriction and lung injury were not attenuated when the blood perfusate was obtained from rats raised on the normal diet, irrespective of whether the excised lungs were obtained from rats raised on the normal or EFAD diet. PMNs obtained from rats raised on the EFAD diet demonstrated decreased superoxide production as well as impaired random migration and chemotaxis in vitro. In contrast, beta-glucuronidase release was quantitatively similar to PMNs from control rats. These data indicate that the EFAD diet-induced attenuation of CVF-induced pulmonary hypertension and acute lung injury is due to defective effector cells in blood rather than modified pulmonary target tissue.

Kidney Int. 1992 May;41(5):1245-53.
Essential fatty acid deficiency normalizes function and histology in rat nephrotoxic nephritis.
Takahashi K, Kato T, Schreiner GF, Ebert J, Badr KF.
The central lipid abnormality in essential fatty acid deficiency (EFAD) is the lack of availability of arachidonic acid. To examine the role of total eicosanoid’s biosyntheses in the pathology and pathophysiology of glomerulonephritis, EFAD was induced in weanling rats, which were then subjected to antiglomerular basement membrane antibody (NTS)-induced injury in adulthood. Glomerular dynamics (as assessed by micropuncture), quantitative histology, and eicosanoid generation rates were measured at two hours and two weeks post-NTS, and compared to those of standard diet-fed (STD) controls. Two hours post-NTS, and despite the occurrence of proteinuria in both EFAD and STD animals, glomerular dynamics were essentially normal in EFAD rats, whereas STD animals had reduced values for glomerular filtration rate (GFR) and renal plasma flow rate (RPF). At two weeks, severe histologic changes were observed in STD animals including mesangial and stalk hypercellularity, moderate sclerosis, and interstitial nephritis, coupled with heavy proteinuria and reduced GFR and RPF. In dramatic contrast, EFAD rats displayed totally normal glomerular structures and functions. In parallel, glomerular generation rates of prostaglandin E2 and thromboxane A2 were suppressed markedly in EFAD rats. Thus, EFAD confers complete protection against the histopathologic and functional sequelae of immune-initiated injury in the glomerulus. The data suggest that the initial wave of complement-induced neutrophil infiltration (with resultant proteinuria) is not sufficient to perpetuate injury into the more destructive chronic phases. The results provide strong impetus for the design of more specific interventional therapies targeting the various enzymes and products of arachidonic acid metabolism in the attempts to control glomerular inflammation.

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