Essential fatty acid supplemented diet increases renal excretion of prostaglandin E2 and water in essential fatty acid deficient rats

Benzydamine inhibits osteoclast differentiation and bone resorption via down-regulation of interleukin-1 β expression

Bone diseases such as osteoporosis and periodontitis are induced by excessive osteoclastic activity, which is closely associated with inflammation. Benzydamine (BA) has been used as a cytokine-suppressive or non-steroidal anti-inflammatory drug that inhibits the production of pro-inflammatory cytokines or prostaglandins. However, its role in osteoclast differentiation and function remains unknown. Here, we explored the role of BA in regulating osteoclast differentiation and elucidated the underlying mechanism. BA inhibited osteoclast differentiation and strongly suppressed interleukin-1β (IL-1β) production. BA inhibited osteoclast formation and bone resorption when added to bone marrow-derived macrophages and differentiated osteoclasts, and the inhibitory effect was reversed by IL-1β treatment. The reporter assay and the inhibitor study of IL-1β transcription suggested that BA inhibited nuclear factor-κB and activator protein-1 by regulating IκB kinase, extracellular signal regulated kinase and P38, resulting in the down-regulation of IL-1β expression. BA also promoted osteoblast differentiation. Furthermore, BA protected lipopolysaccharide- and ovariectomy-induced bone loss in mice, suggesting therapeutic potential against inflammation-induced bone diseases and postmenopausal osteoporosis.

Metabolic utilization of linoleic acid from fat emulsion in infants during total parenteral nutrition

The metabolic utilization of linoleic acid (C18:2w6) from intravenous (iv) soybean oil emulsion via its conversion to higher homologues and prostaglandin biosynthesis was studied in 21 infants. The infants were of normal birth weight, in good clinical and metabolic condition, and aged from 1-4 months. They all received total parenteral nutrition after birth for more than 1 month; the only lipid was provided by iv Intralipid 20%, at levels approximating 350 mg/kg/24 h of linoleic acid (2.5% of the infants' total daily energy intake). Study of the fatty acids of plasma and erythrocyte phospholipids in these infants, compared to healthy controls of the same age (N = 26), showed that 350 mg/kg/24 hr of C18:2w6 supply resulted in normalization of erythrocyte phospholipid fatty acid distribution. This was particularly true of the higher homologues of C18:2w6 (C18:3w6, C20:3w6, and C20:4w6). This suggested that delta 6 and delta 5 desaturation activities are normal in these conditions with this C18:2w6 supply. These results were confirmed by the study of 24-hr urinary excretion of prostaglandins PGE1 and PGE2. With 350 mg/kg/24 hr of C18:2w6 supply their urinary levels were not significantly different from those observed in normal children of the same age receiving an equivalent oral C18:2w6 intake.

Prostaglandin E1: a review

Work on the structure of prostaglandin E1 (PGE1), isolated from natural sources, was completed 25 years ago (1). Shortly after, methods for the chemical synthesis of PG with their natural configuration were developed in the laboratories of the UpJohn Company (2) and of E. J. Corey (3) and, by the late sixties, PGE1 became widely available. The information since accumulated about its biological and clinical effects is more substantial than for any other PG. This review will draw together some of this information, focusing on recent studies of its mechanisms of action.

Plasma phospholipid fatty acids and urinary excretion of prostaglandins PGE1 and PGE2 in infants during total parenteral nutrition, with continuous or sequential administration of fat emulsion

During total parenteral nutrition, using an identical supply of fat emulsion (350 mg/kg/24 hr) to correct essential fatty acid deficiency in children, the efficacy of two methods of administration was studied: continuous over 24 hr, or discontinuous 3 hr/day. At the beginning of the study, all the infants (1-4 months old) had proven essential fatty acid deficiency. After at least 1 month of one of the two nutritional protocols (continuous or discontinuous), plasma phospholipid fatty acid composition and PGE1 and PGE2 urinary excretion were measured. The results obtained indicate better utilization of the fat emulsion when it is administered almost every day, in continuous infusion over 24 hr (1 g/kg/24 hr of Intralipid 20%).

[Comparison of the effect of linolenic acid and eicosapentaenoic acid on prostaglandin biosynthesis and thrombocyte function in humans]

Platelet aggregation, bleeding time, prostaglandin biosynthesis and plasma cholesterol fatty acids were investigated in 12 healthy females (25-32 years), who were given different amounts of linolenic acid (0%, 4%, 8%, 12%, 16% of total energy intake) or eicosapentaenoic acid (1.7%) with formula diets for 2 weeks each. Linolenic and eicosapentaenoic acids prolonged the bleeding time and inhibited platelet aggregation and prostaglandin biosynthesis. These effects became apparent after a linolenic acid intake of 12% of the energy intake. A decrease in PGE in 24 h urine was observed after intake of linolenic acid amounting to 8% of energy intake. Eicosapentaenoic acid influenced all parameters measured ten times more than linolenic acid. Linolenic acid intake had no effect on the ratio of linoleic/arachidonic acids in plasma cholesterol esters in contrast to in vitro findings. Thus energy intake comprising 1.7% of eicosapentaenoic acid is sufficient to affect thrombocyte function in man. The concomitant intake of linolenic-type fatty acids inhibits the biosynthesis of prostaglandins E2 and F2 alpha to different degrees.

Plasma and erythrocyte essential fatty acids during total parenteral nutrition in infants: effects of a cutaneous supply

In order to prevent essential fatty acid (EFA) deficiency induced by fat-free total parenteral nutrition (TPN), 10 infants on TPN were rubbed three times daily for 20 days using oenethera oil (80% EFA). Total EFA amount provided cutaneously was 1900 mg/kg/d. Plasma and red blood cells phospholipids were determined on days 1 and 20 in these 10 treated and six untreated infants on TPN and compared with those of normal control infants. On day 1, plasma nonessential FA including 20:3 n-9(p less than 0.01) were increased in both TPN groups while 18:2 n-6 and 18:3 n-3 (p less than 0.001 and p less than 0.01) were decreased. On the 20th day, EFA deficiency had worsened with a decrease in plasma level of 20:4 n-6 (p less than 0.02) and a higher than normal triene/tetraene ratio : 3.4 +/- 1.1 and 2.3 +/- 0.6 vs 0.1 +/- 0.1 (p less than 0.02). As for red blood cells phospholipids, 16:0 was increased and 18:2 n-6 and 20:3 n-6 were decreased (p less than 0.05) on day 1. On day 20, these FA were more abnormal while 20:3 n-9 became significantly increased (p less than 0.05). No difference was observed between the TPN groups at any time. These results show that cutaneous application of large amounts of EFA-rich oil is unable to prevent or cure TPN induced EFA deficiency.

Cardiovascular actions of dietary polyunsaturates and related mechanisms. A state-of-the-art-review

A survey of the effects of dietary polyunsaturates on the function of the cardiovascular system is given. In isolated hearts of rats dietary linoleate supply increases both coronary flow and heart muscle function. Hearts of rats fed high amounts of linoleic acid are protected against catecholamine (over)-stimulation. Polyunsaturate rich vegetable oils are effective in lowering blood pressure in several murine hypertension models. This effect seems to be closely related to antihypertensive changes in kidney function and in the function of the arterial vessel wall. Dietary polyunsaturates augment the hypotensive effect of antihypertensive drugs. Cardiovascular effects of dietary polyunsaturates are at least partly mediated via changes in the prostanoid metabolism as well as a reduction of the sympathetic activity. Evidence has been accumulated that cardiovascular effects of dietary polyunsaturates in animal and man are comparable. The observed effects are discussed against the background of a reduced risk of cardiovascular disease after a polyunsaturate rich diet in man.

Effectiveness of dietary essential fatty acid deficiency in development of a model of endogenous renal prostaglandin deficiency

An essential fatty acid deficient diet (EFAD) was administered to rats to determine the feasibility of using a model of endogenous arachidonic acid deficiency to study the role of prostaglandins in the kidney. Beginning at weaning rats were fed a diet containing less than 0.2% linoleic acid. Prostaglandin E (PGE) production was determined in vitro by stimulation of renal papillary slices with 1500 mOsm NaCl in Krebs-Henseleit buffer and in vivo by 24 hour urine collection. EFAD caused a reduction of arachidonic acid in the renal papilla to 13% of levels in control rats (P less than .0005). In vitro PGE release from incubated papillae of EFAD rats was barely detectable at baseline but increased with stimulation to approximately 50% of PGE levels observed in normal tissues. Urinary PGE, volume and sodium excretion were not significantly different between EFAD and control rats. These results suggest that despite significant differences in arachidonic acid stores between EFAD and normal rats, the usefulness of this animal model to study prostaglandin-mediated events may be limited by the residual capacity of the EFAD papilla to produce prostaglandin.

Metabolic products of arachidonic acid in rats

The pattern of eicosanoid metabolites appearing in urine and feces following oral administration of radioactive arachidonic acid was investigated using rats deficient in essential fatty acids. About 70-80% of the radioactivity in the urine during the first day after feeding was adsorbed to XAD-2 resin and represented eicosanoid metabolites, whereas the rest of the radioactivity was mainly 3H2O. The eicosanoid metabolites were fractionated into different polarity classes using reverse phase Sep-Pak C18 cartridges. Gas chromatographic analysis of the urinary metabolites following their derivatization into methyl ester-methoxime-tert-butyl-dimethylsilyl ethers revealed that nearly one-half of the metabolites had ECL values less than 22 and represented metabolites more oxidized than commonly described. Only 30% of the metabolites had ECL values between 26 to 32, corresponding to the values for the metabolites that originate from exogenously infused prostaglandins. A large portion of the eicosanoid metabolites was also excreted with the feces. The isotopic patterns from the reverse phase chromatography indicated that many of the fecal metabolites may be similar to those in urine although some metabolites in feces were not present in urine. Based on the specific radioactivity of the administered arachidonic acid, it appeared that at least 6 to 8 mg of eicosanoid metabolites were excreted through urine and feces within 24 hrs following an oral bolus of 60 mg arachidonic acid. The rapid increase and subsequent decrease in eicosanoid metabolite excretion after oral administration of arachidonate indicates that the dietary intake of polyunsaturated fatty acids may have a more rapid effect upon the endogenous production of eicosanoids than is generally recognized.

Essential function of linoleic acid esterified in acylglucosylceramide and acylceramide in maintaining the epidermal water permeability barrier. Evidence from feeding studies with oleate, linoleate, arachidonate, columbinate and alpha-linolenate

Essential fatty acid-deficient rats were supplemented with 300 mg per day of pure fatty acid esters: oleate (O), linoleate (L), arachidonate (A), and columbinate (C) for 10 days. During this period, the rats in groups L, A, and C all showed a decrease in their initially high trans-epidermal water loss, a classical essential fatty acid-deficiency symptom, to a level seen in non-deficient rats (group N). The trans-epidermal water loss in rats of group O was unaffected by the supplementation. Fatty acid composition of two epidermal sphingolipids, acylglucosylceramide and acylceramide, from the skin were determined. The results indicate that re-establishment of a low trans-epidermal water loss was associated with incorporation of linolenate into the two epidermal sphingolipids. Supplementation with columbinate resulted in relatively high amounts of this fatty acid in the investigated epidermal sphingolipids. Analysis of pooled skin specimens from a previous study in which weanling rats were fed a fat-free diet and supplemented orally with pure alpha-linolenate for 13 weeks (Hansen, H.S. and Jensen, B. (1983) Lipids 18, 682-690) revealed very little polyunsaturated fatty acid in the two sphingolipids. These rats showed increased evaporation which was comparable to that of essential fatty acid-deficient rats. We interpret these results as strong evidence for a very specific and essential function of linoleic acid in maintaining the integrity of the epidermal water permeability barrier. This function of linoleate is independent of its role as precursor for arachidonate and icosanoids.

The effect of iron overload on urinary excretion of immunoreactive prostaglandin E2

The effect of in vivo lipid peroxidation on the excretion of immunoreactive prostaglandin E2 (PGE2) in the urine of rats was studied. Weanling, male Sprague-Dawley rats were fed a vitamin E-deficient diet containing 10% tocopherol-stripped corn oil (CO) or 5% cod liver oil (CLO) with or without 40 mg dl-alpha-tocopheryl acetate/kg. To induce a high, sustained level of lipid peroxidation, some rats were injected intraperitoneally with 100 mg of iron as iron dextran after 10 days of feeding. Iron overload stimulated in vivo lipid peroxidation in rats, as measured by the increase in expired ethane and pentane. Dietary vitamin E reversed this effect. Rats fed the CLO diet excreted 9.5-fold more urinary thiobarbituric acid-reactive substances (TBARS) than did rats fed the CO diet. Iron overload increased the excretion of TBARS in the urine of rats fed the CO diet, but not in urine of rats fed the CLO diet. Dietary vitamin E decreased TBARS in the urine of rats fed either the CO or the CLO diet. Iron overload decreased by 40% the urinary excretion of PGE2 by rats fed the CO diet, and dietary vitamin E did not reverse this effect. Iron overload had no statistically significant effect on urinary excretion of PGE2 by rats fed the CLO diet. A high level of lipid peroxidation occurred in iron-treated rats, as evidenced by an increase in alkane production and in TBARS in urine in this study, and by an increase in alkane production by slices of kidney from iron-treated rats in a previous study [V. C. Gavino, C. J. Dillard, and A. L. Tappel (1984) Arch. Biochem. Biophys. 233, 741-747]. Since PGE2 excretion in urine was not correlated with these effects, lipid peroxidation appears not to be a major factor in renal PGE2 flux.

Apical-basolateral membrane asymmetry in canine cortical collecting tubule cells. Bradykinin, arginine vasopressin, prostaglandin E2 interrelationships

The studies reported here were designed to determine if there is an apical-basolateral asymmetry to the release of prostaglandins by or to the biochemical effects of prostaglandins on the renal collecting tubule. Canine cortical collecting tubule (CCCT) cells were isolated by immunodissection and seeded at supraconfluent densities on Millipore filters. The resulting confluent monolayer of CCCT cells: (a) developed and maintained a transcellular potential difference of 1 mV (apical side negative); (b) exhibited a permeability to inulin that was the same as that obtained with similar monolayers of Madin-Darby canine kidney (MDCK) cells; and (c) released adenosine 3',5'-cyclicmonophosphate (cAMP) in response to arginine vasopressin (AVP) added to the basolateral but not the apical surface of the monolayer. These results indicate that confluent monolayers of CCCT cells on Millipore filters have characteristics of asymmetry that are seen with intact collecting tubules. Moreover, PGE2 added to either side of the CCCT cell monolayer crossed the monolayer at the same slow rate as inulin, which demonstrated the feasibility of examining the sidedness of the effects of and the release of PGE2. Although AVP caused cAMP release only when added to the basolateral side of CCCT cells, AVP caused the release of PGE2 when added to either the apical or basolateral surface. This result implies that there are at least two AVP receptor systems, one coupled to cAMP synthesis and one to PGE2 formation. In contrast to the results observed with AVP, bradykinin caused PGE2 release only when added to the apical surface of CCCT cells, which suggested that urinary but not blood borne kinins elicit PGE2 formation by the canine collecting tubule. PGE2 was released in comparable amounts on each side of the monolayer in response both to AVP and to bradykinin. High concentrations (greater than or equal to 10(-8) M) of PGE2 added to either side of the monolayer caused the release of cAMP. However, at concentrations (10(-10) - 10(-12) M) at which PGE2 had no independent effect on cAMP release, PGE2 inhibited the release of cAMP, which normally occurred in response to AVP. This inhibition occurred with PGE2 added to either the apical or basolateral surface of the CCCT cell monolayer. PGE2 (10(-11) M) also inhibited the AVP-induced accumulation of intracellular cAMP by CCCT cells seeded on culture dishes. This inhibition was only observed when the cells were preincubated with PGE2 for greater than or equal to 20 min. Our results are consistent with the concept that inhibiton by prostaglandins of the hydroosmotic effect of AVP is due to inhibition of AVP-induced cAMP production. This inhibition does not appear to involve a direct physical interaction of PGE2 with the AVP receptor which is coupled to adenylate cyclase, since CCCT cells must be preincubated with PGE2 for 20 min for the inhibition to be observed, and since PGE2 added to the apical surface of CCCT cells inhibits cAMP release in response to AVP acting from the basolateral surface.

Extremely decreased release of prostaglandin E2-like activity from chopped lung of ethyl linolenate-supplemented rats

Three groups of weanling male rats were reared on a fat-free diet for 13 weeks. One group received only the fat-free diet (FF rats), the other 2 groups received the fat-free diet and a daily supplement of 2 energy% ethyl linoleate ([n-6] rats), or 2 energy% ethyl linolenate ([n-3] rats). The chopped lung preparation was used to illustrate an in vitro prostaglandin formation. PGE2-like activity was quantified on rat stomach strip. The release of PGE2-like activity expressed as ng PGE2-equivalent per g lung tissue (mean +/- SD) was 23 +/- 7, less than 6, and 65 +/- 20 for the FF rats, the (n-3) rats, and the (n-6) rats, respectively. PGE2 quantification by radioimmunoassay of the chopped lung effluent collected after passing over the rat stomach strip revealed the same release pattern as the bioassay. Fractionation of chopped lung effluent on HPLC with radioimmunoassay detection indicated that the lung tissue from (n-3) rats released very little PGE3, if any, in spite of a 20:5(n-3)/20:4(n-6) ratio of 5.2 in the lipids of the lung. It is suggested that the pool of arachidonic acid for prostaglandin production in vitro is different from the one which functions in vivo, and the these pools are differently affected by dietary EFA.

Urinary prostaglandin E2 and vasopressin excretion in essential fatty acid-deficient rats: effect of linolenic acid supplementation

Three groups of weanling male rats were fed on a fat-free diet for 13 weeks. One group received only the fat-free diet (FF rats), the other 2 groups received the fat-free diet and a daily supplement of 2 energy% ethyl linoleate ([n-6] rats), or 2 energy% ethyl linolenate ([n-3] rats). Urinary excretion of prostaglandin E2 (PGE2), immunoreactive arginine vasopressin (iAVP), and kallikrein were determined. PGE2 was quantitated with a radioimmunoassay having 4.9% cross-reactivity with prostaglandin E3 (PGE3). After 4 weeks on the diet, water consumption and urinary iAVP excretion increased significantly in the FF rats and the (n-3) rats compared with the (n-6) rats. Urinary PGE2 excretion was the same for all 3 groups during the first 10 weeks; thereafter it decreased in FF rats and (n-3) rats compared with the (n-6) rats. There was no difference in urinary PGE2 excretion between the FF rats and the (n-3) rats, even though large differences were found in the percentage of arachidonic acid (20:4[n-6]), icosapentaenoic acid (20:5[n-3]), and icosatrienoic acid (20:3[n-9]) of total kidney fatty acids as well as of kidney phosphatidylinositol fatty acids. Fractionation of urine extracts on high performance liquid chromatography with radioimmunoassay detection indicated that (n-3) rats excreted very little PGE3, if any. Urine output followed the same pattern, as did urinary PGE2 excretion. Urinary kallikrein was estimated at week 12 only. It was found to be significantly lower in FF rats and (n-3) rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Essential fatty acid-supplemented diet decreases renal excretion of immunoreactive arginine-vasopressin in essential fatty acid-deficient rats

Essential fatty acid (EFA)-deficient rats have been reported to have very concentrated urine and low urinary prostaglandin E2 (PGE2) excretion. Both parameters were normalized by feeding an EFA-supplemented diet (H.S. Hansen [1981] Lipids 16, 849-854). The urinary excretion rate of immunoreactive-arginine-vasopressin (iAVP) has been determined in these rats. The iAVP excretion rate was high: ca. 4.8 mU/24 hr, during the EFA-deficient period compared to the controls, 0.7-1.3 mU/24 hr. One day after the dietary change, iAVP excretion rate was still high, but it decreased significantly (p less than 0.05) at the second measurement 7 days later. It is suggested that the water-conserving effect of vasopressin 1 day after the dietary change was suppressed by the very high PGE2 production, resulting in normal renal water excretion. PGE2 and water excretion data were published in the paper just cited.