Fish oil-enriched diet is mucosal protective against acetic acid-induced colitis in rats.

Products of arachidonic acid metabolism are elevated in patients with inflammatory bowel disease and this elevation is correlated with disease activity. Eicosapentaenoic acid competes with arachidonic acid and alters eicosanoid biosynthesis. In this experiment, the possibility that eicosapentaenoic acid could be used in the treatment of inflammatory bowel disease was investigated by determining the effect of 6 weeks of a fish oil-supplemented diet, enriched in eicosapentaenoic acid, on colonic and ileal morphology, histology, and in vivo fluid absorption in rats with 4% acetic acid-induced colitis. The results of an eicosapentaenoic acid-enriched diet were compared with results of saturated and polyunsaturated fatty acid-enriched diets. In rats with misoprostol pretreated acetic acid-induced colitis, an eicosapentaenoic acid-enriched diet reversed net colonic fluid secretion to absorption and prevented macroscopic and histologic injury, compared with saturated and poly-unsaturated fatty acid-enriched diets, which did not. The fish oil mucosal protective effect occurred in the presence of a 30-fold enhancement of PGE2 synthesis. In rats with non-misoprostol pretreated acetic acid-induced colitis, an eicosapentaenoic acid-enriched diet returned ileal fluid absorption to control levels, as compared with saturated and polyunsaturated fatty acid-enriched diets, which did not. In conclusion, a fish oil (eicosapentaenoic acid)-enriched diet, but not a saturated- or a polyunsaturated-enriched diet, protected colonic and ileal net fluid absorption in an experimental model of inflammatory bowel disease.     

Effect of dietary fish oil on platelet aggregability: comparison between two oils with different eicosapentaenoic to arachidonic acid ratio.

Rats, acclimatized on a control diet, were fed for 60 days with diets, supplemented with 10% fat of either marine Hilsa fish (Hilsa ilisa) or fresh-water Chital fish (Notopterus chitala). The percentage of eicosapentaenoic acid in chital oil diet was 0.57 times that of the hilsa oil diet, but the eicosapentaenoic to arachidonic acid ratio in the latter (4.08) was 3.2 times that of the former (1.27). Otherwise these two diets were comparable in respect to total saturated, monounsaturated and n-3 polyunsaturated fatty acid contents. Results showed that of the two only hilsa oil diet could significantly lower platelet aggregability and in vitro thromboxane production, through replacement of arachidonic acid in platelet phospholipid by eicosapentaenoic acid. The antithrombic criteria of the oil seems to be a combination of low arachidonic acid content and high eicosapentaenoic to arachidonic acid ratio.     

Gender differences in eicosanoid production from macrophages of arthritis-susceptible mice

Collagen-induced arthritis (CIA) in rodents is an experimental animal model that shares many clinical and pathologic findings with rheumatoid arthritis in man. Our previous findings suggested that the amelioration of CIA in mice by a fish oil diet was associated with macrophage accumulation and metabolism of eicosapentaenoic acid and a subsequently altered prostaglandin (PG) profile. In these experiments, we examined the role of gender and found that macrophages from female arthritis-susceptible B10.RIII or B10.G mice synthesized more PG and thromboxane than macrophages isolated from the males. Compared with males, female mice had higher circulating anti-type II collagen antibodies but were less likely to develop CIA. Females, especially those on a fish oil diet, developed a much less severe disease than the males. This supports our hypothesis that the type and/or amount of eicosanoid produced from the macrophage may alter the course of experimentally induced arthritis.     

Pharmacokinetics and pharmacodynamics of injectable testosterone undecanoate in castrated cynomolgus monkeys (Macaca fascicularis) are independent of different oil vehicles

Testosterone undecanoate (TU) dissolved in soybean oil was developed in China to improve the pharmacokinetics of this testosterone ester in comparison with TU in castor or tea seed oil. As a pre-clinical primate model, three groups of five castrated cynomolgus macaques received either a single intramuscular injection of 10 mg/kg body weight TU in soybean oil, in tea seed oil, or in castor oil (equals 6.3 mg pure T/kg body weight for all preparations). Testosterone, estradiol, luteinizing hormone, and follicle-stimulating hormone as well as prostate volume, body weight and ejaculate weight were evaluated. After injection supraphysiological testosterone levels were induced. There were no significant differences in the pharmacokinetics of the three TU preparations for testosterone and estradiol. The gonadotropin levels showed a high individual variation. Prostate volumes increased equally in all groups after administration and declined to castrate level afterwards. The results suggest that TU in soybean oil produces similar effects as TU in the other vehicles. This study in non-human primates provides no objection to testing of this new preparation in humans.     

Fish oil reduces cholesterol and arachidonic acid content more efficiently in rats fed diets containing low linoleic acid to saturated fatty acid ratios

Rats were fed diets containing a high level of saturated fatty acids (hydrogenated beef tallow) versus a high level of linoleic acid (safflower oil) at both low and high levels of fish oil containing 7.5% (w/w) eicosapentaenoic and 2.5% (w/w) docosahexaenoic acids for a period of 28 days. The effect of feeding these diets on the cholesterol content and fatty acid composition of serum and liver lipids was examined. Feeding diets high in fish oil with safflower oil decreased the cholesterol content of rat serum, whereas feeding fish oil had no significant effect on the cholesterol content of serum when fed in combination with saturated fatty acids. The serum cholesterol level was higher in animals fed safflower oil compared to animals fed saturated fat without fish oil. Consumption of fish oil lowered the cholesterol content of liver tissue regardless of the dietary fat fed. Feeding diets containing fish oil reduced the arachidonic acid content of rat serum and liver lipid fractions, the decrease being more pronounced when fish oil was fed in combination with hydrogenated beef tallow than with safflower oil. These results suggest that dietary n-3 fatty acids of fish oil interact with dietary linoleic acid and saturated fatty acids differently to modulate enzymes of cholesterol and fatty acid metabolism.     

Modulation of CYP4502E1 and oxidative stress by testosterone in liver and kidney of benzene treated rats

Bilateral castration increased lipid peroxidation and consequently reduced glutathione in both liver and kidney. Testosterone administration reduced lipid peroxidation in the liver of castrated and benzene treated rats, however, reduced glutathione status could not be restored. Benzene depleted CYP4502E1 in castrated rats, however, the enzyme was restored in liver and kidney both after testosterone treatment. The results suggest that testosterone affects the metabolism and disposition of benzene by influencing CYP4502E1. Other hormonal and cellular/molecular factors may also alter the actions of testosterone. Testosterone dependent mechanism of toxicity of benzene in the liver and kidney has been discussed.     

Effect of neonatal androgenization on the testosterone feedback sensitivity in adult rats in two lighting conditions

Neonatally androgenized and intact adult male Wistar rats received daily, during 1 week, either testosterone propionate or sesame oil injections in periodic or constant light. Serum and pituitary gonadotropins and hypothalamic LHRH were measured. In periodic light, neonatal androgenization did not change the serum concentration or pituitary contents of gonadotropins, or the hypothalamic content of LHRH. Testosterone injections decreased serum concentration and pituitary content of gonadotropin of intact rats but failed to decrease the pituitary gonadotropin content of neonatally androgenized rats. In constant light, serum FSH was decreased in neonatally androgenized rats. Testosterone injections decreased both serum LH and FSH concentrations of intact rats but only serum LH of androgenized rats. Pituitary gonadotropin and hypothalamic LHRH contents remained unchanged. We conclude that neonatal androgenization renders the male rat hypothalamo-pituitary axis more resistant to changes of testosterone concentration in adulthood. Constant light did not sensitize the neonatally androgenized rats to testosterone, but on the contrary, testosterone injections were less effective in constant than in periodical light.     

Beneficial effect of fish oil on blood viscosity in peripheral vascular disease.

Reports suggest that the low incidence of ischaemic heart disease in Greenlandic Eskimos is related to the effect of a diet rich in eicosapentaenoic acid on platelet reactivity and plasma lipid concentrations. A double blind randomised investigation was therefore conducted of the effects on blood viscosity of dietary supplementation with an oil rich in this fatty acid (1.8 g/day, given as fish oil) and an eicosapentaenoic acid poor oil (as corn/olive oil) in patients with peripheral arterial disease. A statistically significant reduction in whole blood viscosity was observed at seven weeks in those patients receiving the eicosapentaenoic acid rich oil. No changes in plasma viscosity, haemoglobin concentration, packed cell volume, or platelet count were seen. A significant fall in plasma triglyceride concentration was also noted only in the patients receiving oil rich in eicosapentaenoic acid; plasma concentrations of cholesterol and high density lipoprotein cholesterol were unchanged. It is concluded that rheological changes that result from a diet rich in eicosapentaenoic acid may contribute to the suggested protective effects of such a diet against arterial disease and that such changes are of potential therapeutic importance in established arterial disease.     

Human absorption of fish oil fatty acids as triacylglycerols, free acids, or ethyl esters

The transient rise in plasma triacylglycerol fatty acids after single-dose ingestion of fish oil as triacylglycerols, free acids, or ethyl esters with linseed oil as an absorption standard was used to determine the relative absorption of fish oil fatty acids in eight men. As free acids, the fish oil fatty acids were well absorbed (greater than or equal to 95%). As triacylglycerols, eicosapentaenoic acid (1.00 g) and docosahexaenoic acid (0.67 g) were absorbed only 68% and 57% as well as the free acids. The ethyl esters were absorbed only 20% and 21% as well as the free acids. The incomplete absorption of eicosapentaenoic and docosahexaenoic acids from fish oil triacylglycerols correlates well with known in vitro pancreatic lipase activity.     

In vitro metabolism of 4-androstene-3,17-dione and testosterone by rat submaxillary gland.

Tritiated 4-androstene-3,17-dione and testosterone were incubated with submaxillary gland homogenates of male and female rats. The metabolism was predominately reductive. In 15 and 180 min incubations submaxillary tissue converted 4-androstene-3,17-dione chiefly to androsterone. Less testosterone, 17 beta-hydroxy-5 alpha-androstan-3-one, 5 alpha-androstane-3,17-dione, 5 alpha-androstane-3 alpha, 17 beta-diol, and 4-androstene-3 alpha, 17 beta-diol were also identified. Testosterone was converted to the same products plus 4-androstene-3,17-dione. 5 alpha-Androstane-3 alpha, 17 beta-diol was the major testosterone metabolite. Qualitatively the metabolism by male and female submaxillary gland was similar.     

Effects of Exogenous Testosterone on Parental Care Behaviours in Male Bluegill Sunfish (Lepomis macrochirus)

Androgens are known to mediate aggressive and defensive behaviour in many vertebrate species. However, high concentrations of androgens might also conflict with the expression of nurturing behaviours and therefore a trade‐off can exist between aggressive and nurturing behaviours during parental care. We explored the role of testosterone in paternal care in bluegill sunfish (Lepomis macrochirus), where males provide both sole defence of the young from predators and sole nurturing behaviour such as fanning of the eggs. At the onset of parental care, we manipulated testosterone levels in males using testosterone propionate implants. We then observed the frequency of nurturing and aggressive behaviours displayed by the males over 6 d of parental care. Testosterone‐implanted fish were more aggressive when presented with a brood predator, performing more bites, opercular flares and lateral displays than control males. Testosterone‐implanted males, however, were not less nurturing than control fish, performing similar levels of fanning and nest‐cleaning behaviours. Thus, our results support a positive relationship between testosterone and paternal aggression but no testosterone‐mediated trade‐off between paternal nurturing and aggression.     

The effect of eicosapentaenoic acid on leukotriene B production by human neutrophils

Eicosapentaenoic acid, which is a major fatty acid in fish oil, previously has been shown to competitively inhibit the cyclooxygenase-catalyzed metabolism of arachidonic acid in platelets. In the present study the effect of eicosapentaenoic acid on the production of leukotriene B via the lipoxygenase pathway in human neutrophils was examined. Eicosapentaenoate was incorporated into complex lipids of neutrophils at the same rate as arachidonate; release of the two homologous fatty acids in response to calcium ionophore A23187 was equivalent and both fatty acids were metabolized to a leukotriene B. The products derived from eicosapentaenoic acid were identified as leukotriene B5 and its stereoisomers. Eicosapentaenoate was a less favorable substrate for leukotriene B5 synthesis (94 ng/10(7) cells/5 min at 20 microM exogenous fatty acid) than arachidonate was for leukotriene B4 (401 ng under the same conditions). However, eicosapentaenoate or an oxygenated product inhibited arachidonate metabolism since at equimolar concentrations of eicosapentaenoate and arachidonate leukotriene B4 production was decreased by 68%. The inhibitory effect occurred at the level of leukotriene A hydrolase. The biological activity of eicosapentaenoate -derived products was tested; leukotriene B5 was found to have only approximately 10% of the potency of leukotriene B4 in inducing the aggregation of neutrophils, and the stereoisomers of leukotriene B5 were inactive. These data suggest that diets enriched in eicosapentaenoic acid affect neutrophils by decreasing the quantity of leukotriene B and by the production of a less potent leukotriene.     

Alteration of arachidonate levels in tick salivary glands by dietary modification of host blood lipids

Tick saliva contains prostaglandins of the 2-series, believed to facilitate bloodmeal acquisition. Because ticks cannot synthesize the prostaglandin precursor, arachidonic acid, investigations were undertaken to study the uptake, incorporation, and distribution of arachidonic acid in the salivary glands of the lone star tick in vitro and in vivo. Uptake of [³H]arachidonate by isolated salivary glands was reduced in the presence of low concentrations of arachidonic or eicosapentaenoic acids, but much higher, non-physiological concentrations of oleic and linoleic acids were required to inhibit [³H]arachidonate uptake. The incorporation of [³H]arachidonate into triglycerides increased at high concentrations of arachidonic or eicosapentaenoic acid, but not at any concentration of oleic or linoleic acid. Eicosatetraynoic acid greatly inhibited [³H]arachidonate uptake and increased intracellular unesterified [³H]arachidonic acid. Guinea pigs fed hydrogenated coconut oil, safflower/primrose oil, or fish oil exhibited altered blood lipids; notably increased levels of eicosapentaenoic acid when fed fish oil. Salivary gland lipids in ticks fed on these hosts were also altered. Ticks parasitizing fish oil-fed guinea pigs contained high levels of eicosapentaenoic acid with a 30% reduction in arachidonate levels. The results demonstrated that eicosapentaenoic acid in the host diet had profound effects on arachidonate assimilation by tick salivary glands, which could lead to altered prostaglandin content in tick saliva. © 1996 Wiley-Liss, Inc.     

Effect of age on the modification of rat plasma lipids by fish and soybean oil diets

The effects of sardine and soybean oils on plasma lipids have been studied in young and aged rats. Plasma cholesterol and bile acids of aged rats fed on a sardine oil diet decreased to a greater degree than those of young rats. Cholesterol, bile acids and phospholipids of the soybean oil diet group decreased only in aged rats. Increases in plasma eicosapentaenoic (sardine) and linoleic (soybean) acid levels of aged rats were observed to be greater than those of young rats. These results indicate that the age enhances the effects of fish and soybean oils on plasma lipids by suppressing their characteristic fatty acid metabolism.     

The hormonal control of scent marking and precopulatory behavior in male gray short-tailed opossums (Monodelphis domestica)

Little is known about the hormonal control of behavior in marsupials. In the present study, the effects of castration and of testosterone or estradiol replacement therapy on scent marking and precopulatory behavior in male gray short-tailed oppossums (Monodelphis domestica) were examined. It was found that castration resulted in decreases in chest and flank/hip marking displayed by male gray opossums. Testosterone but not estradiol stimulated chest marking in castrates. Males treated with either estradiol or testosterone displayed more flank/hip marking than control males. Highest levels of female aggression toward males were seen when the males had received testosterone treatment. These findings are discussed with respect to similarities and differences between marsupials and eutherians in the neural metabolism of testosterone and the hormonal control of scent marking behavior.     

Absorption of eicosapentaenoic acid and docosahexaenoic acid from fish oil triacylglycerols or fish oil ethyl esters co-ingested with a high-fat meal

The absorption of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from fish oil triacylglycerols and fish oil ethyl esters consumed in a high-fat meal (44 g total fat) by male volunteers was measured and compared to values previously reported for consumption in a low-fat meal (8 g total fat). Absorption of EPA, but not of DHA, from fish oil triacylglycerols was significantly improved from 69% to 90% by co-ingestion with the high-fat meal. Absorption of both EPA and DHA from fish oil ethyl esters was increased three-fold, to about 60%, by co-ingestion with the high-fat meal, indicating that absorption of fatty acid ethyl esters is highly dependent on the amount of co-ingested fat.     

Le déficit androgénique lié à l’âge: du diagnostic biologique au traitement substitutif

There is increasing interest in the assessment of testicular function in aging men, probably because of an increasing number of males above 60 years and because of the emerging gap in the medical management of aging between men and women. In the last three decades, the endocrinological problems of menopause have been thoroughly taken into consideration, while the decline in testis activity in the so called andropause was only recently recognized to deserve a similar interest. In fact, testis endocrine function is not so easy to evaluate in elderly men: total testosterone (tT) level declines very slowly and it is a fallacious index of testis function because of the increase in testosterone/estradiol binding globulin (TeBG) levels in aging males. Free testosterone level is an accurate index when measured by reference techniques, while routine direct assays using testosterone analogues have been proven to be unreliable diagnostic tools. The measurement of bioavailable testosterone (bT) after ammonium sulfate precipitation of TeBG-bound testosterone is currently considered as the method of choice for diagnosing ADAM syndrome. Indeed, in aging males, bT levels are more closely correlated than tT with bone mineral density, muscle strength and muscle mass. Bioavailable estradiol is also a reliable index of testis aging in elderly males and is strongly correlated with bone mineral density. Unfortunately a serious expertise is needed for accurate measurement of bioavailable estradiol levels. Another difficulty in the diagnosis of ADAM syndrome in the uncertainty in the bT threshold to be taken into account. The 5th percentile of bT levels in young adult men can be arbitrarily choosen; however, there is no definite proof that such a threshold is totally appropriate, since no data are available regarding the evolution with years of androgen receptor sensitivity. Nevertheless, identifying androgen deficiency by means of bT measurement may lead to hormone replacement therapy, at least as a therapeutic test. Several formulations of testosterone are currently available using oral, intra-muscular and transdermal routes. Testosterone undecanoate (Pantestone®) is given orally and is supposed to reach the blood stream via the lymph thoracic channel. Intra-muscular testosterone in oil (Androtardyl® and Testosterone Heptylate®) can maintain high testosterone levels for two to three weeks, but can also induce supra-physiological levels of testosterone and dihydrotestosterone (DHT) within the first week after injection. Transdermal formulations have been recently proposed as non-invasive ways to administer testosterone while by-passing liver metabolism. Permeation enhanced transdermal system (Androderm®) can mimic the testosterone circadian rythm, but testosterone levels may be supra-physiological for several hours. DHT levels however are generally maintained whithin physiological values. Testosterone gel (Androgel®) can induce stable and physiological levels of testosterone, DHT and estradiol. Care should be taken to avoid contamination of the familial environment by testosterone after its application. The choice between these formulations depends obviously on the patient’s needs, the patient’s requests, and the patient’s compliance with a particular formulation.     

Steroid hormones and agonistic behavior in a cichlid teleost, Aequidens pulcher

The effects of three steroid hormones on the agonistic behavior of female Aequidens pulcher have been evaluated. Testosterone, estradiol, and cortisol were tested using an immersion technique to minimize trauma, and we also examined metyrapone, a blocker of cortisol biosynthesis. Two different experimental protocols were employed, the first investigating agonistic interactions within groups of fish, and the second examining the responses of isolated fish to models and mirrors. Differences between replicates were small, and both protocols supported similar conclusions. Each of the three hormones produced a characteristically different spectrum of behaviors when compared to the controls. Testosterone increased agonistic behavior in all experimental situations, while estradiol had a generally opposite effect; this may reflect the natural modulation of behavior by hormones during the reproductive cycle of A. pulcher. Cortisol also had distinct behavioral effects; available evidence suggests that this steroid increases submissive components of agonistic behavior, and that observed increases in some aggressive components are an indirect consequence, dependent upon the feedback of social information received by each fish. Metyrapone treatment greatly reduced all agonistic behaviors, groups of fish forming shoals typical of juveniles. This was not reversed by replacement therapy with cortisol, which suggests that metyrapone affects behavior by an alternative, possibly toxic, mechanism.     

Effects of testosterone and β‐glucan on immune functions in tench

A hormone manipulation was performed to examine the effects of testosterone on basal and β‐glucan‐induced immune functions in wild‐caught male and female tench Tinca tinca . Testosterone administration elevated testosterone concentration in plasma, but did not suppress lytic activity of plasma or the chemiluminescence response of blood or head kidney phagocytes in any of the three successive samples or in any of the treatment groups. Both testosterone and β‐glucan administrations had a negative effect on the relative mass of the spleen, and testosterone‐treated fish lost more mass than control fish. Males had a relatively larger spleen than females, but there were no gender differences in immune function. β‐glucan‐administration did not affect the plasma testosterone concentration.