Estradiol Treatment Ameliorates Acetic Acid-Induced Gastric and Colonic Injuries in Rats

pp1060-ifla-477274 IFLA.cls November 25, 2003 11:29

Inflammation, Vol. 27, No. 6, December 2003 (C© 2003)

Estradiol Treatment Ameliorates Acetic Acid-InducedGastric and Colonic Injuries in Rats

Omer Gunal,1 Berna K. Oktar, 2 Emine Ozcınar,3 Mustafa Sungur,4

Serap Arbak,3 and Berrak C. Yegen2,5

Abstract—To evaluate the role of estrogen treatment on the healing of acetic acid-induced gastricor colonic injury, rats were given 17β estradiol benzoate (0.001, 0.1, and 10 mg/kg) or vehicle for7 days (following the induction of ulcer) or 4 days (following the induction of colitis) until they weredecapitated. Food intake and fecal output were decreased by estradiol treatment but gastric emptyingrate was not changed. Estradiol (10 mg/kg) reduced gastric ulcer index and colonic damage scorecompared to vehicle-treated groups. SEM and light microscopy demonstrated a significant reductionin the severity of ulcers and colitis by estradiol treatment. Gastric microscopic score was not changedby estradiol treatment, whereas in the colonic tissue score was significantly reduced. Elevated gastricMPO levels were reduced in gastric but not in colonic tissues as compared with corresponding vehiclegroups. In conclusion, exogenous estradiol treatment at pharmacological doses improves the healingof both gastric and colonic injury induced by acetic acid in rats.

KEY WORDS: acetic acid; myeloperoxidase; estradiol; experimental colitis; ulcer index.

INTRODUCTION

Several clinical observations and animal experiments haveled to speculation concerning the possible effects of sexsteroids on gastrointestinal function. Gastric mucosal ero-sions were shown to be enhanced in male rats in compari-son with females following oral administration of ethanol(1, 2). In humans, peptic ulcer disease is more frequentin men than in women (3, 4). During pregnancy, hemor-rhage or perforation from gastroduodenal ulceration hasshown to be rare compared to its higher incidence in puer-

1Department of General Surgery, D¨uzce School of Medicine, AbantIzzetBaysal University, D¨uzce, Istanbul, Turkey.

2Department of Physiology Marmara University School of Medicine,Istanbul, Turkey.

3Department of Histology and Embryology, Marmara University Schoolof Medicine,Istanbul, Turkey.

4Student at Marmara University School of Medicine,Istanbul, Turkey.5To whom correspondence should be addressed at Marmara Uni-versity School of Medicine Haydarpa¸sa, Istanbul, 34668, Turkey.E- mail: [email protected]

perium (3). Similarly, symptoms such as abdominal pain,stomach pain, and diarrhea have been reported to increaseduring the premenstrual and menses phases (5). Enhancedabdominal pain and colonic motor disturbances are com-monly observed in patients with irritable bowel syndrome(IBS) and IBS is more common in women than men (6).Gue (7) has demonstrated that a gender difference existsin the sensitivity to rectal distension in both normal andstressed rats.

Sex steroids are shown to alter response of thehypothalamo-pituitary–adrenal (HPA) axis to stress andgender differences in the levels of ACTH and glucocor-ticoids have long been recognized (8). Moreover, clin-ical and experimental evidence indicates that gonadalsteroids can modify immunological function mediated bythe HPA and immune axis and sexual dimorphism is ev-ident during the acute phase of inflammatory processes(9). Studies have demonstrated that female animals shownormal or enhanced immune response after trauma as op-posed to a markedly decreased immune response in malemice (10), while the castration of male mice before the

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352 Gunal, Oktar,Ozcınar, Sungur, Arbak, and Ye˘gen

induction of trauma prevents the occurrence of immun-odepression (11). We have previously demonstrated thatestrogen and antiandrogen treatments ameliorate remoteorgan inflammation induced by burn injury in rats (12).On the other hand, it was also shown that pretreatmentwith testosterone aggravated cysteamine-induced gastro-duodenal mucosal injury (13). It has been recently sug-gested that hormonal therapy, consisting of estrogen or anestrogen–progesterone combination, significantly reducesthe need for blood transfusions and is a promising symp-tomatic therapy for severe gastrointestinal bleeding seenin the elderly or in chronic radiation colitis (14, 15).

Therefore, the aim of this study was to assess thepossible therapeutic effects of exogenous estrogen on thehealing course of acetic acid-induced gastric or colonicinjury in the rats.

MATERIALS AND METHODS

Animals

Wistar Albino rats (250–300 g) of both sexes werekept in a light- and temperature-controlled room on a12:12-h light–dark cycle, where the temperature (22±0.5◦C) and relative humidity (65–70%) were kept con-stant and fed a standard diet and waterad libitum. Experi-ments were approved by the Marmara University, Schoolof Medicine, Animal Care and Use Committee. Inductionof gastric or colonic damage was conducted under briefether anesthesia.

Induction of Gastric Ulcers

Rats were made to fast overnight with free accessto water. Ulcers were induced using a model modifiedfrom that originally described by Okabe and Pfeiffer (16).Briefly, under ether anesthesia, a midline laparotomy wasperformed and the stomach was gently exteriorized. Halfa milliliter of acetic acid (HAc; 80%, vol/vol) was pouredthrough the barrel of a 3-mL syringe placed on the serosalsurface of the stomach in the corpus region and allowed toremain in contact for 1 min. Then, the fluid was aspiratedoff carefully and the area that remained in contact withacid was gently rinsed with saline. The area exposed toHAc was nearly 60 mm2. After the application of HAc,the rats were allowed to recover from anesthesia and re-ceived normal chow and waterad libitumfor the following7 days until they were sacrificed. It was previously demon-strated that these ulcers became chronic within 2–3 days

and healed completely within 2–3 weeks without perfora-tion or penetration to the surrounding organs as describedin the original technique (17, 18).

Induction of Colitis

Under light ether anesthesia 1 mL of 5% aceticacid (HAc; pH= 2.6) solution was instilled through apolyethylene tubing inserted 7 cm from the anal verge.Subsequent to 1 min exposure of HAc to colonic mucosa,1 mL of K2HPO4 (pH = 8.2) was infused through thesame catheter for neutralizing HAc. After the applicationof HAc, the rats (n = 8) were allowed to recover fromanesthesia and received normal chow and waterad libi-tum for the following 4 days until they were sacrificed.It is reported that this reproducible inflammatory model,which heals within 2–3 weeks in rats, mimics some clini-cal features of human IBD (19).

Drugs

Rats were treated subcutaneously with either 17β

estradiol benzoate (0.001, 0.1, and 10 mg/kg, Sigma;n = 16) or vehicle (1 mL/kg; olive oil, Komili;n = 16)for 4 days (following the induction of colitis) or 7 days(following the induction of ulcer) until they were decapi-tated.

Food Intake and the Determinationof Gastric Emptying Rate

On the 6th day following the induction of ulcer, foodintake was evaluated as the intake of preweighed standardchow (g)/100 g of body weight in 24 h. Animals weredeprived of food overnight (14 h), and 50 g of preweighedrat chow was delivered. Pellets and spillage were collectedand weighed at the end of the feeding periods.

On the 7th day, after 16 h of fasting, rats were given15 g of standard laboratory pellet chow and water ad libi-tum. After 3 h, spilled pellets were removed and the foodintake was recorded. Water intake was stopped for the next5 h, after which the rats were decapitated. The stomachswere removed and weighed with the contents, then openedalong the greater curvature from fundus to the pylorus.After removing the contents, the stomach was washed inwarm saline, blotted dry, and the empty stomach weightwas recorded. Gastric emptying of a solid nutrient mealwas calculated using the formula:

Gastric emptying (%)= 1−(gastric content (g)/3 hfood intake (g))×100 (20).


Estradiol Improves Gut Inflammation 353

Assessment of Ulcer Index

On the 7th day after ulcer induction, as the stomachswere opened along the greater curvature for the determi-nation of gastric emptying rate, lesions were examinedmacroscopically to measure the length of ulcers (ulcer in-dex; mm) along their greatest diameters.

Fecal Output and Evaluation of Colonic Damage

On the 4th day following the colitis induction, stoolvolume and the number of fecal pellets were measuredto express the fecal output as the average stool weight(mg/number) in 24 h.

On the third day following the intracolonic adminis-tration of HAc, the last 8-cm of colon was excised, openedlongitudinally, and rinsed with saline. The macroscopicscoring of the colonic damage was performed using thefollowing criteria: 0,no damage; 1, localized hyperemia,no ulcers; 2, ulceration without hyperemia or bowel wallthickening; 3, ulceration with inflammation at one site;4, two or more sites of ulceration/inflammation; 5, ma-jor sites of damage extending more than1 cm along thelength of colon; 6–10,if damage extends more than2-cmalong length of colon, score is increased by one for eachadditional1-cm damage(21).

Measurement of Myeloperoxidase Activity

Myeloperoxidase (MPO) activity levels were mea-sured in 0.2–0.5 g samples of gastric or colonic tissues.The tissue samples were homogenized in 10 vol of ice-cold potassium phosphate buffer (20 Mm K2HPO4, pH=7.4). The homogenate was centrifuged at 12,000 rpm for10 min at 4◦C and the supernatant was discarded. Thepellet was then rehomogenized with an equivalent vol-ume of 50 mM K2HPO4 containing 0.5% (w/v) hexade-cyltrimethylammonium bromide (HETAB). MPO activitywas assessed by measuring the H2O2-dependent oxidationof o-dianisidine.2HCl. One unit enzyme activity is definedas the amount of the MPO present that causes a change inabsorbance of 1.0/min at 460 nm and 37◦C (22).

Histologic Examination and Analysis

Light Microscopy and Scanning Electron Microscopy

Stomachs and colonic tissues were excised and fixedin 10% aqueous neutral-buffered formaldehyde. Five-µm-thick histological sections were cut and stained with hema-

toxylin and eosin (H. E.) and examined with OlympusBH-2 photomicroscope.

For scanning electron microscopy (SEM), gastric orcolonic tissues were fixed for 2 h in a 2.5% phosphatebuffered glutaraldehyde solution and postfixed for 1 h in1% osmium tetroxide solution. Specimens were passedfrom increasing ethyl alcohol and amyl acetate series. Af-ter drying the tissue samples with a “BIORAD” criticalpoint dryer and gold coating with BIORAD SC502, tissuesamples were examined under a JEOL 5200 JSM scanningelectron microscope.

Microscopic scoring of the gastric and colonic tis-sues were made by an observer unaware of the treatmentcondition of the animal. Grading of the histopathologi-cal findings were made by giving the scores 0,none; 1,mild; 2, moderate; 3, severe, for each of the followingcriterion: epithelial desquamation, hemorrhage, glandularirregularity, eosinophilic infiltration, vasocongestion. Anadditional criterion in the scoring of colonic tissues wasinterstitial edema. At least five microscopic areas wereexamined to score each specimen and the total damagescores were calculated as the sum of the scores given foreach criterion (23); that is, maximum score which couldbe obtained was “15” in the ulcer and “18” in the colitisgroups.

Statistical Analysis

All data are expressed as means± SEM with8–10 rats per group. Instat statistical package (GraphPadSoftware, San Diego, CA) was used. Following the assur-ance of normal distribution of data, one-way analysis ofvariance (ANOVA) with the Tukey–Kramer post hoc testwas used for multiple comparison. Values ofp < 0.05were regarded as significant.

RESULTS

Serosal application of acetic acid resulted in thereproducible formation of spherical ulcers (p < 0.05;Fig. 1A), while light microscopic analysis demonstrateda significant surface epithelial desquamation, prominenthemorrhage, and total disruption of the glandular or-ganization in the stomachs of vehicle-treated animals(Fig. 2A). In the rats treated with either dose of estradiol,gastric microscopic scores were significantly reduced,while slight epithelial degeneration, restricted regions ofhemorrhage, and moderately disrupted glands were no-ticed (Fig. 1B and 2B). However, macroscopic appearance



Fig. 1. (A) The effect of oil (vehicle) or 17β estradiol (0.001, 0.1, and 10 mg/kg) on ulcer index and colonic macroscopic damage score followinginduction of gastric ulcer or colitis with acetic acid.∗ p < 0.05, compared to vehicle-treated group. (B) The effect of oil (vehicle) or 17β estradiol(0.001, 0.1, and 10 mg/kg) on microscopic damage scores following induction of gastric ulcer or colitis with acetic acid.∗∗∗ p < 0.001, comparedto vehicle-treated group. (C) Myeloperoxidase activities in gastric and colonic tissues of rats which were treated with oil (vehicle) or estradiol(10 mg/kg), following induction of gastric ulcer or colitis with acetic acid.∗∗∗ p < 0.001, compared to control groups;++ p < 0.01, compared tovehicle-treated groups.

of the ulcer and the ulcer index were significantly reducedat only 10 mg/kg dose, but not at lower doses. Similarly,evaluation of the mucosal injury in the colon revealed thatestradiol treatment at only 10 mg/kg dose for 4 days signif-icantly reduced the macroscopic damage score (p < 0.05;Fig. 1A) when compared with the vehicle-treated colitis

group. Light microscopic evaluation of the colonic tissuesof the vehicle-treated colitis group demonstrated extremesurface epithelial desquamation, significant hemorrhage,extensive disruption in the glandular architecture with in-testinal edema (Fig. 3A). Vasocongestion and eosinophiliawere strongly detected in histological sections. On the



Fig. 2. (A) In the vehicle-treated gastric ulcer group, light micrography indicates epithelial desquamation (→) and hemorrhage with disrupted glands(>). H and E× 66. (B) In the estradiol-treated (10 mg/kg) gastric ulcer group, light micrographs demonstrate a slight epithelial desquamation(→) and restricted regions of hemorrhage (*). H and E× 66. (C) In the vehicle-treated gastric ulcer group, scanning electron micrograph indicatesepithelial desquamation (*), fibrin deposits, and hemorrhage with erythrocytes (>). Bar= 10µm. (D) In the estradiol-treated (10 mg/kg) gastric ulcergroup, scanning electron micrograph indicates a good topography of gastric epithelium with slightly widened gastric pits (*) and few erythrocytes.Bar= 10µm.

other hand, the reductions in the colonic microscopicscores obtained by all the three doses of estradiol weresimilar (p < 0.001, Fig. 1B) with comparably less dam-aged surface epithelium. Hemorrhage areas in the mucosa,intestinal edema and vasocongestion were moderate, witha mild degree of eosinophilia (Fig. 3B). Since the high-est dose of estradiol was found to be effective in reduc-ing both the macroscopic and microscopic damage scoresof gastric and colonic tissues, this pharmacological doseof 10 mg/kg was used to assess the therapeutic action ofestradiol in the rest of the experiments.

In accordance with the light microscopic results,analysis of the surface epithelium by SEM also veri-

fied a moderate degree of epithelial degeneration in theestradiol-treated (10 mg/kg) group (Fig. 2D), while in thevehicle-treated group (Fig. 2C) epithelial desquamationwas more prominent with fibrin deposits and erythrocytes.Vasocongestion and a mild degree of eosinophilia wereevident in groups with both treatment regimens. Simi-larly, SEM analysis of colonic epithelium revealed a nor-mal topography with slight degree of degeneration in theestradiol-treated (10 mg/kg) group (Fig. 3D), while sur-face topography was extremely disrupted with epithelialdesquamation in the vehicle group (Fig. 3C).

Following serosal application of acetic acid MPO ac-tivity was significantly elevated in the gastric tissues of



Fig. 3. (A) In the vehicle-treated colitis group, light micrography indicates extreme surface epithelial desquamation (→), hemorrhage (*), eosinophilia(**), and extensive disruption in the glandular architecture. H and E× 33. (B) In the estradiol-treated (10 mg/kg) colitis group, light micrographsdemonstrate moderate edema and mild degree of eosinophilia (*). H and E× 33. (C) In the vehicle-treated colitis group, scanning electron micrographindicates that surface topography was extremely disrupted with epithelial desquamation (→). Bar= 10µm. (D) In the estradiol-treated (10 mg/kg)colitis group, scanning electron micrograph indicates a normal topography with slight degree of colonic epithelial degeneration (→). Bar= 10µm.

the vehicle group, when compared with the control group(p < 0.001), while treatment with estradiol inhibited thedegree of gastric MPO activity (p < 0.01; Fig. 1C). Intra-colonic administration of acetic acid, led to an elevationin the MPO activity of colonic tissue, compared with thecontrol group (p < 0.001), while estradiol treatment hadno significant effect on the elevated level of colonic MPOactivity (Fig. 1C).

On the 6th day of gastric ulcer, rats in both vehicle-treated (4.4± 0.6 g/100 g bw) and estradiol-treated (3.3±0.5 g/100 g bw) groups consumed significantly less ratchow when compared with the control group (13.7±2.3 g/100 g bw;p < 0.01). In the vehicle- (58.9± 7.4%)or estradiol- (56.1± 8.2%) treated rats, gastric empty-

ing rates determined on the 7th day of gastric ulcer werenot significantly different from the control values (70.7±3.5%). In the colitis-induced animals, average stool weightin a day was found to be increased in the vehicle-treatedrats (275.0± 31.7 mg/pellet number) with respect tocontrol (176.1± 8.9 mg/pellet number;p < 0.05) an-imals, while estradiol treatment reduced average fecaloutput back to control level (169.3± 23.5 mg/pelletnumber).

DISCUSSION

In contrast to previous clinical or experimental stud-ies related with the effects of endogenous sex hormones on



gastrointestinal functions, much less is known about thepossible therapeutic effect of estradiol on gastric or colonicerosions. The results of this study demonstrate that estra-diol treatment at pharmacological doses accelerates thehealing of gastric and colonic inflammation in rats. As ev-ident from the histological analysis and the gross appear-ance of the damaged tissues, post-injury treatment withestradiol has a facilitative effect on the healing process.Although neutrophil-predominant inflammatory responsein the gastric tissue was suppressed by estradiol treatment,the healing-promoting effect of estradiol on the colonic tis-sue appears to be independent of the neutrophil-mediatedinflammatory response.

Peptic ulcer disease is less frequent among pregnantwomen and more frequent in men than in women (4).Since the sexual dimorphism of gastroduodenal ulcers iswell-known, the actions of sex hormones were studied invarious ulcer models. Some investigators found that thefemale sex hormones have significant antiulcer activity inalmost all models (24), some documented that administra-tion of estradiol dose dependently augmented gastric andduodenal mucosal lesions induced by cysteamine (25, 26).On the other hand, inhibition of endogenous testosteroneled to protection, while exogenous testosterone aggravatedagainst gastroduodenal injury provoked by cysteamine(13). Our results show that the severity of gastric ulcerinduced by serosal acetic acid application is attenuatedby estradiol treatment. The appearance of lesion areas inestradiol-treated group is significantly less disrupted withslight epithelial degeneration, restricted regions of hem-orrhage, and only moderately disrupted glandular orga-nization, concomitant with a significantly reduced micro-scopic score. Moreover, as observed by the SEM analyses,estradiol treatment alleviates the epithelial degeneration,indicating the facilitatory effect of estradiol on the healingof gastric mucosal injury. High level of MPO activity ingastric tissues of vehicle-treated group demonstrated thepresence of a neutrophil-predominant inflammatory re-sponse. Since neutrophils are capable of releasing a widevariety of deleterious mediators, including reactive oxy-gen species, that can destroy cells and dissolve connectivetissue, and thereby retard wound healing, attenuation inneutrophil infiltration into the damaged tissue by estradiolsuggests that the healing-promoting effect of estradiol maybe in part dependent on reduced neutrophil infiltration intothe inflamed tissue.

The antiulcer activity of estrogen was previouslyexplained by its stimulatory effect on parietal cell ac-tivity and the maintenance of mucus integrity (24). Theprotective effect of estrogen on endothelial function in-

cludes the antioxidant properties, the cause of vasodi-lation, the prevention of platelet thrombus, and the pro-motion of angiogenesis (27). Several studies support theidea that estrogen-induced vasoprotective effect may bedue to the release of nitric oxide (NO) from the vascu-lar endothelium (28). This is consistent with the Westernblot analysis demonstrating an increase in neuronalNO synthase (nNOS) protein in the gastric fundus andcolon of estradiol- and estradiol plus progesterone-treatedanimals (29).

It has been hypothesized that testosterone receptorblockade inhibits the vasoconstrictive actions of throm-boxane A2, enhances the release of vasodilator prostacy-clin in the aortic-coronary circulation, or both leading toa better organ perfusion after trauma (30). Recently, wereported the therapeutic effects of estrogens on distantorgan inflammation because of burn injury (12). Our re-sults suggested that estradiol has a limiting effect on tissueinjury by depressing neutrophil infiltration and by inhibit-ing the release of inflammatory mediators, such as TNF-α. Moreover, it was shown that estradiol inhibits TNF-α

both in vivo and in vitro (31). In fact, TNF-α may causeleukocyctes to adhere to the vascular endothelium wherethey discharge other mediators that amplify the vasculardamage.

On the 7th day following the induction of gastriculcer, gastric emptying rate in both vehicle- and estradiol-treated rats was found nearly at control levels, indicatingthe absence of any alteration in the gastric motor activ-ity either by ulcer or estradiol treatment. However, foodintake was significantly reduced because of the presenceof ulcer. There is direct and indirect evidence that estra-diol has an inhibitory effect on feeding via the HPA axis(32). However, despite the high dose used in this study,as compared with the aferomentioned study, estradiol hadno further effect on already reduced meal size. It also ap-pears that estradiol, while facilitating the healing processof gastric ulcer, had no beneficial effects on the recoveryof gastric functions.

Epidemiological studies have demonstrated that anincreased risk of IBD occurs among users of high es-trogen dose oral contraceptives (33). Moreover, sponta-neous ischemic colitis was found almost exclusively inwomen and was found to be associated with the use ofexogenous estrogenic agents (34) or pregnancy (35). Itwas also reported that women with irritable bowel syn-drome were more likely to recall exacerbations of bowelsymptoms (36). In contrast to these observations, recentlyit was suggested that estrogen–progesterone combinationshould be considered as a new symptomatic therapy when



multiple degenerative lower gastrointestinal bleeding le-sions are beyond the reach of therapeutic endoscopy lead-ing to high transfusion needs and when surgical risk isunacceptably high (14, 15). In the present study, we alsoevaluated the putative beneficial effects of estradiol in anexperimental colitis model. Consistent with the effectson gastric tissue, estradiol treatment for a week, attenu-ated the colonic damage as assessed both macroscopicallyand microscopically. Anti-inflammatory effect of estra-diol on colonic injury may be attributed to its antioxidant,vasodilatory, antithrombotic, and angiogenetic activities(27). Furthermore, it may be speculated that estradiol ex-erts its healing-promoting effects probably by interferingwith the synthesis and release of proinflammatory me-diators. In contrast to gastric inflammatory response, re-sults from the colonic MPO assay clearly demonstratedthat the anti-inflammatory effects of estradiol may not beattributed to the extent of neutrophil infiltration into thedamaged colon. It was previously demonstrated that 85%reduction in colonic neutrophil content (MPO activity)failed to attenuate any of the indices of acetic acid-inducedcolonic injury (37). Taken together with the present re-sults, it may be suggested that neutrophils do not play acrucial pathogenetic role in the development of colonicinjury. Thus, mechanisms involved in estradiol-enhancedamelioration in colonic damage do not include an influ-ence on neutrophil recruitment. Concomitant with the im-provement in colitis by estradiol, daily fecal output wasalso reduced back to control levels, clinically verifying thehealing of colonic injury.

Our data indicate that exogenous estradiol treatmentsignificantly improves the healing of both gastric andcolonic injury induced by acetic acid in rats. This studysuggests that short-term, high-dose estradiol treatmentmay be effective in stimulating the healing processes ofgastric or colonic injuries. In light of a few case studiesthat show the therapeutic potential of estradiol, results ofthis study indicate that further studies are necessary to de-lineate and clarify the mechanisms whereby sex steroidsare effective in treating gastrointestinal injuries.

REFERENCES

1. Laszlo, F., E. Amani, Cs. Varga, and F. A. Lászlo. 1992. Influenceof sex hormones on ethanol-induced gastric haemorrhagic erosionsin rats.Acta Physiol. Hung.80:289–292.

2. Laszlo, F., E. Amani, G. Karácsony, E. Szabó, B. Rengei, Cs. Varga,and F. A. Laszlo. 1993. The modulatory role of endogenous vaso-pressin in the phenomenon that orally administered ethanol gener-ates more severe gastric erosions in male than in female rats.Ann.N.Y. Acad. Sci.689:623–629.

3. Aston, N. O., S. Kalaichadran, and J. V. Carr. 1991. Duodenal ulcerhemorrhage in the puerperium.Can. J. Surg.34:482–483.

4. Michaletz Onody, P. A. 1992. Peptic ulcer disease in pregnancy.Gastroenterol. Clin. North Am.21:817–826.

5. Heitkemper, M. M., J. F. Shaver, and E. S. Mitchell. 1988. Gastroin-testinal symptoms and bowel patterns across the menstrual cycle indysmenorrhea.Nurs. Res.37:108–113.

6. Almy, T. P. 1967. Digestive disease as a national problem, II. A whitepaper by the American Gastroenterological Association.Gastroen-terology53:821.

7. Gue, M., C. Barnier, C. Del Rio, J. Moré, J. Fioramonti, and L.Bueno. 1997. Gender difference in rectal sensitivity to distensionrats: Role of sexual hormones.Gastroenterology93:15–18.

8. Critchlow, V., R. A. Liebelt, M. Bar-Sela, W. Mountcastle, and H. S.Lipscomp. 1963. Sex difference in resting pituitary-adrenal function.Am. J. Physiol.205:807–815.

9. Davletov, E. G., S. A. El’chaninova, V. B. Rozen, and O. V. Smirnova.1990. Changes in the testosterone levels in the serum and androgenreceptor levels in the liver during experimental burns in immaturerats.Vopr. Med. Khim.36:49–50.

10. Wichmann, M. W., R. Zellweger, C. M. DeMaso, A. Ayala, and H. I.Chaudry. 1996. Improved immune responses in females as opposedto decreased immune responses in males following hemorrhagicshock and resuscitation.Cytokine8:853–863.

11. Wichmann, M. W., A. Ayala, and H. I. Chaudry. 1997. Male sexsteroids are responsible for depressing macrophage immune functionafter trauma hemorrhage.Am. J. Physiol.273:C1335–C1340.

12. Ozveri, E. S., A. Bozkurt, G. Haklar, S¸ , Cetinel, S. Arbak, C. Ye˘gen,and B. C. Yegen. 2001. Estrogens ameliorate remote organ inflam-mation induced by burn injury in rats.Inflamm. Res.50:585–591.

13. Laszlo, F., Cs. Varga, C. Montoneri, and F. Drago. 1997. Damagingactions of testosterone on cysteamine-induced gastroduodenal ulcer-ation and vascular leakage in the rat.Eur. J. Pharmacol.337:275–278.

14. Cacoub, P., A. Sbai, Y. Benhamou, P. Godeau, and J. C. Piette. 2000.Severe gastrointestinal hemorrhage secondary to diffuse angiodys-plasia: Efficacy of estrogen–progesterone treatment.Presse. Med.29:139–141.

15. Wurzer, H., I. Schafhalter-Zoppoth, G. Brandstatter, and H. Stranzl.1998. Hormonal therapy in chronic radiation colitis.Am. J.Gastroenterol.93:2536–2538.

16. Okabe, S. and C. J. Pfeiffer. 1972. Chronicity of acetic acid ulcer inthe rat stomach.Am. J. Dig. Dis.17:619–629.

17. Konturek, S. J., T. Brzozowski, A. Dembinski, Z. Warzecha,P. K. Konturek, and N. Yanaihara. 1988. Interaction of growthhormone-releasing factor and somatostatin on ulcer healing and mu-cosal growth in rats. Role of gastrin and epidermal growth factor.Digestion41:121–128.

18. Okabe, S., C. J. Pfeiffer, and I. L. A. Roth. 1971. A method forexperimental penetrating ulcer in rats.Am. J. Dig. Dis.916:277–284.

19. Elson, C. O., R. B. Sartor, G. S. Tennyson, and R. H.Riddell. 1995. Experimental models of inflammatory bowel disease.Gastroenterology109:1344–1367.

20. Robert, A., A. S. Olafsson, C. Lancaster, and W. R. Zhang. 1991.Interleukin-1 is cytoprotective, antisecretory, stimulates PGE2 syn-thesis by the stomach and retards gastric emptying.Life Sci.48:123–134.

21. Wallace, J. L., P. Braquet, G. C. Ibbotson, W. K. Macnoughton, andG. Cirino. 1989. Assesment of the role of platelet activating factorin an animal model of inflammatory bowel disease.J. Lipid Med.1:13–23.

22. Bradley, P. P., D. A. Priebat, R. D. Christerser, and G. Rothstein.1982. Measurement of cutaneous inflammation: Estimation of neu-trophil content with an enzyme marker.J. Invest. Dermatol.78:206–209.



23. Russel, R. I. 1990. Endoscopic evaluation of etodolac and naproxenand their relative effects on gastric and duodenal prostaglandins.Rheumatol. Int.10(Suppl.):17–21.

24. Aguwa, C. N. 1984. Effects of exogenous administration of femalesex hormones on gastric secretion and ulcer formation in the rat.Eur. J. Pharmacol.104:79–84.

25. Szepes, Z., E. Morschl, J. Kiss, I. Pavo, B. J. Whittle, C. Varga,F. A. Laszlo, and F. Laszlo. 1999. Detrimental effects of estradiolon cysteamine-induced gastroduodenal ulceration in the female rat.J. Physiol. Paris93:491–494.

26. Drago, F., C. Montoneri, C. Varga, and F. L´aszlo. 1999. Dual effectof female sex steroids on drug-induced gastroduodenal ulcers in therat.Life Sci.64:2341–2350.

27. Lindh, A., K. Carlstrom, J. Eklund, and N. Wilking. 1992. Serumsteroids and prolactin during and after major surgical trauma.ActaAnaesthesiol. Scand.36:119–124.

28. Shan, J., L. M. Resnick, Q-Y. Liu, X-C. Wu, M. Barbagallo,and P. K. T. Pang. 1994. Vascular effects of 17β-estradiolin male Sprague–Dawley rats.Am. J. Physiol. 266:H967–H973.

29. Shah, S., L. Nathan, R. Singh, Y. S. Fu, and G. Chaudhuri. 2001. E2and not P4 increases NO release from NANC nerves of the gastroin-testinal tract: Implications in pregnancy.Am. J. Physiol.280:R1546–R1554.

30. Wichmann, M. W., R. Zellweger, C. DeMaso, A. Ayala,and H. I. Chaudry. 1996. Mechanism of immunosupression

in males following trauma-hemorrhage.Arch. Surg.131:1186–1192.

31. Squadrito, F., D. Altavilla, G. Squadrito, G. M. Campo, M. Arlotta,V. Arcoraci, L. Minutoli, A. Saitta, and A. P. Caputi. 1997. Theinvolvement of tumour necrosis factor-α in the protective effects ofthe 17-β oestradiol in splanchnic ischaemia-reperfusion injury.Br.J. Pharmacol.121:1782–1788.

32. Geary, N. and L. Asarian. 1999. Cyclic estradiol treatment normal-izes body weight and test meal size in ovariectomized rats.Physiol.Behav.67:141–147.

33. Boyko, E. J., M. K. Theis, T. L. Vaughan, and B. Nicol-Blades. 1994.Increased risk of inflammatory bowel disease associated with oralcontraceptive use.Am. J. Epidemiol.140:268–278.

34. Deana, D. G. and P. J. Dean. 1995. Reversible ischemic colitis inyoung women. Association with oral contraceptive use.Am. J. Surg.Pathol.19:454–462.

35. Frossard, J. L., L. Spahr, P. E. Queneau, B. Armenian, M. A.Brundler, and A. Hadengue. 2001. Ischemic colitis during pregnancyand contraceptive medication.Digestion64:125–127.

36. Whitehead, W. E., L. J. Cheskin, B. R. Heller, C. Robinson, M. D.Crowell, C. Benjamin, and M. Schuster. 1990. Evidence for exacer-bation of irritable bowel syndrome during menses.Gastroenterology98:1485–1489.

37. Buell, M. G. and M. C. Berin. 1994. Neutrophil-independence of theinitiation of colonic injury: Comparison of results from three modelsof experimental colitis in the rat.Dig. Dis. Sci.39:2575–2588.

Estradiol Treatment Ameliorates Acetic Acid-Induced Gastric and Colonic Injuries in Rats

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