各種 stress가 痢疾아메바 感染에 미치는 影響

Abstract

[한글]

[영문]

Introduction

There has been much work all aspects of Entamoeba histolytica since Losch (1875) found the trophozoite of this parasite. However, little has been written on stress and its effect on parasites.

Tarczynski(1962) demonstrated that parasites may produce stress in the host, thus supporting Poster(1960), who pointed out that parasites may predispose the host to other infectious organisms and aggravate any infection present in the host.

Teodorovic et al. (1963) gave evidence of an adrenal effect. They observed a marked exacerbation of E. histolytica pathogenicity in mice treated with corticosteroids. Conversely, Villarejos (1962) reported that cortisone did not increase the susceptibility of the rat to amebiasis.

Various workers have reported that testosterone causes susceptibility of the gonadectomized animal-host to its parasitic infection in contrast to the effect of ergosterone on female mice (Campbell, 1939; Addis and Solomon, 1964; von Haam and Rosenfeld, 1942; Dobsone, 1961).

The present study is designed to discover whether or not physical, sex hormonal, and toxic bacterial stimulation affects intestinal amebiasis in the rat.

Materials and Methods

1. Cultivation of E. histolytica.

In the modified diphasic medium containing 4 ml. of buffered saline E. histolytica was cultured at 37。C., and suhcultured at a two day interval.

2. Strain of E. histolytita.

YS-9 which was sampled from Cheju-do, Korea was used.

3. Identification of the pathogenicity of E. histolytica in experimental rats.

a) Inoculation technique:

150-180 gm rats, confirmed to be amebae-free, and which had a satisfactory preliminary test, were inoculated with E. histolytica. Amebae were pooled from several 48-hour-old culture tubes and spun for 5 minutes at 800-1,000 rpm. The sedimented amebae, bacteria, and rice starch were suspended in 30 volumes of

sterile saline and counted.

The rats were anesthetized with ether, an incision made slightly to the left of midline of the body and the cecum partially exposed. Through 23 gauge needle and a 5 ml. syringe the inoculum was injected toward the blind end of the oecum from a point anterior to the junction of the cecum and colon. The abdominal muscles and skin were then sutured with surgical silk.

b) Identification method:

The stressed rats were killed with ether 15 days after inoculation of E. histolytica. The entire cecum was removed and slit open. A portion of contents was examined for the presence of amebae in a direct wet mount using saline. Stools containing amebae were cultured again in a modified diphasic media to judge

differentiation between E. histolytica and E. muris, which has been orcasionally found in rats(Mukada, 1950).

After number and size of the crater-like ulcers in the illeocecal area were scored macroscopically, histological changes were studied in all the specimens.

4. Experiment on sex hormone.

a) Testosterone: T-strong injection (Ankuck Pharmaceutical Co.) contained 50 mg testosterone propionate per ml. was used. Experimental rats were injected intramuscularly with 1/8 ml. of T-strong a total of 4 times every other day before and after inoculation of 150,000 organisms.

b) Ergosterone: Estradiol injection (Sam-Woo Pharmaceutical Co.) contained 2 mg Estradiol benzoate per ml. was used. The oophorectomized and estradiol-injected rats, and normal controls were injected intramuscularly with 1/8 ml. of Estradiol a total of 4 times every other day before and after inoculation of 200,000 organisms.

5. Experiment on shaking stress.

All the animals, except a normal control group, were given shaking stress before their inoculation with amebae. They were put into a cage on the shaking machine (Arthur H. Thomas Co.), and stressed for 4 hour? daily for a week.

6. Experiment on physical stimulation.

The exposed ceca of laparectomized rats were compressed to the game degree by surgical forceps. A group among the stimulated rats and normal control were inoculated intracecally with 300,000 parasites.

7. Experiment on rats having a former infection of Shigella dyseteriae :

S. dysenteriae was dipped out by loop from the colonies in the original culture tube, smeared on nutrient agar plates, and incubated 48 hours at 37℃. All the microorganism colonies on the 48-hour-cultured agar plates were harvested into 30 ml. saline and mixed homogeneously. 1 ml. of the above suspension was poured per os into suitable animals. After an incubation period (about a week), a group of these and of normal rats were inoculated into the illeocecal area with 300,000 amebae.

Result

The number of animals with ulcers in the illeocecal area, the average number of ulcerations per rat, and the size (diameter) of ulcers in each group according to the various stress are summarized as follows:

1. The effect of testosterone:

The largest number of animals with more than 10 ulcers was observed in experimental group (4 among 13 rats). Next was the castration control group, and the least were in the normal control group. The average number of ulcerations per rat was 9 in the experimental group, 4 in the castrated group, and none in the

normal control group. Ulcers above 2 mm in diameter were predominantly found in the experimental animals (45.5% ) (Table 1, 2).

2. The effect of ergosterone:

The number of animals with les? than 10 ulcers was similar in each group. Although rats of the control group had ulcers more than 1 mm in diameter (10%), others were below 1 mm (Table 4, 5).

3. The effect of shaking stress and Physical stimulation:

The rats subjected to shaking stress and physical stimulation showed a more severe pathogenicity of their E. histolytica than the control animals (Table 8, 9, 11, 12).

4. The effect of a previous infection of Shigella dysenteriae :

The E histological infection picture was more severe in these experimental animals than in any other group. The average number of ulcerations per rat was 9. The average was 7 in the stressed control group, and 3 in the normal control group (Table 14, 15),

The histological examination to reconfirm the pathogenicity of 5. hisrtolytica-amebic ulceration, and the presence of amoebae in the intestinal tissue-showed markedly positive findings in all the stressed rats except those treated with ergosterone (Table 3, 6, 10, 13, 16).

Conclusion

Macroscopic and higtologic examination was done of the illeocecal area of rats infected with E. histolytica and subjected to stress.

1. Testosterone promoted amebic infection in gonadectomized male rats, but ergosterone did not affect the amebic infection signs in oophorectomized female rats.

2. The rats subjected to shaking-stress for a week showed an increased susceptibility to infection by E.histolytica, with general edema, vascular congestion and ulcerative changes in the illeocecal area.

3. Direct stimulation of the rat illeocecum with surgical forceps enhanced the E. histolytica infection.

4. Susceptibility to E. histolytita 7vas enhanced by infecting them with S. dysenteriae for a week before the inoculation with 5. histolytica.