The effects of host's sex and hormones on the number of adult Trichinella spiralis in the small intestine, the number of migratory larvae produced in vitro by adult female worms, and the number of muscle larvae per gram of body weight were examined in CD-1 Swiss white mice. Nongonadectomized (intact) male mice housed greater numbers of adult worms and a greater number of muscle larvae per gram of body weight than did intact female mice. Adult female worms isolated from intact male mice deposited greater numbers of migratory larvae in vitro than did those obtained from intact female mice. These differences between intact male and intact female mice were eliminated by gonadectomy of male and female mice. Injection of increasing amounts of heterologous sex hormone into intact male and female mice was accompanied by decreasing rates of in vitro larvaposition by adult worms from male mice; but adult worms isolated from female mice showed increasing rates of in vitro larvaposition. Injection of heterologous sex hormone into gonadectomized male and female mice caused a reversal of the findings for intact, uninjected male and female mice stated above. This study has demonstrated that host sex and host sex hormones affect the biology of T. spiralis in the CD-1 Swiss white mouse.
The effects of cortisone on fecundity, distribution, and numbers of adult Trichinella spiralis and on enteritis in the host were compared in mice receiving different numbers of larvae. As the amount of cortisone given to mice was increased enteritis decreased, and fecundity of adult worms increased. Injection of mice with cortisone caused retention of a greater percentage of adult worms in the anterior regions of the host small bowel than in uninjected mice. By day 11 PI, when adult worms in cortisone-injected mice were more widely distributed along the host small intestine, fecundity of adult worms isolated from mice receiving more worms (500, 1,000, or 2,000 worms) attained levels previously seen only in worms from mice infected with 250 T. spiralis. The extended longevity of adult worms in cortisone-injected mice was accompanied by a severe reduction in fecundity after day 11 PI. Addition of cortisone to the culture medium at concentrations above 0.1 mg% was accompanied by a reduction in fecundity of adult worms.
The effects of host sex on enteric inflammatory response to primary infection with Trichinella spiralis were examined. Enteritis in female mice was greater than that in male mice on days 7, 9 and 11 postinfection (PI) and similar to that in male mice by day 13 PI. Male and female mice given daily injections of 33 or 66 mg/kilo of cortisone acetate exhibited significantly reduced enteritis on days 7, 9 and 11 PI below that seen in uninjected, male and female mice. On days 7, 9 and 11 PI larviposition in vitro by adult worms isolated from uninjected female mice was significantly less than that for adult worms isolated from male mice. Suppression of enteritis below detectable levels in male and female mice by administration of cortisone acetate resulted in similar rates of larviposition by adult worms isolated from male or female mice (day 7 PI, 33 mg/kilo cortisone acetate; days 7, 9 and 11 PI, 66 mg/kilo cortisone acetate). A significantly greater percent of adult worms was recovered from the anterior half of the small intestines of uninjected male than from uninjected female mice on days 7, 9 and 11 PI. The percent of adult worms recovered on these same days from the anterior half of the small intestine of male and female mice injected with cortisone was similar.
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