Effect of the estrous cycle, castration and pseudopregnancy on E. coli in the uterus and uterine secretions of the rat
Wira, C.R.; Merritt, K.
Biology of Reproduction 17(4): 519-522
1977
ISSN/ISBN: 0006-3363 PMID: 336104 DOI: 10.1095/biolreprod17.4.519Document Number: 434483
Uteri and uterine secretions from rats in various stages of the estrous cycle, following castration and after induction of pseudopregnancy were examined for their ability to inhibit microbial growth. When Escherichia coli were placed in the uteri of these animals for 90 min, a marked inhibition of bacterial colony formation was observed in proestrous and estrous rats. Diestrous rats exhibited only a mild inhibitory effect, while castrate and pseudopregnant rat uteri exhibited no bactericidal activity. Tests were made for the presence of a soluble inhibitory agent(s) in uterine flushings using an in vitro assay. Only fluid from proestrous rats was observed to inhibit E. coli colony formation. A bacterial inhibitory agent may be present in the gential tract, varies with the estrous cycle and does not require bacteria to induce its presence. The endocrine balance in the adult female rat may play an important role in modulating the response of the rat genital tract to bacterial infection so as to increase resistance at proestrus and estrus.