Probiotic Administration in an Endometriosis Animal Model Can Influence the Gut Microbiota and Gut‐Brain Axis to Counteract the Effects of Stress

Endometriosis is characterized by endometrial tissue growing in areas outside the reproductive system resulting in discomfort, pain, and infertility. Environmental factors such as stress have been suggested to exacerbate the condition, and our group has previously shown that stress can increase lesion size in a rat model. Animal studies have found increased gram‐negative bacteria in the gut microbiome of endometriosis animals and that oral administration of Lactobacillus gasseri can decrease lesion size however it is unclear whether probiotic use could counteract the effects of stress in our model. Hypothesis Administration of a probiotic mixture can decrease endometrial implants in animals under stress via modulation of the intestinal microflora. Methods Endometriosis was induced in female Sprague Dawley Rats (11–12/group) by implanting uterine tissue next to the intestinal mesentery on day 0. Animals were allowed to recover for seven days before administering placebo (Pl) or probiotic (Pro) in drinking water until time of sacrifice (day 60). Stressed (S) animals were subjected to water avoidance for 60 mins/day (days 14–20). Non stressed (NS) animals stayed in a clean cage. Anxiety was measured before and after stress using open field. Fecal bacterial composition was analyzed at four time points: before surgery, before stress, after stress, and at sacrifice. Results ESPl group had increased anxiety and development of more endometrial lesions (91.27%) which were of a larger size (38.31 ± 6.90mm 2 ) compared with ENSPl (62.50%; 17.94 ± 3.90mm 2 , p<0.05). Administration of the probiotic (ESPro) decreased the number developed (56.25%), the size of the lesions (14.33 ± 3.17mm 2 , p<0.01), as well as colonic damage (p<0.05). Stress caused changes in the microflora including lower alpha diversity and altered firmicutes / bacteroidetes ratio, and these changes appeared to be reversed in those animals receiving the probiotic. Probiotic administration also modulated the effect of stress on bacterial abundance at the genus level. Conclusions Our results suggest that the gut microflora plays an important role in the stress induced‐exacerbation of the endometriosis symptoms in this animal model since administration of a probiotic mixture can decrease lesion size. This offers the potential for further exploration of this complementary therapy in the patient population. Support or Funding Information Supported in part by P20 GM103475‐15, R25GM082406, 2R25GM096955 & MD007579. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .