Temporal dynamics of cytokine expression, oxidative stress, and endocrine dysfunction following Escherichia coli-induced epididymo-orchitis in rats

Bacterial epididymo-orchitis (EO) can compromise male reproductive function, but the temporal relationships among testicular inflammatory, oxidative, and endocrine changes remain incompletely characterized. This study examined these changes after Escherichia coli inoculation in rats. Ninety adult male Wistar rats were allocated to untreated control and 100-μL and 200-μL bacterial-inoculum groups and evaluated at 24 h and 1, 2, 3, and 4 weeks (n = 6 per group per time point). Histological, immunohistochemical, immunofluorescent, biochemical, hormonal, and molecular assessments characterized testicular injury, marker-positive cell distributions, immune cell accumulation, redox status, cytokine expression, and Leydig cell-associated endpoints. Changes in TAC, MDA, CAT, GSH, GSSG, and IL-10 were reported at 24 h, whereas significant SOD suppression and pro-inflammatory cytokine upregulation were reported from 1 week. The assayed steroid-related transcripts were reported to decrease at 24 h; reduced Leydig cell lipid-associated fluorescence and serum testosterone were apparent from 1 week. CD68-positive cell accumulation was greatest during the early period, particularly at 1 week, whereas CD45-positive leukocyte density peaked at 3 weeks. Testicular injury was accompanied by reduced THY-1- and NANOG-positive cell densities. Differences between inoculum-volume groups varied by endpoint and time point. These findings describe temporal associations among testicular injury and redox, inflammatory, and endocrine changes; they do not establish a causal sequence, functional spermatogonial stem cell depletion, or impaired fertility. The timing of potential clinical interventions requires separate validation.