Effect of N-acetyl cysteine treatment on uterine cytokine and chemokine profiles in mares with persistent breeding-induced endometritis.

BACKGROUND

Persistent breeding-induced endometritis (PBIE) is a major cause of infertility in mares. Recent research has shown that PBIE-affected mares treated with intrauterine N-acetyl cysteine (NAC) 12 hours before breeding showed no improvement in clinical signs at 12- and 60-hours post-breeding.

AIMS/

OBJECTIVES

The present study was designed to examine the effects of NAC treatment on the uterine inflammatory cytokine and chemokine profiles in PBIE-affected mares.

METHODS

Using a randomized, blinded, cross-over design, mares susceptible to PBIE (n=9) were allocated to Control and Treatment cycles with at least one washout estrous cycle between the cycles. Intrauterine infusion of 180 mL of 3.3% NAC (Treatment) or sterile saline (Control) was performed 12 hours before insemination. Uterine fluid samples were collected at 12- and 60-hours post-insemination to determine inflammatory cytokine and chemokine profiles. Endometrial biopsies were taken at the same time points to determine gene expression of selected inflammatory cytokines (Interleukin-6, Interleukin-10, Interleukin-1β and Tumor Necrosis Factor-α).

RESULTS

There was no difference (p > 0.05) in the uterine fluid inflammatory cytokines and chemokines between Control and Treatment cycles. Similarly, gene expression of the selected inflammatory cytokines did not differ (p > 0.05) between the two cycles.

CONCLUSION

The absence of any significant effects of NAC on the uterine inflammatory cytokines and chemokines provides a potential mechanism to explain the previously reported lack of improvement in clinical signs in PBIE-affected mares treated with NAC.