Escherichia Coli -induced Inflammation Changes the Expression of Acetylcholine Receptors (M2R, M3R, and α-7 nAChR) in the Pig Uterus

INTRODUCTION: The influence of inflammation on the patterns of muscarinic 2 and 3 receptor subtypes (M2R and M3R), and α-7 nicotinic acetylcholine receptor (α-7 nAChR) expression in the porcine uterus was investigated. MATERIAL AND METHODS: On day three of the oestrous cycle of gilts aged 7–8 months with body weight 90–120 kg, either an E. coli suspension (E. coli group, n = 5) or saline (Sal group, n = 5) was administered into the uterine horns via laparotomy or only laparotomy was performed on control swine (Ctrl group, n = 5). After eight days, and the onset of severe acute endometritis in the E. coli group, the uterine mRNA and protein receptor expression levels were determined using real-time RT-PCR and Western blotting, respectively, with receptor localisation by immunofluorescence. RESULTS: The studied receptors were in the luminal epithelium, glands, blood vessels, and myometrial muscle cells of all gilts. The M2R mRNA level was lower in the inflamed endometrium compared to the Ctrl and Sal groups. Also in this tissue, the expression of M3R mRNA and protein was lower than in the Ctrl and Sal groups. The M3R protein level in the bacterially challenged myometrium was found to be increased compared to unadministered groups. In the endometrium of the E. coli group, the α-7 nAChR protein level was lower than in the Sal group, and in the myometrium it was reduced in relation to both the other groups. P values were ≤ 0.05 in all cases. CONCLUSION: Inflammation causes alterations in the M2R, M3R, and α-7 nAChR expression in the pig uterus, suggesting their significance in the course and repercussions of uterine inflammation.