ASSESSMENT OF MYOMETRIAL CONTRACTILITY, GENE EXPRESSION OF HORMONE RECEPTORS IN UTERUS AND FOETO-MATERNAL VELOCITY INDICES IN CANINE UTERINE INERTIA
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Date
2022-05-19
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR, KERALA VETERINARY AND ANIMAL SCIENCES UNIVERSITY
Abstract
The present study was designed to assess the uterine contractility characteristics, gene expression of hormone receptors and the change in velocity indices of maternal and foetal arteries in canine uterine inertia. Dogs presented (n=22) with dystocia were classified as complete primary uterine inertia CPUI (n=9), partial primary uterine inertia PPUI (n=6) and foetal cause of dystocia FCD (n=7) based on the cause of dystocia, contractile state of the uterus as well as the stage of progress of the foetus. All the selected dogs were subjected to ultrasonography with Pulse wave spectral Doppler analysis, radiography, sigmoidoscopy, non-invasive tocodynamometry, haematology, blood gas, electrolyte and metabolite analysis and serum hormonal profile analysis. Caesarean
section was performed in all the dogs, and after the removal of the foetus, fullthickness uterine biopsy samples were taken and frozen in RNA-later. Apgar scores of all the foetuses were recorded at five minutes, two hours and 24 h. Relative expression of genes regulating myometrial contraction as well as hormonal receptor genes were performed using the qPCR in the study groups. Tocodynamometric studies confirmed that dogs exhibiting less than 15 mm of Hg pressure and feeble or infrequent contractions without delivery for more than 30 min, could be considered as uterine inertia. Apgar scores in pups at five minutes after the surgery were poor in all groups, but the rapid improvement was noticed in two hours. Analysis revealed normal pH, High pO2, low pCO2, low HCO3⁻ and low base excess. Significantly lower Na+and Cl⁻ concentration in the FCD group, and lower iCa and anion gap in the FCD group were noted. Respiratory acidosis and metabolic alkalosis were evident in all animals, with the maximum level in FCD. Quantitative analysis of RI, PI and SVDV of the foetal abdominal aorta and the uterine artery did not differ significantly between the groups. Haematology revealed no significant difference between the groups, but lymphocytosis and anaemia were evident in all groups. The serum hormone profile revealed no significant difference between oestradiol and progesterone concentrations across the groups. However, oestradiol level was higher in all groups than previously reported levels in normal pregnancy. The present study concluded that ionised calcium deficiency, higher oestradiol concentration, upregulation of Erβ receptor gene and downregulation of MLCK gene contributed an additive effect to cause CPUI, along with the possible absence of oxytocin, which was indirectly revealed through the elevated Na+and Cl⁻concentration. Whereas the PPUI was found to be a myometrial defect due to extreme down-regulation of MLCK, MYHII and PKC genes, higher oestradiol levels also might have contributed to the development of the pathology.