The purpose of the study was to study the effect of chronic toxoplasmosis on changes in the levels of pre- and post-implantation mortality in the experiment. Materials and methods. In the experiment there were 90 female Wistar rats with a body weight of 180-200 g. For the development of pregnancy, females of the control and experimental groups were coupled with males for 3 days. After the onset of pregnancy, females of intact controls were orally injected with 2 ml of 0.2 % starch gel. The females of the experimental groups were infected with an invasive culture of Toxoplasma gondii at a dose of 25 tachyzoites per 1 g of body weight (5,000 tachyzoites per rat) and 50 tachyzoites per 1 g of body weight (10,000 tachyzoites per rat). On the 35th day after infection, females of the experimental groups were coupled with males for 3 days before infection. The effect of Toxoplasma on changes in the levels of pre- and post-implantation death was assessed after killing female rats on the 42nd, 49th and 56th (7th, 14th and 21st days after pregnancy) days after infection. Results and discussion. In animals infected at a dose of 25 tachyzoites per 1 g of body weight, there is a decrease in the number of implantation sites in the uterus, the total number of embryos and the number of living embryos at all stages of the development of Toxoplasma by 1.8-2.1 times compared with the control. In females infected at a dose of 50 tachyzoites per 1 g of body weight, a decrease in the number of implantation sites in the uterus and the total number of embryos at all stages of the development of the parasite was recorded by 2.2-2.5 times compared with the control values. There is a decrease in the number of living embryos by the 42nd day after infection by 4.3 times, by the 49th day – by 3.8 times and by the 56th day – by 5.1 times compared to the control. When compared with the results obtained from females with a lower dose of infection, a decrease in this indicator was revealed on the 42nd day after the development of Toxoplasma by 2.1 times, on the 49th day – by 1.7 times and on the 56th day – by 2.5 times. An increase in the number of dead embryos by 0.2-0.4 times in comparison with intact indicators and the results of experimental animals infected at a dose of 5,000 tachyzoites per rat were recorded. There was an increase in the level of resorptions on the 49th and 56th days by 1.4 and 1.6 times in comparison with the control and animals infected at a dose of 25 tachyzoites per 1 g of body weight. Conclusion. Experimental chronic toxoplasmosis causes an increase in pre-implantation and post-implantation embryo death. The recorded effect of Toxoplasma invasion depends on the dose of infection and the duration of the disease
Keywords: rats, toxoplasmosis, pre-implantation and post-implantation death, embryos
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