Investigation of the endometrial receptivity status in experimental hypothyroid-induced female rats

This study aimed to investigate hypothyroidism's effects on endometrial receptivity, creating an experimental hypothyroidism model in female rats.

To induce hypothyroidism in rats of Hipotiroid-ER and Treatment-ER groups, 0.05% 6-propyl-2-thiouracil was freshly added to their drinking water for 8 weeks and then the endometrial receptivity model was applied and sacrificed on the fifth day. In the Treatment-ER group, after sc-administration of 0.8 µg/100 g L-thyroxine for 10 days, the endometrial receptivity model was applied to the rats and sacrificed on the fifth day.

In the histopathological evaluation, epithelial degeneration, vacuolization, enlargement of the uterine glands, and morphological disorders were observed in the endometrial layer of the Hypothyroid-ER group. However, these pathologies were significantly alleviated in the Treatment-ER group. Integrin β3, integrin αvβ3, LIF, and HOXA10 immune reaction intensities were high in the Control-ER and Treatment-ER groups, while in the Hypothyroid-ER group, integrin β3, integrin αvβ3, LIF, and HOXA10 immunoreactivity intensities were low. Also, while MUC1 immunoreactivity was high in the Hypothyroid-ER group, it was low in the other groups. In biochemical analysis, a significant increase in the TSH and progesterone levels and a significant decrease in the FT4, E2, FSH, and LH levels in the Hypothyroid-ER group compared with the Control-ER group were observed. Also, all hormone levels were significantly ameliorated in the rats of the Treatment-ER group compared with the Hypothyroid-ER group.

The results obtained showed that hypothyroidism had a significant effect on endometrial receptivity-the histopathological and biochemical changes caused by hypothyroidism in the experimental rat model were ameliorated with L-thyroxine treatment.