الفهرس 
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Abstract
The present research aimed to investigate the effects of thyroid dysfunction on uterine responsiveness and reproductive tissue metabolism in rats.
Forty eight adult female albino rats weighing 120 ± 10 grams were being classified into 3 equal groups. Group I (Euthyroid group): control group. Group II (Hypothyroid group): Hypothyroidism was induced by oral administration of propylthiouracil (PTU) at a dose of 1mg/kg for four weeks. Group III (Hyperthyroid group): Rats were injected intraperitoneally by L-thyroxine (T4-0.1μg/g) dissolved in normal saline solution for four weeks. Estrus cycles of all rats were followed up by examination of vaginal smear. Rats were tested in estrus and diestrus phases. Weight of rats was measured at the start and at end of the experiment. Retro-orbital blood samples were collected for estimation of TSH, T3, T4, estradiol and progesterone hormones. Rats were then sacrificed by cervical decapitation. Uterus, vagina, ovaries and thyroid gland were excised and weighed. Then, uteri were used for assessment of its responsiveness to acetylcholine, adrenaline, oxytocin, indomethacin and histamine. Paraffin sections were made from these organs and stained by hematoxyline and eosin and Periodic Acid Schiff’s reaction (PAS) for detection of glycogen in reproductive organs.
Weight of rats and their reproductive tissues and TSH hormone significantly decreased in both hypothyroid and hyperthyroid groups. T3 and T4 were decreased in hypothyroid group and increased in hyperthyroid group. Weight of thyroid gland significantly increased in hypothyroid group and non-significantly increased in hyperthyroid group. Disturbance in estrogen- progesterone relationship was detected in hypo and hyperthyroid
Summary & conclusion 111
groups. PAS stain showed an increase in glycogen content in hypothyroid group and decrease in hyperthyroid group.
The effects can be summarized as follow:
Hypothyroidism caused:
Decrease in estrogen level in estrus and diestrus phases.
Decrease in progesterone level in estrus phase and increase its level in diestrus phase.
Decrease in reproductive tissue weight and affect their morphology.
Increase in glycogen content of reproductive tissues.
Decreased in uterine responsiveness to ACh, oxytocin, indomethacin and histamine, but the sensitivity to adrenaline increased.
Hyperthyroidism caused:
Increase in estrogen level in estrus and diestrus phase.
Increase in progesterone level in estrus phase and decrease its level in diestrus phase.
Decrease in reproductive tissue weight and affect their morphology.
Decrease in glycogen content of reproductive tissues.
Increased uterine responsiveness to ACh, oxytocin, adrenaline, indomethacin and histamine.