Endocrine Abstracts

Thyroid Hormones have extensive effects on differentiation, development, and growth of different organs. In this study the effect of the administration of PTU on pregnant and lactating rats on isolated aorta response of their adult offsprings has been investigated. Three groups of female rats were selected. In the first group (fetal group) observation of vaginal plug after mating was considered as the first day of pregnancy, then PTU was added to their drinking water until the end of the gestation period. In the second group PTU was added to the drinking water of their mothers from laboring time for 25 days (neonatal group). The third group was the control group which consumed only drinking water.In all three groups Total?Thyroxine (tT4), Free Thyroxine (fT4), Total triiodothyronine (tT₃), Free Triiodothyronine (fT3) and TSH immediately after discontinuing of the drug were measured in the sera obtained from the mothers.The results indicate that the levels of the above mentioned hormones (except TSH) in fetal and neonatal groups were significantly lower than control group (P<0.05) and TSH on fetal and neonatal group were significantly higher than control (P<0.001). After two months the adult of off springs were anesthetized, dissected and isolated aorta response was examined against KCl and phenylephrine. Results of this study indicated that responsiveness of aorta in fetal group was significantly decreased compared to the control group (P<0.05), but neonatal group had no significant difference with the control group. It can be concluded that hypothyroidism in fetal period has significant effects on differentiation and development of vascular bed (aorta) in a way that can be still observed during adulthood.