Objective: To study the expression rule of proliferating cell nuclear antigen (PCNA) in thyroid when the hyperplasia of male rat thyroid is induced by propylthiouracil (PTU).
Methods: PTU was administered to rats by gavage at a dose of 5.0 mg/kg B. W for 0,3,6,9 and 12 days respectively. All animals were sacrificed after the last dosage, and the expression of PCNA in thyroid was detected by immunohistochemistry and RT-PCR.
Results: Compared with the control group, the PCNA level in the thyroid of rats given PTU for 3 days significantly increased (P < 0.05),and reached the highest expression when it was 6 days, but then when it was 9 days and 12 days, the PCNA expression showed a descending tendency.
Conclusion: PCNA has a expression rule in hyperplastic thyroid: expression increase first but then decrease. This rule confirms the histological change of thyroid in earlier stage. The experimental time of assessment test to thyroid hormone disruptors will be shortened to six days.