The Effect of Tri-iodothyronine on Liver Regeneration after Partial Hepatectomy in Rats: Histological and Immunohistochemical Study

Introduction: The remarkable capacity of liver to regenerate after injury has attracted much interest in living related liver transplants. Aim of the Work: The study aimed at assessing the effect of Tri-iodothyronine (T3) on the regenerative capacity of the rat liver after 70% partial hepatectomy (PH). Materials and Methods: Thirty adult male albino rats were equally divided into 3 groups. The first group received saline by subcutaneous injection and was sham operated (control). The second group was subjected to 70% partial hepatectomy after subcutaneous injection of saline, while the third group received a single subcutaneous dose of T3 (4mg/kg) at the time of PH. Animals were sacrificed 72 hours later. The remnant liver was excised and weighed. Remnant Liver/Body weight ratio was determined. Liver specimens were processed. Sections were subjected to the following stains: H E, PAS, Silver- stained Nucleolar Organizer Regions (AgNORs) and Vascular Endothelial Growth Factor (VEGF) immunostaining. Digital image analysis was applied to determine the number and area of AgNORs and the area percent of VEGF immunostaining. Results were statistically compared. Results: Liver/Body weight ratio was significantly higher in group III (T3+PH) compared to group II (PH). Microscopic examination of PH sections revealed disorganized hepatic architecture with appearance of apoptotic cells. In group III , restored liver appearance with stages of mitosis were seen. Glycogen content decreased in group II and was regained in group III sections. Proliferating cells (AgNOR sections) were seen in periportal area in group II but in group III sections they were present in midzonal and periportal areas. The number and area of AgNORs per hepatocyte nucleus as well as area percent of VEGF immunostaining were significantly increased in group III compared to group II. Conclusion: T3 administration at the time of partial hepatectomy promoted liver regeneration suggesting its potential application after surgical resection or liver transplantation.