Could Different Doses of Dexmedetomidine Be as Effective as Amifostine Against Radiotherapy-Induced Liver Injury in Rats? Evidence from Mitotic, Apoptotic, Oxidative, and Neurogenic Insights.

Background/Objectives: Radiotherapy (RT) induces oxidative stress and structural damage in solid tissues, including the liver. This study aimed to investigate the histological and immunohistochemical effects of dexmedetomidine (DEX) and amifostine on their potential protective and regenerative properties against liver injury induced by radiation therapy. Methods: This study consisted of five randomized groups: control, RT, RT-D100, RT-D200, and RT-A (Amifostine). A total of 100 µg/kg DEX, 200 µg/kg DEX, and 200 µg/kg amifostine were administered before radiotherapy as per the experimental design. After RT, liver specimens were analyzed for histological alterations, including periportal and perisinusoidal fibrosis, vacuolization, and pyknotic nuclei. Furthermore, immunohistochemistry investigations were conducted to evaluate apoptosis, mitosis, oxidative stress, and neural regeneration in non-neuronal liver tissue following radiotherapy and subsequent treatment. Results: The control group's liver tissue exhibited standard histological architecture, whereas the RT group displayed severe cellular degeneration, periportal and perisinusoidal fibrosis, cytoplasmic vacuolization, and an increase in pyknotic nuclei. The apoptotic index was markedly reduced in the RT-D100 and RT-D200 groups relative to the RT group. Furthermore, caspase-3 immunoactivity was negligible in the control group, while a significant increase was observed in the RT group. The administration of amifostine significantly increased GAP-43 levels. Conclusions: DEX mitigates RT-induced hepatic injury chiefly through antioxidant and anti-apoptotic pathways, whereas amifostine promotes hepatic regeneration by modulating GAP-43.