Propolis reduced the radiation-induced bystander effect in rat liver exposed to total head irradiation

In the realm of radiation oncology, the observation of the radiation-induced bystander effect (RIBE) has raised concerns about off-target tissue effects caused by radiation. The concept of RIBE encompasses the response of non-irradiated tissue to radiation exposure. This study investigated the impact of cranial irradiation on oxidative/nitrosative stress and inflammatory responses in liver tissue. Thirty-two male Sprague-Dawley rats were divided into four groups: sham, irradiation (IR), propolis plus IR, and propolis control. The IR group received an initial 1 ml oral dose of saline via an orogastric tube. Subsequently, the IR and IR plus propolis groups received a single dose of 5 Gy (Gy) gamma irradiation to the entire cranium. The IR plus Propolis Group received propolis (80 mg kg/day) via an orogastric tube one hour before IR, and this procedure was continued daily for 10 days. Liver tissue was analyzed for biochemical parameters at the study's conclusion. In the IR group, total antioxidant status (TAS), total sulfhydryl groups (-SH) levels, paraoxonase (PON) and arylesterase (ARYL) activities were significantly diminished compared to all other groups, while nitric oxide synthase (NOS) activity, nitric oxide (NO^•), lipid hydroperoxide (LOOH), oxidative stress index (OSI), and total oxidant status (TOS) values were elevated. Conversely, ceruloplasmin (Cp) levels were markedly higher in the IR group than in the Sham and propolis control groups. These results suggest that propolis may serve as a radioprotective agent against radiation-induced bystander effects by enhancing antioxidant activity and mitigating oxidative/nitrosative stress in liver tissue.