Propolis extract protects against radiation-induced intestinal mucositis through anti-apoptotic mechanisms

Intestinal mucositis is a common side effect during radiotherapy that could be largely prevented by compounds possessing anti-inflammatory or anti-oxidant properties, including extracts of propolis containing a high proportion of flavonoids. A specially formulated aqueous extract of propolis (PWE) has been prepared in such a way to preclude the inclusion of flavonoids but contain mostly organic aromatic acids to study whether it would still protect against radiation-induced intestinal mucositis and to study the possible involvement of apoptotic pathways. Rats were exposed to a gamma radiation dose of 8 Gy from a Cesium-137 source in order to inflict intestinal mucositis. Three days before exposure, rats were given PWE orally and treatment continued for 2 more days. Twenty-four hours later, rats were sacrificed, the small intestine was excised, and sections were examined histologically. Different parameters for apoptosis, inflammation, and oxidative stress were determined in the serum and in intestinal homogenates. Radiation exposure led to histological and biochemical signs of intestinal damage. This was associated with an increase in apoptotic indicators and derangement in oxidative stress parameters. All deranged parameters were largely prevented by PWE. The findings provide evidence that the protective effect of PWE against intestinal radiation damage involves not only its anti-inflammatory and anti-oxidant effects but also its anti-apoptotic properties as well.