Intravenous injections of the ribosome inactivating protein trichosanthin did not affect methionine enkephalin and beta-endorphin levels in the mouse brain and pituitary.

The effect of trichosanthin on levels of the neuropeptides beta-endorphin (beta-EP) and methionine enkephalin (met-EK) in the mouse brain and pituitary was investigated. Mature male ICR mice were divided into two groups. One group received intravenous injections of physiological saline and served as the control. Another group received daily intravenous injections of trichosanthin (0.2 mg/25g/injection) for three consecutive days. The animals were sacrificed four hours after the last injection. Their brains were dissected into three regions: A (thalamus and hypothalamus), B (cerebral cortex) and C (cerebellum and brainstem) and their pituitaries were collected. The samples were then extracted and assayed for beta-EP and met-EK by specific radioimmunoassays. It was found that there were no statistically significant changes in the levels of the two neuropeptides in the pituitary and the brain regions except for the level of beta-EP in brain region A.