Abstract
OBJECTIVE: Cholesterol 24-hydroxylase catalyzes the conversion of cholesterol to 24-hydroxycholesterol, which is a major pathway for cholesterol elimination from the brain, since 24-hydroxycholesterol can readily cross the blood brain barrier. The present study aimed to elucidate the distribution of cholesterol 24-hydroxylase in the monkey brain. METHODS: The distribution of cholesterol 24-hydroxylase in the monkey brain was examined using Western blot and immunohistochemistry methods, and was observed under light microscopy and electron microscopy. RESULTS: High levels of cholesterol 24-hydroxylase were observed in projection neurons and neuropil in structures derived from telencephalon, including the cerebral neocortex, hippocampus, amygdala, nucleus basalis of Meynert, and striatum. Electron microscopy revealed that the enzyme was localized in the axon terminals. One the other hand, cholesterol 24-hydroxylase was expressed at a lower level in the thalamus, globus pallidus and brainstem. CONCLUSION: The high level of cholesterol 24-hydroxylase in the telencephalon possibly reflects a high rate of cholesterol turnover in this part of brain.