24hydroxycholesterol

24hydroxycholesterol, also known as 24HC or cholesterol 24-hydroxylase, is an oxysterol that is primarily synthesized in the brain. It is produced by the enzyme cholesterol 24-hydroxylase (CYP46A1), which is responsible for hydroxylating cholesterol at the C24 position of the side chain. This enzymatic conversion is the main pathway for cholesterol catabolism in the central nervous system. 24HC is a lipid-soluble molecule and can cross the blood-brain barrier.

The primary function of 24HC in the brain is related to cholesterol homeostasis. By facilitating cholesterol removal from the brain, it plays a role in preventing cholesterol accumulation. Elevated levels of 24HC have been observed in various neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and Huntington's disease. Research suggests that 24HC may have both neuroprotective and neurotoxic effects depending on the context and concentration. It has been implicated in modulating synaptic plasticity, neuronal excitability, and inflammatory responses within the brain.

Beyond the brain, 24HC is also found in lower concentrations in other tissues, including the liver and plasma. Its presence in peripheral circulation is thought to be due to transport from the brain or synthesis in other organs. The precise roles and mechanisms of action of 24HC outside the central nervous system are still subjects of ongoing investigation. Its involvement in cellular signaling pathways and its potential as a biomarker for neurological disorders continue to be active areas of research.