Unusual urinary cholesterol metabolites following intracerebral injection of [4-14C]cholesterol into rats: I. The minor 14C-metabolite.

[4-14C]Cholesterol injected intracerebrally into 10-12-day-old rats becomes localized largely in central nervous system myelin. If sufficient 14C is injected, myelin cholesterol remains labeled for the rest of the rats' lives. In the course of the slow myelin cholesterol turnover that ensues, a unique series of cholesterol metabolites is excreted exclusively in the rats' urine. There is reason to believe that the metabolites are formed in the central nervous system before entering the urine. This manuscript describes separation of the 2 urinary 14C-labeled metabolic types and isolation and identification of the minor 14C-labeled material which consists of cholesterol and 2 other sterols bound covalently to short-chain peptides. The minor sterols have been tentatively identified as 24- and 26-hydroxycholesterol. The sterol-peptide combinations have been isolated from human male urine, also.