Expression of cytochrome P450 side-chain cleavage enzyme mRNA and production of pregnenolone in the brain of the red-bellied newt Cynops pyrrhogaster

► This study was conducted to understand pregnenolone formation in the newt brain. ► P450 side-chain cleavage enzyme (P450scc) catalyzes pregnenolone formation. ► We first demonstrated that the newt brain produces pregnenolone from cholesterol. ► Subsequently, cDNA encoding P450scc was isolated from the newt. ► Finally, the site of P450scc mRNA expression was localized in the newt brain.