Lipid-induced modulation of opiate receptors in mouse brain membranes.

The binding of [3H] D-Ala-enkephalinamide (DAEA) to crude mitochondrial fractions (P2M) from mouse forebrain was determined after modulation of membrane lipid microviscosity. Lipid fluidization of P2M membranes, following treatment with egg lecithin, resulted in a 50% loss of specific binding of DAEA. Increasing the P2M lipid microviscosity, by incorporation of cholesteryl hemisuccinate (CHS), increased the accessibility of the opiate receptors up to a peak level of 170% which decreased sharply upon further increase in lipid microviscosity. The processes resulting from lipid rigidification may have important implications for aging and for drug addiction.