Influence of cholesterol and unsaturated fatty acids on [125I]hCG binding to rat testicular membranes.
Incubation of testicular membranes with cholesteryl-hemisuccinate resulted in an increase of both the membrane microviscosity and [125I]hCG specific binding. 14C-labelled cholesterol as well as fatty acids were effectively incorporated into membrane preparations. Insertion of unsaturated fatty acids (cis-vaccenic, linoleic, oleic, linolenic and arachidonic) into the membrane decreased its microviscosity under simultaneous disappearance of [125I]hCG specific binding. The latter phenomenon seems to be caused by an increase of nonspecific binding which was not due to the uptake of radio-activity from labelled gonadotropin by fatty acids or double bonds of fatty acids incorporated into testicular membranes or taken up by a resin Amberlite IRA-400. The disappearance of specific binding of [125I]hCG by the fluidizing action of unsaturated fatty acids can be reversed by the subsequent action of cholesterol.
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000494:pharmacology*; D006063:Chorionic Gonadotropin / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D011974:Receptors, LH; D013737:Testis / Q000378:metabolism*
D006063:Chorionic Gonadotropin; D005231:Fatty Acids, Unsaturated; D011956:Receptors, Cell Surface; D011974:Receptors, LH; D002784:Cholesterol