Activation of myelin-associated cholesteryl ester hydrolase in developing rat brain

Short-term regulation of rat brain cholesteryl ester hydrolase (CEH) by protein kinases is described. CEH was activated 280-340% in the presence of Mg2(+)-ATP and this inhibition was partially abolished by rabbit skeletal muscle protein kinase inhibitor or chlorpromazine, a phospholipid interacting drug, suggesting the involvement of cAMP-dependent protein kinase and protein kinase C, respectively. However, the involvement of other kinases cannot be ruled out. In developing rat brain, CEH activity per unit brain weight closely correlated with myelination. During the premyelination period (5 days postnatal), significantly higher activation (P less than 0.001) of CEH was observed by cAMP-dependent protein kinase or protein kinase C, when compared to activation observed during the period of active myelination (20 days postnatal). These results indicate that CEH in rat brain is tightly regulated and closely related to myelination.