In addition, inhibition of spinal P450c17 with the P450c17 inhibitor, ketoconazole blocks the early development of MA induced by administration of an IL-1 receptor antagonist, suggesting that the nerve injury-induced increase in IL-1β may produce an analgesic effect through inhibition of both the expression of astrocyte P450c17 and the concomitant production of neurosteroids in astrocytes as possible control mechanisms against the development of neuropathic pain. This evidence concerns the gene IL1B and microtia.