['Acetoacetyl-CoA synthetase (AACS) is the enzyme responsible for the utilization of ketone bodies for the synthesis of cholesterol and fatty acids and the gene is highly expressed only in the male subcutaneous white adipose tissue (WAT).', 'This study is to elucidate how AACS is involved in sex-dependent metabolic differences in adipose tissues. To answer this question, we examined the effect of castration on AACS mRNA expression in rat WAT.', 'Castration did not affect any changes in the level of serum ketone bodies, but it significantly decreased AACS gene expression in subcutaneous WAT. In contrast, expression of the other ketone body utilizing enzyme, succinyl-CoA: 3-oxoacid CoA-transferase (SCOT), did not change. Moreover, the AACS gene was highly expressed in larger-sized adipocytes obtained from rat subcutaneous WAT, and was up-regulated by testosterone in differentiated adipocytes.'] Is ketone body utilization regulated by male-specific factors in rat subcutaneous adipocytes?