Resumen: Hepatic fat-specific protein 27 (Cidec/Fsp27) mRNA levels have been associated with hepatic lipid droplet extent under certain circumstances. To address its hepatic expression under different dietary conditions and in both sexes, Apoe-deficient mice were subjected to different experimental conditions for 11 weeks to test the influence of cholesterol, Western diet, squalene, oleanolic acid, sex and surgical castration on Cidec/Fsp27 mRNA expression. Dietary cholesterol increased hepatic Cidec/Fsp27ß expression, an effect that was suppressed when cholesterol was combined with saturated fat as represented by Western-diet feeding. Using the latter diet, oleanolic acid or squalene did not modify its expression. Females showed lower levels of hepatic Cidec/Fsp27ß expression than males when they were fed Western diets, a result that was translated into lesser amount of CIDEC/FSP27 protein in lipid droplets and microsomes. This was also confirmed in Ldlr-deficient mice. Incubation with estradiol resulted in decreased Cidec/Fsp27ß expression in AML12 cells. While male surgical castration did not modify the expression, ovariectomized females did show increased levels compared to control females. Females also showed increased expression of Pgc1a, suppressed by ovariectomy, and the values were significantly and inversely associated with those of Cidec/Fsp27ß. When Pgc1a-deficient mice were used, the sex differences on Cidec/Fsp27ß expression disappeared. Therefore, hepatic Cidec/Fsp27ß expression has a complex regulation influenced by diet and sex hormonal milieu. The mRNA sex differences are controlled by Pgc1a. Idioma: Inglés DOI: 10.1152/ajpendo.00199.2019 Año: 2020 Publicado en: AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM 318, 2 (2020), E249–E261 ISSN: 0193-1849 Factor impacto JCR: 4.31 (2020) Categ. JCR: PHYSIOLOGY rank: 15 / 81 = 0.185 (2020) - Q1 - T1 Categ. JCR: ENDOCRINOLOGY & METABOLISM rank: 57 / 144 = 0.396 (2020) - Q2 - T2 Factor impacto SCIMAGO: 1.506 - Endocrinology, Diabetes and Metabolism (Q1) - Physiology (medical) (Q1) - Physiology (Q1)