ODP037 Effects of DHCR24 Inhibitor on Excessive Adrenal Steroidogenesis in db/db mouse

BACKGROUND AND PURPOSE: Patients with type 2 diabetes have an elevated basal level of cortisol, which has been suggested to be involved in the exacerbation of hyperglycemia and the progression of organ complications. Furthermore, it has been reported that adrenal steroidogenesis increases in db/db mice, an animal model of type 2 diabetes. However, the mechanism of the increased adrenal steroidogenesis in type 2 diabetes is unclear. In this study, we aimed to elucidate the mechanism of increased adrenal steroidogenesis in db/db mice and examine whether it is a therapeutic target. EXPERIMENT 1: METHODS: Gene expression in adrenal glands of 10-week-old male db/db mice and db/+ mice was examined by DNA microarray and real-time PCR. RESULTS: In the adrenal glands of db/db mice, expression of Acc and Scd1, which are involved in fatty acid synthesis, was decreased by 3.7-fold and 2.6-fold, respectively, compared with db/+ mice. However, expression of Cpt1α, which is involved in acetyl-CoA production by lipolysis, was increased by 1.8-fold and expression of Dhcr24, the final enzyme of the de novo cholesterol synthesis system, was increased by 2.5-fold. Thus, fatty acid degradation and endogenous cholesterol synthesis had increased in the adrenal glands of db/db mice. EXPERIMENT 2: METHODS: 8-week-old male db/db mice were divided into two groups, PBS administration (P) and 10mg/kg DHCR24 inhibitor (U18666A) administration (U) groups. PBS or U18666A was injected intraperitoneally into mice once a week. 4 weeks later, the mice were euthanized, blood corticosterone was measured by LC-MS/MS, and gene expression in adrenal glands was measured by real-time PCR. RESULTS: The blood corticosterone level was 196.6±12.7ng/mL in the U group and 245.8±15.4ng/mL in the P group, which was significantly lower in the U group (unpaired t-test, p<0. 05). mRNA expression of Acc and Scd1 was increased by 3.1-fold and 1.3-fold, respectively, in the U group compared with the P group. CONCLUSION: These results suggest that increased endogenous cholesterol synthesis may be a cause of steroid overproduction in the adrenal glands of db/db mice and a DHCR24 inhibitor suppresses the increase in steroid hormone synthesis. This study indicates that changes in adrenal fatty acid metabolism and endogenous cholesterol synthesis might play a major role in understanding the mechanism of increased adrenal steroidogenesis and finding a new therapeutic target to prevent organ complications of type 2 diabetes. Presentation: No date and time listed