Duloxetine (DLX) is a dual serotonin and norepinephrine reuptake inhibitor, widely used for the treatment of major depressive disorder. Although DLX has shown good efficacy and safety, serious adverse effects (e.g., liver injury) have been reported. The mechanisms associated with DLX-induced toxicity remain elusive. Drug metabolism plays critical roles in drug safety and efficacy. However, the metabolic profile of DLX in mice is not available, although mice serve as commonly used animal models for mechanistic studies of drug-induced adverse effects. Our study revealed 39 DLX metabolites in human/mouse liver microsomes and mice. Of note, 13 metabolites are novel, including five N -acetyl cysteine adducts and one reduced glutathione (GSH) adduct associated with DLX. Additionally, the species differences of certain metabolites were observed between human and mouse liver microsomes. CYP1A2 and CYP2D6 are primary enzymes responsible for the formation of DLX metabolites in liver microsomes, including DLX-GSH adducts. In summary, a total of 39 DLX metabolites were identified, and species differences were noticed in vitro. The roles of CYP450s in DLX metabolite formation were also verified using human recombinant cytochrome P450 (P450) enzymes and corresponding chemical inhibitors. Further studies are warranted to address the exact role of DLX metabolism in its adverse effects in vitro (e.g., human primary hepatocytes) and in vivo (e.g., Cyp1a2-null mice). SIGNIFICANCE STATEMENT This current study systematically investigated Duloxetine (DLX) metabolism and bioactivation in liver microsomes and mice. This study provided a global view of DLX metabolism and bioactivation in liver microsomes and mice, which are very valuable to further elucidate the mechanistic study of DLX-related adverse effects and drug-drug interaction from metabolic aspects.

One of the endogenous estrogens, 17β-estradiol (E 2 ) is a female steroid hormone secreted from the ovary. It is well established that E 2 causes biochemical and histological changes in the uterus. However, it is not completely understood how E 2 regulates the oviductal environment in vivo. In this study, we assessed the effect of E 2 on each oviductal cell type, using an ovariectomized-hormone-replacement mouse model, single-cell RNA-sequencing (scRNA-seq), in situ hybridization, and celltype-specific deletion in mice. We found that each cell type in the oviduct responded to E 2 distinctively, especially ciliated and secretory epithelial cells. The treatment of exogenous E 2 did not drastically alter the transcriptomic profile from that of endogenous E 2 produced during estrus. Moreover, we have identified and validated genes of interest in our datasets that may be used as cell-and region-specific markers in the oviduct. Insulin-like growth factor 1 (Igf1) was characterized as an E 2 -target gene in the mouse oviduct and was also expressed in human fallopian tubes. Deletion of Igf1 in progesterone receptor (Pgr)-expressing cells resulted in female subfertility, partially due to an embryo developmental defect and embryo retention within the oviduct. In summary, we have shown that oviductal cell types, including epithelial, stromal, and muscle cells, are differentially regulated by E 2 and support gene expression changes, such as growth factors that are required for normal embryo development and transport in mouse models. Furthermore, we have identified cell-specific and region-specific gene markers for targeted studies and functional analysis in vivo. K E Y W O R D Sembryo development, embryo transport, estrogen, insulin-like growth factor 1, oviduct, scRNA-seq 2 of 19 | MCGLADE Et AL.