RESUMEN
Objective To investigate the role and mechanism of SR8278,a synthetic antagonist of nuclear receptor subfamily 1 group D member 1(NR1D1),in alleviating the structural and functional impairment of the extraorbital lacrimal glands induced by jet lag in mice.Methods Totally 36 healthy wild C57BL/6J mice aged 8-10 weeks were randomly divid-ed into 3 groups(normal group,jet-lag group,and jet-lag+SR8278 group)after adapting to a circadian rhythm chamber under the 12 h light/12 h dark(12 h/12 h LD)cycle for 2 weeks,with 12 mice in each group.Mice in the normal group were fed in a circadian rhythm chamber in a 12 h LD cycle,mice in the jet-lag group were fed in a 12 h/12 h LD cycle with an 8-hour advanced LD schedule,and mice in the jet lag+SR8278 group were fed in a 12 h/12 h LD cycle with an 8-hour advanced LD schedule and received 25 mg·kg-1 SR8278.At the end of 5 days of intervention,locomotor activity,core body temperature and tear secretion of mice in each group were collected,and the weight of lacrimal gland tissues and size of lacrimal gland cells were measured.Immunohistochemical methods were used for histological evaluation of the extraor-bital lacrimal glands in mice.Lacrimal ribonucleic acid(RNA)was extracted for high-throughput RNA-sequencing analysis containing NR1D1,and the obtained transcriptomic data were used for KEGG and GO functional enrichment analysis.Re-sults Compared with the normal group,the jet-lag group had higher daytime activity,lower nighttime activity,higher daytime core body temperature,and lower nighttime core body temperature,with statistically significant differences(all P＜0.05).Compared with the jet-lag group,the jet-lag+SR8278 group had lower daytime activity,higher nighttime activi-ty,lower daytime core body temperature,and higher nighttime core body temperature,with statistically significant differ-ences(all P＜0.05).Compared with the normal group,the jet-lag group showed a decrease in lacrimal gland weight and tear secretion and an increase in size of lacrimal gland cells,with statistical significance(all P＜0.05);compared with the jet-lag group,the jet-lag+SR8278 group had an increase in lacrimal gland weight and tear secretion and a decrease in size of lacrimal gland cells,with statistical significance(all P＜0.05).Compared with the normal group,the jet-lag group showed a higher expression of NR1D1 in the lacrimal gland at night;compared with the jet-lag group,the jet-lag+SR8278 group showed a lower expression of NR1 D1 in the lacrimal gland at night(both P＜0.05).Bioinformatics analysis showed 947 significantly different genes in the jet-lag group and the jet-lag+SR8278 group,of which 43 are significantly upregulated genes,and 904 are significantly downregulated genes.The Notch signaling pathway has the most significant difference.Conclusion SR8278 effectively enhances the tear secretion function of jet-lagged mice by targeting NR1D1 inhibition.This process may be completed through the Notch signaling pathway.