Fig. 1

Melatonin and related receptors in humans and rats with sepsis. (A) Serum levels of melatonin in patients with sepsis and age-/sex-matched health controls (n = 16). (B) Experimental scheme and the timeline for the sepsis model. (C) Representative images of M-mode echocardiography of rats 16 h after LPS treatment or CLP surgery and the left ventricle ejection fraction in control and sepsis-induced rats (n = 6). (D) Representative hematoxylin and eosin (H&E) staining images of the heart section (scale bar of 100 μm). (E) Melatonin levels in serum (n = 5) and cardiac tissues (n = 4) among rats with sepsis and control. (F) Relative mRNA levels of melatonin receptors in heart tissue (n = 5–6). (G) Western blots and quantifying melatonin receptors MTNR1A, MTNR1B, and RORα (n = 4). (H) Immunohistochemical staining of RORα in the sepsis heart (scale bar of 50 μm). (I) Relative mRNA levels of RORα in HL-1 cells with LPS treatment (n = 3, GSE56584). (J) Cellular viability of H9C2 myoblasts in response to different doses of LPS (n = 5). (K) Western blots and quantification of RORα expression in H9C2 cells treated with low and high doses of LPS (n = 4)