Fig 2: CSE expression in cochlea.A: Immunofluorescent photograph of CSE in the cochlea (bar = 200 µm). CSE protein was positively expressed in the stria vascularis (yellow arrow) and the wall of the spiral modiolar artery (red arrow). B and C are mean CSE mRNA expression in rat cochlea and ABR threshold shifts. The relative expressions after noise exposure for 0 d, 1 d, 1 w and 3 w were 1.00±0.17, 1.12±0.17, 1.95±0.31 and 0.76±0.19, respectively. ABR threshold shifts were 1.56±3.26, 26.88±5.79, 35.00±5.18 and 56.25±5.67 dB SPL, respectively. They both increased with increased exposure time initially. In the 3-week exposure group, the expression of CSE mRNA decreased inversely.

Fig 3: Doppler ultrasound experimental design. A. Experimental design. Ovariectomized WT or CSE KO mice received two daily subcutaneous injections of hormone or sesame oil vehicle. Ultrasounds were conducted just prior to and two days following the first injection, after which mice were euthanized and tissues collected. B. Example color Doppler sonogram of mouse uterine artery. The yellow dashed line denotes uterine horn edge. C. Calculation of volumetric blood flow (Q), which depends on blood vessel diameter (Dm) and average blood velocity. Assuming laminar parabolic flow, average blood velocity is half maximal velocity (vm). D. Uterine artery spectral Doppler scans exemplifying hemodynamic parameters. Cardiac cycle: duration per heartbeat. Mean velocity (MV): average blood speed per cardiac cycle. Peak systolic velocity (PSV) and end diastolic velocity (EDV) are the highest and lowest blood velocities during a cardiac cycle, respectively. E. Derived hemodynamic parameters. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig 4: Serum arginine metabolism is disrupted in CSE KO mice. A. Pathways of arginine metabolism. Arginine is a substrate for NO production via endothelial NO synthase (eNOS) and urea elimination via arginase (ARG), which yield citrulline and ornithine, respectively. Ornithine transcarbamylase (OTC) converts ornithine to citrulline. Argininosuccinate synthase (ASS) and argininosuccinate lyase (ASL) regenerate arginine from citrulline. B–C. Serum arginine and ornithine levels do not vary with genotype or E2 injection. D. CSE KO serum contains more citrulline than WT serum, regardless of E2 injection. P-values denote significance by Sidak posttests after one-way ANOVA. NS: not significant. n: number of individual mice (listed in figure).

Fig 5: DNMTs inhibition reversed the repression of Hcy on CSE expression. DNMTs inhibition with its inhibitor Aza (A,B) or DNMT1 siRNA (C) almost reversed the decreases of CSE expression induced by Hcy treatment. The knockdown efficiency of DNMT1 siRNA was determined by immunoblotting analysis (D). n = 3–4. * p < 0.05, ** p < 0.01, *** p < 0.001. N.S., not significant.