Sex-Specific Role of the Circadian Clock Protein PER1 in the Regulation of Renal Endothelin-1 in Dahl Salt-Sensitive Rats

Background: We previously demonstrated that after 3 weeks on a high-salt diet (4% NaCl), male Dahl Salt-Sensitive (SS) rats lacking the circadian protein Period1 (PER1 KO) display a worsened hypertensive phenotype when compared to SS controls (Zietara et al., Hypertension 2022). The mechanism relating PER1 KO with a hypertensive phenotype may be through PER1’s negative regulation of the vasoconstricting peptide endothelin-1 (ET-1) by transcriptional control of its gene, Edn1. In this study, we aimed to investigate the effect PER1 KO had on ET-1 in the kidneys of male and female SS rats. Hypothesis: We hypothesized that Period1 is necessary to repress Edn1 expression in male SS rats. This hypothesis predicts increased transcription of Edn1 and heightened ET-1 peptide levels in the kidneys of male PER1 KO rats. Methods: To investigate the effect of PER1 KO on renal ET-1 levels, we quantified mRNA and protein expression in male and female kidney tissue. Male and female SS and PER1 KO rats were maintained on a normal-salt (0.4% NaCl) diet or placed on three weeks of a high-salt diet (4% NaCl). Kidneys were collected at 2 AM, corresponding to the active period for rats, and used for protein and mRNA analyses. Renal ET-1 protein levels were measured by ELISA, and quantitative PCR was performed to quantify the mRNA levels of the genes of interest. Statistical comparisons were made using Two-Way ANOVA. Results: In males, renal ET-1 protein levels were significantly higher in PER1 KO rats when compared to SS controls (p genotype = 0.0126*, n = 5). Additionally, renal Edn1 mRNA levels were significantly increased in male PER1 KO rats on a high-salt diet compared to other groups (p interaction = 0.0103*, p diet = 0.0194*, p genotype = 0.002**, n = 5-6). In females, no significant differences were seen in renal ET-1 peptide (p genotype = 0.1572, p diet = 0.7810, p interaction = 0.2939, n = 5) or Edn1 mRNA levels (p interaction = 0.0714, p diet = 0.6363, p genotype = 0.6820, n = 5-6). Conclusions: These data support the hypothesis that PER1 is required to suppress Edn1 at the onset of salt-sensitive hypertension in male SS rats. Additionally, this lack of increase in ET-1 or Edn1 levels in females shows a sex-specific function for Period1 in SS rats. National Institute of Health R35 HL135749 (to A.S.), R01 DK109570 (to M.L.G. and A.S.), and the Department of Veteran Affairs I01 BX004024 (to A.S.) This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.