CYP2C11 played a significant role in down-regulating rat blood pressure under the challenge of a high-salt diet

Establishment and characterization of liver-specific Apoa4-Cre and Cyp2c11-Cre rat models in juvenile and adult stages

BACKGROUND

Liver diseases are a major contributor to both morbidity and mortality. Conditional knockout animals are always produced through crossing floxed animals with a tissue-specific Cre animal. The use of floxed rat resource has rapidly increased, but the liver-specific Cre rat lines for studying liver diseases and interested genes are limited, especially in a spatially and temporally restricted manner.

METHODS

RNA sequencing and real-time polymerase chain reaction (PCR) were used to screen and confirm the presence of liver-specific genes. Apoa4-Cre rats and Cyp2c11-Cre rats were produced by CRISPR/Cas9 knockin. Rosa26-imCherry rats were employed to hybridize with the Cre rats to obtain the Apoa4-Cre/Rosa26-imCherry and Cyp2c11-Cre/Rosa26-imCherry rats. The temporal and spatial patterns of Cre expression were determined by the observation of red fluorescence on tissue sections. Hematoxylin-eosin stain was used to evaluate the liver histopathologic changes. The blood biochemical analysis of several liver enzymes and liver lipid profile was performed to evaluate the liver function of Cre rats.

RESULTS

Apoa4 and Cyp2c11 were identified as two liver-specific genes. Apoa4-Cre and Cyp2c11-Cre rats were produced and hybridized with Rosa26-imCherry rats. The red fluorescence indicated that the Cre recombinases were specially expressed in the juvenile and adult liver and not in other organs of two hybridized rats. All the blood biochemical parameters except low-density lipoprotein (LDL) did not change significantly in the Cre rats. No histological alterations were detected in the livers of the Cre rats.

CONCLUSIONS

Liver-specific Apoa4-Cre and Cyp2c11-Cre rats have been established successfully and could be used to study gene knockout, specifically in juvenile and adult liver.

Acclimation to a High-Salt Diet Is Sex Dependent

Background Premenopausal women are less likely to develop hypertension and salt-related complications than are men, yet the impact of sex on mechanisms regulating Na+ homeostasis during dietary salt challenges is poorly defined. Here, we determined whether female rats have a more efficient capacity to acclimate to increased dietary salt intake challenge. Methods and Results Age-matched male and female Sprague Dawley rats maintained on a normal-salt (NS) diet (0.49% NaCl) were challenged with a 5-day high-salt diet (4.0% NaCl). We assessed serum, urinary, skin, and muscle electrolytes; total body water; and kidney Na+ transporters during the NS and high-salt diet phases. During the 5-day high-salt challenge, natriuresis increased more rapidly in females, whereas serum Na+ and body water concentration increased only in males. To determine if females are primed to handle changes in dietary salt, we asked the question whether the renal endothelin-1 natriuretic system is more active in female rats, compared with males. During the NS diet, female rats had a higher urinary endothelin-1 excretion rate than males. Moreover, Ingenuity Pathway Analysis of RNA sequencing data identified the enrichment of endothelin signaling pathway transcripts in the inner medulla of kidneys from NS-fed female rats compared with male counterparts. Notably, in human subjects who consumed an Na+-controlled diet (3314-3668 mg/day) for 3 days, women had a higher urinary endothelin-1 excretion rate than men, consistent with our findings in NS-fed rats. Conclusions These results suggest that female sex confers a greater ability to maintain Na+ homeostasis during acclimation to dietary Na+ challenges and indicate that the intrarenal endothelin-1 natriuretic pathway is enhanced in women.