In contrast, gene expression profiling of Spontaneously Hypertensive (SHR) rats, a genetic model of hypertension, demonstrated decreased expression of Bmal1 and Npas2, while Per1, Per2, Per3, Cry1, Cry2, Bhlhe41 and Csnk1D were all upregulated compared to naïve WKY controls. This evidence concerns the gene PER1 and hypertensive disorder.