Molecular and cellular biochemistryAug 16, 2006

Daily rhythms of clock gene activity in the heart, kidney, and blood pressure control brain areas of high blood pressure rats

Circadian Biology Weekly Brief ↗PubMed ↗DOI ↗

Updated Apr 2, 2026

Abstract

Blood pressure and relative heart weight were significantly elevated in TGR rats compared to control.

Expression of the clock genes bmal1 and clock was increased in the suprachiasmatic nucleus (SCN) of TGR rats.
Daily rhythm patterns for per2 and dbp expression were similar in both TGR and control rats.
Mesor (mean level) of per2 expression in the rostral ventrolateral medulla (RVLM) was significantly higher in TGR rats.
In the nucleus of the solitary tract (NTS), per2 expression in TGR rats was phase delayed by 3.5 hours compared to control rats.
Bmal1 did not show a rhythmic pattern in the NTS of TGR rats.
Circadian oscillators in specific brain regions were more affected than those in the heart and kidney by the additional renin gene.

Simplified

Hypertensive TGR(mREN-2)27 rats exerting inverted blood pressure (BP) profile were used to study clock gene expression in structures responsible for BP control. TGR and control Sprague Dawley male rats were synchronized to the light:dark cycle 12:12 with food and water ad libitum. Daily rhythm in per2, bmal1, clock and dbp expression in the suprachiasmatic nucleus (SCN), rostral ventrolateral medulla (RVLM), nucleus of the solitary tract (NTS), heart and kidney was determined in both groups. Sampling occurred in regular 4 h intervals when rats of both strains were 11-weeks-old. Blood pressure and relative heart weight were significantly elevated in TGR rats in comparison with control. Expression of bmal1 and clock was up regulated in SCN of TGR rats but daily rhythm in per2 and dbp expression was similar in both groups. Mesor of per2 expression in RVLM was significantly higher in TGR than in control rats. In NTS of TGR rats expression of per2 was phase delayed by 3.5 h in comparison with control and bmal1 did not exert rhythmic pattern. Our study provided the first evidence about modified function of central and peripheral circadian oscillators in TGR rats at the level of clock gene expression. Expression of clock genes exerted up regulation in SCN and RVLM and down regulation in NTS. Circadian oscillators in selected brain structures were influenced more than oscillators in the heart and kidney by additional renin gene. Interactions of RAS and circadian system probably contribute to the development of inverted BP profile in TGR rats.

Full Text

Full text is available at the source.

View Full Text ↗

Daily rhythms of clock gene activity in the heart, kidney, and blood pressure control brain areas of high blood pressure rats

Abstract

Full Text

You found one interesting study. We’ll send the next 7.

What Lands in Your Inbox Each Week:

Recent issues from the circadian biology brief