Aims: 

To elucidate expression of arginine vasopressin (Avp) and vasoactive intestinal peptide (Vip) gene in the suprachiasmatic nucleus (SCN) and in the paraventricular nucleus (PVN) of the hypothalamus in TGR[mREN2]27 hypertensive (TGR) and control Sprague-Dawley (SD) normotensive rats. TGR rats have an additional mouse renin gene that results in higher activity of the renin-angiotensin system (RAS), subsequent systemic hypertension and an inverted daily blood pressure profile.

Methods: 

Rats were kept under 12h light: 12h dark regimen. Animals were decapitated in 4h intervals during 24-hour period. Brains were extirpated and frozen on dry ice. Expression of Avp and Vip was assessed by in situ hybridization on 14 mm thick coronal sections of the hypothalamus with ³⁵S radiolabelled oligoprobes. Results were expressed as relative optical density and data obtained in single time points were statistically analyzed by Student t-test between TGR and SD groups.

Results: 

Expression of Avp gene in the SCN was rhythmic both in SD and TGR rats with peak during the light phase. Up regulated Avp expression in TGR as compared to control animals was found at the beginning and at the end of the light phase. No significant differences were found in Vip expression in the SCN between TGR and SD rats.

Conclusion: 

Up regulated RAS in TGR animals resulted in increased Avp expression at the beginning and at the end of the light phase in the SCN compared to control animals while expression of Vip was not altered. Supported by grants APVV 20-022-704 and UK/209/200.