Down-regulation of corticotropin-releasing hormone receptor type 2beta mRNA expression in the rat cardiovascular system following food deprivation

The present study was conducted to assess the effect of nutritional stress induced by food deprivation on expression of messenger ribonucleic acid (mRNA) for corticotropin-releasing hormone receptor type 2beta (CRH-R2beta) in the rat cardiovascular system in the presence or absence of changes in circulating corticosterone. Food deprivation for 96 h caused a robust increase in plasma corticosterone levels and a significant decrease in CRH-R2beta mRNA expression in the rat heart. Starvation for 48 and 96 h decreased CRH-R2beta mRNA expression in the atria, ventricle as well as aorta of sham-adrenalectomized (sham) rats. Surprisingly, clamping plasma glucocorticoids at low levels by adrenalectomy with corticosterone pellet replacement (ADX+B) did not completely prevent starvation-induced decreases of CRH-R2beta mRNA expression in the rat cardiovascular system. Urocortin (Ucn) mRNA expression was increased significantly by food deprivation in the heart of sham as well as ADX+B rats. We speculate that food deprivation may increase urocortin, which in turn down-regulates CRH-R2beta mRNA expression in cardiovascular system. These data indicate that food deprivation despite the presence or absence of changes in circulating corticosterone may have an inhibitory effect on CRH-R2beta mRNA expression in the rat cardiovascular system.