Excitatory responses of cardiovascular activities to urocortin3 administration into the PVN of the rat.

Urocortin3 (Ucn3) is an endogenous ligand for corticotropin-releasing factor receptor subtype 2 (CRF2R). In this study, we examined its potential cardiovascular effects by microinjection of Ucn3 and anti-sauvagine 30 (ASV30), a selective antagonist of CRF2R, into the paraventricular nucleus (PVN) of the hypothalamus. After Ucn3 (10 pmol/100 nl) was microinjected into the PVN of anesthetized rats, significant increases of systolic blood pressure, heart rate and renal sympathetic nerve activity were observed. Furthermore, all these cardiovascular and autonomic effects induced by Ucn3 could be blocked totally by administration of ASV30 into the PVN. These results are consistent with the idea that Ucn3 might be involved in the central nervous control of cardiovascular function by acting centrally to increase sympathetic outflow via the activation of CRF2R within the PVN.