PVN lesions prevent the endothelin 1-induced increase in arterial pressure and vasopressin.

Endothelin (ET) acts within the central nervous system to increase arterial pressure and arginine vasopressin (AVP) secretion. This study assessed the role of the paraventricular nuclei (PVN) in these actions. Intracerebroventricular ET-1 (10 pmol) or the ET(A) antagonist BQ-123 (40 nmol) was administered in conscious intact or sinoaortic-denervated (SAD) Long-Evans rats with sham or bilateral electrolytic lesions of the magnocellular region of the PVN. Baseline values did not differ among groups, and artificial cerebrospinal fluid (CSF) induced no significant changes. In sham-lesioned rats, ET-1 increased mean arterial pressure (MAP) 15.9 +/- 1.3 mmHg in intact and 22.3 +/- 2.7 mmHg in SAD (P < 0.001 ET-1 vs. CSF) rats. PVN lesions abolished the rise in MAP: -0.1 +/- 2.8 mmHg in intact and 0.0 +/- 2.9 mmHg in SAD. AVP increased in only in the sham-lesioned SAD group 8.6 +/- 3.5 pg/ml (P < 0.001 ET-1 vs. CSF). BQ-123 blocked the responses. Thus the integrity of the PVN is required for intracerebroventricularly administered ET-1 to exert pressor and AVP secretory effects.