AV3V lesion suppresses the pressor, dipsogenic and natriuretic responses to cholinergic activation of the septal area in rats

In the present study we investigated the effect of anteroventral third ventricle (AV3V) lesion on pressor, dipsogenic, natriuretic and kaliuretic responses induced by the injection of carbachol (a cholinergic agonist) into the medial septal area (MSA) of rats. Male rats with sham or AV3V lesion and a stainless-steel cannula implanted into the MSA were used. Carbachol (2 nmol) injected into the MSA in sham lesion rats produced pressor (43 ± 2mmHg), dipsogenic (9.6 ± 1.2ml/h), natriuretic (531 ± 82 μEq/120min) and kaliuretic (164 ± 14 μEq/120min) responses. In AV3V-lesioned rats (1–5 days and 14–18 days), the pressor (11 ± 2 and 14 ± 2mmHg, respectively), dipsogenic (1.9 ± 0.7 and 1.4 ± 0.6ml/h), natriuretic (21 ± 5 and 159 ± 44 μEq/120min) and kaliuretic (124 ± 14 and 86 ± 13 μEq/120min) responeses induced by carbachol injection into the MSA were reduced. These results show that the AV3V region is essential for the pressor, dipsogenic, natriuretic and kaliuretic responses induced by cholinergic activation of the MSA in rats.