Re-examination of the effect of either a lateral or third ventricular cannula on captopril-induced salt appetite in rats

In Study A, rats were implanted with a cannula aimed at either the lateral (LV) or ventral third (V3V) brain ventricles 1 week prior to starting a chronic oral regimen of captopril. The presence of neither cannula significantly impaired the emergence of captopril-induced appetite for NaCl solution. In Study B, V3V cannulae were implanted in rats after a captopril-induced appetite for NaCl was established. The surgery produced a 1-2 day attenuation of NaCl intake, but this was no greater than that observed in a sham-operated group that received no cannula. These results do not support those of others who suggest that captopril (and, by inference, other agents) can leak across a damaged blood-brain barrier for at least 2 weeks after placement of a cannula. Possible reasons for the differences in results are addressed.