Alterations of ventricular pH alter water intake and food consumption in rats

The pH of third ventricular CSF was altered by infusing acidic or alkaline solution of artificial cerebrospinal fluid (aCSF) through chronically implanted stainless steel cannula. In two separate group of rats (n=18 each) water and food consumptions were recorded 30 min, 1 hr, and 24 hr after intraventricular infusions of the modified aCSF solutions having pH 6.0, 8.0 and 7.4 (control). On raising the CSF pH, water intake increased in all three observations. Feeding was not affected in the observations taken after 30 min and 1 hr, but significantly reduced food consumption was observed 24 hr after the infusions. Lowering of pH had no effect either on dipsogenic or feeding response. The CSF pH correlated positively with drinking in all three observations. Since dipsogenic and feeding responses are centrally regulated by ion sensitive cells, it may be presumed that altered CSF pH influenced the activities of the sensors by altering ionic conductance across their membranes.