Third ventricular chloride infusions enhance drinking in water deprived rats

The influence of intraventricularly infused anions on drinking was studied in 54 water deprived male rats, divided in 9 equal groups. Stainless steel cannulae were chronically implanted into the anteroventral part of the third ventricle (AV3V) and the animals were water deprived for 24 hr prior to the infusions. Control group (n = 6) was given 10 microliters of artificial cerebrospinal fluid. The rats of the remaining 8 groups received similar quantity of equiosmolar chloride or bicarbonate solution of either sodium, potassium, calcium or barium. Cumulative quantity of water consumed in 30 min, 1 hr, and 24 hr after the infusion was recorded. All the chloride solutions, irrespective of the associated cation, enhanced drinking. Effects of the bicarbonates were relatively weak and transient. Dipsogenic effects of the solutions depended on their anionic composition. Thus, chlorides of all the cations elicited greater drinking than their bicarbonates. Responses of the similar anionic solutions were comparable. It appears that intraventricularly infused chloride ions stimulate drinking in water deprived rats.