Influence of intracerebroventricularly infused anions on feeding response

Chloride and bicarbonate solutions of potassium, calcium, sodium, and barium were infused into the third ventricle of the rats to observe the influence of anions on feeding response. Stainless steel cannulae were chronically implanted into the anteroventral part of the third ventricle of 54 rats, which were divided in 9 equal groups. While the control group was given 10 microliters of artificial cerebrospinal fluid intraventricularly, the remaining 8 groups received the equal quantity (10 microliters) of one of the hypertonic equimolar test solutions. Chloride solutions of potassium, calcium, and barium evoked significantly (p less than 0.05) higher feeding than the control group, while none of the bicarbonate solutions influenced feeding significantly. Chloride solutions of all the 4 cations elicited significantly (p less than 0.05) higher feeding than the corresponding bicarbonate solutions in 24 hr. It was observed that though the cations differed, there was no significant difference in the responses elicited by the different chloride solutions. Similarly, various bicarbonate solutions elicited similar responses. Osmolality and pH of the infusion solution have not influenced feeding significantly. It is concluded that the anionic, but not the cationic concentration of the fluid bathing juxtacerebroventricular sensors, predominantly influence the feeding response.