INFLUENCE OF DRUGS, IMPLANTED INTO THE HYPOTHALAMUS, ON THE WATER CONSUMPTION OF RATS

¹ Department of Pharmacology, Hebrew Univercity-Hadassah Medical School, Jerusalem, Israel

The water intake evoked by hypertonic saline is reduced by intraperitoneal injection of milligram quantities of digitoxin into normal rats: the effect is enhanced by bilateral nephrectomy. When deposited bilaterally in the hypothalamus, microgram quantities of the glycoside are sufficient to suppress both spontaneous drinking and the response to a hypertonic stimulus for a considerable period. In addition, the same or slightly larger amounts of digitoxin produce convulsions lasting a few hours. Ethacrynic acid, when implanted into the hypothalamus in quantities of 5 to 25 µg, exerts a strong antidipsic effect but does not evoke convulsions. Furosemide is active only in amounts of about 100 µg, and the effect lasts for only a few days. Likewise, the adipsia observed after hypothalamic implantation of 100 µg of hydrochlorothiazide is of transient character. The antidipsic activity of drugs which have been deposited in the hypothalamus does not Parallel their diuretic effect upon systemic application.