THE EFFECT OF WITHDRAWAL OF WATER ON THE SALIVARY CONDITIONED REFLEX INDUCED BY MORPHINE

Abstract

It was previously shown that the morphine-salivary conditioned reflex was abolished by a starvation regimen. Starving dogs drink less than normally. Water withdrawal was studied to test whether starvation or "dehydration" was more important in this abolition. Withdrawal of drinking water and NaCl diuresis were used to "dehydrate" the animals. Three to five days of such "dehydration" led to complete abolition of the reflex. This is 1/3 the time required by starvation. Control experiments showed no such falling off in pilocarpine-unconditioned secretion, indicating that the effects follow some central rather than peripheral change. Thirsting dogs eat less than normally, but since the depression of the reflex during starvation with water ad libitum is less than during absence of water with food ad libitum, the water element appears more important than starvation in the abolition.