350 



p. TEITELBAUM AND A. N. EPSTEIN 



(Epstein and Teitelbaum, 1962) coupled between the animal's gastric tube 

 and the pump allows the animal to spend day and night in the cage. The 

 joint swivels with the animal and prevents its movement around the cage 

 from kinking the delivery tube. The rat can therefore feed or water itself 

 day and night without tasting, smelling, or feeling food or water in its 

 mouth, and without even the act of eating or drinking. Does regulation of 

 food and water intake continue in the absence of taste and smell? Let us 

 first consider water intake. 



As shown in Fig. 3, from the work by Epstein (1960), the rat will regulate 

 its daily water intake, and even compensate for the increased water loss of 

 diabetes insipidus by pressing a bar for direct injection into its stomach. 



300 



u 

 u 



Z 250 



< 



5 200 



I 150 



Q 100 



O 



•- 50 



ORAL 



I I I 



INTRAGASTRIC 



NORMAL 



1 2 3 



6 7 

 DAYS 



t-^ 



10 11 12 



Fig. 3, Oral and intragastric water intake in normal rats and in an animal with 

 diabetes insipidus. (From Epstein, 1960.) 



Food intake is also regulated normally in the absence of taste and smell. 

 Epstein and Teitelbaum (1962) have shown that rats feeding themselves by 

 intragastric self-injection regulated their daily food intakes and body 

 weights with remarkable precision for periods of 13 to 44 days despite 

 variations in the concentration of the diet, the size of individual stomach 

 loads and the number of presses required for a single load. All of the 

 animals continued their normal slow weight gain during the period of 

 intragastric feeding. Figure 4 shows 3 days of oral feeding and the data 

 of the first 25 days of the intragastric period of the animal studied for the 



