REGULATION OF FOOD AND WATER INTAKE 



355 



when 75 per cent of the diet is cellulose. In contrast, hyperphagic animals 

 do not increase their intake when the diet is mixed with cellulose. Although 

 they eat two to three times as much of the ordinary diet, they refuse to eat 

 the cellulose-adulterated diet when it contains as little as 25 per cent 

 cellulose. The effect is particularly marked in obese hyperphagic animals, 

 which eat httle or nothing for a week at a time and lose a great deal of weight. 

 If as little as one part of quinine sulphate by weight is mixed in 800 parts 

 of their ordinary food, as shown in Table 1, obese hyperphagics stop eating 

 although normal animals are unaffected (Teitelbaum, 1955). If the diet is 

 sweetened with dextrose, as shown in Table 2, normal animals regulate 



Table 1. The effect of 0.125 per cent quinine sulphate 

 on the food intake of normal, dynamic, and obese 

 hyperphagic rats. each number represents mean daily 



INTAKE FOR 5 DAYS. (FrOM TEITELBAUM, 1955.) 



Table 2. The effect of flavouring the diet with dextrose 

 ON the food intake of normal, dynamic, and obese 



HYPERPHAGIC RATS. EaCH NUMBER REPRESENTS MEAN DAILY 

 INTAKE FOR 5 DAYS. (FrOM TeITELBAUM, 1955.) 



their intake by eating slightly less, whereas obese hyperphagics show marked 

 increase in food intake (Teitelbaum, 1955). All these effects are most 

 exaggerated in obese hyperphagic animals, but Graff and Stellar (1962) in a 

 recent analysis of the effects of positive and negative taste stimuli on feeding, 

 have shown that all hyperphagics, obese or dynamic, react exaggeratedly 

 to taste stimuli in their food. This finickiness shown by hyperphagic 

 animals indicates a basic disturbance in their motivation for food, as was 

 pointed out by Miller, Bailey and Stevenson (1950). 



When such animals are required to feed themselves intragastrically, they 

 again show impaired motivation coupled with an increased dependence 

 upon taste and smell. Figure 7 shows the results of an experiment (done in 

 collaboration with Mr. Dennis McGinty) in which a dynamic hyperphagic 



