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p. TEITELBAUM AND A. N. EPSTEIN 



the usual 6 bar presses were required, (the 15th day in Fig. 4) the animal 

 obtained 28 ml of liquid diet by pressing 180 times for 17 self loads. One 

 week later, when 36 bar presses were needed for each gastric load, the 

 animal pressed 822 times to obtain 18 self loads and 29 ml of liquid diet. 



Although the method of intragastric feeding by self-injection appears to 

 ehminate the influence of taste and smell from the regulation of food and 

 water intake, it is conceivable that other possibilities of tasting the diet 

 might have been present. Thus, taste might have resulted from some slight 

 regurgitation of the diet after each injection. Or perhaps some intravenous 

 taste might arise from some nutrients after absorption from the stomach. 

 To control for this possibility, we allowed three rats to feed themselves 

 intragastrically for three days with a diet adulterated with 0.05 per cent 

 quinine hydrochloride (5.0 ml of a 1.0 per cent stock solution added to 

 95 ml pure diet). This adulterated diet is so bitter that animals ingesting 

 it by mouth either refuse it completely or decrease their daily intake very 

 markedly. Figure 5 shows the result of such an experiment. 



The average daily intake of the pure liquid diet of both groups of animals 



Fig. 5. Daily food intake (in ml.) during one day on pure liquid diet and three 



succeeding days on 0.05 per cent quinine adulterated diet of a group of rats 



feeding orally (A'^ = 4) and a group feeding intragastrically (N -- 3). (From 



Epstein and Teitelbaum, 1962b.) 



is shown for one day before adulteration and for three days of quinine 

 adulteration. Oral intake of the quinine adulterated food by the control 

 group fell sharply on the first day in all four animals and then rose to 

 slightly below normal on the third day of the test. Averaged across the 

 3-day period, oral intake of the adulterated food was only 57 per cent of the 

 previous intake of the pure liquid diet. This was reflected in an average 

 loss in body weight of 12 g suffered by the animals in the same period. In 

 contrast, the intake of the animals ingesting the adulterated diet by intra- 

 gastric self-injection was essentially unchanged and they lost no weight 

 during the quinine test period. 



The rats studied here fed themselves normal amounts of food and regu- 

 lated their body weights by injecting a hquid diet into their own stomachs 

 on an ad libitum schedule for as long as 44 days. During all of this time, 



