When rats are fed fats or carbohydrates orally, blood levels of triglycerides or glucose temporarily rise then fall. This is called a fat or carbohydrate tolerance test. If the same amount of fat or carbohydrate is fed intragastrically, blood levels of triglycerides or gluccose rise sooner, reach higher levels, and fall sooner than with oral tolerance tests. Evidence is presented that an oral stimulus given immediately before an intragastric fat tolerance test, partially normalizes blood triglycerides; hence, digestion, absorption and/or metabolism of the fat. The experiments attempt to improve our understanding of these phenomena by: 1) characterizing some of the alterations in digestion and metabolism that result from intragastric feeding in rats, and 2) identifying sensory stimuli and physiologic factors which may ameliorate the abnormal fat and carbohydrate tolerance resulting from intragastric feeding in rats. Both fat (vegetable oil) and carbohydrate (soluble polysaccharide) will be examined. The methods to be used to study alterations in digestion and metabolism will include: 1) measurements of the movement of radio-labeled nutrients from the stomach and into intestines and body tissues, and 2) measurements of the rate of hydrolysis of fat and carbohydrate in the digestive tract following intragastric and oral feeding. Similar studies will be conducted in which these nutrients will be introduced directly into the small intestines. These studies will allow direct examination of intestinal effects on fat and carbohydrate tolerance. Experiments are also proposed to examine the metabolic effects of an oral stimulus presented immediately prior to intragastric or entric feeding. Certain sensory and physiologic factors which might ameliorate the abnormal effects of intragastric feeding will be examined. Available evidence suggests that under certain conditions, rats may learn to adapt to intragastric feeding; this phenomena will be examined in detail. Since the preliminary data suggest that small oral loads of fat partially normalize the fat tolerance curves resulting from intragastric feeding, the effects of taste on fat and carbohydrate tolerance will be explored. The effects of adding saliva, lingual lipase and acid to intragastric meals will be examined since intragastric feeding may result in reduced levels of these substances in the stomach.
| Ramirez, I; Tordoff, M G; Friedman, M I (1989) Dietary hyperphagia and obesity: what causes them? Physiol Behav 45:163-8 |
| Ramirez, I (1987) Feeding a liquid diet increases energy intake, weight gain and body fat in rats. J Nutr 117:2127-34 |
| Ramirez, I (1987) Practical liquid diets for rats: effects on growth. Physiol Behav 39:527-30 |
| Ramirez, I (1987) When does sucrose increase appetite and adiposity? Appetite 9:1-19 |
| Ramirez, I (1987) Diet texture, moisture and starch type in dietary obesity. Physiol Behav 41:149-54 |
| Ramirez, I (1986) Intragastric feeding differentially affects apparent rate of gastric emptying of phenol red and carbohydrate. Physiol Behav 36:941-5 |
| Ramirez, I (1986) Hypophagia following dietary obesity. Physiol Behav 38:95-8 |
| Ramirez, I (1985) Oral stimulation alters digestion of intragastric oil meals in rats. Am J Physiol 248:R459-63 |
