Effects of intragastric administration of predigested nutrients on food intake, body weight and taste acceptability: Potential relevance of the cephalic/neural phase of digestion

Abstract

In this study we analyzed the effect of the intragastric administration of partially digested and natural nutrients on subsequent food intake, body weight and flavor acceptability in rats. The results showed that enterally administered natural nutrients reduced the subsequent ingestion of food to a greater degree compared with the same nutrients in partially digested form. This greater reduction does not appear to be due to a higher nutritional effect of the former, because the body weight of both groups of animals was similar. Animals intragastrically administered with partially digested nutrients developed an acceptance response to a previously paired flavored stimulus, in contrast to animals receiving natural nutrients under the same conditions. These results are interpreted in terms of the cephalic phase of digestion and may be relevant to the treatment of clinical symptoms associated with enteral feeding.

Enteral Feeding: Brain-Visceral Interactions in the Processing of Nutrients

“…Results obtained with the enteral administration of natural food markedly contrast with those obtained for the intragastric administration of food subjected to cephalic processing (aspirated from the stomachs of donor subjects shortly after its oral consumption). Unlike observations with natural food, the animals developed a strong preference for the taste stimulus associated with the administration of "predigested" food and rejected the stimulus associated with physiological saline [80,81,[86][87][88]. Hence, enterally administered foods are experienced as rewarding/ positive when they have undergone oropharyngeal processing, and assistance of the cephalic phase appears to adapt enteral diets more closely to digestive physiology.…”

“…Studies using this technique have demonstrated that the direct administration of complex food into the gastric cavity is a powerful way to establish flavor-conditioned aversions [66,80,[84][85][86]. Thus, when rats were subjected to a discriminative flavor learning task using whole milk as visceral stimulus, they preferred the flavor associated with physiological saline and strongly rejected the flavor associated with the food, even after a 22-h food deprivation period [80,[84][85][86].…”

“…Studies using this technique have demonstrated that the direct administration of complex food into the gastric cavity is a powerful way to establish flavor-conditioned aversions [66,80,[84][85][86]. Thus, when rats were subjected to a discriminative flavor learning task using whole milk as visceral stimulus, they preferred the flavor associated with physiological saline and strongly rejected the flavor associated with the food, even after a 22-h food deprivation period [80,[84][85][86]. Similar results were observed with intraintestinal feeding, finding that association of the intraduodenal administration of fats or glucose with the oral intake of saccharose or water produced a strong rejection of both in subsequent presentations [66,80,81,[86][87][88].…”

Differential rewarding effects of electrical stimulation of the lateral hypothalamus and parabrachial complex: Functional characterization and the relevance of opioid systems and dopamine

“…In sequential learning, the taste stimulus is associated with intragastric administrations on alternating days/sessions (Mediavilla et al 2000, 2005; Zafra et al, 2002, 2007b). In the concurrent modality, these stimuli are presented at the same time, pairing the intake of tastes with the simultaneous intragastric administration of either the visceral stimulus or an innocuous substance, e.g., physiological saline (Mediavilla et al, 2000; Puerto et al, 1976; Zafra et al, 2007a). Concurrent learning permits a rapid detection of biologically relevant substances in the upper gastrointestinal tract, allowing individuals to efficiently select food without waiting for the long-term benefits that result from its absorption (Puerto et al, 1976).…”

“…Results are expressed as nCi). Examined sections (abbreviations): , 1976;Zafra et al, 2007a). Concurrent learning permits a rapid detection of biologically relevant substances in the upper gastrointestinal tract, allowing individuals to efficiently select food without waiting for the long-term benefits that result from its absorption (Puerto et al, 1976).…”