Nutrient-specific preferences by lambs conditioned with intraruminal infusions of starch, casein, and water.
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We hypothesized that lambs discriminate between postingestive effects of energy and protein and associate those effects with a food's flavor to modify food choices. Based on this hypothesis, we predicted that 1) lambs would acquire a preference for a poorly nutritious food (grape pomace) eaten during intraruminal infusions of energy (starch) or protein (casein) and that 2) shortly after an intraruminal infusion of energy or protein (preload), lambs would decrease their preferences for foods previously conditioned with starch or casein, respectively. Thirty lambs were allotted to three groups and conditioned as follows. On d 1, lambs in each group received grape pomace containing a different flavor and water was infused into their rumens as they ate the pomace. On d 2, the flavors were switched so each group received a new flavor and a suspension of starch (10% of the DE required per day) replaced the water infusion. On d 3, the flavors were switched again, and a suspension of casein (2.7 to 5.4% of the CP required per day) replaced the starch infusion. Conditioning was repeated during four consecutive trials. Lambs in Trial 1 had a basal diet of alfalfa pellets (e.g., free access from 1200 to 1700) and 400 g of rolled barley. Lambs in Trials 2, 3, and 4 received a restricted amount of alfalfa pellets (990 g/d) as their basal diet. After conditioning, all animals received an infusion of water, and, 30 min later, they were offered a choice of the three flavors previously paired with water, starch, or casein. On the ensuing days, the choice was repeated, but starch, casein, and barley replaced the water preload. The nutrient density of the infused preloads was increased during consecutive trials. Lambs preferred the flavors paired with starch > water > casein during Trial 1 (P < .05) and the flavors paired with starch > casein > water during Trials 2 (P < .05), 3 (P < .001), and 4 (P < .001). Preloads of casein decreased preferences for flavors previously paired with casein (P < .10 [Trial 2]; P < .001 [Trial 3], and increased preferences for flavors paired with starch (P < .05 [Trial 2]; P < .001 [Trial 3]). Preloads of energy (barley) had the opposite effect (P < .05 [Trial 3]). These results indicate that lambs discriminated between the postingestive effects of starch and casein and associated the effects with specific external cues (i.e., added flavors) to regulate macronutrient ingestion. (+info)
The role of apolipoprotein A-IV in food intake regulation.
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Apolipoprotein (apo) A-IV is a glycoprotein synthesized by the human intestine. In rodents, both the small intestine and the liver secrete apo A-IV; the small intestine, however, is by far the major organ responsible for the circulating apo A-IV. Intestinal apo A-IV synthesis is markedly stimulated by fat absorption and appears not to be mediated by the uptake or reesterification of fatty acids to form triglycerides. Rather, it is the formation of chylomicrons that acts as a signal for the induction of intestinal apo A-IV synthesis. Intestinal apo A-IV synthesis is also enhanced by a factor from the ileum and that factor is probably peptide tyrosine-tyrosine (PYY). The inhibition of food intake by apo A-IV is probably mediated centrally. The stimulation of intestinal synthesis and secretion of apo A-IV by lipid absorption are rapid; thus, apo A-IV likely plays a role in the short-term regulation of food intake. Other evidence suggests that apo A-IV may also be involved in the long-term regulation of food intake and body weight. Chronic ingestion of a high fat diet blunts the intestinal apo A-IV response to lipid feeding and may explain why the chronic ingestion of a high fat diet predisposes both animals and humans to obesity. (+info)
Geriatric cachexia: the role of cytokines.
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Weight loss in elderly patients is a common clinical problem. Wasting and cachexia are associated with severe physiologic, psychologic, and immunologic consequences, regardless of the underlying causes. Cachexia has been associated with infections, decubitus ulcers, and even death. Multivariate analyses of risk and prognostic factors in community-acquired pneumonia in the elderly have found that age by itself is not a significant factor related to prognosis. Among the significant risk factors, only nutritional status is amenable to medical intervention. Cachexia in the elderly may have profound consequences: medical, cognitive, and psychiatric disorders may diminish self-reliance in activities of daily living, thus reducing quality of life and increasing the frequency of secondary procedures, hospitalizations, and the need for skilled care. Cachexia is associated with higher-than-normal concentrations of tumor necrosis factor alpha (TNF-alpha), interleukin (IL) 1, IL-6, serotonin, and interferon gamma. The role of these proinflammatory cytokines has been established in the cachexia seen in cancer and AIDS patients. Reduction in the concentrations of these cytokines is associated with weight gain. Drugs that promote appetite stimulation and weight gain, such as progestational agents, cyproheptadines, pentoxifylline, and thalidomide may work by down-regulating these proinflammatory cytokines. An understanding of the relation between cachexia and negative regulatory cytokines may point to effective treatment of geriatric cachexia as well. (+info)
p-Chloroamphetamine (PCA) suppresses ingestive behavior in male rats.
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Ingestive behavior was activated in male rats by intraoral intake and intake from a bottle of 1-M solution of sucrose. Intraperitoneal injection of p-chloroamphetamine (PCA), releasing central 5-hydroxytryptamine (5-HT) from serotonergic nerve terminals, inhibited ingestion of the sucrose solution. Significant inhibition of sucrose intake by PCA was observed at 1.25 and 2.5 mg/kg dose in a bottle intake test, and at 5.0 mg/kg dose in an intraoral intake test. These findings suggested that 1.25 and 5.0 mg/kg of PCA suppressed appetitive ingestive behavior and consummatory ingestive behavior in male rats, respectively. (+info)
Simultaneous observation of ingestive and copulatory behavior of the male rat.
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In a preliminary test male rats were allowed to ingest a 1 M solution of sucrose from a drinking spout. After daily intake of sucrose became stabilized, the males were given a sexually receptive or non-receptive female and the bottle filled with sucrose solution simultaneously. The ingestive and copulatory behavior was observed for 60 min under illumination by a red lamp. The data obtained from this study showed that the ingestive behavior of males was suppressed by the presence of sexually receptive females and, conversely, the sexual behavior of males was not affected by the presence of a bottle of sucrose. These results suggest that the presence of a sexual partner inhibits appetitive ingestive behavior, i.e., the responses used by male rats to obtain food. (+info)
Origins of nutritional imbalance in cancer.
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Some parallels and differences are considered between the nutritional circumstances that favor carcinogenesis and those that favor tumor growth and host cachexia. From evidence on deletion of physiological feeding controls and changes in feeding behavior during tumor growth and from evidence on differences in sets of available feeding controls and in feeding behavior among normal individuals, it is suggested that acquisition of possibly carcinogenic dietary habits may originate, in part, from innate deficits in physiological feeding controls. (+info)
Neurobiology of zinc-influenced eating behavior.
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Zinc is an essential nutrient that is required in humans and animals for many physiological functions, including immune and antioxidant function, growth and reproduction. Many aspects of zinc deficiency-induced anorexia have been well studied in experimental animals, most notably the laboratory rat. There is evidence that suggests zinc deficiency may be intimately involved with anorexia in humans: if not as an initiating cause, then as an accelerating or exacerbating factor that may deepen the pathology of the anorexia. The present review describes recent research investigating the relationship between zinc deficiency and the regulation of food intake, along with advances in the understanding of the food intake and body weight regulation systems. For more comprehensive reviews of zinc nutrition and zinc deficiency, readers are referred to the other reviews in this volume and the review text of Mills (1989). An excellent review focused solely on zinc status and food intake has been presented by O'Dell and Reeves (1989). (+info)
Secretory, endocrine and autocrine/paracrine function of the adipocyte.
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Obesity is a major public health problem in Western countries, and >55% of adult Americans are overweight or obese. A major contributor to the epidemic of obesity is the current environment, which is characterized by increased availability of high energy foods and decreased physical activity. Several studies also demonstrated that genetic susceptibility contributes to obesity in some populations. Obesity research has focused primarily on the role of the hypothalamus in neuroendocrine regulation of food intake. However, a growing number of studies support a potential contribution of adipose tissue, via its newly discovered secretory function, to the pathogenesis of obesity and co-morbid conditions including cardiovascular disease, diabetes and hypertension. This paper will review the role of four factors secreted by adipose tissue (leptin, agouti, angiotensin II and prostaglandins) and their functions in the regulation of energy balance and whole-body homeostasis. Several other peptide and nonpeptide substances are secreted from adipose tissue; their function and regulation have been documented extensively. (+info)