Hayes, Matthew R., Rachael L. Moore, Samit M. Shah, and Mihai Covasa. 5-HT 3 receptors participate in CCK-induced suppression of food intake by delaying gastric emptying. Am J Physiol Regul Integr Comp Physiol 287: R817-R823, 2004. First published June 10, 2004 10.1152/ajpregu.00295.2004.-Serotonin type 3 (5-HT 3) receptors have been shown to participate in the negative-feedback control of food intake. We previously reported that cholecystokinin (CCK)-induced suppression of food intake is partly mediated through 5-HT 3 receptors when rats were tested on a preferred liquid diet, but whether such an effect occurs when they are tested on a solid maintenance diet is unknown. In the present study, we examined the effects of ondansetron, a selective 5-HT 3 antagonist, on CCK-induced suppression of solid chow intake. Intraperitoneal administration of ondansetron significantly attenuated 30-and 60-min CCK-induced reduction of food intake, with suppression being completely reversed by 120 min. It is not known whether 5-HT 3 receptors directly mediate CCK-induced satiation or whether their participation depends on CCK acting as part of a feedback cascade to inhibit ongoing intake. Because CCKinduced inhibition of sham feeding does not depend on additive gastric/postgastric-feedback signals, we examined the ability of ondansetron to reverse CCK-induced satiation in sham-feeding rats.Ondansetron did not attenuate reduction of sham feeding by CCK, suggesting that ondansetron does not directly antagonize CCK-satiation signals. CCK suppresses real feeding through a delay in gastric emptying. Ondansetron could attenuate CCK-induced reduction of food intake by reversing CCK-induced inhibition of gastric emptying. We found that blockade of 5-HT3 receptors attenuates CCK-induced inhibition of gastric emptying of a solid meal, as well as saline and glucose loads. We conclude that 5-HT 3 receptors mediate CCKinduced satiation through indirect mechanisms as part of a feedback cascade involving inhibition of gastric emptying. ondansetron; serotonin; osmotic; glucose; satiety GASTRIC EMPTYING IS ONE MECHANISM involved in the regulation of food intake (33, 43). A delay in gastric emptying limits the rate of absorption by reducing the rate of nutrient delivery to the small intestine (5, 15, 58) and is associated with suppression of food intake (43). Inhibition of gastric emptying is mediated by peripheral vagal and sympathetic nerves and by the release of a variety of peptides and neurotransmitters (43,54). Cholecystokinin (CCK) and serotonin [5-hydroxytryptamine (5-HT)] are two humoral signals thought to exert control on gastric emptying and are released in response to nutrients entering the duodenum (6,28,30,43,49,60). Both of these satiety signals bind to receptors on terminals of vagal afferent fibers, resulting in a delay in gastric emptying (4, 24, 49).Considerable evidence indicates that the serotonergic system participates in the negative-feedback control of food intake (for review see Ref. 25). Systemic serotonergic activity h...

Background Body temperature can be measured in seconds with tympanic thermometers as opposed to minutes with mercury ones. The aim of this study was to compare tympanic and oral mercury thermometer measurements under high ambient field temperatures. Results Tympanic temperature (measured thrice by 3 operators) was compared to oral temperature measured once with a mercury-in-glass thermometer in 201 patients (aged ≥5 years), on the Thai-Myanmar border. Ambient temperature was measured with an electronic thermo-hygrometer. Participants had a mean [min-max] age of 27 [5–60] years and 42% (84) were febrile by oral thermometer. The mean difference in the mercury and tympanic temperature measurement for all observers/devices was 0.09 (95%CI 0.07-0.12)°C and intra-class correlation for repeat tympanic measurements was high (≥0.97) for each observer. Deviations in tympanic temperatures were not related to ambient temperature. Conclusion Clinically significant differences were not observed between oral and tympanic temperature measurements at high ambient temperatures in a rural tropical setting.