Changed central and peripheral catecholamines and indoleamines in one-way crossed-intestine rats: relationship to...

The involvement of central and peripheral catecholamines and serotonin (5-HT) in regulation of feeding and energy metabolism was examined in one-way crossed intestine rats that show large and sustained changes in daily food intake. Five to six weeks after the crossed-intestinal surgery, catecholamines and indoleamines in dissected major brain regions and in the heart, intrascapular brown adipose tissue (IntBAT), pancreas, and serum were determined using HPLC with electrochemical detection. The food-losing rats increased daily food intake from 70.8 to 126.3 g, whereas their partners decreased daily food intake from 67.1 to 38.7 g (p < .001). Compared with the partners and sham-operated controls, the food-gaining rats had increased 5-hydroxy-indoleacetic acid (5-HIAA) throughout the brain [hypothalamus, 442.9 vs. 383.5 (p < .05) and 404.2 ng/g (p < .05), Lateral cortex plus amygdala (LC + A), 236.6 vs. 216.8 (p < .05) and 212.0 ng/g (p < .05), brain stem, 282.9 vs. 238.7 (p < .05) and 245.1 ng/g (p = .05), cerebellum, 56.7 vs. 49.6 (p < .05) and 44.4 ng/g (p < .05)]. Higher 5-HIAA in food-gaining rats that were undereating are consistent with serotonin's role in inhibiting food intake. Peripherally, the rats gaining food showed significantly lower NE, 5-HT, and 5-HIAA in IntBAT compared with their partners (NE, 994.2 vs. 1236 ng/g, 5-HT 338.0 vs. 527 ng/g, and 5-HIAA, 39 vs. 51 ng/g). Because NE and 5-HT have been shown to exert stimulating effects on BAT-mediated thermogenesis, lower levels of NE, 5-HT, and 5-HIAA in IntBAT of food gaining rats are compatible with the lower metabolic rate observed in these animals. The results show that both central and peripheral catecholamines and serotonin are involved in regulation of food intake and energy metabolism.