Characterization of cholecystokinin-producing cells and mucus-secreting goblet cells in the blacktip grouper, Epinephelus fasciatus.
ABSTRACT The characteristics and distributions of cholecystokinin (CCK)-producing cells and mucus-secreting goblet cells were investigated in the digestive tract of the blacktip grouper (Epinephelus fasciatus). CCK-producing cells were scattered throughout the digestive tract. The highest frequency of CCK-producing cells was observed in the anterior intestine portion and pyloric ceca, with a very small number of cells distributed as far as the rectum. Mucus-secreting goblet cells were found to differ remarkably in their regional distributions and relative frequencies. High frequencies of mucus-secreting goblet cells were found in the digestive tract, mainly in the anterior intestine portion and pyloric ceca, but not the esophagus; the frequency decreased slightly toward the rectum. Our result suggests that food digested by gastric acid in the stomach moves on the anterior (including the pyloric ceca) and mid intestine portion, thereby ensuring effective stimulation of the CCK-producing cells. In addition, the distribution pattern of the CCK-producing cells closely resembled that of mucus-secreting goblet cells. In E. fasciatus, CCK-producing cells and mucus-secreting goblet cells seem to be well adapted to promoting optimal control of the digestive process.
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ABSTRACT: cDNAs encoding the appetite regulating peptides apelin, cocaine and amphetamine regulated transcript (CART), cholecystokinin (CCK), peptide YY (PYY) and orexin were isolated in red-bellied piranha and their mRNA tissue and brain distributions examined. When compared to other fish, the sequences obtained for all peptides were most similar to that of other Characiforme fish, as well as to Cypriniformes. All peptides were widely expressed within the brain and in several peripheral tissues, including gastrointestinal tract. In order to assess the role of these peptides in the regulation of feeding of red-bellied piranha, we compared the brain mRNA expression levels of these peptides, as well as the gut mRNA expression of CCK and PYY, between fed and 7-day fasted fish. Within the brain, fasting induced a significant increase in both apelin and orexin mRNA expressions and a decrease in CART mRNA expression, but there where were no significant differences for either PYY or CCK brain mRNA expressions between fed and fasted fish. Within the intestine, PYY mRNA expression was lower in fasted fish compared to fed fish but there was no significant difference for CCK intestine mRNA expression between fed and fasted fish. Our results suggest that these peptides, perhaps with the exception of CCK, play a major role in the regulation of feeding of red-bellied piranha.Peptides 04/2014; · 2.52 Impact Factor