Involvement of cholecystokinin (CCK) in the daily pattern of gastrointestinal regulation of Senegalese sole (Solea senegalensis) larvae reared under different feeding regimes.
Cholecystokinin (CCK) is an important regulator of pancreatic enzyme secretion in adult mammals and teleosteans. Although some studies have focused on the interaction between CCK and trypsin in marine fish larvae, little is known about the circadian patterns of the regulatory mechanism involving these two digestive components. In this study, we took advantage of the characteristic change from a diurnal to a nocturnal feeding habit that occurs in Senegalese sole (Solea senegalensis) post-larvae, to conduct an experiment where larvae and postlarvae were submitted to three different feeding regimes from mouth opening: continuous feeding, diurnal feeding and nocturnal feeding. The aim was to establish different daily feeding scenarios to uncover the operating mechanisms of CCK and tryptic enzyme activity over the 24-hourcycle to better understand the regulation of digestion in developing fish larvae. Results show a prevalence of simultaneous and opposing trends of CCK level and tryptic activity as a function of the postprandial time. This finding supports the existence of a regulatory loop between these two digestive components in pre- and post-metamorphic Senegal sole larvae. In addition, CCK level was also modulated by the gut content, tending to be lower when the gut is full and higher when is being emptied. Furthermore, larvae were able to synchronize digestive functions to very different feeding regimes, although it seems to be important having a diurnal feeding phase during pre-metamorphic stages for a proper development.
Instituto de Ciencias Marinas de Andalucía (ICMAN-CSIC), Apartado Oficial, 11519 Puerto Real, Cádiz, Spain. Electronic address: carmen.navarro@icman.csic.es.
Carmen
C
Navarro-Guillén
Department of Biology, University of Bergen, Po. Box 7803, NO-5020 Bergen, Norway.
Ivar
I
Rønnestad
Department of Biology, University of Bergen, Po. Box 7803, NO-5020 Bergen, Norway.
Ann-Elise Olderbakk
AO
Jordal
Dept. of Applied Biology, EPS Campus de Excelencia Internacional del Mar (CEI·MAR), Universidad de Almería, Cañada de San Urbano s/n, 04120 Almería, Spain.
Francisco Javier
FJ
Moyano
Instituto de Ciencias Marinas de Andalucía (ICMAN-CSIC), Apartado Oficial, 11519 Puerto Real, Cádiz, Spain.
Manuel
M
Yúfera
D000818:Animals; D002766:Cholecystokinin / Q000502:physiology*; D005247:Feeding Behavior; D005412:Flatfishes / Q000502:physiology*; D041981:Gastrointestinal Tract / Q000502:physiology*
D002766:Cholecystokinin
Cholecystokinin; Daily pattern; Endocrine control; Feeding behavior; Solea senegalensis larvae; Trypsin