The European eel (Anguilla anguilla) has a complex life cycle that includes migrations to and from seawater at different life stages. Yellow eels grow in freshwater, then metamorphose in silver eels and start a long migration to the Sargasso Sea for reproduction. The regulation of energetic metabolism in the life stages is an interesting issue, since silver specimens migrate for 6,000 km without eating. We investigated the adrenergic control of glucose metabolism in liver of eels collected from the Comacchio lagoon (North Adriatic Sea, Italy) at different silvering stages. Eels were captured in Oct-Nov and Dec-Jan. Morphometric parameters were measured and animals were classified as silver eels at the 3rd and 4th stage, respectively. For comparison, yellow eels were collected during autumn and spring. Glycogen content measured in liver was significantly higher in yellow than in silver eels. Hepatocytes were isolated through collagenase perfusion and glycogen levels and glucose release were evaluated. As expected, glycogen levels were significantly higher in yellow eel hepatocytes. Both basal and epinephrine stimulated glucose release were significantly higher in yellow than silver eels. To evaluate whether epinephrine sensitivity is related to a differential expression of adrenergic receptors in hepatocytes, expression of α1- and β2- AR mRNAs in yellow eels and silver at the 4th stage was evaluated, revealing a higher AR mRNA expression in silver than in yellow eels. The analysis of AR mRNA expressions in silver eels at the 3rd stage will provide a complete assessment of AR mRNA expression changes across life stages.
Adrenergic regulation of hepatic glycogenolysis at different silvering stages
KIWAN, ALISAR;FRANZELLITTI, SILVIA;VALBONESI, PAOLA;FABBRI, ELENA
2014
Abstract
The European eel (Anguilla anguilla) has a complex life cycle that includes migrations to and from seawater at different life stages. Yellow eels grow in freshwater, then metamorphose in silver eels and start a long migration to the Sargasso Sea for reproduction. The regulation of energetic metabolism in the life stages is an interesting issue, since silver specimens migrate for 6,000 km without eating. We investigated the adrenergic control of glucose metabolism in liver of eels collected from the Comacchio lagoon (North Adriatic Sea, Italy) at different silvering stages. Eels were captured in Oct-Nov and Dec-Jan. Morphometric parameters were measured and animals were classified as silver eels at the 3rd and 4th stage, respectively. For comparison, yellow eels were collected during autumn and spring. Glycogen content measured in liver was significantly higher in yellow than in silver eels. Hepatocytes were isolated through collagenase perfusion and glycogen levels and glucose release were evaluated. As expected, glycogen levels were significantly higher in yellow eel hepatocytes. Both basal and epinephrine stimulated glucose release were significantly higher in yellow than silver eels. To evaluate whether epinephrine sensitivity is related to a differential expression of adrenergic receptors in hepatocytes, expression of α1- and β2- AR mRNAs in yellow eels and silver at the 4th stage was evaluated, revealing a higher AR mRNA expression in silver than in yellow eels. The analysis of AR mRNA expressions in silver eels at the 3rd stage will provide a complete assessment of AR mRNA expression changes across life stages.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
