Faculty of Veterinary Medicine University of Zagreb
Abstract
Blood glucose concentration, liver and kidney gluconeogenic enzyme activities were investigated during a six-day fasting period in ducklings (English heavy breed Peking Duck). Food deprivation commenced when ducklings reached the age of twenty-eight days. Normally fed ducklings were used as a control group. The ducklings were sacrificed by decapitation after a fasting period of three, four, five and six days, and blood and tissue samples were collected from both groups for analysis. During the experiment the concentration of blood glucose was above 6 mmol/L in both the control and experimental groups, except on experimental day three. Significant rises in glucose-6-phosphatase (EC 3.1.3.9) (G6Pase) activities in the liver were observed on starvation days four, five and six (P = 0.0012, P = 0.0109, P = 0.0279), and in the kidney on starvation days five and six (P = 0.0373, P = 0.0206, respectively). Hepatic fructose-1.6-bis-phosphatase (EC 3.1.3.11) (FDPase) activity showed a significant difference between the fasted and control group only after a four-day fast (P = 0.0491), whereas renal enzyme activity increased after four (P = 0.0279) and six (P = 0.0373) days of food deprivation. Phosphoenolpyruvate carboxykinase (EC 4.1.1.32) (PEPCK) activity in the liver of fasted ducklings significantly decreased on fasting day five (P = 0.0012), whereas in the kidney a significant rise in four-day fasted animals (P = 0.032) was observed in comparison with the normally fed controls. The results showed that ducklings are able to maintain blood glucose concentration during a six-day fasting period. Changes in gluconeogenic enzyme activities indicate the important role of liver and renal gluconeogenesis for the maintenance of blood glucose concentration in fasted ducklings. These findings agree with earlier data obtained on chicken, thus confirming the similarities between the two avian species regarding the maintenance of blood glucose level with the process of gluconeogenesis during longer fasting.Istraživana je koncentracija glukoze u krvi i aktivnost glukoneogenih enzima u jetri i bubregu pekinških pačića (English heavy breed Peking Duck) tijekom šestodnevnog gladovanja, koje je započeto s navršena četiri tjedna života. Normalno hranjeni pačići služili su kao kontrolna skupina. Pačići su bili žrtvovani dekapitacijom nakon trećeg, četvrtog, petog i šestog dana istraživanja, a krv i uzorci tkiva za analize sakupljani su istovremeno od obje skupine. Tijekom istraživanja, osim trećeg dana, koncentracija glukoze u krvi kontrolne i pokusne skupine bila je veća od 6 mmol/L. Značajan porast aktivnosti glukoze-6-fosfataze (EC 3.1.3.9) (G6Pase) u jetri ustanovljen je četvrtog, petog i šestog dana gladovanja (P = 0.0012, P = 0.019, P = 0.0279), a u bubrezima petog i šestog dana gladovanja (P = 0.0373, P = 0.0206). Aktivnost fruktoze-1,6-bis fosfataze (EC 3.1.3.11) (FDPase) u jetri bila je značajno veća u pokusne nego u kontrolne skupine samo četvrtog dana gladovanja (P = 0.0491), dok je u bubrezima porasla četvrtog (P = 0.0279) i šestog (P = 0.0373) dana gladovanja. Aktivnost fosfoenolpiruvat karboksikinaze (EC 4.1.1.32) (PEPCK) u jetri pačića značajno je pala petog dana gladovanja (P = 0.0012), dok je u bubrezima značajno porasla četvrtog dana gladovanja (P = 0.032). Rezultati su pokazali da pačići s navršena četiri tjedna života mogu održavati koncentraciju glukoze u krvi tijekom šestodnevnog gladovanja. Promjene u aktivnostima glukoneogenih enzima upućuju na važnu ulogu procesa glukoneogeneze u jetri i bubrezima za održavanje normoglikemije pačića koji gladuju. Takvi nalazi slažu se s dobro poznatim podacima za piliće, što pokazuje da postoji sličnost između te dvije ptičje vrste u održavanju razine glukoze u krvi procesom glukoneogeneze tijekom dužeg gladovanja
