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Physiological and metabolic changes associated with weaning in the tammar wallaby,Macropus eugenii

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The tammar wallaby (Macropus eugenii) is a small macropodid marsupial in which the major part of weaning occupies the period between 28 and 36 weeks of pouch life. Before weaning the diet of the tammar is high in carbohydrate and low in lipid/volatile fatty acid whereas the reverse applies after weaning. The adult tammar is a forestomach fermenter. The aim of this study was to elucidate some of the physiological and metabolic changes associated with this major change in the diet.

Hepatic glycogen content increased gradually early in development to a maximum of 7% of liver weight at 28–30 weeks of pouch life. It then fell precipitously to less than 1% of liver weight at 36 weeks before recovering to the adult level of about 3% liver weight. Plasma glucose levels were maintained at about 10 mM until 36 weeks, after which they fell gradually to adult values of about 4 mM. Hepatic hexokinase activity increased several-fold between 18 and 30 weeks of pouch life, remained high until 42 weeks, and then fell to the adult level. The hepatic activities of fructose-bisphosphatase and particulate phosphoenolpyruvate carboxykinase (PEPCK) were unchanged during development but soluble hepatic PEPCK activity, which was low until 28 weeks of pouch life, increased 3–4 fold between 30 and 36 weeks and then fell slightly to the adult level. Hepatic pyruvate kinase increased in activity up to 28 weeks and then fell to about half peak values at 36 weeks and 20% of peak activity in the adult. There was a greater than ten-fold increase in the ratio of soluble PEPCK activity to pyruvate kinase activity between 28 and 36 weeks of development. It has previously been reported that hepatic gluconeogenesis is inducible in pouch young but constitutive in adults. We conclude that the change in regulation of hepatic gluconeogenesis at the PEPCK/pyruvate kinase level is part of the weaning process.

The urea content of the plasma changed little during development but plasma ammonia increased consistently through pouch life. Urine urea content was low until about 28 weeks of age and then increased rapidly to adult levels. Urine ammonia increased from about 20 mM early in pouch life to a maximum of more than 100 mM at 28 weeks. Thereafter, urine ammonia content fell rapidly to the adult value of about 20 mM. For the first 27 weeks of pouch life, urine pH was consistently between 4.4 and 5.7, but subsequently it rose and became more variable. Urine pH in adults was 8.1±0.3. The activities of the five enzymes of the ornithine-urea cycle increased 3–5 fold in activity between 28 and 36 weeks of pouch life.

These findings indicate that there are major changes in metabolic regulation associated with weaning in the tammar. During weaning, glucose becomes essentially unavailable to the young animal and there is an increase in the rate of hepatic gluconeogenesis which is attributable primarily to increased activity of soluble PEPCK. Metabolism, which is acidotic before weaning, becomes alkalotic and there is a decrease in urinary ammonia content as proton excretion decreases. As ammonia excretion falls, the activity of the urea cycle increases and the concentration of urea in the urine rises. Weaning in the tammar is therefore a complex and well-orchestrated process which may be associated with the change in diet.

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  1. Archibald RM (1944) Determination of citrulline and allantoin and demonstration of citrulline in blood plasma. J Biol Chem 156:121–142

  2. Archibald RM (1945) Colorimetric determination of urea. J Biol Chem 157:507–518

  3. Armstrong DG (1965) Carbohydrate metabolism in ruminants and energy supply. In: Dougherty RW (ed) Physiology of digestion in the ruminant. Butterworth London, pp 272–288

  4. Barker J (1961) The metabolism of carbohydrate and volatile fatty acids in the marsupial,Setonix brachyurus. Q J Exp Physiol 46:54–68

  5. Blair JB, Cimbala BA, Foster JL, Morgan RA (1976) Hepatic pyruvate kinase. Regulation by glucagon, cyclic adenosine 3′:5′-monophosphate and insulin in the perfused rat liver. J Biol Chem 251:3756–3762

  6. Brown GW Jr, Cohen PP (1959) Comparative biochemistry of urea synthesis. I. Methods for the quantitative assay of urea cycle enzymes in liver. J Biol Chem 234:1769–1774

  7. Calaby JH (1971) The current status of Australian Macropodidae. Aust Zool 16:17–31

  8. Feliu JE, Hue L, Hers HG (1976) Hormonal control of pyruvate kinase activity and of gluconeogenesis in isolated hepatocytes. Proc Natl Acad Sci USA 73:2762–2766

  9. Green B (1984) Composition of milk and energetics of growth in marsupials. Symp Zool Soc Lond 51:369–387

  10. Green B, Newgrain K, Merchant J (1980) Changes in milk composition during lactation in the tammar wallaby (Macropus eugenii). Aust J Biol Sci 33:35–42

  11. Henning H-V, Seubert W (1964) Zum Mechanismus der Gluconeogenese und ihre Steuerung. I. Quantitative Bestimmung der Pyruvatcarboxylase in Rohextrakten der Rattenleber. Biochem Z 340:160–170

  12. Hume ID (1982) Digestive physiology and nutrition of marsupials. Cambridge University Press, Cambridge

  13. Janssens PA (1984) Nutrition and metabolism in marsupial pouch young with special reference to the tammar wallaby. Proc Nutr Soc Aust 9:68–75

  14. Janssens PA, Jenkinson LA, Paton BC, Whitelaw E (1977) The regulation of gluconeogenesis in pouch young of the tammar wallaby,Macropus eugenii Desmarest. Aust J Biol Sci 30:183–195

  15. Kaplan A (1969) The determination of urea, ammonia and urease. In: D Glick (ed) Methods biochem Anal 17:311–324. John Wiley, New York

  16. Kempton TJ, Murray RM, Leng RA (1976) Methane production and digestibility measurements in the grey kangaroo and sheep. Aust J Biol Sci 29:209–214

  17. Keppler D, Decker K (1974) Glycogen determination with amyloglucosidase. In: HU Bergmeyer (ed) Methods of enzymatic analysis, edn 2, Verlag Chemie, Weinheim, pp 1196–1201

  18. Leng RA (1970) Glucose synthesis in ruminants. Adv Vet Sci Comp Med 14:209–260

  19. Lowry OH, Rosebrough NJ, Farr AL, Randall RJ (1951) Protein measurements with the Folin phenol reagent. J Biol Chem 193:265–275

  20. Messer M, Green B (1979) Milk carbohydrates of marsupials. II. Qualitative and quantitative changes in milk carbohydrates during lactation in the tammar wallaby, (Macropus eugenii). Aust J Biol Sci 32:519–531

  21. Moir RJ, Somers M, Waring H (1956) Studies on marsupial nutrition. 1. Ruminant-like digestion in a herbivorous marsupial (Setonix brachyurus). Aust J Biol Sci 9:293–304

  22. Murphy CR, Smith JR (1970) Age determination of pouch young and juvenile Kangaroo Island wallabies. Trans R Soc S Aust 94:15–20

  23. Newsholme EA, Start C (1973) Regulation in metabolism. John Wiley, London

  24. Paton BC, Janssens PA (1981) Metabolic changes associated with the switch from a milk to a vegetable diet in the tammar wallaby,Macropus eugenii. Comp Biochem Physiol 70B:105–113

  25. Pitts RF (1973) Production and excretion of ammonia in relation to acid-base regulation. In: Orloff J, Berliner RW (eds) Renal Physiology. American Physiology Society: Washington D.C. (Handbook of Physiology. Sect. 8. pp 455–496)

  26. Pontremoli S, Traniello S, Luppis B, Wood WA (1965) Fructose diphosphatase from rabbit liver. 1. Purification and properties. J Biol Chem 240:3459–3463

  27. Poole WE (1980) The status of the Australian Macropodidae. In: Tyler MJ (ed) The Status of Endangered Australian Wildlife. Royal Zoological Society of South Australia. Adelaide, pp 13–27

  28. Purich DL, Fromm HJ, Rudolph FB (1973) The hexokinases: kinetic, physical and regulatory properties. Adv Enzymol 39:249–326

  29. Renfree MB, Tyndale-Biscoe CH (1973) Intrauterine development after diapause in the marsupial,Macropus eugenii. Dev Biol 33:62–79

  30. Rolleston FS (1972) A theoretical background to the use of measured concentrations of intermediates in study of the control of intermediary metabolism. Curr Top Cell Reg 5:47–75

  31. Sharma C, Manjeshwar R, Weinhouse S (1963) Effects of diet and insulin on glucose-adenosine triphosphate phosphotransferase of rat liver. J Biol Chem 238:3840–3845

  32. Söling H-D, Kleineke J (1976) Species dependent regulation of gluconeogenesis in higher animals. In: Hanson RW, Mehlman MA (eds) Gluconeogenesis: its regulation in mammalian species. Wiley-Interscience, New York, pp 369–462

  33. Tyndale-Biscoe CH (1973) Life of marsupials. Edward Arnold, London

  34. Vander AJ (1980) Renal physiology, McGraw-Hill, New York

  35. Wilkes GE, Janssens PA (1986) Development of urine concentrating ability in pouch young of a marsupial, the tammar wallaby (Macropus eugenii). J Comp Physiol B 156:573–583

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Wilkes, G.E., Janssens, P.A. Physiological and metabolic changes associated with weaning in the tammar wallaby,Macropus eugenii . J Comp Physiol B 156, 829–837 (1986). https://doi.org/10.1007/BF00694258

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  • Pyruvate Kinase
  • Adult Level
  • Hepatic Gluconeogenesis
  • Tammar Wallaby
  • Urea Content