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Effects of supplemental cystine or methionine on growth and lifespan of stroke-prone spontaneously hypertensive rats

Published online by Cambridge University Press:  08 March 2007

G. Sarwar Gilani*
Affiliation:
Food Directorate, Health Canada, Banting Building (2203C), Tunney's Pasture, Ottawa, Ontario, Canada K1A 0L2
W. M. Nimal Ratnayake
Affiliation:
Food Directorate, Health Canada, Banting Building (2203C), Tunney's Pasture, Ottawa, Ontario, Canada K1A 0L2
Robert W. Peace
Affiliation:
Food Directorate, Health Canada, Banting Building (2203C), Tunney's Pasture, Ottawa, Ontario, Canada K1A 0L2
Rudolf Muller
Affiliation:
Food Directorate, Health Canada, Banting Building (2203C), Tunney's Pasture, Ottawa, Ontario, Canada K1A 0L2
*
*Corresponding author: fax +1 613 941 6182, [email protected]
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Abstract

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Stroke-prone spontaneously hypertensive (SHRSP) rats are considered a suitable model for studying the effects of dietary and other environmental factors on human essential hypertension and haemorrhagic stroke. To investigate the suitability of a control diet for this strain of rats, we studied the effects of supplementing casein and soya protein isolate (SPI) with two sulphur amino acids (methionine and cystine) on the growth and lifespan of SHRSP rats. The source of dietary protein and the type of supplemental sulphur amino acid had significant (P<0·05) effects on food intake and weight gain measured after 31d of the feeding study, while only the type of supplemental sulphur amino acid had significant effects on mean survival times and the survival rates. On average, the casein groups had higher food intake and weight gain compared with the SPI groups. The methionine-supplemented groups had lower food intake but higher weight gain than the cystine-supplemented groups. Similarly, the methionine-supplemented groups had higher mean survival times and survival rates compared with the cystine-supplemented groups. The data would suggest that a control diet based on cystine-supplemented casein (as recommended for normal healthy rats by the American Institute of Nutrition), may not meet the sulphur amino acid requirements for SHRSP rats, and that the methionine-supplemented casein would be an appropriate control diet for this animal model.

Type
Short Communication
Copyright
Copyright © The Nutrition Society 2006

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