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标题：Testicular Injury to Rats Fed on Soybean Protein-Based Vitamin B12-Deficient Diet Can Be Reduced by Methionine Supplementation
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作者：Kazuhiro YAMADA ; Tetsunori KAWATA ; Masahiro WADA 等
期刊名称：Journal of Nutritional Science and Vitaminology
印刷版ISSN：0301-4800
电子版ISSN：1881-7742
出版年度：2007
卷号：53
期号：2
页码：95-101
DOI：10.3177/jnsv.53.95
出版社：Center for Academic Publications Japan
摘要：We have previously reported that rats fed on a vitamin B₁₂ (B₁₂)-deficient diet containing 180 g soybean protein per kg diet showed marked histologic damage in their testes. In this paper, we report the effect of B₁₂-deficiency on B₁₂-dependent methionine synthase in the rats' testes and the effect of methionine supplementation of the diet on testicular damage. Rats were fed the soybean protein-based B₁₂-deficient diet for 120 d. We confirmed that those rats were in serious B₁₂-deficiency by measuring urinary methylmalonic acid excretion and B₁₂ content in tissues. Methionine synthase activity in the testis of the B₁₂-deficient rats was less than 2% of that in B₁₂-supplemented (control) rats. To complement disrupted methionine biosynthesis, methionine was supplied in the diet. A supplement of 5 g D,L-methionine per kg diet to the B₁₂-deficient diet did not affect urinary methylmalonic acid excretion of B₁₂-deficient rats. The testicular histology of rats fed the methionine-supplemented B₁₂-deficient diet was almost indistinguishable from that of control rats. Thus, we conclude that the lowered testicular methionine synthase activity is the primary cause of the histologic damage due to B₁₂-deficiency and that methionine supplementation to the diet can reduce the damage. These findings would indicate the importance of the methionine synthase activity, especially for testicular function.
关键词：vitamin B12-deficiency;rat;testis;methionine synthase