Testicular injury to rats fed on soybean protein-based vitamin B 12-deficient diet can be reduced by methionine supplementation

Kazuhiro Yamada, Tetsunori Kawata, Masahiro Wada, Kazumi Mori, Hiroko Tamai, Nobuo Tanaka, Tadahiro Tadokoro, Takamasa Tobimatsu, Tetsuo Toraya, Akio Maekawa

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


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 B 12-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 B 12-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.

Original languageEnglish
Pages (from-to)95-101
Number of pages7
JournalJournal of Nutritional Science and Vitaminology
Issue number2
Publication statusPublished - Apr 2007


  • Methionine synthase
  • Rat
  • Testis
  • Vitamin B-deficiency

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics


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