Volume 89, Issue 3, March (2003), pp. 441-445 © The Author 2003
doi:10.1079/BJN2002811

Medline/PubMed Citation | Related Articles in PubMed | Download to Citation Matcher  

Short communication

Hypoxia-induced megaloblastosis in vitamin B₁₂-deficient rats

Shuhei Ebara¹, Satoko Adachi¹, Shigeo Takenaka², Toshiki Enomoto³, Fumio Watanabe⁴, Ryoichi Yamaji¹, Hiroshi Inui^1,* and Yoshihisa Nakano^1
1Department of Applied Biological Chemistry, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
²Department of Veterinary Sciences, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
³Department of Food Science, Ishikawa Agricultural College, Nonoichi, Ishikawa 921-8836, Japan
⁴Department of Food and Nutrition, Kochi Women’s University, Kochi 780-8515, Japan

 (Received 23 May 2002–Revised 25 October 2002–Accepted 8 November 2002)

In rats, in contrast with human subjects who develop megaloblastic anaemia due to vitamin B₁₂ deficiency, haematological abnormalities with anaemia were not observed under normoxic conditions even though plasma vitamin B₁₂ concentration was reduced to <15 % of a normal concentration by depleting dietary vitamin B₁₂. To elucidate whether erythropoiesis was affected by vitamin B₁₂ deficiency in rats, these vitamin B₁₂-deficient rats were exposed to hypoxia (10·5 % O₂) to stimulate erythropoiesis. In the vitamin B₁₂-sufficient control rats, erythrocyte count was significantly (P<0·05) increased 1 week after starting the hypoxic exposure. However, the hypoxia-induced erythropoiesis was affected by vitamin B₁₂ deficiency, and no significant increase in the erythrocyte count was observed even after 6-week exposure to hypoxia in the vitamin B₁₂-deficient rats. In the vitamin B₁₂-deficient rats in hypoxia, erythrocytes became abnormally enlarged, and haemoglobin concentration in peripheral blood was increased in proportion to the increase of mean corpuscular volume. However, the level of the increase in the haemoglobin concentration was significantly (P<0·05) lower in the vitamin B₁₂-deficient rats compared with that in the -sufficient controls. In addition, in the vitamin B₁₂-deficient rats, in contrast to the -sufficient rats, serum erythropoietin concentration was not normalized even after 6-week exposure to hypoxia. These results indicate that a megaloblastic anaemia-like symptom is induced when the vitamin B₁₂-deficient rats are exposed to hypoxia.

Keywords:
Hypoxia-induced erythropoiesis: Megaloblastic anaemia: Erythropoietin: Vitamin B₁₂-deficient rats