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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Ruminant Diseases and Immunology Research » Research » Publications at this Location » Publication #103309
Title: ISOLATION AND IDENTIFICATION OF A NOVEL A-RING HYDROXYLATED METABOLITE OF VITAMIN D2: 4,25-DIHYDROXYVITAMIN D2

Author
item RAO, D - WOMEN&INFANT HOSPITAL, RI
item DAYAL, RAMESH - CASE WESTERN,CLEVELAND,OH
item SIU-CALDERS, MEI-LING - WOMEN&INFANT HOSPITAL, RI
item Horst, Ronald
item USKOKOVIC, MILAN - HOFFMAN-LA ROCHE, NJ
item TSERNG, KUI-YI - CASE WESTERN UNIV., OH
item REDDY, G - WOMEN&INFANT HOSPITAL, RI

Submitted to: Journal of Steroid Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: Milk fever is a disease affecting 6-8% of all U.S. dairy cows each year, which means approximately 700,000 cows are affected each year. This disease has been estimated to cost approximately $300/episode (or $210 million annually) as a result of treatment and production losses. The major clinical symptom seen in cows developing this disorder is their inability to stand and eventual lapse into coma if not treated medically. The cows lose muscle and nerve function because blood calcium concentrations fall below the level required to maintain normal electrical activity of the tissues. All mammals have evolved a very intricate system designed to maintain normal blood calcium. Calcium leaves the body in large amounts, when cows begin making milk which is rich in calcium. This calcium must be replaced, either by absorbing more from the diet or by removing calcium from the skeleton. In cows that develop milk fever, this system has broken down. Vitamin D plays a major role in controlling the movement of calcium into and out of the body. In this paper, we described the isolation and identification of a new vitamin D compound (4,25-dihydrox min D2). This new compound was isolated from the sera of rats receiving excess vitamin D2, and we speculate that formation of this compound represents an important step in the deactivation of vitamin D2 and protects animals from the toxic effects of vitamin D2. This information will assist scientists, as well as nutritionists, and veterinarians alike in understanding how vitamin D is utilized by the body. The information may assist in developing various strategies for treating milk fever and other metabolic disorders in both human and veterinary medicine.

Technical Abstract: Vitamin D2 is less toxic in rats when compared to vitamin D3. Our laboratory has been involved in research projects which were directed towards identifying the possible mechanisms responsible for the toxicity differences between vitamins D2 and vitamin D3 in rats. The present research project was designed to isolate and identify new metabolites of vitamin D2 from serum of rats which were fed toxic doses of vitamin D2. Hypervitaminosis D2 was induced in 30 rats by feeding each rat with 1000 nmoles of vitamin D2/day x 14 days. The rats were sacrificed on the 15th day and obtained 180 mL of serum. The lipid extract of the serum was directly analyzed by a straight phase HPLC system. The various vitamin D2 metabolites were monitored by their ultraviolet (UV) absorbance at 254 nm. One of the UV absorbing peaks did not comigrate with any of the known vitamin D2 metabolites. This unknown metabolite peak was further purified by HPLC and was then subjected to UV absorption spectrophotometry and mass spectrometry. The structure assignment of the new metabolite was established to be 4,25-dihydroxyvitamin D2 [4,25(OH)2D2] by the techniques of UV absorption spectrophotometry and mass spectrometry and by the new metabolite's susceptibility to sodium metaperiodate oxidation. At present the biological activity of this unique "A-ring" hydroxylated vitamin D2 metabolite is not known. As this new metabolite is isolated from the serum of rats intoxicated with vitamin D2, we speculate that 4,25(OH)2D2 may be playing an important role in the deactivation of vitamin D2.