Tissue distribution of 7-dehydrocholesterol, vitamin D3 and 25-hydroxyvitamin D3 in several species of fishes.

Abstract

SummaryA high-performance liquid chromatographic (HPLC) meth od for simultaneous determination of 7-dehydrocholesterol (7-DHC), vitamin D3 and 25-hydroxyvitamin D3 (25-OH-D3) in tissues of fishes was established, and using this method the tissue distribution of the sterols in lamprey (Entosphenus japonicus), great blue shark (Prionace glauca), skipjack (Katsuwonus pelamis) and albacore (Thunnus alalunga) was in vestigated. The results are summarized in the following: 1) Although the alimentary canal, gall bladder and roe of lamprey and the alimentary canal of great blue shark contained comparatively high levels of 7-DHC (higher than 2,000ng/wet tissue g), the other tissues of lamprey and great blue shark and all tissues of skipjack and albacore contained only low levels of 7-DHC (lower than 1,000ng/g). There was no significant correlation between the levels of 7-DHC and vitamin D3 . 2) The contents of 7-DHC in the skin of skipjack and albacore were only 1/1 ,000 of those in the skin of rats. 3) Although the contents of vitamin D3 in the liver of skipjack and albacore were extremely high (41, 240 and 21 ,000ng/g, respectively), those in the skin were very low (454 and 257ng/g , re spectively). 4) 25-OH-D3 was detected in the viscera of skipjack , but the levels were not very high (lower than 150ng/g) . These levels were not significantly correlated with those of vitamin D3. The results suggest that large quantities of vitamin D3 in the liver of Abbreviations:7-DHC, 7-dehydrocholesterol; 25-OH-D3, 25-hydroxyvitamin D3;HPLC, high-performance liquid chromatography; M, mean; SD, standard deviation; nd, not detected.13

Food Contents and Biological Activity of 25-Hydroxyvitamin D: A Vitamin D Metabolite to Be Reckoned With?

“…An internal analytical report from the MAFF in the UK found 25OHD 3 contents of 0.11 Ìg/ 100 g in the flesh of raw salmon and 0.22 Ìg/100 g in raw trout, which are much lower than the measured vitamin D 3 concentrations in the same samples of 5.4 and 8.1 Ìg/ 100 g, respectively [32]. While liver (and oils) in some fish species contains very large amounts of vitamin D 3 , only insignificant amounts of 25OHD 3 are usually present in the liver and other viscera [33].…”

Vitamin D3-induced calcemic and phosphatemic responses in the freshwater mud eel Amphipnous cuchia maintained in different calcium environments

“…Several investigators have studied the presence of vitamin D metabolites in various teleosts (1)(2)(3)(4)(5)(6) and the changes in the blood calcium and phosphate contents of fish after administration of vitamin D and/or its metabolites (7)(8)(9)(10)(11)(12)(13)(14)(15).…”

Vitamin D3 in Tilapia mossambica: Relevance of Photochemical Synthesis.

“…Earlier studies reported a lack of any relation between provitamin D3 and vitamin D3 contents in several fish (10,11,14) and also that the levels of these two compounds in the skin of fish were lower than those of rats (15), suggesting that the photochemical synthesis of vitamin D3 might not be significant in fish. It has been * To whom correspondence should be addressed .…”

“…On exposure to sunlight, the 5,7-diene of 7-DHC (steroid) absorbs ultraviolet (UV) energy (spectral range 290-315nm) that causes the cleavage of C9-C10 bond in the "B ring" to form vitamin D3 (secosteroid) (5-7) . Thus, "sunlight" is the chief energy source for breaking the B-ring of steroid in land animals.Interestingly, certain fish liver oils are rich sources of vitamin D [25,000 250,000IU/g oil (8-11)] when compared to mammals [<1IU/g oil (12)], inspite of the non-availability of enough UV light in their natural habitats (13).Earlier studies reported a lack of any relation between provitamin D3 and vitamin D3 contents in several fish (10,11,14) and also that the levels of these two compounds in the skin of fish were lower than those of rats (15), suggesting that the photochemical synthesis of vitamin D3 might not be significant in fish. It has been * To whom correspondence should be addressed .…”