Studies in the metabolism of cholecalciferol in the Japanese quail
Studies in the metabolism of cholecalciferol in the Japanese quail
The metabolism of cholecalciferol in the Japanese quail was studied using liver homogenates and the technique of thin layer chromatography for sterol analysis. 25 Hydroxycholecalciferol was the major metabolite ofcholecalciferol produced in liver homogenates prepared from laying birds. Very little 25 hydroxycholecalciferol was formed by the-livers of immature birds of either sex or by the livers of adult males. Instead a peak lesspolar than 25 hydroxycholecalciferol (peak X) was formed, Ltogether with a more polar (peak P) that remained at the origin. In these homogenates the radioactivity in the aqueous phase of the incubation mixture was also high and the cholecalciferol substrate was extensively metabolised. When cock birds or immature females were treated with oestrogen their livers produced mainly 25 hydroxycholecalciferol and a larger amount of cholecalciferol substrate was recovered unchanged at the end of the incubation.. The administration of oestrogen to cockbirds was thus found to protect 25 hydroxycholecalciferol from further metabolism in the liver to more polar products. Oestrogen treated quail were also found to have much greater Calcium Binding Protein activity in the duodenum than control animals.The oestrogen induced increase in cholecalciferol 25-hydroxylase activity was shown to be microsomal in origin. However, liver microsomes harvested from oestrogen treated birds would only support 25-hydroxylation in the presence of added cytoplasmic fraction. Without the cytoplasmic fraction, these microsomes rapidly degraded cholecalciferol and the production of peaks X and P occurred.The increase in hepatic cholecalciferol 25-hydroxylase activity and the protection of cholecalciferol and 25 hydroxycholecalciferol from further metabolism to more polar products observed after oestrogen treatment may be of fundamental importance to the high calcium turnover found in laying birds. A separate study revealed that both cholecalciferol and 25 hydroxycholecalciferol are accumulated by developing ovarian follicles.
University of Southampton
Nicholson, Russell Alfred
1976
Nicholson, Russell Alfred
Nicholson, Russell Alfred
(1976)
Studies in the metabolism of cholecalciferol in the Japanese quail.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
The metabolism of cholecalciferol in the Japanese quail was studied using liver homogenates and the technique of thin layer chromatography for sterol analysis. 25 Hydroxycholecalciferol was the major metabolite ofcholecalciferol produced in liver homogenates prepared from laying birds. Very little 25 hydroxycholecalciferol was formed by the-livers of immature birds of either sex or by the livers of adult males. Instead a peak lesspolar than 25 hydroxycholecalciferol (peak X) was formed, Ltogether with a more polar (peak P) that remained at the origin. In these homogenates the radioactivity in the aqueous phase of the incubation mixture was also high and the cholecalciferol substrate was extensively metabolised. When cock birds or immature females were treated with oestrogen their livers produced mainly 25 hydroxycholecalciferol and a larger amount of cholecalciferol substrate was recovered unchanged at the end of the incubation.. The administration of oestrogen to cockbirds was thus found to protect 25 hydroxycholecalciferol from further metabolism in the liver to more polar products. Oestrogen treated quail were also found to have much greater Calcium Binding Protein activity in the duodenum than control animals.The oestrogen induced increase in cholecalciferol 25-hydroxylase activity was shown to be microsomal in origin. However, liver microsomes harvested from oestrogen treated birds would only support 25-hydroxylation in the presence of added cytoplasmic fraction. Without the cytoplasmic fraction, these microsomes rapidly degraded cholecalciferol and the production of peaks X and P occurred.The increase in hepatic cholecalciferol 25-hydroxylase activity and the protection of cholecalciferol and 25 hydroxycholecalciferol from further metabolism to more polar products observed after oestrogen treatment may be of fundamental importance to the high calcium turnover found in laying birds. A separate study revealed that both cholecalciferol and 25 hydroxycholecalciferol are accumulated by developing ovarian follicles.
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Published date: 1976
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Local EPrints ID: 458707
URI: http://eprints.soton.ac.uk/id/eprint/458707
PURE UUID: 9afabdb7-6a53-4cfd-b7d9-ad70c7d6ecdb
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Date deposited: 04 Jul 2022 16:54
Last modified: 04 Jul 2022 16:54
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Author:
Russell Alfred Nicholson
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