Nova Publishers
My Account Nova Publishers Shopping Cart
HomeBooksSeriesJournalsReference CollectionseBooksInformationSalesImprintsFor Authors
  Top » Catalog » Books » Biology » Nutrition » New Topics in Vitamin D Research chapters » My Account  |  Cart Contents  |  Checkout   
Quick Find
Use keywords to find the product you are looking for.
Advanced Search
What's New? more
Communications: Government Policies and Programs
Shopping Cart more
0 items
Shipping & Returns
Privacy Notice
Conditions of Use
Contact Us
01.Vitamin D as a Neurosteroid Hormone: From Neurobiological Effects to Behavior (pp. 29-65)
02.Is Calcidiol an Active Hormone? (pp. 1-28)
03.Vitamin D Use among Older Adults in U.S.: Results from National Surveys 1997 To 2002 (pp. 181-198)
Notifications more
NotificationsNotify me of updates to Is Calcidiol an Active Hormone? (pp. 1-28)
Tell A Friend
Tell someone you know about this product.
Is Calcidiol an Active Hormone? (pp. 1-28) $25.00
Authors:  Yan-Ru Lou and Pentti Tuohimaa (University of Tampere, Finland)
Vitamin D3 is produced in the skin during exposure to sunlight and is then 25-hydroxylated in the liver, yielding the major circulating metabolite 25-hydroxyvitamin D3 (25OHD3, calcidiol). Calcidiol is converted to 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) mainly in the kidney by 25OHD3-1-hydroxylase (1-hydroxylase). Calcidiol and 1,25-(OH)2D3 are further hydroxylated into less active metabolites by 25OHD3-24-hydroxylase (24-hydroxylase, CYP24). Vitamin D3 metabolites exert their effects by binding to the nuclear vitamin D receptor. 24-Hydroxylase is highly inducible by vitamin D3 metabolites at transcriptional level and it controls the biological action of calcidiol and 1,25-(OH)2D3. It has been proposed that the local production of vitamin D metabolites is important.
Calcidiol is generally considered a prehormone, which is activated via 1-hydroxylation. 1,25-(OH)2D3 plays a central role in calcium homeostasis but only at hypercalcemic (pharmacological) concentrations it regulates the proliferation and differentiation of various cell types in vivo and in vitro. However, we show direct evidence that calcidiol at physiological concentration possesses an inherent hormonal activity. Other hormonal factors can enhance vitamin D action by inhibiting its degradation. 5-dihydrotestosterone (DHT) and all-trans-retinoic acid (ATRA) enhance antiproliferative activities of calcidiol and 1,25-(OH)2D3 by suppressing the expression of 24-hydroxylase, which suggests that both at physiological concentrations combined with DHT or ATRA are active and can be used for therapeutic purposes. The novel vitamin D3 endocrine system of calcidiol seems to explain the discrepancies of the epidemiological and clinical data on the association between vitamin D insufficiency and many chronic diseases. We propose that calcidiol is more potent hormone regulating cell proliferation and differentiation than calcitriol in the physiological condition. Therefore, seasonal fluctuation of calcidiol might be directly involved in the development of chronic diseases. 

Available Options:
Customers who bought this product also purchased

High Levels of Active 1,25-Dihydroxyvitamin D Despite Low Levels of the 25-Hydroxyvitamin D Precursor - Implications of Dysregulated Vitamin D for Diagnosis and Treatment of Chronic Disease (pp. 1-23)
Special Focus Titles
01.Flavonoids in the Fight against Upper Gastrointestinal Tract Cancers
02.Resilience and Health: A Potent Dynamic
03.Alpha Lipoic Acid: New Perspectives and Clinical Use in Obstetrics and Gynecology
04.Advances in Psychobiology
05.Biodiversity in Time and Space
06.Multifaceted Autoethnography: Theoretical Advancements, Practical Considerations and Field Illustrations
07.Islam and Muslims in Europe
08.Violence Against Women in the 21st Century: Challenges and Future Directions
09.Challenges and Opportunities for Eurozone Governance
10.Flour: Production, Varieties and Nutrition
11.Liquid Metals: From Atomistic Potentials to Properties, Shock Compression, Earth's Core and Nanoclusters
12.Polyunsaturated Fatty Acids (PUFAs): Food Sources, Health Effects and Significance in Biochemistry

Nova Science Publishers
© Copyright 2004 - 2018

Is Calcidiol an Active Hormone? (pp. 1-28)