Vitamin embryonic development

Underhill T, Kotch L, and Linney E (1995) Retinoids and mouse embryonic development. Vitamins and Hormones 51. 

Vitamin A is a fat soluble vitamin derived from carotene. The alcohol form of vitamin A, retinol, is the storage form in the body. The aldehyde form, retinal, has a role in vision. The acid form, retinoic acid, functions in embryonic development. Vitamin A acts to some extent in the body as an antioxidant, protecting against oxidative damage. 

Clagett-Dame M and DeLuca HF. 2002. The role of vitamin A in mammalian reproduction and embryonic development. Annu Rev Nutr 22 347—381. 

Vitamin Vitamin A [retinol] RDA/AI Men 900 pg/d Women 700 pg/d Physiological function Required for normal vision, gene expression, reproduction, embryonic development, and immune function Adverse Effects of Excessive Consumption Teratological effects liver toxicity... 

In mammals, the first report of induction of congenital malformations attributed to extrinsic factors is a single observation in 1921. This report linked a dietary deficiency of a fat soluble factor with rudimentary limb development in pigs, subsequently determined to be vitamin A. It was not until 1929 that X-rays were shown to affect embryonic development. 

Vitamin A is a fat-soluble vitamin involved in critical biological functions, such as embryonic development, growth and vision. It has three primary forms retinol, retinal and retinoic acid. In addition, (3-carotene can be converted to some extent in the body into retinol and is therefore called provitamin A. The bioactivity of these vitamin A compounds varies considerably, ranging from 100% for all-trans retinol, 75% for 13-eis retinol and to just 17% for (3-carotene. All-trans retinol is the major form of vitamin A in milk fat, with values ranging from 8.0 to 12.0 pg/g fat in samples of commercial butter. In contrast, 13-cA retinol is present at a very low... 

Further evidence that C-25 and C-l hydroxylation are the activation steps of vitamin D3, and that C-24/C-23 and C-23/C-26-lactone metabolic conversions do not produce physiologically important products is with the use of side-chain fluoridated analogues of 25-OH-D3 [87, 88], Studies with these analogues were prompted by assertions that 24-hydroxylated or lactone metabolites are involved or required for such biological actions as mineralization of bone [89], suppression of parathyroid hormone secretion [90], cartilage metabolism [91], and embryonic development in the chick [92]. It is well established that plasma 24,25-(OH)2D3 concentrations (2-5 ng/ml) are approximately 50 times greater than those of l,25-(OH)2D3. Even so,... 

ZileMH (2001) Function of vitamin Ain vertebrate embryonic development./ownta/ of Nutrition 131,705-8. 

Zile MH. Function of vitamin A in vertebrate embryonic development. J Nutr 2001 131 705-8. 

In addition to Its structural role In membranes, discussed In Chapter 5, cholesterol Is the precursor for several Important bloactive molecules. They Include bile acids (see Figure 18-6), which are made In the liver and help emulsify dietary fats for digestion and absorption In the Intestines, steroid hormones produced by endocrine cells (e.g., adrenal gland, ovary, testes), and vitamin D produced In the skin and kidneys. Arthropods need cholesterol or other sterols to produce membranes and ecdysterold hormones, which control development however, they cannot make the precursor sterols themselves and must obtain these compounds In their diet. Another critical function of cholesterol Is Its covalent addition to Hedgehog protein, a key signaling molecule In embryonic development (Chapter 15). 

Most hormones interacting with intracellular receptors exert their effects by controlling rates of transcription of specific genes. In this case, the hormone binds to a receptor and the complex migrates to the nucleus, where it interacts with specific DNA sites. Hormones in this class include steroids, thyroid hormones (see here), and the hormonal forms of vitamin D. In addition, retinoids, derived from retinoic acid (related to vitamin A), exert regulatory effects in embryonic development through interactions with intracellular receptors. 

In mice and rats hematopoiesis occurs in the liver during embryonic development. Besides spleen and bone marrow cell suspensions from adult animals, embryonic liver cell suspensions have been used to test substances which stimulate hematopoiesis. The cells are seeded on soft (0.3%) agar and supplemented with inactivated serum, amino acids, and vitamins for the in vitro culture (Pluznik and Sachs, 1965). Two groups of investigators have purified substances which stimulate the formation of colonies of granulocytes (leukocytes with segmented nuclei) and a cell type which has been called macrophages (or monocytes). 

Vitamin A deficiency must be prolonged if it is to affect fertility thus, animals may suffer blindness before their reproductive organs are affected (by keratinisation of the vagina or degeneration of the testes). An extreme and long-lasting deficiency of vitamin A may prejudice embryonic development and the ovarian cycle of mares, although this rarely occurs. Recently 3-carotene has been claimed to have a specific effect on fertility (i.e. independent of its role as a precursor of vitamin A), but the claim has yet to be adequately confirmed (see Chapter 6). 

Vitamin A (retinol) is a fat-soluble vitamin important for the maintenance of skin, bone, and blood vessels, as well as for the promotion of vision (Theodosiou et al. 2010). It is obtained from the diet either as all-trans-retinol, retinyl esters, or P-carotene (Blomhoff and Blomhoff 2006) and is stored in the liver (Moise et al. 2007). Vitamin A is converted to retinoic acid (RA), which is formed mainly through intracellular oxidative metabolism by retinal dehydrogenases (RALDHs) (Lampen et al. 2000). RA plays important roles in embryonic development, organogenesis, tissue homeostasis, cell proliferation, differentiation, and apoptosis (Theodosiou et al. 2010). In adult mammals, RALDH is found in intestinal epithelial cells (lECs) and gut associated-dendritic cells (DCs) from Peyer s patches and mesenteric lymph nodes (Iwata 2004, Coombes et al. 2007). Gut-associated DCs and lECs can metabolize vitamin A to RA in vitro (Lampen 2000), which indicates they may be a source of RA in gut mucosa. RA binds to two families of nuclear receptors, RA receptor (RAR) isotypes (a, p, and y) and retinoic X receptor (RXR) isotypes (a, p, and y). RAR and RXR form heterodimers and interact with retinoic acid response elements (RAREs) within the promoters of retinoic acid responsive genes (Blomhoff and Blomhoff 2006). RAR is ubiquitously expressed and up-regulated by RA. RXR also... 

The reproductive system requires a vitamin A-active substance for maintaining a normally differentiated epithelium, for other functions supportive of spermatogenesis in males (Palludan, 1966 Ahluwalia and Bieri, 1971 Thompson et al, 1964 Coward et al, 1969 Mitranond et al, 1979 Sobhon et al, 1979), and of a full gestation, embryonic development, and delivery in females (Thompson et al, 1964 Takahashi et al, 1975) it is also required for hatch-ability of the fertile eggs of fowl (Thompson et al, 1969). Retinoic acid can fulfill the role of epithelial maintenance, but retinol is required for the other functions noted. An exception appears to occur in the cockerel, in which retinoic acid is reported to maintain spermatogenesis (Thompson et al, 1969). 

---