scholarly journals Studies on metabolism of vitamin A. The effect of vitamin A status on the secretion rates of some steroids into the ovarianvenous blood of pregnant rats

1971 ◽  
Vol 122 (2) ◽  
pp. 235-239 ◽  
Author(s):  
J. Ganguly ◽  
G. S. Pope ◽  
S. Y. Thompson ◽  
Joyce Toothill ◽  
J. D. Edwards-Webb ◽  
...  
Keyword(s):  
Retinoic Acid ◽  
Vitamin A ◽  
Venous Blood ◽  
Retinyl Acetate ◽  
Deficient Diet ◽  
Pregnant Rats ◽  
Vitamin A Status ◽  
Previous Demonstration ◽  
Secretion Rates ◽  
Steroid Dehydrogenase

1. Rats raised on a vitamin A-deficient diet supplemented with either retinyl acetate or retinoic acid were mated and became pregnant. 2. The rates of secretion of progesterone, 20α-hydroxypregn-4-en-3-one, oestradiol-17β and oestrone into the ovarian-venous blood of rats in these two groups were measured on days 9 and 15 of pregnancy. 3. Rates of secretion of progesterone and 20α-hydroxypregn-4-en-3-one, both on days 9 and 15, were lower for the rats given retinoic acid. No such differences were found in ovarian oestrogen secretion. 4. The implications of these results are discussed in the light of the previous demonstration that the activity of ovarian 3β-hydroxy-Δ5-steroid dehydrogenase was markedly less in pregnant rats given retinoic acid.

scholarly journals The retinol requirements of rats for spermatogenesis and vision

1969 ◽  
Vol 23 (3) ◽  
pp. 619-626 ◽  
Author(s):  
W.A. Coward ◽  
J.McC. Howell ◽  
J.N. Thompson ◽  
G. A. J. PITT
Keyword(s):  
Retinoic Acid ◽  
Vitamin A ◽  
Beneficial Effect ◽  
General Health ◽  
Vitamin A Deficiency ◽  
Experimental Period ◽  
Normal Vision ◽  
Retinyl Acetate ◽  
Deficient Diet ◽  
Histological Appearance

1. Hooded rats were fed from weaning on a basal retinol-deficient diet containing retinoic acid. Such a diet maintains growth and general health but does not prevent the appearance of lesions associated with vitamin A deficiency in the retina and testis. Some animals were also given supplements of retinol averaging 0.1, 0.25, 1 or 5 μg retinyl acetate per day. Rats were killed at intervals up to 28 weeks after weaning. The weights of the testes and the histological appearance of the testes and epididymides indicated that 5 μg retinyl acetate per day had maintained spermatogenesis throughout the experimental period. Doses averaging 1 μg retinyl acetate per day were only partially effective and the two smaller doses had little beneficial effect.2. In a second similar experiment rats were given doses of retinyl acetate averaging 0.25, 0.5, 1, 2 or 100 μg per day. Measurements of the electroretinogram thresholds of the rats indicated that a dose of 1 μg retinyl acetate per day maintained mainly normal vision until the end of the experiment 29 weeks after weaning. Additional histological observations made 21 weeks after weaning showed that this dose level had not maintained spermatogenesis but that doses of 2 μg retinyl acetate per day had been effective.3. The experiments show that the differing functions of vitamin A in spermatogenesis and vision are reflected in the hooded rat in differences in the dietary retinol levels needed to maintain these processes.

scholarly journals Studies on metabolism of vitamin A. The effect of hormones on gestation in retinoate-fed female rats

1969 ◽  
Vol 111 (1) ◽  
pp. 97-105 ◽  
Author(s):  
H. S. Juneja ◽  
N. R. Moudgal ◽  
J. Ganguly
Keyword(s):  
Vitamin A ◽  
Sole Source ◽  
Compensatory Hypertrophy ◽  
Female Rats ◽  
Corpora Lutea ◽  
Retinyl Acetate ◽  
Deficient Diet ◽  
Unilateral Ovariectomy ◽  
Normal Males ◽  
Steroid Dehydrogenase

1. Female rats, raised to maturity on a vitamin A-deficient diet supplemented with retinoate as the sole source of vitamin A, conceived when allowed to mate with normal males, but the conception resulted in foetal resorption, beginning from day 14 or 15 of pregnancy. 2. Daily injections of pregnenolone or oestradiol-17β, but not of progesterone, were fully effective, and transplantation of pituitary homografts under kidney capsules was 80% effective, in preventing resorption. 3. Unilateral ovariectomy, leading to compensatory hypertrophy of the remaining ovary, resulted in significantly fewer corpora lutea and in lower weight of the hypertrophied ovary of the retinoate-treated rats, as compared with the corresponding retinyl acetate-fed ones. 4. The activity of the enzyme system Δ5-3β-hydroxy steroid dehydrogenase was significantly less in the ovaries of the retinoate-fed rats that were subjected to unilateral ovariectomy or were made pregnant, when compared with that of the corresponding controls. Also, the ovaries of the retinoate-treated rats were insensitive to both exogenous and endogenous gonadotrophin stimulus. 5. These results indicate that one of the reasons for foetal resorption in the retinoate-fed rats might be inadequate synthesis of steroid hormones such as pregnenolone and oestrogen.

Vitamin A Status and Hepatic Drug Metabolism in the Rat

1973 ◽  
Vol 51 (1) ◽  
pp. 6-11 ◽  
Author(s):  
G. C. Becking
Keyword(s):  
Vitamin A ◽  
Drug Metabolism ◽  
Vitamin A Deficiency ◽  
Hepatic Drug Metabolism ◽  
Deficient Diet ◽  
Hepatic Drug ◽  
Vitamin A Status ◽  
Cytochrome P 450 ◽  
Liver Vitamin

The effect of vitamin A status on hepatic drug metabolism was studied in rats. Animals were fed diets with and without vitamin A for 20 and 25 days. Weight gains of control and deficient animals were not significantly different, whereas liver vitamin A levels had decreased to less than 10% of control animals after 20 days and were essentially zero after eating the deficient diet for 25 days. Aniline metabolism in vitro and aminopyrine metabolism in vitro and in vivo were significantly lower in male weanling rats fed a vitamin A deficient diet for 20 days. No alteration in in vitro p-nitrobenzoic acid metabolism was noted after 25 days on the test. Vitamin A deficiency did not alter microsomal protein levels or cytochrome c reductase activity but deficient animals did have a lower microsomal cytochrome P-450 content. Hepatic enzyme activities and cytochrome P-450 levels were restored to values approaching those found in control animals by feeding vitamin A deficient rats the vitamin A containing diet for 21 days. Liver vitamin A levels were markedly increased after re-feeding studies but were still significantly lower than control animals.

Retinol is specifically required during midgestation for neonatal survival

1997 ◽  
Vol 272 (1) ◽  
pp. E25-E29 ◽  
Author(s):  
D. M. Wellik ◽  
D. H. Norback ◽  
H. F. DeLuca
Keyword(s):  
Single Dose ◽  
Retinoic Acid ◽  
Vitamin A ◽  
Respiratory Distress Syndrome ◽  
Respiratory Distress ◽  
Distress Syndrome ◽  
Skin Tone ◽  
Healthy Skin ◽  
Human Infants ◽  
Pregnant Rats

Previous work has demonstrated that vitamin A-deficient, retinoic acid-supplemented pregnant rats cannot complete gestation without the administration of retinol. As little as 2 micrograms administered on day 10 of gestation is sufficient to prevent the characteristic fetal resorption that begins at day 15 of gestation. This single dose of retinol supports continued development through day 20 of gestation. However, if gestation is allowed to proceed to parturition, the newborn pups die within a few minutes of being severed from the umbilical cord. The pups are born with a pink and healthy skin tone, but within seconds of umbilical separation, they begin to gasp for air, become cyanotic in appearance, and die within several minutes from an apparent inability to obtain oxygen. Histological examination of these neonates demonstrates delayed pulmonary development. Branching and scalloping of ducts and saccule and subsaccule formation are decreased. This phenotype is consistent with that observed in respiratory distress syndrome seen in some premature human infants.

scholarly journals Dietary Retinoic Acid Alters Vitamin A Kinetics in Both the Whole Body and in Specific Organs of Rats with Low Vitamin A Status

2005 ◽  
Vol 135 (4) ◽  
pp. 746-752 ◽  
Author(s):  
Christopher J. Cifelli ◽  
Joanne Balmer Green ◽  
Michael H. Green
Keyword(s):  
Retinoic Acid ◽  
Vitamin A ◽  
Whole Body ◽  
Vitamin A Status

scholarly journals Effects of Vitamin-A Status on Hamster Tracheal Epithellum in Viva in Vitro

1989 ◽  
Vol 11 (3) ◽  
pp. 1-6 ◽  
Author(s):  
Luigi M. De Luca ◽  
Elizabeth M. McDowell
Keyword(s):  
Retinoic Acid ◽  
Vitamin A ◽  
Retinoic Acid Receptor ◽  
Normal Liver ◽  
Acid Receptor ◽  
New Horizons ◽  
Vitamin A Status ◽  
Essential Nutrient ◽  
Hepatoma Tissue

In this paper we have suggested the new concept of exotrophic cells, i.e. cells that have conditionally escaped the need for an essential nutrient, such as vitamin A. These exotrophs might become fixed by a mutation and eventually contribute to the tumorigenic phenotype. The discovery of the retinoic acid receptor (RAR) has opened up new horizons in the search for the mechanism of action of retinoic acid [17; 18]. It is intriguing that a second retinoic acid receptor, RARE, is abundantly expressed in hepatoma tissue and not in normal liver; Benbrook et al. [191 suggest that the erroneous expression of the RARE might contribute to tumour development in liver. How and whether these findings relate to the vitamin-A-deficient status of hepatoma cells remains to be understood.

Quantitative Aspects of the Urinary and Fecal Excretion of Radioactive Metabolites of Vitamin A in the Rat

1972 ◽  
Vol 50 (11) ◽  
pp. 1026-1037 ◽  
Author(s):  
R. N. Varma ◽  
G. H. Beaton
Keyword(s):  
Vitamin A ◽  
Experimental Studies ◽  
Urinary Metabolites ◽  
Fecal Excretion ◽  
Plasma Vitamin ◽  
Second Phase ◽  
Retinyl Acetate ◽  
Deficient Diet ◽  
Liver Vitamin

Urinary and fecal excretion of radioactive metabolites has been followed for 8 days (12 days in one group) in groups of rats having different initial body stores of vitamin A and given a single oral dose of 11,12-3H-retinyl acetate in oil. During the collections animals were fed a vitamin A deficient diet except for one group which was given laboratory chow throughout. At the end of the collection period animals were killed for determination of liver, kidney, and plasma vitamin A and radioactivity. Specific activities were similar in the three tissues; total liver vitamin A contents ranged from undetectable to 7700 μg. Excretion of fecal and urinary radioactivity was high initially but fell to apparently stable levels by day 8. When the combined urinary and fecal excretion was expressed in terms of the liver vitamin A equivalent (ELV), there was a gradual increase in excretion rate with the logarithm of liver vitamin A up to 150–300 μg/g liver; thereafter the rate of excretion increased more rapidly with liver stores to the highest level studied, 500–550 μg/g. In the initial phase the ELV values were 4–10 μg/day, rising to 22–24 μg/day in the second phase. These studies suggest that (a) a portion of newly absorbed vitamin A is metabolized before mixing with general body pools and probably without greatly altering the metabolism of endogenous vitamin A, (b) after equilibration of body pools, urinary excretion of radioactivity should be a useful index in experimental studies of factors affecting vitamin A metabolism, and (c) chemical determination of urinary metabolites of vitamin A is a potential index of vitamin A nutritional status.

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