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.

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 Changes in the tissues of guinea-pigs fed on a diet free from vitamin A but containing methyl retinoate

1967 ◽  
Vol 21 (1) ◽  
pp. 37-44 ◽  
Author(s):  
J. McC. Howell ◽  
J. N. Thompson ◽  
G. A. Pitt
Keyword(s):  
Vitamin A ◽  
Salivary Glands ◽  
Guinea Pigs ◽  
Vitamin A Deficiency ◽  
In Utero ◽  
Seminal Vesicles ◽  
Retinyl Acetate ◽  
Deficient Diet ◽  
Synthetic Diet ◽  
Normal Males

1. Forty-eight guinea-pigs were fed from weaning on a semi-synthetic diet free of retinol and carotenoids. Twenty-two of these animals received a twice-weekly supplement of methyl retinoate and fifteen received a twice-weekly supplement of retinyl acetate. The remaining eleven animals were fed on the vitamin A-free diet without supplementation.2. At varying times throughout the experiment, animals died or were killed by chloroform inhalation. Testes and seminal vesicles were weighed and these tissues together with trachea, lungs, salivary glands, bladder, eyes and vagina were examined histologically.3. The eleven guinea-pigs that received the unsupplemented diet developed signs of vitamin A deficiency after being fed on the diet for 3 or 4 weeks. Many epithelia showed a metaplastic change to the stratified squamous form often with keratinization.4. The guinea-pigs given supplements of either methyl retinoate or retinyl acetate grew at a normal rate and developed none of the signs of vitamin A deficiency that appeared in the animals on the unsupplemented diet. Evidence of metaplastic change in epithelia was not seen in any of these animals.5. Thirteen males were fed on the deficient diet and methyl retinoate. The testicles and seminal vesicles of these animals weighed less than those of the ten males fed on the deficient diet and retinyl acetate. The testes of the former showed severe histological degeneration of the seminiferous epithelium. The testes of the guinea-pigs fed on retinyl acetate were normal.6. Fifteen guinea-pigs fed on the deficient diet and retinyl acetate were mated to normal males. Eleven were thought to have become pregant. Eight of these gave birth to twenty-four pups. One died in advanced pregnancy with five apparently normal pups in utero and one produced three living young and died with one still in utero. Sixteen guinea-pigs fed on the deficient diet and methyl retinoate were mated to normal males. Twelve were thought to have conceived but all resorbed their foetuses.7. The vision of guinea-pigs fed on the synthetic diet and methyl retinoate deteriorated progressively, and after 150 days on the experiment the pupils did not respond to light. However, degeneration of the retina, such as had been seen in rats fed on a vitamin A-deficient diet containing methyl retinoate, was not seen in any of the guinea-pigs.

STEROID-INDUCED BLOCK OF OVARIAN COMPENSATORY HYPERTROPHY IN HEMICASTRATED FEMALE RATS

1964 ◽  
Vol 29 (3) ◽  
pp. 255-NP ◽  
Author(s):  
D. L. PETERSON ◽  
R. A. EDGREN ◽  
R. C. JONES
Keyword(s):  
Follicular Development ◽  
Compensatory Hypertrophy ◽  
Left Ovary ◽  
Female Rats ◽  
Corpora Lutea ◽  
Steroidal Hormones ◽  
Ovarian Compensatory Hypertrophy ◽  
Ovarian Size ◽  
The Right ◽  
Higher Doses

SUMMARY Removal of the right ovaries of 160–180 g. rats was followed in 2 weeks by a hypertrophy of 55 % of the left ovary. This postoperative growth was prevented by the administration of various natural and synthetic steroidal hormones, which were compared at daily doses estimated to produce a 100 % block of the hypertrophy. The following steroids, together with approximate ED 100, were studied: oestrone, 17·8 μg.; oestradiol-17β, 20·4 μg.; oestriol, 95·5μg.; norethynodrel, 72·5μg.; progesterone, 3630μg.;testosterone, 436 μg.; norethisterone, 479 μg.; norbolethone, 155 μg. At doses above ED 100 the natural oestrogens and norethynodrel produced a secondary cycle of ovarian growth, whereas the Δ4-3-oxosteroids depressed ovarian size further. Hemicastrated rats had histologically normal ovaries which contained larger numbers of corpora lutea than those of the intact controls. All compounds appeared to increase follicular development at the ED 100 level; the higher doses of the oestrogens and norethynodrel stimulated excessive luteinization, whereas the Δ4-3-oxosteroids inhibited luteal development and produced large vesicular and cystic follicles.

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.

UTILIZATION BY THE RAT OF LARGE LIVER RESERVES OR OF A SMALL DAILY INTAKE OF VITAMIN A

1962 ◽  
Vol 40 (10) ◽  
pp. 1407-1413
Author(s):  
T. K. Murray
Keyword(s):  
Growth Rate ◽  
Vitamin A ◽  
Normal Development ◽  
Daily Intake ◽  
Entire Period ◽  
Female Rats ◽  
Liver And Kidney ◽  
Weaning Age ◽  
Normal Males ◽  
Sufficient Vitamin

Weanling female rats were given a massive dose of vitamin A and thereafter fed a vitamin A free diet while similar rats were provided with the same diet plus a small daily intake of vitamin A for the entire period. Some of the rats from each group were bred to normal males. There were no differences in the growth rate, the number of young produced and weaned, nor in the weight of the young. Somewhat more vitamin A was transferred to the liver and kidney of the young by mothers with large liver stores but these differences had disappeared by weaning age. It was concluded that sufficient vitamin A could be given a rat at weaning to allow normal development and the production of at least one normal litter.

EFFECT OF SUCKLING AND ASSOCIATED FACTORS ON OVARIAN COMPENSATORY HYPERTROPHY DURING LACTATION IN THE RAT

1974 ◽  
Vol 61 (3) ◽  
pp. 317-330 ◽  
Author(s):  
F. MENA ◽  
D. AGUAYO ◽  
G. REYES ◽  
C. BEYER
Keyword(s):  
Spinal Cord ◽  
Associated Factors ◽  
Wistar Rats ◽  
Post Partum ◽  
Compensatory Hypertrophy ◽  
Ovariectomized Rats ◽  
Interstitial Tissue ◽  
Corpora Lutea ◽  
Unilateral Ovariectomy ◽  
Ovarian Compensatory Hypertrophy

SUMMARY The mechanism by which suckling affects the hypothalamo-pituitary-ovarian system was studied in lactating Wistar rats. Unilateral ovariectomy was carried out on day 4 post partum and the subsequent ovarian compensatory hypertrophy (OCH) was assessed on day 14 post partum. The weight of the corpora lutea (CL) of lactation, the CL of pregnancy and of the remainder of the ovary, here termed interstitial tissue, was determined for both ovaries. A clear OCH, mainly due to an increase in interstitial tissue, occurred in rats whose pups were removed on day 4 post partum. Suckling by two pups inhibited OCH, whereas suckling by six or ten pups produced significant ovarian atrophy, these effects being due to a decrease in weight of both interstitial tissue and CL of pregnancy which overcame an increase in weight of the CL of lactation. Inhibition of OCH occurred in spinal-cord transected rats suckling six pups. Suckling was suspended in unilaterally ovariectomized rats nursing ten pups on day 14 post partum, and the weight of the remaining ovary was determined 16, 32, 64 and 96 h later in four groups of rats. The weight of the remaining ovary returned to that of the control ovary 64 h after withdrawal of suckling. This effect was due to an increase in weight of interstitial tissue and of the CL of lactation. Maintenance of suckling for 64 h in rats with the galactophores ligated to prevent milk removal, inhibited OCH. By contrast, both oxytocin injections and exteroceptive stimulation provided by litters failed to block ovarian growth after suckling withdrawal. The results suggest that suckling itself is an important influence in the inhibition of OCH, but that other factors may contribute to the ovarian changes observed during lactation in the rat.

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.

UTILIZATION BY THE RAT OF LARGE LIVER RESERVES OR OF A SMALL DAILY INTAKE OF VITAMIN A

1962 ◽  
Vol 40 (1) ◽  
pp. 1407-1413
Author(s):  
T. K. Murray
Keyword(s):  
Growth Rate ◽  
Vitamin A ◽  
Normal Development ◽  
Daily Intake ◽  
Entire Period ◽  
Female Rats ◽  
Liver And Kidney ◽  
Weaning Age ◽  
Normal Males ◽  
Sufficient Vitamin

Weanling female rats were given a massive dose of vitamin A and thereafter fed a vitamin A free diet while similar rats were provided with the same diet plus a small daily intake of vitamin A for the entire period. Some of the rats from each group were bred to normal males. There were no differences in the growth rate, the number of young produced and weaned, nor in the weight of the young. Somewhat more vitamin A was transferred to the liver and kidney of the young by mothers with large liver stores but these differences had disappeared by weaning age. It was concluded that sufficient vitamin A could be given a rat at weaning to allow normal development and the production of at least one normal litter.

scholarly journals α-Retinol and 3,4-didehydroretinol support growth in rats when fed at equimolar amounts and α-retinol is not toxic after repeated administration of large doses

2013 ◽  
Vol 111 (8) ◽  
pp. 1373-1381 ◽  
Author(s):  
Napaporn Riabroy ◽  
Joseph T. Dever ◽  
Sherry A. Tanumihardjo
Keyword(s):  
Vitamin A ◽  
Liver Toxicity ◽  
Repeated Administration ◽  
Negative Control ◽  
Retinol Binding Protein ◽  
Retinyl Acetate ◽  
Deficient Diet ◽  
Treatment Groups ◽  
Body Weights ◽  
Growth Assay

Dietary α-carotene is present in oranges and purple-orange carrots. Upon the central cleavage of α-carotene in the intestine, α-retinal and retinal are formed and reduced to α-retinol (αR) and retinol. Previous reports have suggested that αR has 2 % biopotency of all-trans-retinyl acetate due in part to its inability to bind to the retinol-binding protein. In the present work, we carried out three studies. Study 1 re-determined αR's biopotency compared with retinol and 3,4-didehydroretinol in a growth assay. Weanling rats (n 40) were fed a vitamin A-deficient diet for 8 weeks, divided into four treatment groups (n 10/group) and orally dosed with 50 nmol/d retinyl acetate (14·3 μg retinol), α-retinyl acetate (143 μg αR), 3,4-didehydroretinyl acetate (14·2 μg DR) or cottonseed oil (negative control). Supplementation was continued until the control rats exhibited deficiency signs 5 weeks after the start of supplementation. Body weights and AUC values for growth response revealed that αR and DR had 40–50 and 120–130 % bioactivity, respectively, compared with retinol. In study 2, the influence of αR on liver ROH storage was investigated. The rats (n 40) received 70 nmol retinyl acetate and 0, 17·5, 35 or 70 nmol α-retinyl acetate daily for 3 weeks. Although liver retinol concentrations differed among the groups, αR did not appreciably interfere with retinol storage. In study 3, the accumulation and disappearance of αR over time and potential liver pathology were determined. The rats (n 15) were fed 3·5 μmol/d α-retinyl acetate for 21 d and the groups were killed at 1-, 2- and 3-week intervals. No liver toxicity was observed. In conclusion, αR and didehydroretinol are more biopotent than previously reported at sustained equimolar dosing of 50 nmol/d, which is an amount of retinol known to keep rats in vitamin A balance.

scholarly journals The biological activity of retinoic acid in the domestic fowl and the effects of vitamin A deficiency on the chick embryo

1969 ◽  
Vol 23 (3) ◽  
pp. 471-490 ◽  
Author(s):  
J. N. Thampson ◽  
J. McC. Howell ◽  
G. A. J. Pitt ◽  
Catherine I. McLaughlin
Keyword(s):  
Retinoic Acid ◽  
Chick Embryo ◽  
Vitamin A ◽  
Progressive Failure ◽  
Vitamin A Deficiency ◽  
Sole Source ◽  
Retinyl Acetate ◽  
Histological Changes ◽  
Acid Methyl ◽  
Vitamin A Acid

1. Male and female chickens were reared from hatching on vitamin A-free diets, either unsupplemented or containing retinoic acid (vitamin A acid), methyl retinoate or retinyl acetate (vitamin A acetate). The birds given retinyl acetate grew well and had a normal appearance, but those given the unsupplemented diet died before 4 weeks of age after developing typical signs of avitaminosis A. The birds given retinoic acid or methyl retinoate did not show overt signs of vitamin A deficiency or other abnormalities except for a progressive failure of vision. Minimal histological changes were found in their retinas, and their vision was rapidly restored after feeding with retinyl acetate.2. The cocks maintained with retinoic acid or methyl retinoate had normal testes and the hens laid eggs at a normal rate, but although their eggs could be obtained fertile the development of the embryo became abnormal after 2 days incubation and it always died. The development of the embryos could be stimulated and sometimes restored to normal by injection of various forms of vitamin A into the eggs before incubation, or by previous administration of retinyl acetate to the hens.3. It is concluded that feeding retinoic acid as the sole source of vitamin A enables the hen to produce eggs that lack vitamin A but are otherwise normal, thus permitting the demonstration of a hitherto undescribed requirement of the early chick embryo for vitamin A.4. The toxicity of vitamin A derivatives to chick embryos was investigated; injected retinoic acid was found to be extremely toxic.

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