Metabolic role of vitamins A and D

Ameliorating Effects of Natural Antioxidant Compounds on Female Infertility: a Review

The prevalence of female infertility cases has been increasing at a frightening rate, affecting approximately 48 million women across the world. However, oxidative stress has been recognized as one of the main mediators of female infertility by causing various reproductive pathologies in females such as endometriosis, PCOS, preeclampsia, spontaneous abortion, and unexplained infertility. Nowadays, concerned women prefer dietary supplements with antioxidant properties over synthetic drugs as a natural way to lessen the oxidative stress and enhance their fertility. Therefore, the current review is an attempt to explore the efficacy of various natural antioxidant compounds including vitamins, carotenoids, and plant polyphenols and also of some medicinal plants in improving the fertility status of females. Our summarization of recent findings in the current article would pave the way toward the development of new possible antioxidant therapy to treat infertility in females. Natural antioxidant compounds found in fruits, vegetables, and other dietary sources, alone or in combination with other antioxidants, were found to be effective in ameliorating the oxidative stress-mediated infertility problems in both natural and assisted reproductive settings. Numerous medicinal plants showed promising results in averting the various reproductive disorders associated with female infertility, suggesting a plant-based herbal medicine to treat infertility. Although optimum levels of natural antioxidants have shown favorable results, however, their excessive intake may have adverse health impacts. Therefore, larger well-designed, dose-response studies in humans are further warranted to incorporate natural antioxidant compounds into the clinical management of female infertility.

Prenatal vitamin A supplementation associated with adverse child behavior at 3 years in a prospective birth cohort in Japan

BACKGROUND

Many pregnant women take vitamin supplements during pregnancy. The aim of this paper was to clarify the effects of dietary supplementation prior to and/or during pregnancy on child behavior.

METHODS

A prospective birth cohort study from pregnancy to 3 years of age involving 1271 pairs of Japanese pregnant women and their newborns, was carried out. The women completed a self-administered questionnaire during the third trimester of pregnancy. To evaluate deviations in child behavior as an endpoint, each mother completed the Japanese Child Behavior Checklist for ages 2-3 years after 3 years of birth. Participant characteristics were compared between supplement takers and non-takers.

RESULTS

Among many kinds of supplements, intake of supplemental vitamin A/β-carotene prior to and/or during pregnancy was associated with hazardous effects on child behavior at 3 years of age (total t-score, P = 0.003; internal t-score, P = 0.027; external t-score, P = 0.013). This association held true even after adjusting for age, number of deliveries, infertility treatment, consumption of fast food, smoking status, maternal and paternal education, maternal and paternal income, gestational age at birth, anthropometry at birth (weight, height, head circumference and body circumference), and the State-Trait Anxiety Inventory at 3 years of age by means of multiple imputation.

CONCLUSIONS

Intake of supplemental vitamin A prior to and/or during pregnancy may worsen child behavior at 3 years of age.

The effects of vitamin A supplementation to rats during gestation and lactation upon redox parameters: increased oxidative stress and redox modulation in mothers and their offspring

Vitamin A is an essential nutrient required in adequate amounts for reproduction and development. Subtle variations in the status of maternal nutrition may affect physiological and metabolic parameters in the fetus. Evidence suggests a key role for oxidative stress in these events. Literature is controversial about the effects of vitamin A supplementation. Here, we studied the effects of vitamin A supplementation on female Wistar rats during gestation and lactation on oxidative stress parameters of maternal and offspring tissues. Rats received daily doses of vitamin A at 2500, 12,500 and 25,000IU/kg. We observed an increase of oxidative damage markers in the reproductive tissues and plasma of dams. The activity of glutathione-S-transferase was modulated by vitamin A supplementation. It was found to be increased in the liver of dams and decreased in the kidneys of mothers and offspring. In pups, supplementation decreased the total antioxidant potential of the liver along with decreased superoxide dismutase/catalase activity ratio in the kidney. The levels of lipoperoxidation were increased in male offspring, but decreased in female pups. Collectively, the results suggest that excessive vitamin A intake during gestation and lactation might be toxic for mothers with adverse effects for the developing offspring.

Influence of cholecalciferol (vitamin D(3)) on the initial kinetics of the uptake of calcium ions by rat small-intestinal mucosa (Short Communication)

The uptake of Ca(2+) by isolated small-intestinal mucosa from vitamin D-depleted and -repleted rats was analysed for the effects of vitamin D on initial kinetics. The rapid association of Ca(2+) with the tissue, which is complete within 1min, was unaffected by the vitamin, whereas the subsequent, linear, uptake was significantly increased. Neither the tissue space accessible to inulin nor the permeability to thiourea was influenced by vitamin D treatment.

Cholesteatoma prevention by local treatment with vitamin A

HYPOTHESIS

In view of the proven effectiveness of vitamin A for the treatment of hyperkeratosis, it was hypothesized that vitamin A may also be a feasible therapeutic option for cholesteatoma, which has similar histologic features.

BACKGROUND

Cholesteatoma is a major cause of chronic ear disease, often requiring surgery. The recurrence rate may exceed 20%. Hyperkeratosis is a major sequela of tympanomastoid surgery, causing chronic ear hygiene problems.

METHODS

The external auditory canals of 40 Mongolian gerbils were ligated to induce cholesteatomas. The ears were divided into three groups by type of treatment: group I, vitamin A drops (n = 40); group II, Cortisporin drops (n = 20); group III, no treatment (control subjects) (n = 20). Examination for the development and grade of cholesteatomas was performed after 9 months.

RESULTS

Cholesteatomas developed in 26 ears (65%) of group I, 12 ears (60%) of group II, and 20 ears (100%) of group III. The differences were significant between groups I and III and groups II and III for both rate of cholesteatomas and severity of grade. There were no significant differences between groups I and II.

CONCLUSION

Local treatment reduces the risk of cholesteatomas in ligated gerbilline ears. Cortisporin and vitamin A are equally effective as local treatments.

Retinoic acid receptor transcripts and effects of retinol and retinoic acid on glucagon secretion from rat islets and glucagon-secreting cell lines

Using intact rat islets, hamster In-R1-G9 cells, and mouse alphaTC-1 clone 9 transgenic tumoral glucagon-secreting cells, we determined the effects of retinol (ROH) and retinoic acid (RA) on glucagon secretion. Since vitamin A effects may be mediated through nuclear RA receptors (RARs) and cytoplasmic ROH- and RA-binding proteins (CRBP and CRABP), cells were also assayed for RARs, CRBP, and CRABP mRNA by Northern blot analyses. Islets and cells were cultured in 2.8 mmol/L glucose and vitamin A-deficient (A-def) medium or in different concentrations of ROH and RA. Using intact islets, RA 10 and 100 nmol/L inhibited glucagon secretion to approximately 60% of control levels. Using In-R1-G9 cells, ROH 0.175 to 5.0 micromol/L inhibited glucagon secretion to 60% to 83% of control levels, and RA 100 and 1,000 nmol/L inhibited glucagon secretion from 72% to 43% of control levels, respectively. Using alphaTC-1 cells, ROH 1.75 micromol/L inhibited glucagon secretion to 80% of control levels, and RA 1 to 100 nmol/L inhibited secretion from 83% to 68% of control levels. Inhibition of secretion was dose-dependent. RARalpha RNA transcripts were detected in alpha TC-1 and In-R1-G9 total RNA extracts; RAR gamma transcripts were detected in alphaTC-1 cells. We conclude the following: (1) ROH and RA inhibit glucagon secretion in cultured rat islets and glucagon-secreting cell lines, and in cell lines the effect of RA is dose-dependent; (2) on a molar basis, RA is on the order of 10- to 100-fold more potent than ROH, a finding consistent with RA being the active metabolite of ROH at the alpha-cell level; and (3) this inhibition may be mediated through classic pathways of retinoid action involving nuclear RARs and gene expression of specific proteins.

Retinoids upregulate phagocytosis by human dermal microvascular endothelial cells

Animals fed a diet deficient in vitamin A show severe physiological changes that often result in death. At the cellular level, retinoids have been shown to induce differentiation of cells derived from a wide spectrum of tissues, including the vasculature. To understand further the mechanisms for these events, we studied the effects of 13-cis-retinoic acid, all-trans-retinoic acid, all-trans-retinol, and all-trans-retinol acetate on human dermal microvascular endothelial cells (HDMEC). Concentrations of retinoids in the physiological range from 0 to 1 microM were used in our experiments. These concentrations were nontoxic to HDMEC. Here we report that in addition to the known effect of retinoids on keratinocytes and sebacytes, retinoids induced morphological and functional changes in HDMEC that gave these cells macrophage like characteristics. 13-Cis-retinoic acid and all-trans-RA induced HDMEC to phagocytize and to increase the production of hydrogen peroxide and superoxide anion. These two retinoids also changed the morphology of endothelial cells from typical small compact cuboidal epithelioid cells to cells with larger cytoplasm and indistinct cell membranes. The retinoid-stimulated HDMEC deposited increased amounts of extracellular matrix. All-trans-retinol and all-trans-retinol acetate did not significantly affect HDMEC in all parameters tested. The induction of these properties provides a new model with which to study how retinoids regulate gene expression using a normal, nontransformed cell line.

A mechanism of retinoid potentiation of murine T-cell responses: early upregulation of interleukin-2 receptors

The capacity of retinoids to amplify the proliferative response of BALB/c lymphocytes to concanavalin A (Con A)2 in the presence of exogenous interleukin-2 (IL-2) and the induction of IL-2 receptors (IL-2R) on L3T4+ and Lyt-2+ T-cells was evaluated. Preincubation with Con A for 8 h in the presence of retinoids resulted in a greater than two-fold increase in spleen cell proliferative response to Con A plus rIL-2 over the following 72 h relative to the response of cells preincubated with Con A alone. Peak potentiation of IL-2 responses occurred over a pharmacologic range of retinoic acid (RA) concentration (10(-10)-10(-8) M) in the presence of 20 U/ml rIL-2. This potentiation of the response to IL-2 was likewise observed after 8 h prestimulation with Con A with splenic T-cells enriched by passage over nylon wool. Preincubation of the spleen cells with Con A plus RA without the subsequent addition of IL-2 resulted in a proliferative response that was potentiated nearly to the level of the response produced by subsequent addition of IL-2 to Con A-activated cells. Preincubation of the cells with Con A in the presence of RA produced a true synergy with IL-2; the resulting increase in response was greater than the sum of the increases produced by RA or IL-2 alone.(ABSTRACT TRUNCATED AT 250 WORDS)

The hypervitaminosis-A rat: a model for mucin hypersecretion in cystic fibrosis?

Cystic fibrosis is a devastating disease with pathognomonic features typically displayed in the exocrine system. An obvious drawback with human clinical studies of the disease is the relative inaccessibility of its "target-tissues," i.e., the salivary glands, intestine, pancreas, and tracheobronchial tree. Thus, little is known about its underlying cellular mechanisms. For this reason, physiologically relevant animal models for the disease are vitally needed. At present, there are animal models available for certain salivary gland biochemical aspects of the disease and for bicarbonate ion secretory alterations. However, no adequate model exists for excessive mucus production, an aspect of the disease which sets the stage for life-threatening infections and digestive disorders. This manuscript examines morphological and biochemical changes occurring in various biological systems exposed to high levels of vitamin A and correlates such changes with abnormalities commonly seen in cystic fibrosis.

Retinol induces platelet aggregation via activation of phospholipase A2

All-trans-retinol induced aggregation of rabbit platelets, and this effect could be inhibited by a cyclooxygenase inhibitor and a thromboxane A2 (TXA2) receptor antagonist, indicating an essential role for endogenously produced TXA2. We found a two-phase arachidonic acid release in retinol-stimulated platelets. The first phase was induced by the action of retinol alone and not inhibited by TXA2 receptor antagonist. The second phase was induced via synergistic action of retinol and initially generated small amount of TXA2, and was inhibited by the antagonist. Moreover, we discussed that the arachidonic acid release may be mediated by the action of phospholipase A2.

Effect of a vitamin A-free diet on [3H]diazepam and [3H]GABA binding in the rat retina

Benzodiazepine and GABA binding sites in the rat retina are influenced by a vitamin A-free diet. In rats fed a vitamin A-free diet, the total number of [3H]GABA and [3H]diazepam binding sites was markedly higher than in rats given a balanced diet. No differences were found in the apparent affinities of [3H]GABA and [3H]diazepam for their specific binding sites. The results suggest that GABA and benzodiazepine binding sites have a role in the function of the retina.

Familial progressive myoclonic epilepsy. A clinical, genetical, biochemical and patho-anatomical study of a family with a 6-year follow-up

Six siblings, including 4 cases of myoclonic epilepsy, their parents and 2 grandmothers were subjected to systematic investigation, and the patients were followed-up. The genetic studies revealed in the mother's family a patient with Lafora bodies demonstrated at autopsy. No chromosome abnormalities were found nor any linkage to the HLA system. The affected family members were characterized biochemically by an increased excretion of total glycosaminoglycans and/or an abnormal electrophoretic pattern of urinary glycosaminoglycans with an increased proportion of low-sulfated glycosaminoglycans. In the healthy family members this pattern of electrophoresis could also be demonstrated in the father and the paternal grandmother. Based on the biochemical results and the genetic studies it is suggested that the family members with progressive familial myoclonic epilepsy present a combination of at least 2 hereditary defects. The course of the disease has been relatively benign and treatment with sodium valproate, baclofen and clonazepam has shown quite satisfying results. In consequence of the biochemical findings combined treatment with A and E vitamins has been initiated.

Is the cancer process caused by deletion of one or more differentiation genes normally activated by steroid hormones?

The hypothesis is proposed that: 1. Aflatoxin B1 and polycyclic hydrocarbon carcinogens cause the deletion of genes necessary for the production of a substance required for differentiation of the cell and activated by a steroid hormone possibly a corticosteroid. 2. Such genes could include genes for production of: glutamine transaminase, glutamine synthetase, genes involving vitamin A metabolism. 3. Deletion of any of these genes could cause the cell to remain in an undifferentiated and replicating state.

Vitamin A stimulation of parathyroid hormone: interactions with calcium, hydrocortisone, and vitamin E in bovine parathyroid tissues and effects of vitamin A in man

The effect of vitamin A, a membrane surface-active agent, on parathyroid hormone secretion was studied in vitro, using bovine parathyroid tissue, and in vivo in man. Parathyroid tissues were incubated with vitamin A (retinol), retinoic acid, and calcium, and with hydrocortisone and vitamin E, agents that antagonize the membrane effects of vitamin A. The stimulation of parathyroid hormone release by vitamin A, 10(-6) to 10(-9) mol/1 in vitro, was dose and time dependent. Retinoic acid did not stimulate secretion. High calcium concentration, hydrocortisone, 10(-5) mol/1 and 10(-6) mol/1, and vitamin E, 10(-5) mol/1, antagonized vitamin A-induced parathyroid hormone secretion. Vitamin A increased the lysosomal cathepsin D activity of parathyroid tissues. In human studies, eleven healthy men received two intramuscular injections of vitamin A palmitate, 25 000 units each, within 24 h. In every subject, serum parathyroid hormone increased after vitamin A administration. Our studies indicate that: (1) vitamin A stimulates parathyroid hormone secretion in vitro, possibly through modification of the cell or secretion granule membrane, or through stimulation of lysosomal proteolytic activity, and (2) vitamin A increases serum parathyroid hormone in vivo, and this effect may be important in clinical states of vitamin A excess.

Actions of vitamins A and E and some nicotinic acid derivatives on plasma lipids and on lipid infiltration of aorta in cholesterol-fed rabbits

Marked hypercholesterolemia and moderate lipid infiltration of the aorta were induced by feeding rabbits a diet containing 1% cholesterol + 3% corn oil for 70 days. In the liver the concentration and pool size of cholesterol increased and those of triglycerides (TG) decreased. On dietary addition of vitamin A and vitamin E (44 000 I.U. and 125 mg respectively, once daily for 5 days a week) the following changes were noted in comparison with the fat-fed rabbits not receiving extra addition of vitamins. There was a slight decrease of the levels of plasma cholesterol and an increase of those of plasma TG. The liver cholesterol concentration increased but, according to the concomitant reduction of the liver weight, there was no significant change in lever cholesterol or TG pools. In the aorta the vitamins markedly reduced the lipid infiltrated area as well as the cholesterol content. Both niceritrol** and S-2040 [pyridine-2,5-dicarboxylic acid di(beta-pyridylcarbinol ester)] in a dietary concentration of 0.5% decreased plasma cholesterol by about 20%. This reduction, as well as that induced by the vitamins, was confined to the VLDL-fractions only. S-2040 slightly reduced the cholesterol accumulation in the aorta. In rabbits given both the vitamins and niceritrol or S-2042 there was an additive reduction of plasma cholesterol. Here the nicotinic acid derivatives were partly able to counteract the increases of plasma TG induced by the vitamins. In the aorta the combination vitamins + S-2042 but not that of vitamins + niceritrol tended to give a better protection than the vitamins alone. On a normal diet vitamins A + E significantly increased the liver cholesterol concentration and pool and decreased the liver TG pool, but did not affect the other parameters. Possible mechanisms for the prophylactic action of the vitamins against lipid infiltration of the aorta of cholesterol-fed rabbits are discussed.

Diphenylhydantoin: effects on calcium metabolism in the chick

Rickets, hypocalcemia, decreased duodenal calcium transport, and reduction of calcium binding protein have been produced in chicks treated with diphenylhydantoin. These effects are directly related to diphenylhydantoin dose and inversely related to the intake of vitamin D(3) (cholecalciferol).

Environmental effects on the autoxidation of retinol

1. The behaviour of retinol in aqueous colloidal dispersions has been studied because, if membranes are a physiological site of action of vitamin A, the reactions of colloidal retinol may be relevant to the functions of the vitamin in vivo. 2. Dispersions of retinol in NaCl exhibit characteristic spectral changes, and they consume O(2), within minutes of preparation. 3. The maximum rate of O(2) uptake is approximately linearly dependent on the concentration of O(2). 4. At limiting concentrations of O(2), the spectral changes are accelerated by catalase, indicating that H(2)O(2) is one of the reaction products. 5. The autoxidation, which is relatively unaffected by light, has the characteristics of a radical-catalysed reaction. O(2) uptake is preceded by an exceptionally short induction period; the reaction is catalysed by Fe(2+) ions and is inhibited by diphenylpicrylhydrazyl. 6. The maximum rate of autoxidation, which is less in water or sucrose solution than in saline, depends on the degree of aggregation of retinol molecules induced by cations. 7. In the absence of O(2), the cation-induced aggregates exhibit a spectral red-shift, which difference-spectra indicate is caused by formation of a species with lambda(max.) 370-380nm. 8. This species, from which retinol can be quantitatively recovered, is apparently the oxygen-sensitive form of retinol that initiates the rapid autoxidation. 9. The possible biological significance of the production of a highly reactive form of retinol in micellar aggregates is discussed.