Interrelations between Iron and Vitamin A-Studied Using Systems Approach.

A deficiency of vitamin A (VAD) and iron is the most common nutritional problem affecting people worldwide. Given the scale of the problem, the interactions between vitamin A and iron levels are widely studied. However, the exact mechanism of the impact of vitamin A on the regulation of iron metabolism remains unclear. An extremely significant issue becomes a better understanding of the nature of the studied biological phenomenon, which is possible by using a systems approach through developing and analyzing a mathematical model based on a Petri net. To study the considered system, the t-cluster analysis, the significance analysis, and the analysis of the average number of transition firings were performed. The used analyses have allowed distinguishing the most important mechanisms (both subprocesses and elementary processes) positively and negatively regulating an expression of hepcidin and allowed to distinguish elementary processes with a higher frequency of occurrence compared to others. The analysis also allowed to resolve doubts about the discrepancy in literature reports, where VAD leads to positive regulation of hepcidin expression or to negative regulation of hepcidin expression. The more detailed analyses have shown that VAD more frequently positively stimulates hepcidin expression and this mechanism is more significant than the mechanism inhibiting hepcidin expression indirectly by VAD.

Fenretinide inhibits vitamin A formation from ß-carotene and regulates carotenoid levels in mice.

N-[4-hydroxyphenyl]retinamide, commonly known as fenretinide, a synthetic retinoid with pleiotropic benefits for human health, is currently utilized in clinical trials for cancer, cystic fibrosis, and COVID-19. However, fenretinide reduces plasma vitamin A levels by interacting with retinol-binding protein 4 (RBP4), which often results in reversible night blindness in patients. Cell culture and in vitro studies show that fenretinide binds and inhibits the activity of ß-carotene oxygenase 1 (BCO1), the enzyme responsible for endogenous vitamin A formation. Whether fenretinide inhibits vitamin A synthesis in mammals, however, remains unknown. The goal of this study was to determine if the inhibition of BCO1 by fenretinide affects vitamin A formation in mice fed ß-carotene. Our results show that wild-type mice treated with fenretinide for ten days had a reduction in tissue vitamin A stores accompanied by a two-fold increase in ß-carotene in plasma (P < 0.01) and several tissues. These effects persisted in RBP4-deficient mice and were independent of changes in intestinal ß-carotene absorption, suggesting that fenretinide inhibits vitamin A synthesis in mice. Using Bco1-/- and Bco2-/- mice we also show that fenretinide regulates intestinal carotenoid and vitamin E uptake by activating vitamin A signaling during short-term vitamin A deficiency. This study provides a deeper understanding of the impact of fenretinide on vitamin A, carotenoid, and vitamin E homeostasis, which is crucial for the pharmacological utilization of this retinoid.

Vitamin A deficiency in K14E7HPV expressing transgenic mice facilitates the formation of malignant cervical lesions.

Infection with high-risk human papillomavirus (HR-HPV) is the main cause of cervical cancer (CC), but viral infection alone does not guarantee the development of this malignancy. Indeed, deficiencies of dietary micronutrients could favor cervical cancer development in individuals that harbor HR-HPV infections. The status of retinoid levels, natural and synthetic derivatives of vitamin A, is important in maintaining cellular differentiation of the cervical epithelium. Moreover, many studies show a link between deficient intake of retinoids or alteration of the retinoid receptors and CC development. In spite of this, the effect of vitamin A deficiency (VAD) in presence of HR-HPV oncoproteins on cervical carcinogenesis in vivo has not been reported. Transgenic mice expressing E6 or E7 oncoproteins (K14E6 or K14E7 mice, respectively) were used to evaluate the possible role of VAD in the development of malignant cervical lesions. The survival of the mice in VAD condition was studied, and histopathological analysis and immunohistochemical detection of molecular cancer markers such as the tumor suppressor retinoic acid receptor beta (RARß), proliferating cell nuclear antigen (PCNA), cleaved caspase 3, and the tumor suppressor protein p16INK4A (inhibitor of CDK4) were performed. Our results show that K14E6/VAD mice showed moderate cervical dysplasia; notably, K14E7/VAD mice developed severe cervical dysplasia and cervical in situ carcinoma at an early age. VAD synergizes with HPV16E7 oncoprotein expression favoring cervical carcinogenesis in vivo.

Vitamin A bio-modulates apoptosis via the mitochondrial pathway after hypoxic-ischemic brain damage.

Our previous studies demonstrated that vitamin A deficiency (VAD) can impair the postnatal cognitive function of rats by damaging the hippocampus. The present study examined the effects of retinoic acid (RA) on apoptosis induced by hypoxic-ischemic damage in vivo and in vitro, and investigated the possible signaling pathway involved in the neuroprotective anti-apoptotic effects of RA. Flow cytometry, immunofluorescence staining and behavioral tests were used to evaluate the neuroprotective and anti-apoptotic effects of RA. The protein and mRNA levels of RARα, PI3K, Akt, Bad, caspase-3, caspase-8, Bcl-2, Bax, and Bid were measured with western blotting and real-time PCR, respectively. We found impairments in learning and spatial memory in VAD group compared with vitamin A normal (VAN) and vitamin A supplemented (VAS) group. Additionally, we showed that hippocampal apoptosis was weaker in the VAN group than that in VAD group. Relative to the VAD group, the VAN group also had increased mRNA and protein levels of RARα and PI3K, and upregulated phosphorylated Akt/Bad levels in vivo. In vitro, excessively low or high RA signaling promoted apoptosis. Furthermore, the effects on apoptosis involved the mitochondrial membrane potential (MMP). These data support the idea that sustained VAD following hypoxic-ischemic brain damage (HIBD) inhibits RARα, which downregulates the PI3K/Akt/Bad and Bcl-2/Bax pathways and upregulates the caspase-8/Bid pathway to influence the MMP, ultimately producing deficits in learning and spatial memory in adolescence. This suggests that clinical interventions for HIBD should include suitable doses of VA.

Roux-en-Y Gastric Bypass Aggravates Vitamin A Deficiency in the Mother-Child Group.

OBJECTIVE: The objectives of this study are to compare the nutritional status of vitamin A in women who previously underwent Roux-en-Y gastric bypass (RYGB) who became pregnant or did not, in the same period after surgery, and to assess its effects on mother and child health. METHODOLOGY: A retrospective longitudinal study conducted with women who previously underwent RYGB, paired by age and BMI measured before surgery, divided into group 1 (G1) comprising 77 women who did not become pregnant and group 2 (G2) with 39 women in their third gestational trimester. Both groups were assessed before surgery (T0) and in the same interval after surgery: less than or equal to 1 year (T1) or over 1 year (T2), during a maximum of 2 years. Serum concentrations of retinol and ß-carotene, night blindness (NB), and gestational and neonatal complications were investigated [urinary tract infection, iron deficiency anemia, hypertensive syndrome of pregnancy, dumping syndrome, birth weight, gestational age at birth (GAB), and correlation between weight and GAB]. Data were analyzed by the Statistical Package for Social Sciences 21.0 (p < 0.05). RESULTS: RYGB reduced the serum levels of retinol and ß-carotene, especially before the first postsurgical year. When associated with pregnancy, inadequacy rate was 55% higher in T1 and T2. Comparing G1 to G2, we noted that pregnancy in women undergoing RYGB can contribute to increased inadequacy of retinol and ß-carotene, reaching a higher percentage of women with NB after 1 postsurgical year. High prevalence of pregnancy/neonatal complications was found in T1 and T2. NB was correlated with inadequacy of ß-carotene. CONCLUSION: Pregnancy after RYGB aggravates vitamin A deficiency, increases the percentage of NB cases, and can contribute to pregnancy and neonatal complications even in 1 postsurgical year.

All-trans retinoic acid ameliorates hepatic stellate cell activation via suppression of thioredoxin interacting protein expression.

Activation of hepatic stellate cells (HSCs) is the effector factor of hepatic fibrosis and hepatocellular carcinoma (HCC) development. Accumulating evidence suggests that retinoic acids (RAs), derivatives of vitamin A, contribute to prevention of liver fibrosis and carcinogenesis, however, regulatory mechanisms of RAs still remain exclusive. To elucidate RA signaling pathway, we previously performed a genome-wide screening of RA-responsive genes by in silico analysis of RA-response elements, and identified 26 RA-responsive genes. We found that thioredoxin interacting protein (TXNIP), which inhibits antioxidant activity of thioredoxin (TRX), was downregulated by all-trans retinoic acid (ATRA). In the present study, we demonstrate that ATRA ameliorates activation of HSCs through TXNIP suppression. HSC activation was attenuated by TXNIP downregulation, whereas potentiated by TXNIP upregulation, indicating that TXNIP plays a crucial role in activation of HSCs. Notably, we showed that TXNIP-mediated HSC activation was suppressed by antioxidant N-acetylcysteine. In addition, ATRA treatment or downregulation of TXNIP clearly declined oxidative stress levels in activated HSCs. These data suggest that ATRA plays a key role in inhibition of HSC activation via suppressing TXNIP expression, which reduces oxidative stress levels.

Retinoic-acid-mediated HRas stabilization induces neuronal differentiation of neural stem cells during brain development.

Ras signaling is tightly regulated during neural stem cell (NSC) differentiation, and defects in this pathway result in aberrant brain development. However, the mechanism regulating Ras signaling during NSC differentiation was unknown. Here, we show that stabilized HRas specifically induces neuronal differentiation of NSCs. Lentivirus-mediated HRas overexpression and knockdown resulted in stimulation and inhibition, respectively, of NSC differentiation into neuron in the ex vivo embryo. Retinoic acid, an active metabolite of vitamin A, promoted neuronal differentiation of NSCs by stabilizing HRas, and HRas knockdown blocked the retinoic acid effect. Vitamin-A-deficient mice displayed abnormal brain development with reduced HRas levels and a reduced thickness of the postmitotic region containing differentiated neurons. All of these abnormal phenotypes were rescued with the restoration of HRas protein levels achieved upon feeding with a retinoic-acid-supplemented diet. In summary, this study shows that retinoic acid stabilizes HRas protein during neurogenesis, and that this is required for NSC differentiation into neurons and murine brain development.

Optical Coherence Tomography Assessment Before and After Vitamin Supplementation in a Patient With Vitamin A Deficiency: A Case Report and Literature Review.

Vitamin A is an essential fat-soluble vitamin important for the function of various body systems. In the eye, vitamin A is essential for the synthesis of visual pigments in photoreceptors. Vitamin A deficiency is a rare condition in the developed countries and might follow bariatric or intestinal bypass surgery.We present the case of a 67-year-old male that complained of visual loss and nyctalopia. Patient had bariatric surgery 15 years before for weight loss. Low serum levels of vitamin A confirmed the diagnosis and patient started vitamin A supplementation. Visual fields, macular thickness, and ganglion cell layer thickness were recorded and monitored 1 month, 6 months, and 1 year after the beginning of therapy. Visual fields were significantly altered and central macular thickness and ganglion cell layer thickness were reduced, but the first 2 showed a significant recovery with vitamin supplementation therapy. By the 1st month of treatment patient referred a complete remission of visual symptoms. Further, we observed hyperreflective material accumulating beneath a partially disrupted ellipsoid band in the high definition optical coherence tomography that also improved progressively with vitamin repletion.Newer and more sophisticated imaging systems have increased our knowledge of the mechanisms responsible for retinal diseases. To our knowledge, this is the first description of the effect of vitamin A deficiency and vitamin supplementation on macular thickness. This case also highlights the importance of considering bariatric bypass surgery as a cause of vitamin A deficiency in developed countries.

Pathologic changes associated with suspected hypovitaminosis A in amphibians under managed care.

Vitamin A deficiency is a recently recognized nutritional disease in amphibians fed insect-based diets. The classic pathologic lesion that has been associated with hypovitaminosis A in amphibians is squamous metaplasia of the lingual and oral mucosa. In an attempt to further characterize the range of lesions that may be associated with vitamin A deficiency, we reviewed archived amphibian necropsy reports from three facilities. As previously reported, the tongue was the most commonly affected site in animals presenting with squamous metaplasia. However, metaplastic changes were also observed in a variety of locations that included the oral cavity, nasal cavity, pharynx, esophagus, stomach, cloaca, skin, urinary bladder, ureter, and reproductive tract. In addition, species and age-specific differences were noted in the development of squamous metaplasia. This review highlights the need to establish standardized guidelines for optimal postmortem tissue sampling of amphibians in order to maximize the accurate diagnosis of pathologic lesions that may be associated with hypovitaminosis A. Zoo Biol. 33:508-515, 2014. © 2014 Wiley Periodicals Inc.

Similar appearance, different mechanisms: xerosis in HIV, atopic dermatitis and ageing.

Xerosis is one of the most common dermatologic disorders occurring in the elderly and in patients with atopic dermatitis (AD) and human immunodeficiency virus (HIV) infection. Xerosis has been linked to an impaired skin barrier function of the stratum corneum. Using Raman microspectroscopy, we concentrated on deeper skin layers, viable epidermis and dermis of 47 volunteers and associated molecular alterations to the evolution of xerosis and the skin barrier, for example, lipid, water and antioxidant content. A decrease in lipids within the viable epidermis is found for elderly and HIV-patients. Lipid and water values of AD patients and their healthy reference group are similar. Decreases in lipids and simultaneous increases in water are found in the dermis for HIV and AD patients in comparison to their healthy reference groups. Excessive levels of epidermal carotenoids, mainly lycopene, in HIV-patients were found potentially leading to adverse effects such as premature skin ageing.

Vitamin A deprivation affects the progression of the spermatogenic wave and initial formation of the blood-testis barrier, resulting in irreversible testicular degeneration in mice.

The blood testis-barrier (BTB) is essential for maintaining homeostasis in the seminiferous epithelium. Although many studies have reported that vitamin A (VA) is required for the maintenance of spermatogenesis, the relationships between the BTB, spermatogenesis and VA have not been elucidated. In this study, we analyzed BTB assembly and spermatogenesis in the testes of mice fed the VA-deficient (VAD) diet from the prepubertal period to adulthood. During the prepubertal period, no changes were observed in the initiation and progression of the first spermatogenic wave in mice fed the VAD diet. However, the numbers of preleptotene/leptotene spermatocytes derived from the second spermatogenic wave onwards were decreased, and initial BTB formation was also delayed, as evidenced by the decreased expression of mRNAs encoding BTB components and VA signaling molecules. From 60 days postpartum, mice fed the VAD diet exhibited apoptosis of germ cells, arrest of meiosis, disruption of the BTB, and dramatically decreased testis size. Furthermore, vacuolization and calcification were observed in the seminiferous epithelium of adult mice fed the VAD diet. Re-initiation of spermatogenesis by VA replenishment in adult mice fed the VAD diet rescued BTB assembly after when the second spermatogenic wave initiated from the arrested spermatogonia reached the preleptotene/leptotene spermatocytes. These results suggested that BTB integrity was regulated by VA metabolism with meiotic progression and that the impermeable BTB was required for persistent spermatogenesis rather than meiotic initiation. In conclusion, consumption of the VAD diet led to critical defects in spermatogenesis progression and altered the dynamics of BTB assembly.

Needle biopsy for hepatic vitamin A levels in lions (Panthera leo).

Hypovitaminosis A (HA)-related skull malformations resulting in neurologic abnormalities and death have been, and still are, reported in captive lions (Panthera leo) worldwide. Liver vitamin A (VA) concentration is the most reliable indicator of animals' VA status, and its assessment is essential in prevention and treatment of HA in lions. A percutaneous needle liver biopsy using high-performance liquid chromatography ultraviolet retinoid analysis for VA concentration measurement was validated. It was first assessed in vitro using chicken liver. Later, the safety and feasibility of ultrasound-guided percutaneous needle liver biopsy was assessed in living lions. Hepatic VA concentrations in lion liver were measured using the above laboratory method. Mean chicken hepatic VA concentration in needle biopsy (NB) and wedge biopsy (WB) of the same liver lobes were 108.66 and 60.89 microg/g wet tissue, respectively, and were significantly (P = 0.03) correlated (r = 0.74). The calculated linear regression for predicting VA concentration in WB using NB VA for chicken liver was 25.194 + 0.3234x NB (microg/g). Four ultrasound-guided percutaneous needle liver biopsies were obtained from each of the four lions under general anesthesia. Mean hepatic VA concentration was 8.25 microg/g wet tissue (range 1.43-25.29 microg/g). Mean serum VA concentration, measured in these four lions was 1,011.1 nmol/L with a standard deviation of 337.91 nmol/L (range 590.26-1,077.2 nmol/L). The lions recovered uneventfully, and no complications were observed during a 4-yr follow-up period. In conclusion, the percutaneous needle liver biopsy technique is a reliable, practical, safe tool for obtaining liver tissue samples antemortem for assessment of the VA status in lions and can be used in future studies.

Vitamin A deficiency induces fluid hyposecretion from the airway submucosal glands of mice.

Vitamin A deficiency (VAD) alters the phenotype of airway epithelium and attenuates the epithelial defense system, and many studies have reported the association of VAD with respiratory disease. In this study, we investigated changes in submucosal glands (SMG) in a mouse model of VAD. C57BL/6 mice were fed a vitamin A-devoid diet and the others were fed a control diet (1.2 mg retinol/kg). The areas of serous and mucous cells of SMG were measured in 4-, 8-, and 20-wk-old male mice. The volume and lysozyme concentration of glandular secretions were also measured. The 2 groups did not differ in body weight or general morbidity at 3-10 wk of age, although serum retinol concentrations were greater in the control mice than in the VAD mice after 4 wk. Upon histological evaluation, we found that the areal ratio of serous cells:total SMG cells was significantly lower after 8 wk in the VAD mice compared with the control mice, although the total area of SMG did not differ between groups throughout the 20-wk experiment. The number of secretory bubbles did not differ between the groups, but total secretion volume was reduced by 35% in 8-wk-old VAD mice compared with controls. Furthermore, the concentration of lysozyme in secretions from 8-wk-old VAD mice was also less than in controls, compounding the effect of diminished secretion volume. In this study, we found serous cell hypotrophy/hypoplasia and dysfunction in VAD mice, which may contribute to the susceptibility to airway infection linked to VAD.

Implication of vitamin A deficiency on vascular injury related to inflammation and oxidative stress. Effects on the ultrastructure of rat aorta.

BACKGROUND: Vitamin A deficiency induces activation of NF-kB and impairs activities of antioxidant enzymes in aorta. AIM OF THE STUDY: We study the effect of vitamin A deficiency on the aorta histoarchitecture and the possibly contribution of its prooxidant and inflammatory effects to artery alterations. METHODS: Twenty-one-day-old Wistar male rats were fed during 3 months with vitamin A-deficient diet (-A, n = 8) or the same diet containing 8 mg of retinol palmitate/kg of diet (+A, control, n = 8). In aortas, thiobarbituric reactive substances and reduced glutathione levels were measured by spectrophotometry. Expressions of TNF-alpha, NOX-2, VCAM-1, and TGF-beta1 were assessed by RT-PCR and Western Blot. The morphology of aorta was examined by light and transmission electron microscopy. RESULTS: In -A rats, high levels of TBARS in serum and aorta and low levels of GSH in aorta were found. An increased expression of TNF-alpha, NOX-2, VCAM-1, and TGF-beta1 in aorta from -A rats was observed. Examination of the intimal layer by light microscopy indicated the presence of an irregular surface in -A aortas. TEM studies showed large vacuoles and multivesicular bodies along the endothelium and also multivesicular bodies in the subendothelial space of aortas from -A rats. Furthermore, the histological appearance of internal elastic lamina was different from control. Small vesicles in the medial layer were observed in aortas from vitamin A-deficient rats. CONCLUSIONS: Vitamin A deficiency produces histoarchitectural alterations in aorta, which can be associated, at least in part, to the oxidative stress and inflammation induced by vitamin A deficiency.

Deficiency of vitamin A delays bone healing process in association with reduced BMP2 expression after drill-hole injury in mice.

Although it is predicted that vitamin A and its active form, retinoic acid, regulate osteoblast lineage, this has not been elucidated in growing mammalians. To clarify the direct effect of retinoic acid on bone, we observed the process of filling up newly generating bone into a drill-hole of the bone, which is understood as membranous ossification, in vitamin A-deficient mice. Mice were assigned to three groups: a vitamin A-deficient group (VAD), which was fed a diet without vitamin A from the 10th day of gestation to the end of the experiments; a vitamin A-deficient-sufficient group (VADS), which was fed a diet without vitamin A from the 10th day of gestation to 4 weeks of age; and a vitamin A-sufficient group (VAS), which was fed a standard diet to the end of the experiment. In mice at 10 weeks of age (day 0), a drill-hole injury was made with a diameter of 1mm at the anterior portion of the diaphysis of the bilateral femurs. In VAD, retardation in repairing the drill-hole was demonstrated by in vivo micro-CT and histomorphometry from day 7 and after surgery. During repair of the bone defect, increases of bmp2, dlx5, msx2, col1a1, and osteocalcin mRNA expression were suppressed, and runx2-p2 mRNA expression was accelerated in VAD. Implantation of BMP2 in the bone defect of VAD normalized the delayed bone healing and mRNA expressions. We concluded that vitamin A regulates bmp2 mRNA expression and plays a crucial role in osteoblastogenesis and bone formation.

Vitamin A deficiency associated with enhanced proliferation of bile duct epithelial cells in the rat.

BACKGROUND: Vitamin A and its derivative retinoic acid regulate various aspects of cell behavior as growth, differentiation, and proliferation. Retinoic acid derivative have been suggested to play a role in processes such as hepatic regeneration and fibrosis. OBJECTIVES: To evaluate the influence of vitamin A on rat liver epithelial cell proliferation. METHODS: We performed common bile duct ligation in rats that had been subjected to differing vitamin A diets and compared their livers to control rats. Proliferation, apoptosis, and retinoic acid receptors were evaluated by histology and immunohistochemistry in bile duct cells and hepatocytes. RESULTS: Vitamin A deficiency was found to be associated with enhanced proliferation of bile duct epithelial cells following CBD ligation. The proliferation was manifested by increased numbers of ducts, by aberrant extended ductal morphology, and by elevated numbers of nuclei expressing the proliferation marker Ki67. The amount of vitamin A in the rat diet did not affect detectably ductal cell apoptosis. We observed up-regulated expression of the retinoid X receptor-alpha in the biliary epithelium of vitamin A-deficient rats that had undergone CBD ligation, but not in vitamin A-sufficient rats. CONCLUSIONS: We speculate that the mechanism underlying the ductal proliferation response involves differential expression of RXR-alpha. Our observations suggest that deficiency of vitamin A may exacerbate cholestasis, due to excessive intrahepatic bile duct proliferation.

Vitamin A deficiency alters rat lung alveolar basement membrane: reversibility by retinoic acid.

Vitamin A is essential for lung development and pulmonary cell differentiation and its deficiency results in alterations of lung structure and function. Basement membranes (BMs) are also involved in those processes, and retinoic acid, the main biologically active form of vitamin A, influences the expression of extracellular matrix macromolecules. Therefore, we have analyzed the ultrastructure and collagen content of lung alveolar BM in growing rats deficient in vitamin A and the recovering effect of all-trans retinoic acid. Male weanling pups were fed a retinol-adequate or -deficient diet until they were 60 days old. A group of vitamin A-deficient pups were recovered by daily intraperitoneal injections of all-trans retinoic acid for 10 days. Alveolar BM in vitamin A-deficient rats doubled its thickness and contained irregularly scattered collagen fibrils. Immunocytochemistry revealed that these fibrils were composed of collagen I. Total content of both collagen I protein and its mRNA was greater in vitamin-deficient lungs. In agreement with the greater size of the BM the amount of collagen IV was also increased. Proinflammatory cytokines, IL-1alpha, IL-1beta and TNF-alpha, did not change, but myeloperoxidase and TGF-beta1 were increased. Treatment of vitamin A-deficient rats with retinoic acid reversed all the alterations, but the BM thickness recovered only partially. Retinoic acid recovering activity occurred in the presence of increasing oxidative stress. In conclusion, vitamin A deficiency results in alterations of the structure and composition of the alveolar BM which are probably mediated by TGF-beta1 and reverted by retinoic acid. These alterations could contribute to the impairment of lung function and predispose to pulmonary disease.

Cystitis, pyelonephritis, and urolithiasis in rats accidentally fed a diet deficient in vitamin A.

Female Sprague-Dawley rats (n = 100; age, 3 wk) were fed diets that included a vitamin premix and either albumin or milk powder. Rats fed the albumin diet gained weight more slowly than did the other group. Between 19 and 28 wk of being fed the albumin diet, 12 rats died of bacterial cystitis and pyelonephritis. In addition, 2 more rats from the same dietary group developed peritonitis after ovariohysterectomy. Examination of the 44 rats fed the albumin diet that completed the 34-wk experiment revealed pyelonephritis in 68%, cystitis in 66%, urolithiasis in 27%, and nephrolithiasis in 5%. Squamous metaplasia of the transitional epithelium was present in all 44 rats, although other epithelia were histologically normal. Vitamin A deficiency was diagnosed after analyses of blood and liver samples. Analysis of the vitamin premix revealed approximately 25% of the expected amount of vitamin A. Because the milk powder contained sufficient vitamin A, deficiency did not occur in rats fed the milk powder diet. The major consequences of vitamin A deficiency in the rats were squamous metaplasia, bacterial infection, and calculus formation within the urinary tract. This report illustrates the importance of careful formulation and storage of vitamin premixes used in experimental diets. Vitamin A deficiency should be considered in rats with decreased weight gain and urinary tract disease even if ocular lesions are not present.

The effect of vitamin A deficiency in maternal rats on tumor formation in filial rats.

PURPOSE: We established a vitamin A-deficient (VAD) model of pregnant rats to evaluate the effect of vitamin A deficiency in maternal rats on tumor formation in filial rats. METHODS: Ten pregnant Wistar rats were divided into 2 groups: (1) VAD group, 6 rats were given nonvitamin A diet from 2 weeks before mating till delivery and (2) normal diet (ND) group, 4 rats were given normal diet. Twenty random neonatal rats from each group were killed on the next day of delivery. The rest neonates were given normal diet for 1 year until killed. Serum levels of vitamin A, morphology of the kidney, incidence of tumor formation, and retinoid X receptor (RXR) alpha messenger RNA (mRNA) expression in renal tissue were assessed for the filial rats. RESULTS: Fifty-six and 49 neonatal rats were born for VAD group and ND group, respectively. The detection rate of nephrogenic rests (NRs) from neonates in VAD group (50%) was significantly higher than that in ND group (20%; P < .05). The incidence of nephroblastoma was 13.9% in filial rats of VAD group and 0% for ND group. The detection rate of NRs for filial rats of VAD group (30.6%) was significantly higher than that of ND group (6.9%; P < .01). The expression of RXRalpha mRNA in tumor tissue of the filial rats of VAD group (3.17 +/- 0.15) was significantly lower than that in kidney tissue of ND group (3.58 +/- 0.20; P < .01). CONCLUSION: Deficiency in vitamin A for pregnant rats resulted in renal dysplasia, increased NRs, and higher incidence of nephroblastoma.