Rat Model Of Vitamin Research Articles

Liprotide-encapsulated vitamin D3 modulates circulated PTH levels and improved bone microstructure

Background: vitamin D (25(OH)D) is a fat-soluble vitamin that is unstable in the gastrointestinal environment and has low bioavailability. A protein-lipid complex (liprotide) can be used as a shell to increase vitamin D stability and bioavailability. Liprotide can also serve as a delivery system for transporting vitamin D to its intended site. Little attention has been paid to utilizing liprotide as a delivery system for vitamin D and evaluating its functional activity.Objective: to investigate the effect of liprotide-encapsulated vitamin D3 on PTH levels and bone microstructure in vitamin D and calcium (VD-Ca) deficient rats.Materials and Methods: an overall of 24 Wistar rats had been divided into four groups, a normal control group (K), a VD-Ca group without treatment (K-), a VD-Ca group with 180 IU/200 gBW/day free vitamin D3 (FVD3), and a VD-Ca group with 180 IU/200 gBW/day liprotide-encapsulated vitamin D3 (LVD3). Before and after 28 days of vitamin D intervention, blood samples were taken and analysed for serum PTH levels. The microstructure of the bone was analyzed using the Scanning Electron Microscope (SEM).Results: the VD-Ca rats supplemented with vitamin D3 (FVD3 and LVD3) had a significant decrease in serum PTH levels (p<0.001) and improved bone microstructure (p<0.05) compared to the (K-) group. The reduction of PTH in the LVD3 group was higher compared to the FVD3 group. The bone microstructure between the FVD3 and LVD3 groups is significantly different, as seen in the Ct.Wi parameter, with the LVD3 group having a higher Ct.Wi than the FVD3 group.Conclusion: liprotide-encapsulated vitamin D3 improves the serum PTH level and bone microstructure in a rat model of vitamin D and calcium deficiency.

AORTIC REACTIVITY IN VITAMIN D DEFICIENCY IN A RAT MODEL OF POLYCYSTIC OVARY SYNDROME

Objective: Polycystic ovary syndrome (PCOS) and vitamin D deficiency are associated with elevated cardiovascular risk, whereas vitamin D deficiency is a common comorbidity in PCOS that may contribute to the pathogenesis and complications of the disease. Our aim was to investigate the role of vitamin D status on the aortic function of hyperandrogenic female rats showing the symptoms of PCOS. Design and method: Female Wistar rats received an 8-week-long transdermal Androgel treatment to induce hyperandrogenism, another group remained untreated. Half of each group was fed with vitamin D reduced rat chow, while the other half received normal chow with further supplementation of vitamin D. Norepinephrine-induced contraction, acetylcholine, insulin, and estrogen-induced relaxation of thoracic aortae was examined by wire myography. Elastic fiber density was evaluated on resorcin-fuchsin stained tissue sections. Estrogen receptor alpha, endothelial nitric oxide synthase (eNOS), and cyclooxygenase 2 (COX-2) density and protein tyrosine nitration (NT) was measured by immunohistochemistry. Results: There was no difference in the norepinephrine-induced contraction of the aortas between experimental groups. Reduced acetylcholine-, insulin- and estrogen-evoked relaxation was observed in vitamin D deficient groups. A lower level of resorcin-fuchsin staining and elevated 3- nitrotyrosine immunostaining was observed in non-hyperandrogenic vitamin D deficient rats. eNOS staining intensity was reduced by vitamin D deficiency, while COX-2 density was increased by testosterone treatment. Estrogen receptor alpha density was increased by testosterone treatment but reduced by vitamin D deficiency. Conclusions: We demonstrated an early endothelial dysfunction in a rat model of vitamin D deficient polycystic ovary syndrome. Vitamin D supplementation could prevent vascular damage. On the other hand, vitamin D deficiency itself led to decreased endothelium-dependent relaxation and increased nitrative stress. Vitamin D deficiency also led to decreased estrogen receptor alpha and eNOS density independently from hyperandrogenism. Vitamin D deficiency found in approximately 80% of PCOS women may have a significant role in the development of vascular dysfunction and may contribute to their increased cardiovascular risk.

Vitamin D Supplementation Improves Uterine Receptivity in a Rat Model of Vitamin D Deficiency: A Possible Role of HOXA-10/FKBP52 Axis.

Synchronized uterine receptivity with the time of implantation is crucial for pregnancy continuity. Vitamin D (VD) deficiency has been linked to the failure of implantation. Therefore, we tested the link between the Homeobox transcription factor-10/immunophilin FK506-binding protein 52 (HOXA-10/FKBP52) axis and the uterine receptivity in VD-deficient rats. The effect of VD supplementation at different doses was also investigated. Forty-eight pregnant rats were divided into six groups (eight/group); normal control rats fed with standard chow (control), control rats supplemented with VD (equivalent dose of 400 IU/day) (control-D400). VD-deficient group (DEF) and the three VD deficiency groups with VD supplementation were equivalent to 400, 4,000, and 10,000 IU/day (DEF-D400, DEF-D4000, and DEF-D10000, respectively). The expression levels of HOXA-10/FKBP52, progesterone level, and histological evaluation of decidualization using osteopontin (OSN) and progesterone receptor (PGR) were estimated. An assessment of the uterine contractility was conducted for all rats. This study showed the downregulation of HOXA-10/FKBP52 together with increased amplitude and frequency of the uterine contractility in the DEF group compared to control. VD dose-dependent supplementation restored progesterone/receptor competency, upregulated the expressional response of HOXA-10 and its downstream FKBP52, and improved uterine receptivity and endometrial decidualization at the time of implantation that was documented by increased area% of OSN and the number of implantation beads.

Thyroid Function Changes in a Rat Model of Vitamin D Deficiency and Effect of Vitamin D and Metformin Treatment

Abstract Background: Previous studies showed controversies about the association of vitamin D deficiency and thyroid dysfunction and up to our knowledge there was no study that were con-ducted to study the effect of vitamin D deficiency on thyroid function. Metformin is an antidiabetic drug that is widely used and also there was contradictory data about its effect on thyroid function. Aim of Study: To identify whether vitamin D deficiency is considered a cause for hypothyroidism or not. Also, to investigate the effect of metformin treatment on thyroid function in a rat model of vitamin D deficiency. Material and Methods: 40 Adult male albino rats of local strains were divided randomly into 5 equal groups; control, control metformin treated (control + metformin), vitamin D deficient, vitamin D deficient metformin treated (vitamin D deficient + metformin) and vitamin D deficient vitamin D treated (vitamin D deficient + vitamin D). Results: Vitamin D deficiency model significantly in-creased final Body Mass Index (BMI), relative thyroid weight, serum Thyroid Stimulating Hormone (TSH), serum reverse triiodothyronine (rT3) and hepatic deiodinase 3 activity but significantly declined serum levels of each of triiodothyronine (T3), thyroxin (T4), 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)2D) when compared to control group. Metformin treatment of vitamin D deficient rats significantly reduced relative thyroid weight with a significant decreased in TSH level when compared with vitamin D deficient group. A significant negative correlation was reported between serum 25(OH)D and each of final BMI, serum TSH, relative thyroid weight, hepatic deiodinase activity and serum rT3 but it was positively correlated to serum level of both T3 and T4. Histopathology and histomorphometric studies of the thyroid gland in vitamin D deficient rats showed a large number of follicles with increased dimensions, the follicular colloid showed no vacuolation, the amount of colloid increased and the follicles were found to be lined by simple cuboidal epithelial cells with basal nuclei. Conclusion: As vitamin D deficiency decreased thyroid function through affecting hepatic deiodinase 3 activity and this change was deteriorated with vitamin D supplementation, thus, monitoring of vitamin D levels and its supplementation may play a role in management of hypothyroidism. Also, metformin exerted an anti-proliferative activity, improved thyroid structure and lowered TSH without affecting serum levels of T4 or T3, thus it could provide a rationale for an innovative therapy of thyroid proliferative diseases.

LncRNA-SULT1C2A regulates Foxo4 in congenital scoliosis by targeting rno-miR-466c-5p through PI3K-ATK signalling.

Congenital scoliosis (CS) is the result of anomalous vertebrae development, but the pathogenesis of CS remains unclear. Long non‐coding RNAs (lncRNAs) have been implicated in embryo development, but their role in CS remains unknown. In this study, we investigated the role and mechanisms of a specific lncRNA, SULT1C2A, in somitogenesis in a rat model of vitamin A deficiency (VAD)‐induced CS. Bioinformatics analysis and quantitative real‐time PCR (qRT‐PCR) indicated that SULT1C2A expression was down‐regulated in VAD group, accompanied by increased expression of rno‐miR‐466c‐5p but decreased expression of Foxo4 and somitogenesis‐related genes such as Pax1, Nkx3‐2 and Sox9 on gestational day (GD) 9. Luciferase reporter and small interfering RNA (siRNA) assays showed that SULT1C2A functioned as a competing endogenous RNA to inhibit rno‐miR‐466c‐5p expression by direct binding, and rno‐miR‐466c‐5p inhibited Foxo4 expression by binding to its 3′ untranslated region (UTR). The spatiotemporal expression of SULT1C2A, rno‐miR‐466c‐5p and Foxo4 axis was dynamically altered on GDs 3, 8, 11, 15 and 21 as detected by qRT‐PCR and northern blot analyses, with parallel changes in Protein kinase B (AKT) phosphorylation and PI3K expression. Taken together, our findings indicate that SULT1C2A enhanced Foxo4 expression by negatively modulating rno‐miR‐466c‐5p expression via the PI3K‐ATK signalling pathway in the rat model of VAD‐CS. Thus, SULT1C2A may be a potential target for treating CS.

Melatonin protected against the detrimental effects of microRNA‐363 in a rat model of vitamin A‐associated congenital spinal deformities: Involvement of Notch signaling

Congenital spinal deformities are a result of defective somitogenesis and are associated with vitamin A deficiency (VAD). However, the molecular mechanisms of VAD-associated congenital spinal deformities remain largely unknown. Increasing number of studies suggested that microRNAs and melatonin played important roles in the development of congenital spinal deformities. In this study, we showed that the whole-embryo expression of miR-363 was upregulated in VAD rats. Furthermore, we demonstrated that miR-363 inhibited the proliferation and neuronal differentiation of primary cultured NSCs, accompanied by downregulation of Notch1. To this end, melatonin suppressed miR-363 expression and rescued the effects of miR-363 on NSC proliferation and neuronal differentiation together with restoration of Notch signaling. The present study provided new insights into the mechanism of VAD-associated spinal deformities and the therapeutic effect of melatonin that may lead to novel understanding of the molecular mechanisms of congenital spinal deformities.

A novel rat model of vitamin D deficiency: safe and rapid induction of vitamin D and calcitriol deficiency without hyperparathyroidism.

Vitamin D deficiency is associated with a range of clinical disorders. To study the mechanisms involved and improve treatments, animal models are tremendously useful. Current vitamin D deficient rat models have important practical limitations, including time requirements when using, exclusively, a vitamin D deficient diet. More importantly, induction of hypovitaminosis D causes significant fluctuations in parathyroid hormone (PTH) and mineral levels, complicating the interpretation of study results. To overcome these shortcomings, we report the successful induction of vitamin D deficiency within three weeks, with stable serum PTH and minerals levels, in Wistar rats. We incorporated two additional manoeuvres compared to a conventional diet. Firstly, the vitamin D depleted diet is calcium (Ca) enriched, to attenuate the development of secondary hyperparathyroidism. Secondly, six intraperitoneal injections of paricalcitol during the first two weeks are given to induce the rapid degradation of circulating vitamin D metabolites. After three weeks, serum 25-hydroxyvitamin D3 (25D) and 1,25-dihydroxyvitamin D3 (1,25D) levels had dropped below detection limits, with unchanged serum PTH, Ca, and phosphate (P) levels. Therefore, this model provides a useful tool to examine the sole effect of hypovitaminosis D, in a wide range of research settings, without confounding changes in PTH, Ca, and P.

Vitamin E in Neural and Visual Function

A rat model of vitamin E (alpha-tocopherol) deficiency with similar "clinical," electrophysiological, and neuropathological abnormalities to those seen in man was used to investigate the effects of various amounts and forms of alpha-tocopheryl acetate (alphaTA) on neural and visual function. Electrophysiological techniques provide an objective, non-invasive measure of neural and visual function. These techniques were used in the animal model to determine the minimum dietary requirement of vitamin E necessary to prevent neural and visual abnormalities. They were also used to compare the biological activities of the natural (RRR-) and synthetic (all-rac-) forms of alpha-tocopherol in neural tissues. The results were as follows: (1) Significant differences in neural and visual function were observed between deficient and control rats after approximately 8 months. (2) An intake of 1.0 mg/kg all-rac- or 0.75 mg/kg RRR-alphaTA was observed to marginally protect nerves from vitamin E deficiency. (3) The biological activity of all-rac-alpha-tocopherol in neural tissues was approximately 75% of RRR-alpha-tocopherol. (4) The concentration of free malondialdehyde (an indicator of lipid peroxidation) was significantly increased in tissues from the deficient compared to the control animals. These results are consistent with a deficiency of alpha-tocopherol causing increased lipid peroxidation leading to abnormal neural electrophysiology. They could also be explained by more specific but as yet undefined function(s) of alpha-tocopherol in neural tissues.

Influence of sex and estrogen on vitamin D‐induced arterial calcification in rats

Background: It is known that the process of arteriosclerosis is affected by sex and estrogen. The present study was thus undertaken to examine the effects of these factors on arterial calcification, a form of arteriosclerosis, using a rat model of vitamin D toxicity.Methods and results: Vehicle or 5 µg/kg per day 1α(OH)D3 was given to male and female 30‐week‐old Fisher rats for 2 weeks. Arterial calcification, evaluated by calcium content in the aorta, was 70% more marked in male rats compared to that in female rats, whereas calcium content in the aorta was similar in vehicle‐treated male and female rats. Next, the effects of ovariectomy and estrogen replacement (estradiol dipropionate 20 µg/kg per week) were examined in female rats given 5 µg/kg per day 1α(OH)D3 for 2 weeks. Calcium content in the aorta was significantly higher in ovariectomized rats than in sham‐operated rats and in ovariectomized and estrogen‐replaced rats. No difference between the groups was seen when vehicle was given to the animals.Conclusions: These results suggest that sex and estrogen can modify the process of arterial calcification. The mechanisms remain to be determined, although the effects were independent of serum calcium level.

The effects of different levels of all-rac- and RRR-alpha-tocopheryl acetate (vitamin E) on visual function in rats.

A rat model of vitamin E (alpha-tocopherol) deficiency with similar "clinical", electrophysiological and neuropathological abnormalities to that seen in man was used to investigate the effects of various dietary intakes of synthetic (all-rac-) and natural (RRR-) alpha-tocopheryl acetate (alphaTA) on visual function. Longitudinal measurements of the electroretinogram (ERG) and visual evoked potentials (VEPs) were made monthly for 14 months in 9 groups of rats (n=12/group) receiving different amounts and types of alphaTA. The animals were then killed for biochemical analyses. (1) The first significant abnormalities of both the ERG and VEP were found after 8 months of deficiency. (2) A diet containing 1.25 mg/kg of alphaTA provided marginal protection. (3) The biological activity of all-rac- was approximately 75% of RRR-alphaTA. (4) The concentration of free malondialdehyde (a measure of lipid peroxidation) was significantly increased in all tissues, including the eye, from deficient compared to control rats. These results are consistent with alpha-tocopherol deficiency causing increased lipid peroxidation leading to abnormal visual function but could also be explained by more specific but undefined function(s) of alpha-tocopherol in the eye.

Neurological Disease

From theoretical considerations, the nervous system is likely to be particularly vulnerable to oxidative stress. The brain contains high concentrations of polyunsaturated fatty acids that are susceptible to lipid peroxidation, receives a disproportionately large percentage of oxygen, is relatively deficient in antioxidant systems, and contains specific regions that have high concentrations of iron. The retina is also served with a plentiful supply of oxygen, has an abundant supply of mitochondria, and has an unusually high rate of oxidative metabolism. The retinal rod outer segments are particularly vulnerable to lipid peroxidation as more than 65 % of the membrane fatty acids are polyunsaturated, which is the highest proportion found in any vertebrate tissue examined to date. The retina is also frequently exposed to intense light, which can be phototoxic. There are essentially two situations where oxidative stress may be involved in neural and retinal dysfunction: where there is a deficiency of an antioxidant and where antioxidant protection is compromised by increased oxidative stress. In both of these situations treatment with added antioxidants may be beneficial. These two aspects are considered in turn in this chapter. The chapter discusses antioxidant deficiency, decreased serum concentrations of vitamin E in the newborn and oxidative stress, intraventriculor hemorrhage (IVH), and retinopathy of prematurity (ROP). There are notes on the chronic fat malabsorptive states such as abetalipoproteinemia, retinal involvement in fat malabsorptive states, familial isolated vitamin E deficiency, and neuropathology associated with vitamin E deficiency. Observations from the functional and biochemical studies in a rat model of vitamin E deficiency are given. Oxygen-derived free radicals have been implicated in the pathogenesis of a number of neurological conditions discussed—Parkinson's disease, Tardive dyskinesia, Down syndrome, Alzheimer's disease,Motor Neuron disease, Ischemia/Reperfusion and trauma. There is mention of Neuronal ceroid lipofuscinoses (NCL) or Batten's disease.

Normal plasma calcium, phosphate, and parathyroid hormone levels during 1,25(OH)2D3 infusions in rats

The changes in plasma calcium, phosphate, and parathyroid hormone (PTH) levels that accompany 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] administration to experimental animals represent major obstacles to determining the precise role that 1,25(OH)2D3 plays in cell function in vivo. These difficulties arise because calcium, phosphate, and PTH have major cellular effects independent of 1,25(OH)2D3. To circumvent this obstacle, we have developed an animal model in which plasma 1,25(OH)2D3 levels were raised from 20 +/- 3 to 96 +/- 19, 240 +/- 49, and 459 +/- 66 pg/ml in vitamin D-deficient rats without influencing plasma ionized calcium, total calcium, phosphate, or NH2-terminal immunoreactive PTH (irPTH) levels. The elevated 1,25(OH)2D3 levels were achieved by constant subcutaneous infusion of 1,25(OH)2D3 using osmotic minipumps. Progressive reduction in the calcium and phosphorus content of the diet as the 1,25(OH)2D3 infusion rate was increased prevented concomitant changes in plasma calcium, phosphate, and irPTH levels. This experimental model, in conjunction with our previously developed normocalcemic rat model of vitamin D deficiency, provides a powerful experimental tool for the investigation of 1,25(OH)2D3 effects in vivo in the absence of concomitant changes in other parameters of calcium homeostasis.