Developmentally vitamin D-deficient rats show enhanced prepulse inhibition after acute δ9-tetrahydrocannabinol

Developmental vitamin D (DVD) deficiency has been proposed as a risk factor for schizophrenia. DVD-deficient rats show selective cognitive deficits and novelty-induced hyperlocomotion and enhanced locomotor responses from acute treatment with psychomimetic drugs, such as amphetamine and MK-801. Here we aimed to examine the effect of a drug from a different class of psychomimetic/psychoactive compounds, Δ-tetrahydrocannabinol (THC), on tasks of relevance to the cognitive and positive symptoms of schizophrenia. The aim of this study was to investigate whether DVD deficiency modulates the behavioural effects of THC on tests of delay-dependent memory, sensorimotor gating and locomotion. Adult control and DVD-deficient rats were injected with THC (0, 0.3, 0.6, 1.25, 2.5 mg/kg) 15 min before a delay match to sample (DMTS) task using variable delays (0-24 s). A separate group of rats was injected with either 2.5 mg/kg THC or vehicle before tests of either prepulse inhibition (PPI) of the acoustic startle response or in the open field. Control and DVD-deficient rats showed a similar dose-dependent impairment in performance on the DMTS. The greatest impairment was observed at 2.5 mg/kg for all delays (0-24 s). DVD-deficient rats showed THC-induced enhancement of PPI, which was not observed in control rats. There was no effect of maternal diet on acoustic startle response or locomotor responses in the open field. This study reports the novel findings that DVD-deficient rats were more sensitive to the acute effects of THC on PPI. It appears that prenatal vitamin D deficiency has long-term effects on sensitivity to the behavioural effects of cannabinoids

Does Vitamin D Deficiency and Renal Dysfunction Play a Role in the Pathogenesis of Fluorotoxic Metabolic Bone Disease (FMBD)?

Through this study, an Ion Chromatography method has been validated and has been found to have a good correlation with the well-established ISE method. Ion Chromatography is therefore a reliable method in assessment of fluoride levels in the drinking water, but may have a few drawbacks. IC method is known to be expensive and more tedious as it requires chloride and other cations to be extracted from serum and urine samples prior to analysis, which makes the ISE method much easier to perform. The IC method was used to analyse the ground water and drinking water levels of 165 villages in and around the Vellore district, Tamil Nadu. About 46.06% of the villages assessed had water fluoride levels recorded above the Indian standards (<1.00ppm); 19.39% of the villages had water fluoride levels ranging from 1-1.5ppm; 10.91% had levels ranging from 1.5-2 ppm and 12.73% had water fluoride levels ranging from 2.0-3.0 ppm.The Jolarpet taluk of Vellore district has been found to have high levels (0.86-3.56 ppm) of fluoride in drinking water, which makes the people residing in this areaat high risk to develop dental and skeletal fluorosis. Vitamin D deficiency was produced in an experimental group of rats. To assess the changes occurring in bone,in these animals, full body DEXA scan, was usedfor the first time to assess BMDin control and Vitamin D deficient rats. There was a significant decrease in BMD (p<0.05) and BMC (p<0.05) among the vitamin D deficient rats. Thus, Vitamin D deficiency has been shown to play a vital role in bone formation and in maintaining BMC and BMD. It was interesting to note that there was a significant increase in the fat mass (p<0.05) and fat percentage (p<0.01) among the Vitamin D deficient rats. It may be hypothesised that Vitamin D deficiency can lead to an increase in fat mass in individuals. The biochemical parameters of calcium, albumin and alkaline phosphatasewere found to be unchanged in the early stages of Vitamin D deficiency in this rat model. The study found that with increasing levels of water fluoride levels there was a significant increase in BMD (p<0.05). Alkaline Phosphatase, serum and bone fluoride content and Osteocalcin were found to be increased in the Vitamin D deficient rats when compared to the control group rats, as the water fluoride levels increased. On the other hand, increased levels of fluoride was found to have a stimulating and then an inhibitory effect on the activity of the osteoclasts as evidenced by the elevated C terminal telopeptide levels with exposure to moderate fluoride levels and a fall in the levels on exposure to high levels of fluoride . Thus, highlighting that fluoride may affect the osteoblast activity and fluoride deposition in bone while Vitamin D deficiency may accentuate this effect. This could possibly lead to the causation of fluorotoxic metabolic bone disease. Pathological changes of mild bone thickening and increased osteoid in the bone were noticed among five (80%) of the Vitamin D deficient rats exposed to high levels of fluoride. A lesser percentage (40%) two of the rats belonging to the control group exposed to high levels of fluoride showed these same changes in bone. Renal function was assessed by analysing the serum creatinine, urine fluoride and urine Cystatin C which were higher among the rats treated with high levels of fluoride when compared to those treated with low and moderate levels of fluoride. Renal tubular changes may not have been found in all the cases but it was observed that fluoride does play a role in renal damage in selected cases. CONCLUSION: In conclusion, IC is a reliable method of analysing water fluoride levels. Using the IC method for analysis, Jolarpet taluk of Vellore district was found to have high levels of ground water fluoride which may predispose the population to develop dental and skeletal fluorosis. Researcher found that, Vitamin D deficiency affectsBMD,BMC and fat mass in individuals. Fluoride also does have an effect on the osteoblastic activity as well as fluoridedeposition in bone and these effects are accentuated in the presence of Vitamin D deficiency, perhaps leading to the causation of FMBD. Though high fluoride intake is known to deteriorate renal tubular function but it may do so only in selected cases. This paves way for future research to analyse other factors involved in causation of FMBD

Increased Prevalence of Bisphosphonate-Related Osteonecrosis of the Jaw with Vitamin D Deficiency in Rats

Necrotic bone exposure in the oral cavity has recently been reported in patients treated with nitrogen-containing bisphosphonates as part of their therapeutic regimen for multiple myeloma or metastatic cancers to bone. It has been postulated that systemic conditions associated with cancer patients combined with tooth extraction may increase the risk of osteonecrosis of the jaw (ONJ). The objective of this study was to establish an animal model of bisphosphonate-related ONJ by testing the combination of these risk factors. The generation of ONJ lesions in rats resembling human disease was achieved under the confluence of intravenous injection of zoledronate (ZOL; 35 µg/kg every 2 weeks), maxillary molar extraction, and vitamin D deficiency [VitD(−)]. The prevalence of ONJ in the VitD(−)/ZOL group was 66.7%, which was significantly higher (p < .05, Fisher exact test) than the control (0%), VitD(−) (0%), and ZOL alone (14.3%) groups. Similar to human patients, rat ONJ lesions prolonged the oral exposure of necrotic bone sequestra and were uniquely associated with pseudoepitheliomatous hyperplasia. The number of terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate–biotin nick-end label–positive (TUNEL+) osteoclasts significantly increased on the surface of post–tooth extraction alveolar bone of the VitD(−)/ZOL group, where sustained inflammation was depicted by [18F]fluorodeoxyglucose micro-positron emission tomography (µPET). ONJ lesions were found to be associated with dense accumulation of mixed inflammatory/immune cells. These cells, composed of neutrophils and lymphocytes, appeared to juxtapose apoptotic osteoclasts. It is suggested that the pathophysiologic mechanism(s) underpinning ONJ may involve the interaction between bisphosphonates and compromised vitamin D functions in the realm of skeletal homeostasis and innate immunity. © 2010 American Society for Bone and Mineral Research

Observations Suggesting a Possible Link Between Gammacarboxyglutamic Acid and Porcine Bioprosthetic Valve Calcification

Observations that link gammacarboxyglutamic acid (Gla) peptides with ectopic calcification are accumulating in the literature and may be summarized as follows: 1) Gla peptides selectively bind calcium and hydroxyapatite. 2) The presence of detectable levels of Gla in calcified tissue is concurrent with the onset of mineralization. 3) In an animal model, osteocalcin (a Gla-containing protein) accounts for more than 90% of all the Gla found in the resulting subcutaneously implanted calcified leaflet. 4) Vitamin D stimulates osteocalcin synthesis in cultures of osteosarcoma cells, and in vitamin D deficient rats subcutaneously implanted valve leaflets are not calcified. 5) Gla content and the degree of calcification in degenerated porcine bioprosthetic valves removed from humans are positively correlated. 6) Porcine bioprosthetic valves implanted in children are calcified more rapidly than those of adults, and the normal GIa levels in the urine of children are more than twice those of normal adults

Effects of vitamin D on vascular function and oxidative stress in the microcirculation of diabetics

Diabetes mellitus contributes to macro- and microvascular complications, leading to adverse cardiovascular events. Vitamin D deficiency is associated with the development of diabetes-related cardiovascular complications. This study was divided into two parts: (i) animal study and (ii) human study. This animal study aims to determine the effects of vitamin D deficiency on (a) microvascular endothelial and smooth muscle functions in normal and diabetic rats; (b) the changes to endothelial nitric oxide synthase (eNOS) protein expression and oxidative stress parameters in mesenteric arterial tissue of normal and diabetic rats; (c) to study whether oral calcitriol supplementation is able to ameliorate microvascular dysfunction in vitamin D-deficient rats. This human study aims to evaluate the effects of vitamin D deficiency on oxidative stress status in subcutaneous arteries of diabetic patients. Animal study: (a) Male Sprague-Dawley (SD) rats were subdivided into three equal groups of 10 rats each: (i) rats receiving 10-weeks of normal diet (Group NC), (ii) rats receiving 10- weeks of vitamin D-deficient diet (Group ND) and (iii) rats receiving 10-weeks of vitamin D-deficient diet with four weeks of oral calcitriol supplementation, starting from week 7 (Groups NDS). (b) Streptozotocin-induced diabetic male SD rats were subdivided into three equal groups of 10 rats each: (i) diabetic rats receiving 10-weeks of normal diet (Group DC), (ii) diabetic rats receiving 10-weeks of vitamin D-deficient diet (Group DD) and (iii) diabetic rats receiving 10-weeks of vitamin D-deficient diet with four weeks of oral calcitriol supplementation, starting from week 7 of diabetes induction (Groups DDS). At the end of 10 weeks, all rats were sacrificed. Rats’ mesenteric arteries were isolated and dissected to undergo vascular function studies using wire myograph. Protein expression of eNOS in mesenteric arterial tissue was determined using Western blot. Immunohistochemistry was used to detect the presence and localization of eNOS in mesenteric arteries. Superoxide dismutase (SOD) and malondialdehyde (MDA) levels in mesenteric arterial tissue; fasting blood glucose (FBG), serum 25(OH)D and calcium levels in blood were also measured. Human study: Diabetic patients were categorised into two groups based on serum 25(OH)D levels: (i) vitamin D non-deficient diabetic patients (Group DNP, n = 10) and (ii) vitamin D-deficient diabetic patients (Group DDP, n = 13). The levels of SOD and MDA in subcutaneous arterial tissue were measured. Results of animal study: (a) Normal rats. Endothelium-dependent relaxation to acetylcholine (ACh) was significantly attenuated in mesenteric arteries of vitamin D-deficient rats. Reduced SOD levels and protein expression of eNOS were observed in vitamin D-deficient rats. However, calcitriol supplementation showed no significant improvement in these parameters. Endothelium-dependent contraction to calcium ionophore (CaI) was augmented in vitamin D-deficient rats receiving calcitriol supplementation. Increased calcium levels were also found in calcitriol-supplemented vitamin D-deficient rats. (b) Diabetic rats. ACh-induced endothelium-dependent relaxation was significantly impaired in mesenteric arteries of vitamin D-deficient diabetic rats. Reduced SOD levels and protein expression of eNOS and enhanced MDA levels were found in vitamin D-deficient diabetic rats. These impairments were successfully ameliorated by calcitriol supplementation. Augmented CaI-induced endothelium-dependent contraction and impaired sodium nitroprusside (SNP)-induced endotheliumindependent relaxation occurred in vitamin D-deficient diabetic rats. However, calcitriol supplementation failed to show improvement in these vascular responses There were no significant differences in endothelium-independent relaxation to salbutamol (SB) and contraction to phenylephrine (PE) as well as in general parameters such as body weight changes and FBG levels between study groups in both normal and diabetic rats. Results of human study: Markedly augmented MDA levels were found in subcutaneous arterial tissues of vitamin D-deficient diabetic patients. However, SOD levels in vitamin D-deficient diabetic patients showed the reduced trend (p = 0.072) compared to vitamin D non-deficient diabetic patients. In conclusion, this study demonstrated that vitamin D deficiency attenuates microvascular endothelial function in both normal and diabetic rats. The impairment for endothelial function was likely due to the diminished nitric oxide contribution, associated with reduced eNOS protein expression and augmented oxidative stress. Vitamin D deficiency in diabetic rats also impairs vascular smooth muscle function. The study also showed that calcitriol supplementation to diabetic rats with vitamin D deficiency improves endothelium-mediated vasodilation, by upregulating eNOS expression and improving oxidative stress status. However, calcitriol supplementation to normal rats with vitamin D deficiency induces hypercalcaemia, leading to augmented endothelium-dependent contraction. Besides that, vitamin D deficiency in diabetic patients as well showed augmented oxidative stress

Effects of vitamin D, dietary calcium and vitamin D restriction, pregnancy and lactation on gene expression of calcium transporting factors

The purpose of the first study was to determine the changes in intestinal vitamin D-dependent plasma membrane calcium ATPase (PMCA1) and calcium binding protein-9K (CaBP-9K) mRNA induced by a single injection of 1,25-D3 or 1,25,28-trihydroxyvitamin D2 (1,25,28-D2) in vitamin D-deficient rats. The results indicated that a single injection of 20 ng of 1,25-D3 per rat double intestinal PMCA1 mRNA at 4, 8, 12, hours and CaBP-9K mRNA at 8, 12, and 24 hours after injection. The mRNA of PMCA1 and CaBP-9K could be increased by a larger dose of 1,25,28-D2 (20 ng). These data suggest that the up-regulation of PMCA1 and CaBP-9K mRNA may be critical to active calcium transport;In the second study, the effect of dietary calcium and/or vitamin D-deficiency on intestinal PMCA1 and CaBP-9K mRNA expression in rats was examined. The results indicate both intestinal CaATPase and CaBP-9K mRNA are down-regulated in rats fed diets containing no vitamin D. However, our data suggest that dietary calcium restriction alone did not have any effect on CaATPase and CaBP mRNA. This study demonstrates that dietary calcium itself is probably not a regulator of mRNA gene expression of PMCA1 and CaBP-9K;In the third study, intestinal PMCA1, CaBP-9K and vitamin D receptor (VDR) mRNA were determined at different stages of pregnancy and early lactation in rats. At 21 days gestation and 7 days of lactation, both PMCA1 and CaBP-9K mRNA levels increased 2-3 fold. PMCA1 and CaBP-9K mRNA remained elevated at 7 days of lactation. Interestingly, VDR mRNA levels did not change during the entire experiment. However, VDR content increased 2-fold in late pregnancy and lactation. These data suggest that the effects of gestation and lactation on PMCA1 and CaBP-9K are probably transcriptional and on VDR are post transcriptional