Sub-chronic iron overload triggers oxidative stress development in rat brain: implications for cell protection

This work was aimed to test the hypothesis that sub-chronic administration of iron-dextran (Fe-dextran) (six doses of 50 mg Fe-dextran/kg) to rats triggers a transient oxidative stress in brain and mechanisms of cellular antioxidant defence. After 2 h of administration of the 6th dose, a significant increase of total Fe, the labile Fe pool (LIP), the lipid radical (LR^?)/α-tocopherol (α-T) content ratio were observed, as compared to values in control brain homogenates. The ascorbyl radical (A^?)/ascorbate (AH^?) content ratio and the oxidation rate of 2′,7′-dichlorodihidrofluorescein (DCFH-DA) were significantly higher in Fe-dextran treated rats, as compared to values in brain from control rats after 4 h treatment. An increase in both catalase (CAT) and superoxide dismutase (SOD) activity was observed at 8 and 1–2 h, respectively. No significant changes were detected in the nuclear factor-κB (NF-κB) levels in nuclear extracts from rat brains after 1–8 h of Fe-dextran administration. After 2 h of Fe administration Fe concentration in cortex, striatum and hippocampus was significantly increased as compared to the same areas from control animals. Both, CAT and SOD activities were significantly increased in cortex after Fe administration over control values, without changes in striatum and hippocampus. Taken as a whole, sub-chronic Fe administration enhances the steady state concentration of Fe in the brain LIP that favors the settlement of an initial oxidative stress condition, both at hydrophilic and lipophilic compartments, resulting in cellular protection evidenced by antioxidant enzyme upregulation.     

Iron overload prevents oxidative damage to rat brain after chlorpromazine administration

The hypothesis tested is that Fe administration leads to a response in rat brain modulating the effects of later oxidative challenges such as chlorpromazine (CPZ) administration. Either a single dose (acute Fe overload) or 6 doses every second day (sub-chronic Fe overload) of 500 or 50 mg Fe-dextran/kg, respectively, were injected intraperitoneally (ip) to rats. A single dose of 10 mg CPZ/kg was injected ip 8 h after Fe treatment. DNA integrity was evaluated by quantitative PCR, lipid radical (LR^·) generation rate by electron paramagnetic resonance (EPR), and catalase (CAT) activity by UV spectrophotometry in isolated brains. The maximum increase in total Fe brain was detected after 6 or 2 h in the acute and sub-chronic Fe overload model, respectively. Mitochondrial and nuclear DNA integrity decreased after acute Fe overload at the time of maximal Fe content; the decrease in DNA integrity was lower after sub-chronic than after acute Fe overload. CPZ administration increased LR^· generation rate in control rat brain after 1 and 2 h; however, CPZ administration after acute or sub-chronic Fe overload did not affect LR^· generation rate. CPZ treatment did not affect CAT activity after 1–4 h neither in control rats nor in acute Fe-overloaded rats. However, CPZ administration to rats treated sub-chronically with Fe showed increased brain CAT activity after 2 or 4 h, as compared to control values. Fe supplementation prevented brain damage in both acute and sub-chronic models of Fe overload by selectively activating antioxidant pathways.     

Characterization of the stimulation of neuronal Na+, K+-ATPase activity by low concentrations of ouabain

Low concentrations (< 10^?7 M) of ouabain stimulate the activity of Na⁺, K⁺-ATPase in whole homogenates of rat brain. The magnitude of this stimulation varies from 5 to 70%. The concentrations of ouabain which induces maximal stimulation is also highly variable and ranges between 10^?9 to 10^?7 M. The ouabain stimulation disappears following 1:50 dilution and 2 h preincubation or freezing and thawing of the membranes or their treatment with deoxycholate. “Aging” of a preparation of ATPase also results in loss of its ability to be stimulated by ouabain but ouabain inhibition is preserved. No stimulation of enzyme activity by ouabain is observed in rat brain microsomal fraction. The β-adrenergic blocker propranolol does not inhibit the ouabain induced stimulation of ATPase activity. It is suggested that the stimulation of Na⁺, K⁺-ATPase activity by low concentrations of cardiac glycosides if a result of either the displacement of an endogenous ouabain-like compound from the enzyme or an indirect effect by changing membrane surrounding environment of the Na⁺, K⁺-ATPase.     

Persistent facial pain increases superoxide anion production in the spinal trigeminal nucleus

Previous studies have demonstrated that there is an increase in oxidative stress in the cerebral cortex of rats after repeated painful stimulation and that long-lasting pain increases the production of superoxide ion (O₂ ^?), nitric oxide and peroxynitrite due to the activation of AMPA and NMDA receptors. The purpose of the present study was to evaluate the possible role of O₂ ^? in the transmission of oro-facial pain. Formaldehyde 1% was injected subcutaneously into one vibrissal pad of adult male Sprague-Dawley rats as a model of persistent pain, then O₂ ^? production and superoxide dismutase (SOD) activity were evaluated in the left and right spinal trigeminal nuclei. O₂ ^? production was revealed using dihidroetidium (DHE) injected at 10 or 45 min after the formalin injection in conscious or anaesthetized rats. A histochemical assay for SOD was performed to evaluate the activity of SOD at 10 min after the formalin injection. The results showed a significant increase in O₂ ^? production in the homolateral nucleus at 45 min. However, there was no significant difference between the two sides at 10 min after the formalin injection. No significant difference was observed in SOD activity between the two sides of the spinal trigeminal nucleus. This study demonstrated that there is an increased production of O₂ ^? in the second phase but not in the first phase of the formalin test; thus O₂ ^? is involved in pain induced by inflammation, but not in acute pain.     

Propofol Increases Expression of Basic Fibroblast Growth Factor After Transient Cerebral Ischemia in Rats

Anesthetics such as propofol can provide neuroprotective effects against cerebral ischemia. However, the underlying mechanism of this beneficial effect is not clear. Therefore, we subjected male Sprague–Dawley rats to 2 h of middle cerebral artery occlusion and investigated how post-ischemic administration of propofol affected neurologic outcome and the expression of basic fibroblast growth factor (bFGF). After 2 h of ischemia, just before reperfusion, the animals were randomly assigned to receive either propofol (20 mg kg^?1 h^?1) or vehicle (10 % intralipid, 2 ml kg^?1 h^?1) intravenously for 4 h. Neurologic scores, infarct volume, and brain water content were measured at different time points after reperfusion. mRNA level of bFGF was measured by real-time PCR, and the protein expression level of bFGF was analyzed by immunohistochemistry and Western blot. At 6, 24, 72 h, and 7 days of reperfusion, infarct volume was significantly reduced in the propofol-treated group compared to that in the vehicle-treated group (all P < 0.05). Propofol post-treatment also attenuated brain water content at 24 and 72 h and reduced neurologic deficit score at 72 h and 7 days of reperfusion (all P < 0.05). Additionally, in the peri-infarct area, bFGF mRNA and protein expression were elevated at 6, 24, and 72 h of reperfusion compared to that in the vehicle-treated group (all P < 0.05). These results show that post-ischemic administration of propofol provides neural protection from cerebral ischemia–reperfusion injury. This protection may be related to an early increase in the expression of bFGF.     

Interactions of cardiac glycosides with cultured cardiac cells: II. Biochemical and electron microscopic studies on the effects of ouabain on muscle and non-muscle cells

Electron microscopic and biochemical studies revealed a salient difference in the response to toxic doses of ouabain by cultured cardiac muscle and non-muscle cells from neonatal rats. Progressive cellular injury in myocytes incubated with 1 · 10^?4–1 · 10^?3 M ouabain ultimately leads to swelling and necrosis. The morphological damage in myocytes was accompanied by a drastic decrease in ¹⁴CO₂ formation from ¹⁴C-labeled stearate or acetate but not glucose. Neither morphological nor biochemical impairments were observed in non-muscle cells. The interaction between ouabain and the cultured cells, using therapeutic doses of ouabain (i.e., <1 · 10^?7 M), was characterized. Two binding sites were described in both classes of cells, one site is a saturable K⁺-sensitive site whereas the other is non-saturable and K⁺-insensitive. The complexes formed between the sarcolemma receptor(s) and ouabain, at low concentrations of the drug (e.g., 7.52 · 10^?9 M), had K_d values of 8.9 · 10^?8 and 2.3 · 10^?8 M for muscle and non-muscle cells, respectively. The formation and dissociation of the complexes were affected by temperature and potassium ions.     

A functional variant of pre-miRNA-196a2 confers risk for Behcet’s disease but not for Vogt–Koyanagi–Harada syndrome or AAU in ankylosing spondylitis

This study aimed to investigate the predisposition of common pre-miRNA SNPs with Behcet’s disease (BD), Vogt–Koyanagi–Harada (VKH) syndrome and acute anterior uveitis (AAU) associated with ankylosing spondylitis (AS). A two-stage association study was carried out in 859 BD, 400 VKH syndrome, 209 AAU⁺AS⁺ patients and 1,685 controls all belonging to a Chinese Han population. Genotyping, the expression of miR-196a and Bach1 (the target gene of miR-196a), cell proliferation, cytokine production were examined by PCR–RFLP, real-time PCR, CCK8 and ELISA. In the first stage study, the results showed significantly increased frequencies of the miR-196a2/rs11614913 TT genotype and T allele in BD patients (adjusted P _c = 0.024, OR = 1.63; adjusted P _c = 5.4 × 10^?3, OR = 1.45, respectively). However, no significant association of the tested SNPs with VKH and AAU⁺AS⁺ patients was observed. The second stage and combined studies confirmed the association of rs11614913 with BD (TT genotype: adjusted P _c = 6×10^?5, OR = 1.53; T allele: adjusted P _c = 8×10^?6, OR = 1.35; CC genotype: adjusted P _c = 0.024, OR = 0.68). A stratified analysis showed an association of the rs11614913 TT genotype and T allele with the arthritis subgroup of BD (P _c = 5.3 × 10^?3, OR = 1.89; P _c = 0.015, OR = 1.56, respectively). Functional experiments showed a decreased miR-196a expression, an increased Bach1 expression and an increased production of IL-1β and MCP-1 in TT cases compared to CC cases (P = 0.023, P = 0.0073, P = 0.012, P = 0.002, respectively). This study shows that a functional variant of miR-196a2 confers risk for BD but not for VKH syndrome or AAU⁺AS⁺ by modulating the miR-196a gene expression and by regulating pro-inflammatory IL-1β and MCP-1 production.     

Oxidative Stress and Ca2+ Signals Involved on Cadmium-Induced Apoptosis in Rat Hepatocyte

Cadmium (Cd) is an important industrial and environmental pollutant. In animals, the liver is the major target organ of Cd toxicity. In this study, rat hepatocytes were treated with 2.5～10 μM Cd for various durations. Studies on nuclear morphology, chromatin condensation, and apoptotic cells demonstrate that Cd concentrations ranging within 2.5～10 μM induced apoptosis. The early-stage marker of apoptosis, i.e., decreased mitochondrial membrane potential, was observed as early as 1.5 h at 5 μM Cd. Significant (P?P?2+ concentration ([Ca²⁺] _i ) of Cd-exposed cells significantly increased (P?2+] _i may play an important role in apoptosis. Overall, these results showed that oxidative stress and Ca²⁺ signaling were critical mediators of the Cd-induced apoptosis of rat hepatocytes.     

Increase in calcium content and Ca2+-ATPase activity in the brain of fasted rats: Comparison with different ages

The effect of fasting on calcium content and Ca²⁺-ATPase activity in the brain tissues of 5 weeks and 50 weeks old rats was investigated. Brain calcium content and Ca²⁺-ATPase activity in the microsomal and mitochondrial fractions of the brain homogenate from young and elderly rats were significantly increased by overnight–fasting. These increases were appreciably restored by a single oral administration of glucose solution (400 mg/100 g body weight) to fasted rats. In comparison with young and elderly rats, brain calcium content and microsomal Ca²⁺-ATPase activity were significantly elevated by increasing ages. The effect of ageing was not seen in the brain mitochondrial Ca²⁺-ATPase activity. When calcium (50 mg/100 g) was orally administered to young and elderly rats, brain calcium content was significantly elevated. The calcium administration–induced increase in brain calcium content was greater in elderly r crease in Ca²⁺-ATPase activity in the microsomal and mitochondrial fractions of brain homogenates from young rats. In aged rats, the microsomal Ca²⁺-ATPase activity was not further enhanced by calcium administration, although the mitochondrial enzyme activity was significantly raised. The present study demonstrates that the fasting–induced increase in brain calcium content is involved in Ca²⁺-ATPase activity raised in the brain microsomes and mitochondria of rats with different ages, supporting a energy–dependent mechanism in brain calcium accumulation.     

Thulium Ion Promotes Apoptosis of Primary Mouse Bone Marrow Stromal Cells

Bone is one of the main target organs for the lanthanides (Ln). Biodistribution studies of Tm-based compounds in vivo showed that bone had significant uptake. But the effect of Tm³⁺ on primary mouse bone marrow stromal cells (BMSCs) has not been reported. So we investigated the effect and underlying mechanisms of Tm³⁺ on BMSCs. Cell viability, cell apoptosis, reactive oxygen species (ROS) level, lactate dehydrogenase (LDH) activity and mitochondrial membrane potential (MMP) were studied. The results indicated that Tm³⁺ increased the viability of BMSCs at concentrations of 1?×?10^?7, 1?×?10^?6, 1?×?10^?5, and 1?×?10^?4 mol/L in a dose-dependent manner, turned to decrease the viability of BMSCs at the highest concentration of 1?×?10^?3 mol/L for 24, 48, and 72 h. Tm³⁺ at 1?×?10^?3 mol/L promoted apoptosis of BMSCs, increased the ROS and LDH levels, and decreased MMP in BMSCs. Taken together, we demonstrated that Tm³⁺ at 1?×?10^?3 mol/L might induce cellular apoptosis through mitochondrial pathway. These results may be helpful for more rational application of Tm-based compounds in the future.     

Acetaminophen at Different Doses Protects Brain Microsomal Ca2+-ATPase and the Antioxidant Redox System in Rats

Acetaminophen, an analgesic and antipyretic drug, rescues neuronal cells from mitochondrial redox impairment and reactive oxygen species (ROS). Excessive administration of acetaminophen above the recommended daily dose range has some negative effects on the brain. We investigated the effects of different doses of acetaminophen on Ca²⁺-ATPase and the antioxidant redox system in rats. Seventy rats were randomly divided into seven equal groups. The first was used for the control. One dose of 5, 10, 20, 100, 200, and 500 mg/kg acetaminophen was intraperitoneally administered to rats constituting the second, third, fourth, fifth, sixth, and seventh groups, respectively. After 24 h, brain cortical samples were taken and brain microsomal samples were obtained by ultracentrifugation. Brain and microsomal lipid peroxidation (LP) and brain calcium levels in the sixth and seventh groups were increased compared to control. LP levels in the second, third, and forth groups; brain vitamin E levels; brain and microsomal glutathione peroxidase (GSH-Px); and Ca²⁺-ATPase activity in the sixth and seventh groups were lower than in control, although brain vitamin E concentrations in the second, third, fourth, and fifth groups and microsomal GSH-Px activity in the third and fourth groups were higher than in control. Brain cortical β-carotene and vitamin A concentrations did not differ in the seven groups. In conclusion, 5–100 mg/kg acetaminophen seems to have protective effects on oxidative stress-induced brain toxicity by inhibiting free radicals and supporting the antioxidant redox system.     

The Protective Effect of N-Acetylcysteine on Oxidative Stress in the Brain Caused by the Long-Term Intake of Aspartame by Rats

Long-term intake of aspartame at the acceptable daily dose causes oxidative stress in rodent brain mainly due to the dysregulation of glutathione (GSH) homeostasis. N-Acetylcysteine provides the cysteine that is required for the production of GSH, being effective in treating disorders associated with oxidative stress. We investigated the effects of N-acetylcysteine treatment (150 mg kg^?1, i.p.) on oxidative stress biomarkers in rat brain after chronic aspartame administration by gavage (40 mg kg^?1). N-Acetylcysteine led to a reduction in the thiobarbituric acid reactive substances, lipid hydroperoxides, and carbonyl protein levels, which were increased due to aspartame administration. N-Acetylcysteine also resulted in an elevation of superoxide dismutase, glutathione peroxidase, glutathione reductase activities, as well as non-protein thiols, and total reactive antioxidant potential levels, which were decreased after aspartame exposure. However, N-acetylcysteine was unable to reduce serum glucose levels, which were increased as a result of aspartame administration. Furthermore, catalase and glutathione S-transferase, whose activities were reduced due to aspartame treatment, remained decreased even after N-acetylcysteine exposure. In conclusion, N-acetylcysteine treatment may exert a protective effect against the oxidative damage in the brain, which was caused by the long-term consumption of the acceptable daily dose of aspartame by rats.     

Disposition of fucose in brain

Abstract— Labelled fucose administered to rats in vivo was rapidly incorporated into brain glycoproteins, but not into any other brain constituents, including glycolipids and acid mucopolysaccharides. Maximum incorporation of tritium-labelled fucose into brain glyco-proteins occurred 3–6 h after intraperitoneal injection in young or adult rats, and the half-time for the turnover of glycoprotein-fucose in young rats was approximately 2 weeks. Within 3 h after the administration of either [1-³H]fucose or fucose generally labelled with tritium, 75 per cent of the total acid-soluble radioactivity in plasma and brain was found to be volatile, and by 24 h after injection more than 90 per cent of the acid-soluble radioactivity was volatile. The tritium in labelled fiicose appears to undergo arapid exchange reaction with hydrogen atoms in body water, although the tritium in fucose glycosidically- linked to glycoproteins is biologically stable. The rapid disappearance of labelled free fucose from the plasma and tissues of the rat precludes the possibility of any significant degree of reutilization of labelled precursor, and provides support for other data indicating that the turnover of fucose in brain glycoproteins is relatively slow in comparison to that of hexosamine and sialic acid. Activities of α-L-fucosidase in rat brain, with pH optima at 40 and 6.0, had essentially the same K_m (4 × 10^?4 M and 3.2 × 10^?4 M, respectively) with p-nitrophenyl-α-L-fucopyranoside as substrate. Activities of both were competitively inhibited by L-fucose. However, the K_t measured at pH 4 (1.9 × 10^?2) was almost ten times greater than that measured at pH 6 (1.5 × 10^?4).     

Brain Trace Element Concentration of Rats Treated with the Plant Alkaloid, Vincamine

Trace elements are essential for normal brain functions. Tiny amounts of these elements help in the formation of neurotransmitters and involved in the antioxidant defense and intracellular redox regulation and modulation of neural cells. Vincamine is a plant alkaloid used clinically as a peripheral vasodilator that increases cerebral blood flow and oxygen and glucose utilization by neural tissue to combat the effect of aging. Neurodegenerative diseases associated with aging characterized by a disturbance in trace element levels in the brain. The objective of this study was to determine the level of zinc (Zn), copper (Cu), iron (Fe), Selenium (Se), and chromium (Cr) in the brain of rats treated with vincamine. Vincamine was injected i.m. to rats at a dose of 15 mg/Kg bodyweight daily for 14 days. Twenty-four hours after the last injection, rats were killed, and brains were ashed and digested by concentrated acids and analyzed for trace elements concentrations by flame emission atomic absorption spectrophotometer. The results showed that Zn was the highest trace element in the brain of control rats (3.134?±?0.072 ppm) and Cr was the lowest (0.386?±?0.027 ppm). Vincamine administration significantly (p?<?0.01) reduced the brain Fe concentration (1.393?±?0.165 ppm) compared to control (2.807?±?0.165 ppm). It was concluded that Zn was the highest trace element in the brain of rats. Vincamine administration resulted in approximately 50% reduction in brain Fe concentration which suggests its beneficial effect to prevent the oxidative stress of Fe in neurodegenerative diseases such as Parkinson’s, Alzheimer’s, and Huntington’s diseases.     

In vitro transformation of dehydroepiandrosterone or its sulphate into androstenediol or its sulphate by rat brain and blood preparations

Abstract— –Enzymic transformation of [4-¹⁴C]dehydroepiandrosterone or [4-¹⁴C]dehydro-epiandrosterone sulphate to androstenediol or its sulphate occurred when incubated with a microsomal preparation of rat brain or a whole rat blood homogenate. The brain enzyme which appeared to cause this transformation had a pH optimum at 60, was NADPH₂-dependent, and had an apparent K_m of 4·6 × 10^?6m . When the subcellular fractions of rat brain were compared for transformation, microsomes had the highest specific activity, followed by the cytosol. The crude nuclear and mitochondrial fractions had no significant activity. The level of enzymic activity in the brain microsomes increased from that for rats sacrificed at 7 days of postnatal age to a maximum for rats sacrificed at 1 month of age; then the activity appeared to level off in rats older than 1 month. Microsomes obtained from the cerebellum had the highest specific activity in comparison to that obtained from the cerebral cortex, the diencephalon, and the brain stem. The incubated preparations of rat brain also converted dehydroepiandrosterone sulphate to androstenediol sulphate without hydrolysis. The enzyme in rat blood which was similar to that in the brain was also partially characterized. The blood enzyme had a pH optimum at 6–5, was nearly exclusively present in erythrocytes, was also NADPH₂-dependent, and had an apparent K_m of 2·7 × 10^?4m . The developmental pattern of the blood enzyme specific activity was similar to that of the rat brain enzyme. Upon haemolysis, most activity was recovered in the haemolysate.     

Antioxidant activity and hepatoprotective potential of Hammada scoparia against ethanol-induced liver injury in rats

The present work was aimed at studying the antioxidative activity and hepatoprotective effects of methanolic extract (ME) of Hammada scoparia leaves against ethanol-induced liver injury in male rats. The animals were treated daily with 35 % ethanol solution (4 g?kg^?1?day^?1) during 4 weeks. This treatment led to an increase in the lipid peroxidation, a decrease in antioxidative enzymes (catalase, superoxide dismutase, and glutathione peroxidase) in liver, and a considerable increase in the serum levels of aspartate and alanine aminotransferase and alkaline phospahatase. However, treatment with ME protects efficiently the hepatic function of alcoholic rats by the considerable decrease in aminotransferase contents in serum of ethanol-treated rats. The glycogen synthase kinase-3 β was inhibited after ME administration, which leads to an enhancement of glutathione peroxidase activity in the liver and a decrease in lipid peroxidation rate by 76 %. These biochemical changes were consistent with histopathological observations, suggesting marked hepatoprotective effect of ME. These results strongly suggest that treatment with methanolic extract normalizes various biochemical parameters and protects the liver against ethanol induced oxidative damage in rats.     

TNFAIP3 gene polymorphisms confer risk for Behcet’s disease in a Chinese Han population

The tumor necrosis factor alpha-inducible protein 3 (TNFAIP3) gene polymorphisms have recently been reported to be associated with the susceptibility to several immune-related diseases. This study was performed to evaluate the potential association of TNFAIP3 polymorphisms with Behcet’s disease (BD) in a Chinese Han population. Five single-nucleotide polymorphisms (SNPs), rs10499194, rs610604, rs7753873, rs5029928, and rs9494885 of TNFAIP3 were genotyped in 722 BD patients and 1,415 healthy controls using a PCR-restriction fragment length polymorphism assay. Allele and genotype frequencies were compared between patients and controls using the χ ² test. The results showed a significantly increased prevalence of the rs9494885 TC genotype and C allele in BD patients compared with controls (Bonferroni corrected p (p _c) = 1.83 × 10^?10, odds ratio (OR) [95 % CI] 2.03 [1.65–2.49]; p _c = 8.35 × 10^?10, OR [95 % CI] 1.81 [1.51–2.18], respectively).The frequency of the TT genotype and T allele of rs9494885 was markedly lower in BD patients than that in controls (p _c = 1.23 × 10^?10, OR [95 % CI] 0.50 [0.40–0.61]; p _c = 8.35 × 10^?10, OR [95 % CI] 0.55 [0.46–0.66], respectively). For rs10499194, a higher frequency of the CC genotype (p _c = 0.015, OR [95 % CI] 1.96 [1.30–2.97]) and C allele (p _c = 0.005, OR [95 % CI] 1.92 [1.28–2.90]), and a lower frequency of the TC genotype (p _c = 0.015, OR [95 % CI] 0.51 [0.34–0.77]) and T allele (p _c = 0.005, OR [95 % CI] 0.52 [0.35–2.97]) were found in BD patients. Concerning rs7753873, a higher frequency of the AC genotype (p _c = 0.015, OR [95 % CI] 1.49 [1.17–1.91]) and C allele (p _c = 0.025, OR [95 % CI] 1.39 [1.11–1.76]), and a lower frequency of the AA genotype (p _c = 0.03, OR [95 % CI] 0.68 [0.53–0.87]) and A allele (p _c = 0.025, OR [95 % CI] 0.72 [0.57–0.91]) were observed in BD patients. This study identified one strong risk SNP rs9494885 and two weak risk SNPs rs10499194 and rs7753873 of TNFAIP3 in Chinese Han BD patients.     

Colon Delivery of Budesonide: Evaluation of Chitosan–Chondroitin Sulfate Interpolymer Complex

The present study was aimed at formulating tablets comprising of coating susceptible to microbial enzyme degradation for releasing budesonide in the colon. Tablets prepared by using Avicel® pH 102 as diluent and Eudragit® L100-55 as binder were coated to a weight gain of 10% w/w employing aqueous mixtures containing chitosan (CH) and chondroitin sulfate (CS). The interpolymer complex between CH and CS was characterized using Fourier transform infrared (FTIR) and differential scanning calorimetery (DSC) studies. The tablets were evaluated for release of budesonide through in vitro in vivo studies. Formation of bonds between –COO^? and –OSO ₃ ^? groups of CS and –NH ₃ ⁺ groups of CH was evident in the FTIR spectra of these interpolymer complexed (IPC) films. The DSC thermograms of these films revealed one endothermic transition between 190°C and 205°C, suggesting the formation of new bonds in the IPC. The pH sensitive swelling exhibited by these films was observed to be a function of CH concentration. Tablets coated with aqueous mixtures containing 40:60 or 50:50 ratio of CH/CS totally prevented the release of budesonide in pH 1.2 buffer. The peaks (FTIR) and endothermic transitions (DSC) characteristic of interpolymer complexation were observed to remain unaffected after sequential exposure of the films to pH 1.2 and pH 7.4 buffer IP. This proved the versatility of these IPC films for colon delivery. C _max of 1,168.99 and 1,174.2 ng/mL, respectively, at 12 and 8 h post-oral dosing of tablets coated with 40:60 or 50:50 ratio of CH/CS was observed in rats. The aqueous CH/CS (40:60) coating could provide a facile method for delivering budesonide to the colon.