Iranian Journal of Basic Medical Sciences
Volume:15 Issue: 4, Jul-Aug 2012

Tissue nutrient supply may be synchronized with endogenous physiological rhythms to optimize animal and human health. Glucose tolerance and insulin sensitivity have endogenous rhythms that are not essentially dependent on food type and eating. Human glucose tolerance declines as day comes into night. Based on such evolutionary findings, large evening meals must be avoided to reduce risks of visceral adiposity, diabetes, hypertension and related cardiovascular complexities. Ruminants as extremely important food-producing livestock have evolved to ruminate mostly overnight when little grazing occurs, and when rumen reaches a larger volume and fermentation capacity. As such, eating time (e.g., evening vs. morning) will alter postprandial and diurnal patterns of food intake, rumen and peripheral metabolites production and supply, and milk and meat production efficiency. Most recent discoveries suggest that eating time modulates postprandial intake and metabolism patterns in non-grazing lactating cows. Eating rate and absolute intake can increase by evening vs. morning feeding in dairy cows. Evening feeding increased postprandial rumen volatile fatty acids (VFA) peak, and surges of blood insulin, lactate and beta-hydroxybutyrate, and induced a peripartal decline in blood glucose. As a result, milk fat and energy production were increased. While being unfavorable to human health, evening and night feeding have proved beneficial to ruminants. These findings establish a differential chronological basis for food intake and nutrient metabolism in man and food-producing animals. Eating time is a major external cue and a feasible life strategy that affects production and health physiology.

Arsenic compounds are potent human carcinogen and produce a variety of stress responses in mammalian cells. Recently sodium arsenite has been recommended to be used as anti malignancy drug by American food and drug administration (FDA). In this study, we aimed to determine the apoptosis inducing effect of sodium arsenite on rat bone marrow mesenchymal stem cells exposed in vitro. Cell morphology was studied with the help of Hoechst and propidium iodide as well as with single cell gel electrophoresis (comet assay), TUNEL assay and caspase activity base on immunocytochemistry using commercial kit were considered to study the mechanism of cell death. Our result showed that the sodium arsenite with concentration of 0.1 µM in 36 hr induces caspase dependent apoptosis in rat bone marrow mesenchymal stem cells. This concentration is the lowest level of sodium arsenite to be reported with apoptosis induction ability in stem cells.Since sodium arsenite is used in therapy, more research should be carried out on the effect of this chemical on stem cells, especially MSCs.

The aims of present study were to elucidate the effect of NaHS as a H2S donor on precontracted rat trachea smooth muscle, role of epithelium and nitric oxide in this action. Tracheal rings from male adult Wistar rats were isolated and mounted in an organ bath containing Krebs–Henseleit solution under 1.5 g resting tension and contractions were recorded isometrically. After equilibrium period (60 min), cumulative concentrations of NaHS (0.2-1.2 mM) were applied on the tracheal basal tone or on the plateau of contractions induced by KCl (60 mM) or carbachol (CCh, 0.55 μM) in the absence and presence of certain antagonists and inhibitors. The tracheal basal tone was unaffected by NaHS but tracheal contractions induced by KCl and CCh were attenuated by NaHS in a concentration-dependent manner (P< 0.001). Removing the tracheal epithelial did not attenuate the NaHS spasmolytic effect in the tissue precontracted by KCl and CCh. The bronchodilatory effect was unaffected by tissue incubation (30 min, 1 μM) with, glibenclamide, propranolol, indomethacin, methylene blue (10 μM), and L-NAME (300 μM). It seems that bronchodilatory effect of H2S was not mediated by KATP channels, β-adrenoceptors, epithelium and production of nitric oxide, cGMP and prostaglandins. Since CCh and KCl activate Ca2+ influx and CCh promotes Ca2+ from intracellular pool as well, therefore, we may conclude that the relaxant effect of NaHS was mediated by the Ca2+ influx blockade and cholinergic receptors inactivation. This preliminary study shows the possible therapeutical property of H2S in obstructive pulmonary diseases.

PDE3 has a functional role in insulin secretion and action. We investigated the metabolic effects of new synthetic PDE3 inhibitors (mc1, mc2, mc5 and mc6), on mice and hyperglycemic rat.The test compound or solvent was injected subcutaneously to mice, for 7 days. On day 8, blood and liver samples were obtained. In hyperglycemic rat, 0.5 g/kg glucose with or without test compounds was injected, and followed with infusion of 1.5 g/kg/hr glucose. Blood samples were collected in mentioned intervals and liver was dissected.In hyperglycemic rat, all test compounds decreased blood glucose and the effect of milrinone was potentiated by glybenclamide. Milrinone or IBMX did not change plasma insulin levels, but it was augmented by combination of milrinone and glybenclamide. In both species, liver glycogen storage was decreased by IBMX, mc5, mc6 or MCPIP, increased by mc2 (liver glycogen, rat, control=56±2, mc2=70±3 P< 0.01, mice, control=33±0.7, mc2=42±2.3 P< 0.01) and was not changed in the presence of mc1. Milrinone did not change the glycogen storage in rats though increased it in mice (control= 33±0.7, milrinone= 40±1 P< 0.05).Increasing plasma insulin levels by combination of milrinone and glybenclamide confirmed that in hyperglycemic rat, the hypoglycemic effect was correlated with increasing insulin secretion. Variations of plasma insulin were obscured by the pulsative characteristic of pancreatic insulin release. Decreasing glycogen storage reflected inhibition of liver PDE activity. The reasons for ineffectiveness of mc1, anabolic effect of mc2, and differential effects of milrinone were not clear.

The objective of this study was to evaluate the effect of cannabinoid on cortical spreading depression (CSD) in rat brain. Cannabis has been used for centuries for both symptomatic and prophylactic treatment of different types of headaches including migraine. CSD is believed to be a putative neuronal mechanism underlying migraine aura and subsequent pain. The effects of Delta9-tetrahydrocannabinol (THC), as well as, cannabinoid CB1 and CB2 receptor agonists on CSD in rat neocortical slices were investigated. Furthermore, the effect of cannabinoid CB1 agonist was tested on field excitatory postsynaptic potentials (fEPSP) and long-term potentiation (LTP).HC (1-20 microM) dose dependently suppressed CSD amplitude, duration, and propagation velocity. Cannabinoid CB1 agonist, WIN 55,212-2 mesylate (1-10 microM), also significantly suppressed all characteristic features of CSD. However, cannabinoid CB2 agonist, JWH-133 (1-20 microM), did not affect CSD. FEPSP and induction of LTP were suppressed by application of WIN55212-2. Suppression of CSD by activation of CB1 receptors points to the potential therapeutic effects of cannabinoids in migraine with aura. More research is needed before we know whether cannabinoids may be helpful in treating migraine pain.

Alzheimer’s disease (AD) is a complex disease with multifactorial etiology. Inflammation has been proven to have an important role in the pathogenesis of AD. Both CCR2 and CCR5 genes expression increase in AD patients comparing to control subjects. CCR5 gene encodes a protein which is a member of the beta chemokine receptors family of integral membrane proteins. CCR5-Δ32 is a genetic variant of CCR5 and is characterized by the presence of a 32-bp deletion in the coding region of the gene, which leads to the expression of a nonfunctional receptor, and the CCR2-64I has a change of valine to isoleucine at codon 64, in the first transmembrane domain. It has been proved that both genes have important roles in different stages of inflammation. The frequencies of CCR5∆32 and CCR2-64I variations were determined in 156 AD patients and 161 control subjects using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) methods, and the results were compared among AD and healthy controls.Statistical analysis showed no significant difference in the distributions of CCR5∆32 and CCR2-64I between the AD patients and healthy controls (P> 0.05). Stratifying the samples by gender, genetic background and presence of ApoEε4 allele showed no significant effect on the distributions of CCR5∆32 and CCR2-64I (P> 0.05). Our study did not show an association between CCR5∆32 and CCR2-64I variations and AD in the Iranian population. Further confirmatory studies with bigger number of samples are recommended.

Inhibitors of p38 MAP kinase are considered as suitable target in the treatment of inflammatory diseases such as rheumatoid arthritis and bowel inflammatory diseases. The development of 5-alkylthio-1-aryl-2-(4-pyridinyl) triazoles as inhibitors of p38 MAP kinase is described. These are analogues of 4- pyridinyl imidazole p38 MAP kinase inhibitor reported by Merck Research Laboratories, in which imidazole ring has been replaced with triazole. Reaction of pyridine-4-carboxylic acid hydrazide 1 and arylisothiocyanate (2a, b) gave the intermediate thiourea derivative 3a, b (Figure 2). Refluxing of the latter in aqueous saturated sodium carbonate gave 1-aryl-5-mercapto-2-(4-pyridinyl) triazoles 4a, b. Treatment of 4a, b with alkyl iodide afforded the desired 5-alkylthio-1-aryl-2-(4-pyridinyl) triazoles (5a-d). P38 MAP kinase inhibitory activity of the synthesized compounds was evaluated in vitro by ELISA method and also by molecular docking. Compound 5c at 1 µM concentration and compound 5d at 1 µM and 10 µM significantly inhibited the p38 phosphorylation. These inhibitory effects are equal to those of standard compound SB202190 and no significant differences were observed.We demonstrated that both tested compounds have inhibitory effect on p38 MAP kinase and we did not find significant difference between their inhibitory effects and those of standard inhibitor SB202190.

High blood glucose induces molecular, cellular, morphological and behavioral changes in the brain. Metabolic disturbances, contribute to the hippocampus injury and development of partial focal seizures. The aim of this study was to investigate the effects of infantile repeated hyperglycemia on neuronal density of hippocampal CA3 region in newborn Wistar male rats and its effect on chemoconvulsant pentylentetrazol (PTZ) induced generalized seizures in adults.Ten days old male Wistar rats were randomly divided into 2 groups (n=20 for each): hyperglycemic and control. Hyperglycemia was induced by intraperitoneal injections of 2 g/kg dextrose solution, twice a day, for 2 weeks. Control animals received saline solution in the same manner. Blood glucose was regularly measured. After that, the brains of rats from each group (n=10) were removed for histological analysis of the CA3 region of hippocampus by stereological method. Other animals (n=10) were kept to grow older. Afterwards, seizure was induced in hyperglycemic and control adult rats, by an intraperitoneal injection of 45 mg/kg PTZ solution and then latency of convulsions onset and severity of seizures for each group were recorded.Results showed that hippocampal neuronal density decreased significantly and susceptibility to PTZ induced convulsions increased in experimental animals. The result determined that repeated increments in daily blood sugar levels in infantile period may damage neuronal structures of hippocampus and also make adults more susceptible to PTZ induced convulsions in adulthood period.

Oxidized low-density lipoproteins (ox-LDLs) appear to play a significant role in atherogenesis. In fact, circulating ox-LDL concentrations have been recognized as a risk factor for cardiovascular disease (CVD). The main objectives of this study were to assess the effects of antioxidant vitamins on ox-LDL as a biomarker of CVD in male subjects with CVD risk factors.The effect of antioxidant vitamins on ox-LDL as a biomarker of CVD in male subjects with CVD in male subjects with CVD risk factors at baseline and after 12 weeks of supplementation with vitamin E (400 IU), C (500 mg), ß-carotene (15 mg), and the combined supplements (E, C, and ß-carotene) respectively defined as group E, C, B and control group was considered as group P. The mean values for ox-LDL at the baseline were 86.93 ± 26.30 U/l in group C, 94.52 ± 38.40 U/l in group E, 79.73±2.07 U/l in group B, 85.97±23.07 U/l in combined group, and 84.90± 14.66 U/l in group P. After 12 weeks of intervention the percentage of changes for group C, group E, group B, COM group, and group P were (-18.32), (-2286), (-17.31), (-19.01) and (-2.0), respectively. Using Wilcoxon method, significant differences were detected in the mean ox-LDL concentrations of baseline and after intervention, values in the C, E, B and combined groups (P< 005). This study illustrated that diet supplemented with vitamin C (500 mg), vitamin E (400 IU), ß-carotene (15 mg), and the combination of these vitamins was associated with lower serum ox-LDL levels.

The purpose of this study was to investigate the role of oxidative stress in Purkinje cell neurotoxicity ofethanol-treated rat. Male rat pups 4-day-old was used in this study. Ethanol was administered to rat pups at a dose of 6 g/kg from postnatal days (PDs) 4 to 5. Pups were killed 90 min after the second alcohol treatment on PD 5 by decapitation and the brain was immediately removed. The cerebellum was dissected for analyzing the oxidative stress parameters and histological study. The activities of several antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) in vermis of cerebellum were assayed. Thiobarbituric acid reactive substances (TBARS) levels were also measured as a marker of lipid peroxidation. Administration of ethanol significantly increased TBARS levels in the cerebellum compared to control pups (P< 0.01). The treated pups with ethanol exhibited a marked decrease in the GPx activity (P< 0.01) whereas, in spite of decrease in the activities of SOD and CAT, when compared to control, there were not significant differences. The spherical cell bodies of Purkinje cells in control rats are aligned nicely between the granular and molecular layers. In ethanol treated pups, Purkinje cells scattered within the Purkinje cell layer and shrinkage of the cell somata is seen.The results of the present work demonstrated that ethanol exposure during the vulnerable window could increase TBARS levels (lipid peroxidation) and decrease GPx levels in pup's cerebellum. Also, the results confirmed ethanol-induced microencephaly, cerebellar Purkinje cell loss. These findings suggest that Purkinje cell loss is, in part through decrease in the activity of GPx and increase of lipid peroxidationin the rat cerebellum.

Staphylococcus aureus is both a successful human commensal and a major pathogen. In this study we investigated the genetic diversity of 26 S. aureus isolates recovered from human skin and urinary tract infections. Typing procedure for the studied S. aureus isolates was performed based on PCR amplification of the aroA gene, which encodes the enzyme 5-enolpyruvylshikmate-3-phosphate synthase (EPSPS) that involves in aromatic amino acid biosynthesis, and restriction fragment length polymorphism (RFLP) analysis of the product. All S. aureus isolates produced a single PCR amplification product of 1,153 bp. Digestion of the PCR products with the TaqI endonuclease revealed four different aroA gene patterns designated as A, B, N and H according to the nomenclature system of previous studies. In general, 80.77% of the studied isolates displayed type N, 7.69% were type B, 7.69% were type H and 3.85% displayed type A. Divergent aroA types were detected among S. aureus isolates from skin and urinary tract infections. The results showed that urinary tract infections were contaminated by S. aureus isolates with identical banding patterns (A), while isolates recovered from skin infections had different aroA types. This study also indicates that aroA genotypes vary not only from region to region, but also in individual hosts within a region.

Since diabetes mellitus is accompanied by cognitive impairment in diabetic patient and animal models and since lipids play important roles in neuronal membrane composition, structure and function; we intended to evaluate the effect of dietary butter oil on passive avoidance memory of streptoztosin (STZ)-induced diabetic rats in this study. Thirty six adult male rats were randomly allocated to four equal groups: normal (N) and diabetic control (D) groups with free access to regular rat diet; but the diet of normal butter oil (NB) and diabetic butter oil (DB) groups was supplemented with 10% butter oil. Diabetes in D and DB groups was induced by intravenous (i.v.) injection of 50 mg/kg.bw of STZ. Passive avoidance memory and cholesterol of brain and hippocampal tissues has been measured six weeks after diabetes confirmation. Diabetes, especially in diabetic butter oil group decreased the abilities of learning and memory. The level of cholesterol in hippocampus was higher in NB (P< 0.05) and DB (P< 0.01) groups.We suggest consumption of butter oil may worsencognitive impairment of diabetic animal. This may be related to the higher elevation of cholesterol in the hippocampus of diabetic animals.

Motor deficit and neuron degeneration is seen after nerve transection. The aim of this study is to determine whether a poled polyvinelidene fluoride (PVDF) tube with other supportive strategies can protect the neuronal morphology and motor function after sciatic nerve transaction in rats.After transection of the left sciatic nerve in 60 male Wistar rats (200-250 g), the epineural group was sutured end to end. In the autograft rats, a 10 mm piece of sciatic nerve was rotated 180 °C and sutured back into the nerve gap. In the nerve guidance channel (NGC) group, polarized piezoelectric PVDF tube containing NGF and collagen gel was sutured in the gap. In control group sciatic nerve was removed (10 mm) without repair. After one, four and eight weeks, the L4-L6 spinal cord segment was removed for histological study using transmission electron microscope. Functional outcome was assessed using the Basso, Bresnahan and Beattie (BBB) locomotor scale at both four and eight weeks after the lesion.Chromatin condensation was seen after 4 weeks in the repair groups. Cell membrane shrinkage and mitochondrial degeneration was observed after 4 and 8 weeks respectively, in the autografted and NGC rats. In the control group, chromatin condensation, cell membrane shrinkage with mitochondrial degeneration and vacuolization of perikaryon was seen after 1, 4 and 8 weeks, respectively. At 56 days, the functional recovery of the epineural rats significantly increased in comparison to the other groups (P< 0.05).The epineural suture has more efficacies, and NGC may be used as a proper substitute for autograft in nerve injury.

This study was conducted to evaluate the effects of niacin on glucocorticoid-induced dyslipidemia and fatty liver in rats. Twenty four adult male rats were divided randomly into four equal groups: 1- normal saline (control), 2- dexamathasone 0.125 mg/kg/day, i.m., 3- dexamathasone + niacin 200 mg/kg/day, oral gavages, 4- niacin. After 2 weeks, serum total cholesterol, triglycerides, HDL-c, LDL-c and VLDL-c concentrations were assayed and liver sections examined for fatty liver changes. Data were analyzed by ANOVA method and P< 0.05 was considered significant.Dexamethasone increased all lipid parameters as compared to control (P< 0.05). Lipid parameters in group 3, were lower than group 2 (P< 0.05) except for HDL-c which remained statistically the same. Moderate fatty liver changes were observed in one third of rats in dexamethasone group. Rats in groups 1, 3 and 4 had no sign of fatty changes. Niacin positively affects glucocorticoid-induced dyslipidemia and fatty liver changes in rats.