[Effect of oral vanadyl sulphate on ultrastructure of pancreatic islets beta cells in streptozotocin-induced diabetic rats]

Considering insulin like effects of vanadium salts, these compounds have been evaluated as a therapeutic agent for treatment of diabetes mellitus in the experimental models of the disease in animals. This study was performed to study the ultrastructrure of islet beta cells in streptozotocin [STZ]- induced diabetes in rats after treatment with vanadyl sulfate [VS]. diabetes was induced in male Wistar rats by intravenous injection of 40 mg/kg STZ. Equal volume of normal saline was injected via lateral tail vein in sham animals. Seven days after injection animals in both groups were divided into treated and control groups. VS was added to the drinking water of the diabetic treated [DT] and Sham treated [NT] animals with a concentration of 0.5 mg/ml for one week and 1mg/ml up to three months. Untreated diabetic [DC] and sham rats [NC] received tap water during this period. Two months later all animals were killed. Langerhans islets were isolated from exocrine parts by use of collagen digestion, and were fixed in glutaraldehyde. Ultrastructure of islet beta cells were studied by means of transmission electron microscope. VS treatment led to amelioration of the symptoms of diabetes including hyperglycemia and polydepsia in DT rats. DC rats remained diabetic during the period of study. No significant changes were observed in plasma glucose and fluid intake of NT animals. Ultrastructural studies of islet beta cells of DT rats showed normal cells with normal chromatin distribution, well-developed rough endoplasmic reticulum, increased cytoplasmic granules and no clear sign of cell injury. Lymphocytic infiltration was not detected in langerhans islets of DT group. Nuclear pyknosis, cytoplasmic vacuolization, lymphocytic infiltration and signs of cell death such as cell necrosis were found in the islets of beta cells of DC rats. Cytoplasm of islets beta cells of NT rats were more granular in comparison to NC rats. Considering the results of this study we concluded that amelioration of diabetes signs in VS treated STZ induced diabetic rats are accompanied by preservation of islets beta cells ultrastructure

[Twenty four- hour circadian melatonin profile among women shift work nurses]

According to previous studies shift work could desynchronize the natural circadian rhythm of the body. Although some of the internal physiologic processes become active for adaptation of the body with this desynchronization. One of these physiologic processes is endocrine system and melatonin release. This hormone is one of the most important variants which represent the circadian rhythm in human. Since the pattern of secretion of this hormone in first ours of morning and during the day in Iranian workers in particular in shift workers is unknown, therefore we aimed to determine the 24 hours profile of melatonin in shift work and permanent day shift nurses. This experimental study was carried out on forty four female nurses of the Shiraz university hospital, during 2006-2008. Thirty four people in study group had a cyclic shift work and 10 persons in control group had permanent day shift work. The serum samples with 3 hours intervals during 24 hours were taken from each person. The plasma concentration of melatonin was measured by ELISA. Our study was carried out under realistic conditions. The data were analyzed using one -way ANOVA. The age range was between 22 to 50 years with a mean work history of 5.5 years. The highest and the lowest melatonin levels was found in shift work nurses at 04:00 pm [14.91 pg/mL], and 04:00 am [131.49 pg/mL]. These values for permanent day work nurses in the same times was 1.02 pg/mL and 177.40 pg/mL respectively. There was a significant difference between circadian melatonin profile at different time points [P= 0.000]. The results of this study revealed that night work induces a consistent change in melatonin circadian profile with a progressive reduction at early morning [04:00 am] and awaking time [07:00 am]. These changes will also disturb sleep cycle and level of consciousness during the night and activities during the day

role of K-ATP channel in the preconditioning effect of magnesium in the rat isolated heart

There is growing interest for beneficial effect of Mg in the cardiovascular disorders. A number of cardiovascular disorders including myocardial infarction, arrhythmias and congestive heart failure have been associated with low extracellular or intracellular concentrations of Mg. The aim of present study was to investigate the preconditioning effects of magnesium [Mg] on cardiac function and infarct size in the globally ischemic-reperfusion in isolated rat heart. Rat hearts were Langendorff-perfused, subjected to 30 minutes of global ischemia and 90 minutes of reperfusion, and assigned to one of the following treatment groups with 7 hearts in each group: [1] control, [2] ischemic- reperfusion, [IR], [3] ischemic preconditioning, [IPC] of 5 minutes of global ischemia - reperfusion before lethal ischemia; or pretreatment with [4] 30 Mu mol/L of Diazoxide [Dia], [5] 8 mmol/L magnesium, [6] 10 Mu mol/L glibenclamid [Gli], [7] magnesium and Dia and [8] magnesium and Gli. Infarct size was measured by the triphenyltetrazolium chloride method. Left ventricular function was assessed by left ventricular developed pressure [LVDP], heart rate and coronary flow [CF]. Mg limited infarct size [9.76% vs 44.47% in IR, P< 0.001] as did Dia [10.2% vs 44.4% in IR P< 0.001] and IPC [8.69% vs 44.47% in IR, P< 0.001]. The protective effect of magnesium was abolished by Gli. Administration of Mg had an anti-infarct effect in ischemic-reperfusion isolated rat hearts and improved cardiac function. Blockade of K-ATP channel abolished the protective effects of magnesium and suggest that K-ATP channel has an important role in this effects

Effect of Zinc on brain GABAergic system activity in animal model of seizure induced in rat

In epileptic patients, seizure and behavioral disorders are the most important signs; therefore evaluation of these disorders using annual model can be conducive to advantage. Determination of the role of zinc in seizure and the relation of zinc concentrations in serum and hippocampus may be beneficial in developing preventive and therapeutic measures for epilepsy. The main purpose of this study was to evaluate the effect of zinc on seizure and its relation with GABAergic system activity. This was a prospective, empirical and blind study. 48 adult male Sprauge-Dawley rats were randomly assigned in six groups [n=8]. 3 groups were treated with zinc and other 3 groups with tap water. Epileptic model was induced by injection of Lithium chloride [127mg/kg] and 24 hr later, pilocarpin [50 mg/kg] into peritoneum. After first injection, group 1 and 4 received saline, group 2 and 5 bicuculine [1 mg/kg] and group 3 and 6 pentobarbital [10mg/kg] injections, Episodes of seizure disorders were recorded at 1 and 2 hrs after injection. The results of this study showed that Zn had a potentiating effect on seizure. GABA A antagonists had the same effect as Zn on seizure but GABA A agonists ameliorate it significantly. Serum zinc level didn't change significantly among the animals but hippocampus zinc declined significantly in Zn treated animals compared with those of the controls. This study shows that Zn deleterious effects on seizure were probably carried out via GABAergic system

Histological and immunohistochemical study of pancreatic islet beta cells of diabetic rats treated with oral vanadyl sulphate

Vanadium salts have been suggested as a possible therapeutic agent for the treatment of diabetes. The aim of the present study was to clarify histological and immunohistochemical changes that occur in the pancreatic [beta] cells of vanadyl sulphate [VS]-treated streptozotocin [STZ] induced diabetic rats. Male Wistar rats were made diabetic by injecting a single intravenous dose of STZ [40 mg/kg] and were divided into two groups seven days after STZ injection. In the first group VS was administered via drinking water at a concentration of 1 mg/mL and treatment was maintained until normoglycemia appeared [DT]. A second group of diabetic animals received distilled water for the same period and were considered as control diabetic [DC]. One group of animals [NC] was injected intravenously with the same amount of vehicle as the diabetic rats and was considered as non-diabetic control. VS treatment was accompanied by amelioration of the signs of diabetes in DT rats while DC animals remained diabetic during this period. Hemotoxylin - Eosin stained pancreatic sections of DC rats showed a decrease in the number and size of islets and a disruption in their architecture. In DT rats the histological appearance of the islets was normal, their shape and size being within normal limits. In horseradish peroxidase procedure [using guinea pig antiserum to insulin as primary antibody] performed on pancreatic islet paraffin sections of rats, insulin immunoreactivity was found in the majority of the islets in DT rats while in the islets of DC rats immunoreactivity was rare. The results of this study indicated that amelioration of diabetes in vanadyl sulphate treated diabetic rats was accompanied with well preservation of islet structure and insulin immunoreactivity