مجله فیزیولوژی و فارماکولوژی ایران
پیاپی 1 (بهار 1396)

Bisphenol A (BPA), known as a xenoestrogen, is widely used in industry and dentistry. Epigallocatechin-3-gallate (EGCG) is a strong antioxidant playing important role in scavenging of free radicals .This study aims to investigate the protective role of EGCG on BPA-induced oxidative stress in mesenchymal stem cells (MSCs).

After isolation and culture of MSCs from adult rats, cells divided into 4 groups: control, BPA, EGCG, and BPA+EGCG. Then cells were treated for 24, 36, 48, 60, and 72 h and viability, cell morphology and calcium content of cells were evaluated.

BPA caused significant dose- and time-dependent reduction of viability and calcium content. In addition, morphological changes such as cytoplasm shrinkage were observed in the group treated by BPA. EGCG inhibited the cytotoxicity and morphogenic changes induced by BPA.

BPA reduces the viability of mesenchymal stem cells and the antioxidant EGCG reduces the BPA-induced toxic effects.

Fluid therapy can be a useful method in order to save the lives. Although many studies have been done on the effect of isotonic and hypertonic solutions, little attention has paid to their effects in normal animals. Thus, we examined effects of isotonic saline, hypertonic saline 7.2% and hypertonic dextrose 50% solutions on some hematologic parameters in healthy dogs.

Four healthy male dogs (similar age and weight) were treated alternatively by normal saline (30 ml/kg), hypertonic saline (7.2%; 5 ml/kg) and hypertonic dextrose (50%; 5 ml/kg) solutions, or did not get any treatment (control group) and some hematologic parameters were measured at 0, 10, 30, 60, 120 and 240 minutes after rapid intravenous injection.

The most changes were observed in the initial period after injection of solutions but the extent and duration of the changes were different. The changes induced by hypertonic dextrose solution returned to normal level more rapidly than that of induced by normal saline and hypertonic saline. Thus changes were made by normal saline and hypertonic saline solution was more stable.

High dose normal saline and low dose hypertonic saline exhibit fairly similar effects on hematologic parameters. Therefore, use of hypertonic saline can be a good choice in emergency conditions due to rapid increase in blood volume and more stability.

Acute injection of corticosterone impairs memory retrieval in experimental animals.  On the other hand, sex hormones can modulate memory retrieval. The aim of this study was to examine the effects of concurrent injections of corticosterone and progesterone on memory retrieval in the proestrus (when the levels of endogenous estrogen and progesterone are high) and diestrous (when the levels of endogenous estrogen and progesterone are low) stages in adult female rats.

Adult female Wistar rats were trained in an inhibitory avoidance task (1mA, 3s). The latency to reenter the dark compartment and also time spent in the dark chamber were recorded in the retention test performed 48 h after training. In experiments 1 and 2, corticosterone (3 mg/kg, i.p) or vehicle was injected to intact female rats in the proestrus or diestrus phases 30 min before retention test. In experiments 3 and 4, rats in the proestrus or diestrus phase were received vehicle or progesterone (5 mg/kg, i.p) 60 min, and vehicle or corticosterone (3 mg/kg) 30 min before the test.

Acute injection of corticosterone to female rats in the diestrous stage, but not in the proestrus stage impaired memory retrieval. Pretreatment with progesterone did not influence the corticosterone effects on memory retrieval in the proestrus or diestrus phases.

Corticosterone impairs memory retrieval only in the proestrus phase and this effect did not change with pharmacological levels of progesterone.

 Licorice (Glycyrrhiza glabra) rhizome has been widely used in traditional medicine for treatment of gastrointestinal disease. In the present study, the effect of a hydro-alcoholic extract of licorice rhizome on mechanical activity of isolated ileum of male rats has been studied.

The hydro-alcoholic extract of licorice rhizome prepared by percolation method. Adult male rats were anesthetized by ethyl ether, their abdomen was opened, the ileum dissected and divided into 1 cm segments. The segments were connected to a force transducer longitudinally and inserted to an organ bath with oxygenated Tyrode’s solution (37°C, pH 7.4). The mechanical activity of ileum was recorded by force isotonic transducer and Power Lab AD instrument in basal condition, and after administration of acetylcholine10-5 M, phenylephrine 2×10-5 M, Isoproterenol 10-4 M and propranolol 10-4 M in the presence and absence of  the extract.

A significant decrease in mechanical activity of the isolated ileum occurred after administration of the extract alone, or the extract along with acetylcholine. However, mechanical activity did not changed when the extract was administered with phenylephrine, with isoproterenol, or with propranolol.

The hydro-alcoholic extract of licorice modulates ileum motility. It seems that the cholinergic system but not the adrenergic system might be involved in this effect.

Estimation of maximal exercise capacity can be used as a diagnostic test in patients with cardiovascular disorders without clinical symptoms. Deficiency of thyroid hormones during fetal life can puts the cardiovascular system at risk. The aim of this study was to assess maximal exercise capacity in offspring male rats with fetal hypothyroidism (FH).

FH was induced in pregnant Wistar rats by administrating 0.025% 6-propyl-2-thiouracil (PTU) in drinking water throughout pregnancy (from first day of pregnancy till delivery), while pregnant rats in control group used only tap water. Maximum exercise capacity (n = 10) was evaluated by running adult male offspring on the treadmill.

The results showed that heart and body weight were lower in FH group than control group. The maximum exercise capacity in offspring rats with FH was also low (p< 0.05). In addition, these rats significantly lost body weight during exercise (adaptation to treadmill and maximum exercise capacity test) compared to control rats.

These findings suggest that maternal thyroid hormone deficiency can lead to reduced maximum exercise capacity in offspring at adulthood.

Production of reactive oxygen species (ROS) and induction of oxidative stress are the main mechanisms of xenobiotics-induced liver injury. Carbon tetrachloride, an organic solvent, has been extensively used as an animal model of liver toxicity through production of free radicals. Polygonum hyrcanicum, Polygonaceae, is an endemic species which grows in north and northeast parts of Iran. Decoction of this plant has been traditionally used in northern parts of Iran, mainly Turkman Sahra, for alleviation of anemia, kidney stones and liver disorders. Considering the phytochemical properties of this plant and its traditional use, in this study the hepatoprotective effect of the aerial parts of P. hyrcanicum was evaluated in CCL4-induced hepatotoxicity in mice.

P. hyrcanicum was collected from Veresk region in Mazandaran province. Methanolic extract of the aerial parts was prepared using maceration at room temperature. Male albino mice weighing 23±5 g were treated with different doses of P. hyrcanicum (500, 750 and 1000 mg/kg), N-acetylcystein (200 mg/kg, as positive control) and water (10 ml/kg, as negative control) by gavage for seven days. Two hours after the last dose, 0.5 ml/kg CCL4 was injected to mice intraperitoneally (i.p.) to induce liver toxicity. Twenty-four hours later, the animals were sacrificed and liver enzymes in the serum and lipid peroxidation in the liver samples were determined.

CCL4 significantly increased the serum levels of ALT and AST and lipid peroxidation in liver samples. Treatment of mice with P. hyrcanicum for seven days decreased significantly the serum liver enzymes and liver lipid peroxidation.

We showed for the first time that methanolic extract of P. hyrcanicum, an Iranian endemic plant, has hepatoprotective properties in mice through inhibition of oxidative stress iduced by oxidants. It is suggested that further studies on the fractions of the crude extract take place to determine the effective ingredient (s) and therapeutic mechanisms.

Evidence indicates an impairment of mitochondrial functions and alterations in potassium channel activities in diabetes mellitus. This study was carried out to consider whether the biophysical properties of the mitochondrial 93 pS cationic channel are altered in diabetes.

Diabetes mellitus was induced in male Wistar rats (200-250 g) by single intraperitoneal injection of 45 mg/kg streptozotocin dissolved in 0.1 M citrate buffer (pH 4.5). The brain mitochondrial inner membranes were extracted and vesicles were incorporated into lipid bilayer membranes, and single potassium channel properties were evaluated. Purity of the cell fraction was also tested by Western blotting. Data were analyzed by Makov noise free single channel analysis.

Based on our previous data, mitochondrial inner membrane has a potassium channel with a main conductance of 93 pS, which was 4-AP-sensitive and voltage-insensitive at -50 to +50 mV. Our data showed that channel conductance decreased to 48 pS and inwardly rectifying current voltage curve was altered to an ohmic behavior in vesicles of diabetic rats but there was no effect on channel open probability. Western blotting and antibodies directed against various cellular proteins revealed that the extracted material contains only mitochondria.

Our data showed that the biophysical properties (conductance) of potassium channel were significantly altered in diabetes. Based on these findings, we propose that the brain mitochondrial potassium channels are involved in diabetes, and it can be considered as a target for therapeutic plans.

Invention of wireless communication in 20th century has changed human social behavior. Advances in this technology has made life easier, while widespread use of electromagnetic waves in base stations, mobile and cordless phones has caused different neurological symptoms in consumers. Hence, widespread trials are conducted to study the effect of these waves on biologic and physiologic processes of the brain.

The current review has categorized findings at different studies, focusing on the effects of mobile phone electromagnetic waves on the brain.

Findings from 94 papers have reaffirmed the side effects of mobile phone radiation with variety of frequencies and power densities on different parts of the brain.

With rapid increase in number of mobile phones users, and particularly juvenile population, safety standards determined by world commissions are not longer valid for depicting the influence of mobile phone electromagnetic waves on brain as now observed in many studies. Thus, further investigations on side effects of mobile phone radiation are deemed.