Physiology and Pharmacology
Year:2012 | Volume:15 | Issue:4|Papers Count:18

The submitted articles to Iranian congress of physiology and pharmacology could be analyzed for the distribution of research in different fields. Based on field distribution of articles in 20th congress, it seems that a strategic planning for research development in the field of physiology and pharmacology is essential. It is also suggested to revise the congress scientific structure, and to use a common language for research methodology.

Introduction: Ghrelin increases growth hormone secretion and food intake. Growth hormone (GH), steroid hormones and opioids are involved in the regulation of food intake. So, they may have a role in the regulation of ghrelin secretion. We determined the effect of intravenous injections of progesterone, GH and morphine or co-administration of these hormones on ghrelin concentration and body weight in sheep with food deprivation.Methods: Ten sheep (weighing 30-35 kg) were randomly divided into 2 groups that received either 50% or 100% of their diet for 10 days. Both groups on days 7, 8, 9 and 10 received progesterone (1mg), simultaneous injection of progesterone (1mg) and GH (0.01mg), simultaneous injection of progesterone (1mg) and morphine (1mg) or co-administration of progesterone (1mg), GH (0.01mg) and morphine (1mg) via jugular vein, respectively. Blood samples were taken before injection and 2 h after injection via jugular vein. Body weight was measured on first, 7th and 10th days of experiment. Serum ghrelin concentration was measured by RIA.Results: Results showed that food deprivation increased ghrelin concentration. Also, intravenous injection of progesterone reduced ghrelin concentration in sheep and this reduction was significant in ad libitum (P<0.05). Simultaneous injection of progesterone and GH, simultaneous injection of progesterone and morphine or co-administration of progesterone, GH and morphine significantly increased ghrelin concentration in both groups (P<0.05).Conclusion: Progesterone-induced increase in appetite is not due to ghrelin. Injection of progesterone (1mg) decreased ghrelin concentration, but simultaneous injection of progesterone (1mg) and growth hormone (0.01mg) increased it.

Introduction: There is considerable evidence that glutamate-mediated excitatory neurotransmission plays an important role in mediating the behavioral actions of acutely administered ethanol. The aim of the present study was to investigate the effect of acute ethanol exposure on NR1 subunit of NMDA (n-methyl-d-aspartate) receptor distribution in the cerebral cortex of chick embryo on the 10th and 15th day of egg incubation.Methods: Forty fertilized eggs were divided in two groups; control and ethanol (70% ethanol). In both groups, on the 10th and 15th days of embryonic stage, brain coronal sections were prepared for determination of distribution of NMDA receptor NR1 subunit by immunohistochemical method. Image analyzer software was used for color analysis.Results: Immunohistological findings of these experiments indicated that acute exposure to ethanol significantly decreased the density of NMDA receptors NR1 subunits in chick brain on the 10th and 15th day of the embryonic stage. Also, the ratio of the number of NMDA receptor NR1subunit to immunoreactive cells were significantly decreased in acute ethanol groups.Conclusion: Our results indicated that acute exposure to ethanol decrease NR1 receptor distribution and the ratio of the number of NMDA receptor NR1 subunit to immunoreactive cells in the brain of chick embryo on the 10th and 15th day of embryonic stage.

Introduction: Cisplatin is used as a chemotherapeutic agent for the treatment of human ovarian and testicular cancers. This study was designed to investigate the protective role of taurine against cisplatin-induced kidney injury.Methods: Male Wistar rats were divided into 4 groups (n=8) (1) saline-treated group (2) cisplatin-treated group (10 mg/kg, i.p.), (3) group that received taurine (200 mg/kg, i.p) 1 hr before cisplatin (10 mg/kg, i.p) administration and (4) taurine treated group (200 mg/kg, i.p). The treatment period was 7 days. Animals were then weighed and blood samples were collected from the heart. After sacrifice, kidneys were removed and kept at -70oC until further analyses.Results: Cisplatin significantly elevated the creatinine and blood urea nitrogen (BUN) serum levels (P<0.05). Pretreatment with taurine resulted in a remarkable reduction of these markers. The catalase activity in cisplatin-treated rats was significantly decreased (P<0.05) and taurine administration could remarkably recover this decreased activity. Malondialdehyde (MDA) content of the kidneys was increased in cisplatin-exposed animals and taurine significantly reduced the amount of MDA.Conclusion: Our data suggest that pretreatment with taurine might be considered as a protective approach in cisplatin-induced nephrotoxicity.

Introduction: Pharmacological blockage of glial activity has been proved useful for treatment of neuropathic pain by lowering proinflammatory cytokines. The present study is to confirm the effect of post-injury administration of pentoxifylline on chronic constriction injury (CCI)-induced neuropathic pain symptoms_and improved the efficacy of morphine anti-nociception.Methods: Male Wistar rats (230-270 g) underwent surgery for induction of CCI model of neuropathy. In the sham group the nerve was exposed but not ligated. In 5 groups (n=8) morphine (2.5, 5, 7.5, 10, 15 mg/kg s.c.) was administered in post-operative days (POD) 0, 6 and 14. To evaluate the analgesic effect of different doses of morphine, Von Frey and Hargreaves tests were performed before and 30 minutes after morphine administration. In different groups, pentoxifylline (8, 15, 30 mg/kg i.p.) or normal saline (vehicle) were administered from POD6 to POD13. Behavioral tests were utilized after last dose of pentoxifylline and also on POD14 again after injection of a single dose of morphine (5 mg/kg, s.c.).Results: The analgesic effect of morphine (5 mg/kg) on POD6 and morphine (5, 7.5, 10, 15 mg/kg) on POD14 was significantly decreased in comparison to POD0. Pentoxifylline effectively attenuated thermal hyperalgesia (at 15 and 30 mg/kg) and mechanical allodynia (at 30 mg/kg) on POD13. However, pentoxifylline (15, 30 mg/kg) improved the anti-hyperalgesic effect of morphine (5 mg/kg s.c.) on POD14.Conclusion: Analgesic effect of morphine was reduced after nerve injury and it may be due to the activation of glia. Inhibition of glial activity is an effective way to attenuate CCI-induced neuropathic pain and also to improve the anti-hyperalgesic effect of morphine, without significant effect on its anti-allodynic effect.

Introduction: Recently, hydrogen sulfide has been introduced as the third gas that acts as a transmitter. It has many physiological and pharmacological roles in the human body. The aim of the present study was to investigate the effect of exogenously administered and endogenously produced H2S on the basal and distention-induced gastric acid secretion in rats.Methods: Forty-nine male Wistar rats (150-200 g) were randomly assigned into 7 groups (7 rats per group). To evaluate the effect of H2S on the basal acid secretion, three groups of animals received an IV bolus of NaHS, a H2S donor, at the doses of 20, 40 or 80 mg/Kg. The effects of IV NaHS 20, 40 or 80 mg/Kg were also investigated on distention-induced gastric acid secretion in other three groups. In order to evaluate the effect of endogenously produced H2S on distention-induced gastric acid secretion, one group of animals received IV propargylglycine (PAG), a cystathionine-g-lyase inhibitor, 100 mg/kg.Results: NaHS decreased the basal and distention-induced gastric acid secretion in a dose-dependent manner (P<0.01). PAG increased the gastric output in response to distention compared to the control group (P<0.001).Conclusion: Our results showed that both exogenous administration and endogenous production of H2S decrease the gastric acid output. Also, the findings of the present study suggest that endogenously produced H2S has a modulatory effect on stimulated gastric acid output similar to nitric oxide (NO).

Introduction: Previous studies have indicated a relationship between MPTP pore and AV nodal rate-dependent properties. The aim of present study was to determine acute direct effects of cyclosporine on extracellular field potential of isolated rabbit AV node during experimental atrial fibrillation.Methods: In one group of male New Zealand rabbits (1.5-2.5 kg) cumulative concentrations of cyclosporine (0.5-10mm) were applied on isolated perfused atrio-nodal preparation (n=7). Extracellular field potential recording was sampled during specific stimulation protocols (recovery, zone of concealment and atrial fibrillation) in the presence of drug on electrophysiological properties of AV-node.Results: Cyclosporine significantly decreased the ventricular rate (HH mean) from 231.8±5.7 to 277.4±14.6 msec and functional refractory period during AF (AF FRP) from 138.3±7.5 to 161.2±10.31 msec in control and treated groups, respectively. Effective refractory period during AF (AF ERP) was significantly decreased by cyclosporine 10 mM compared to control group (p<0.05).Conclusion: Cyclosporine-evoked slowing ventricular heart rate during AF was induced by increasing functional refractoy period and ZOC. A possible mechanism can be through blocking of MPT pores.

Introduction: Heart secretes hormones such as natriuretic peptide. The purpose of this study was to investigate the effects of 12 weeks of resistance training on these hormones.Methods: Twenty four healthy men (Mean age±SD: 24.9±3.2 years) were randomly allocated to experimental and control groups. Subjects in the experimental group performed a 12-week resistance training program, 3 sessions per week at an intensity between 55 to 75% of maximum strength. Each session of training included three sets of 10 repetitions for 8 exercises of upper and lower body. Two blood samples were taken before and 48 hours after training period for measuring ANP, BNP, endothelin-1 and angiotensin II.Results: Resting values of ANP before and after 12 weeks of training for experimental group were 0.87±0.22 and 0.89±0.30 nmol/L, respectively, while these values for control group were 0.92±0.30 and 0.92±0.31 nmol/L, respectively. Data analysis revealed no significant difference between the effects of training on resting levels of ANP, BNP, endothelin-1 and angiotensin II in two groups (P>0.05). In addition, no significant difference between pre-and post-training values of ANP and BNP was observed when data were separately compared in each group.Conclusion: Based on the findings of the present study, it could be concluded that resistance training does not induce changes in resting levels of cardiac hormones (ANP and BNP), and that beneficial changes induced by exercise training might not be due to changes in these parameters.

Introduction: Aging has negative effects on motor and cognitive functions, therefore finding appropriate strategies to prevent the decline of these functions is necessary. It seems that cardiovascular fitness obtained by aerobic activity is a physiological mediator that explains the relationship between physical activity and improved cognitive performance. The aim of this research was to assess the effects of aerobic activity on spatial learning and motor activity in aged rats.Methods: 24 Albino Wistar healthy aged male rats were randomly divided into control (weight: 458±34 grams) and aerobic activity (weight: 443±40 grams) groups. Aerobic activity group ran 8 weeks on treadmill according to Brooks et al. (1984) protocol. After the end of physical activity period, Morris Water Maze and open-field tests were performed to assess spatial learning and motor function, respectively. Latency and distance moved to find platform were used as criteria of spatial learning, while distance moved, mobility duration and movement speed were used as criteria of motor function.Results: In spatial learning, aerobic activity group performed better in acquisition (distance moved (F1,22=8.59, p=0.004) and latency time (F1,22=7.22, p=0.007)), probe (time spent in target quadrant (t22=2.24, p=0.018)), and retrieval tests (distance moved (t22=2.823, p=0.005) and latency time (t22=3.73, p=0.001)) compared to the control group. Aerobic activity group performed also better in all indices of motor function including distance moved (t22=2.83, p=0.005), mobility duration (t22=2.15, p=0.03), and movement speed (t22=2.52, p=0.01) compared to control group.Conclusion: Results showed that aerobic activity improves spatial learning and motor function in aged rats.

Introduction: Butylated hydroxytoluene (BHT; 2, 6-di-tert-butyl-p-cresol) is one of the extensively used antioxidants in the food industry. It is used in low-fat foods, fish products, packaging materials, paraffin, and mineral oils. BHT is also widely used in combination with other antioxidants such as BHA, propyl gallate, and citric acid for the stabilization of oils and high-fat foods. On the other hand, some investigators have reported that BHT has psychotic effects. Therefore, the aim of the present study was to investigate the effect of BHT on learning and memory in a model of passive avoidance learning in male rats.Methods: Twenty-eight male rats weighting 180-260 g were used. Animals were divided into 4 groups: 1-control group (received sesame oil with the same volume as experimental groups); -2 experimental 1 (received BHT 25 mg/kg/day); 3- experimental 2 (received BHT 100 mg/kg/day) 4- experimental 3 (received BHT 150 mg/kg/day). BHT was administered by oral intake for 15 days. Learning and memory were assessed by a passive avoidance shuttle-box. Data were analyzed by one way ANOVA and Tucky's post-hoc test. The level of significant was set at P<0.05.Results: Our data showed that BHT at the doses of 25, 100 and 150 mg/kg/day significantly decreased the time spent in light compared to the control group.Conclusion: According to our results, BHT impairs learning and memory in passive avoidance learning.

Introduction: Based on human studies, inequality and social injustice have adverse effects on the individual and community health. In this study, the effects of food intake inequality and social status changes on pain perception and immunological factors were investigated in Balb/C mice.Methods: The present study was conducted by implementing different social stresses including food deprivation, food intake inequality and unstable social status (cage-mate change every 3 days) in 48 female mice. Formalin test was performed and thereafter the viability of peritoneal macrophages and spleen lymphocytes was evaluated by MTT assay.Concentrations of proinflammatory cytokines including IL-6, IL-1 and TNF-a were also measured.Results: Our results showed that the implementation of food deprivation and inequality induced significant changes in chronic phase of formalin test compared to the control group (P<0.05). Pain perception was considerably decreased and this decline in inequality exposed subjects was well above the isolated ones. However, unstable social situation did not affect pain perception. Moreover, cell viability of peritoneal macrophages decreased, while cell viability of spleen lymphocytes and proinflammatory cytokines concentrations were increased in the serum of all stressed animals in comparison with controls (P<0.05).Conclusion: These results revealed that although food deprivation and social inequality can induce analgesia, some socioeconomic situations like social instability does not affect pain perception. All of these situations decrease cell viability in macrophages but enhance cell viability in lymphocytes. It seems that a proinflammatory stress condition is involved in these situations.

Introduction: Liver plays a pivotal role in glucose and lipid homeostasis. This study was undertaken to evaluate the effects of L. acanthodes hydro-alcoholic extract administration on the liver functional and histological parameters in hyperglycemic rats.Methods: Twenty-four male Wistar rats were randomly allocated into four groups; control, hyperglycemic (STZ), hyperglycemic + insulin (STZ+Ins) and hyperglycemic + extract (STZ+Ext). After a single injection of STZ (55 mg/kg, i.p.) and confirmation of hyperglycemia induction, rats of STZ+Ins and STZ+Ext were daily treated with insulin (5 IU/kg/day) and extract (150 mg/kg/day), respectively, for 21 days. To assess the serum levels of biochemical parameters and liver markers, all rats were kept until the 7th week and then they were sacrificed and their livers were histologically examined.Results: Serum levels of ALT, AST, ALP, glucose and triglyceride in STZ and STZ+Ins groups were significantly increased in comparison with control and STZ+Ext groups at the 2nd week. At the 4th week, although the mean levels of liver enzymes were increased in STZ+Ext (p<0.05) but its level of significance was lower that STZ and STZ+Ins groups (p<0.001) groups. Microscopic examination of liver sections showed no histological difference between control and experimental samples.Conclusion: Streptozotocin induced hyperglycemia may result in abnormal levels of liver markers. This liver malfunction is probably caused by hepatocyte membrane damage due to the free radical production induced by hyperglycemia. It seems that antioxidant property of flavonoids constituents of L.acanthodes, may prevent hepatocytes damage and therefore reduce the serum levels of liver markers.

Introduction: Cardiac preconditioning represents the most potent and consistently reproducible method of rescuing heart tissue from undergoing irreversible ischemic damage. The aim of the present study was to evaluate oxytocin (OT) induced cardioprotection and its signaling pathways on lactate dehydrogenase (LDH) and creatine kinase-MB isoenzyme (CK-MB) in the anesthetized rats.Methods: Eighty-four rats were divided into fourteen groups. Animal’s hearts were subjected to 25 min ischemia and 2 h reperfusion (I/R). Oxytocin (0.03 mg/kg) was used 25 min prior to ischemia. Atosiban, an OT receptor antagonist (1.5 mg/kg), 5-hydroxydecanoic acid, an inhibitor of mitochondrial ATP-dependent potassium channel (10 mg/kg), atractyloside, an opener of mitochondrial permeability transition pores (5 mg/kg), chelytraine, a protein kinase C inhibitor (5 mg/kg) and N-acetylcysteine, a reactive oxygen species scavenger (200 mg/kg) were used 10 min prior to OT administration. Then, LDH and CK-MB levels in plasma were measured.Results: OT administration significantly decreased CK-MB and LDH levels compared to I/R group. Administration of atosiban, 5-hydroxydecanoic, atractyloside, chelytraine and N-acetylcysteine abolished the cardiac preconditioning effect of OT.Conclusion: The present study demonstrates that oxytocin cardioprotective effects are complex and its signaling pathways may mediate through mKATP channels, mPTP, PKC activation and increase ROS.