ABSTRACT
Background and Objective: After chronic stress, brain volume and weight reduces and in turn, adrenal weight and volume increases. This study was performed to determine the effect of chronic stress and memantine administration within amygdala on the alterations of brain's volume and weight ratio to volume and weight of the adrenal gland on male mice
Methods: In this experimental study, bi- or unilateral amygdala cannulation was preformed stereotaxically. A week after recovery, animals were received different doses of memantine [1, 0.5, and 0.1 microg/mouse], five min before stress induction. Electric foot shock induced to animals for seven consecutive days. At the end of the seventh day, animals were sacrificed and their brain and adrenal glands were fixed in formalin 4%. The volume and weight was determined by mercury immersion and accurate balance respectively
Results: Stress non- significantly reduced brain's volume ratio to volume of the adrenal gland and brain's weight ratio to weight of the adrenal gland. Memantine administration within amygdala inhibited stress effect. Memantine administration in low and medium doses within right and left amygdala significantly increased brain's volume and weight ratio to volume and weight of the adrenal gland [P<0.05]
Conclusion: Memantine dose and side dependently inhibits the effect of induced stress in male mice. Also, unilateral memantine administration within the left and right amygdala was more effective
ABSTRACT
Studies have emphasized the effect of Trigonella foenum-graecum extract on the reduction of pain and inflammation. In this research we investigated the mechanisms of Trigonella foenum-graecum extract in reducing pain and inflammation induced by formalin. Male Albino mice [weight 20 - 25 g] were evaluated through the injection of 2 microliters of formalin to the plantar part of right foot. Following this, the rate of animal foot pain and inflammation were measured using Dubbison-Dennis and immersion in mercury. Trigonella foenum-graecum extract was injected 30 minutes before administration of formalin to the animals intraperitoneally. In addition, blood samples were taken from animals and corticosterone concentrations were measured. In an in vitro study the effect of extract on the activity of cyclooxygenase type 1 and 2 was assessed. Our results showed that Trigonella foenum-graecum extract inhibits the first and second phase of pain induced by formalin, while inflammation is slightly reduced. Also the effect of Trigonella foenum-graecum extract is reversible with naloxone or memantine administration. Also Trigonella foenum-graecum extract could not increase plasma corticosterone level and was ineffective in activity of cyclooxygenase type 1 and 2 enzyme. Although Trigonella foenum-graecum extract can inhibit pain induced by formalin administration, but it seems that the reduction of pain is due to the possible interaction of components of Trigonella foenum-graecum extract with opioid and/or glutamate systems which occurs in the body and the mechanisms of inflammation reduction are not activated by the extract
ABSTRACT
Several studies have shown that stress has major effects on carbohydrate metabolism. There are some evidences suggesting that stress may induce type 1 and type 2 diabetes mellitus. The effects of psychological stress however need to be investigated. The present study has investigated the role of chronic psychological stress on carbohydrate metabolism in male rats. Animals were assigned in two groups of control and stressed [n=8/group]. The animals of the stressed group were exposed to different restraint stressors [1 hour twice daily] for 15 and 30 days. At the beginning and end of the experimental periods fasting blood samples were obtained by tail snipping and oral glucose tolerance test [OGTT] was carried out. Glucose was measured by glucose oxidase method. Insulin and corticosterone were assayed by their respective RIA kits. Fasting plasma glucose level on the 15th day of the experiment showed significant increase in the stressed rats compared to the controls. The plasma levels of glucose at 15 and 60 min after performing OGTT were significantly increased on the 15th and 30th days of the experiment in the stressed group. Fasting plasma insulin showed significant decrease on the 15th and 30th days of the experiment in the stressed group compared to the controls. On the 15th day of the experiment, at 15 and 60 min after performing OGTT the plasma level of insulin showed significant decrease in the stressed group as compared to the control group. Fasting plasma corticosterone concentration was significantly increased on the 15th day of the experiment in the stressed rats compared with the control rats and the 1st day of the experiment. In the stressed group immediately after stress exposure plasma corticosterone was significantly higher than before stress exposure, only on the 1st day of the experiment. Results have revealed that chronic psychological stress can impair glucose metabolism and this effect may be mediated by changes in insulin and corticosterone secretion. However the role of other stress hormones has to be investigated
ABSTRACT
Despite documented studies, the exact role of stress in diabetes is still unclear. In the present study the effect of chronic psychological stress on insulin release from rat pancreatic islets has been investigated. Male Wistar rats were divided into two equal groups of control and stressed [n=8/group]. The animals of the stressed group were exposed to restraint stressors [1 hour twice daily] for 15 and 30 consecutive days. At the beginning and end of the experimental periods the animals were weighed and blood samples were taken to determine the basal plasma levels of glucose, insulin and corticosterone. Following this, the pancreatic islets of 5/group of the above animals were isolated and the static release of insulin in the presence of different glucose concentrations [2.8, 5.6, 8.3, 16.7 mM] was assessed. The results showed that in the stressed group fasting plasma glucose levels on the 15[th] day were significantly increased compared to those of the control group. However there was no significant increase on the 30[th] day. Fasting plasma insulin showed a significant decrease on the 15[th] and 30[th] days of the experiment in the stressed group. Stressed rats showed significantly higher basal plasma corticosterone levels, only on the 15[th] day, as compared to the controls. Insulin secretion from islets of the stressed group, in response to increasing concentrations of glucose, showed significant increase on the 30[th] day of the experiment compared to the control group. The results suggest that chronic psychological stress could increase response of pancreatic beta cells to glucose and thus, low insulin levels of the stressed animals, in vivo, could be explained by reason[s] other than the reduction of insulin release capacity of pancreatic beta cells