Effect of chronic psychological stress on insulin release from rat isolated pancreatic islets

Despite documented studies, the exact role of stress on diabetes is still unclear. The present study investigates the effect of chronic psychological stress on insulin release from isolated rat pancreatic islets. Male Wistar rats were divided into two groups of control and stressed (n=8/group). The animals of the stressed group were exposed to restraint stressors (1 h twice daily) for 15 or 30 consecutive days. At the beginning and end of the experimental periods, the animals were weighed and blood samples taken to determine the fasting plasma levels of glucose, insulin and corticosterone. On the following day 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 were increased significantly on the 15th day as compared to the control group. However there was no significant increase on the 30th day. Fasting plasma insulin was significantly decreased on the 15th and 30th days of the experiment in the stressed group. Stressed rats showed significantly higher fasting plasma corticosterone levels, only on the 15th day, as compared to the control rats. In response to increasing concentrations of glucose, insulin release from islets of the stressed group was increased significantly on the 30th day of the experiment as compared to the control group. We conclude that chronic psychological stress could increase responsiveness of pancreatic beta cells to glucose, in vitro, and thus, low insulin levels of the stressed animals, in vivo, may be due to reason(s) other than the reduction of insulin releasing capacity of pancreatic beta cells.     

Sex differences impact the pancreatic response to chronic immobilization stress in rats

Chronic stress has been related to multiple diseases. Inflammation is proposed strongly to link stress to stress-related diseases in different organs, such as small intestine, colon, and brain. However, stress cellular effect on the pancreatic tissue, especially the exocrine one, had received relatively little attention. This work aimed to evaluate the cellular effect of chronic immobilization stress on the pancreatic tissue function and structure along with evaluating the sex role in this type of pancreatic injury. Thirty rats were equally divided into 5 groups: control male, control female, stressed male, stressed female, and stressed female with bilateral ovariectomy. Stressed rats were exposed to immobilization for 1 h/day, 6 days/week, for 3 weeks. Rats were then decapitated for further biochemical, histological, histo-morphometric, and immunohistochemical study. The results showed that, in male and female rats, chronic immobilization stress produced hypoinsulinemia and hyperglycemia, with increasing exocrine pancreatic injury markers by increasing oxidative and inflammatory status of the pancreatic tissue, and exhibited a degenerative effect on the pancreatic tissue. However, the stress-induced pancreatic effects were more obvious in male rats and female rats with bilateral ovariectomy than that in female rats. It could be concluded that male animals were more susceptible to stress-induced pancreatic damage than females. The ovarian hormones are responsible, at least partly, for pancreatic tissue protection since the stress-induced pancreatic injury in females was exacerbated by ovariectomy. In this study, inflammatory and oxidative stress differences in both sexes could provide a plausible explanation for sex differences.     

The effect of repeated immobilization on the level of plasma corticosterone and on the activity of several liver enzymes in rats.

The effect of repeated stress on the level of plasma corticosterone and on the activity of several target enzymes for this hormone in the liver was studied. In adult male rats immobilized for 2.5 hrs daily, on day 7 the response of both plasma corticosterone and hepatic tyrosine aminotransferase is modified: After similar increases immediately after immobilization as in aminals stressed for the first time, in the conditioned rats precocious decreases to initial values take place. Moreover, on day 4, 24 hrs after a third immobilization, there are increases arise partly at least as a consequence of diminished food intake, as shown by comparing them with data from pair-fed rats. Partial fasting leading also to slight increase of hepatic glucose-6-phosphatase activity constitutes an important part of repeated stress with substantial impacts on metabolic processes.     

Sex differences in adrenocortical sensitivity and resistance to cerebrovascular damage in rats under strong stress]

Dynamics of changes in adrenal and plasma corticosterone and the development of cerebrovascular lesions were studied in both male and female rats, exposed to strong stress (combined immobilization and intermittent found sound for 2 hours). Plasma corticosterone levels in stressed females were 460% and 660% of the control values when measured on stress minute 10 and 120. The corresponding values in male rats were 220% and 360%. The stress-induced dilatation of brain vessels and the increases in vascular permeability were less pronounced in females than in males, when studied 0.1 and 24 hours after termination of stress. The number of brain perivascular haemorrhages was markedly reduced in females compared with males. It is supposed that higher resistance to stress-induced cerebrovascular lesions in females may be attributed to higher functional reserves of steroidogenesis.     

Effect of prenatal stress on the hormonal response to acute and chronic stress and on immune parameters in the offspring

The effect of prenatal stress on the time course of the corticosterone response to acute and chronic stress and on hematological and immunological parameters in the offspring were analized in the present study. Pregnant Sprague-Dawley rats were stressed daily for 2 hours during the last week of gestation, and female and male off-spring were studied during adulthood. Corticosterone response to acute immobilization stress was not significantly different in either control or prenatally stressed rats. However, after 10 days of immobilization stress the corticosterone response completely disappeared in the control animals but not in the prenatally stressed group: high levels of corticosterone were found during the first hour of stress, although they were lower than those found in acutely stressed rats. Adrenal hypertrophy in response to prenatal stress was observed in females but not in male offspring, and chronic stress only increased adrenal weights in the male control group. Prenatal stress decreased the total peripheral leukocyte count, altered its diferential count decreasing lymphocytes and increasing neutrophil and eosinhophil counts, and significantly reduced the percentage of peripheral lymphocyte T CD8+ subset in male offspring. Chronic stress also reduced the percentage of the peripheral T CD8+ lymphocyte subset in the control group but not in the prenatally stressed group. These results suggest that the exposure to stress during pregnancy alters the adaptative response of the hypothalamus-pituitary-adrenocortical axis to chronic stress and presumably the immune competence in the offspring.     

Liver glucocorticoid receptor and heat shock protein 70 levels in rats exposed to different stress models

The aim of the present study was to define the stress-induced pattern of cytosolic glucocorticoid receptor (GR) and Hsp70 protein in the liver of male Wistar rats exposed to different stress models: acute (2 h/day) immobilization or cold (4 degrees C); chronic (21 days) isolation, crowding, swimming or isolation plus swimming and combined (chronic plus acute stress). Changes in plasma levels of corticosterone were studied by radioimmunoassay (RIA). The results obtained by Western immunoblotting showed that both acute stressors led to a significant decrease in cytosolic GR and Hsp70 levels. Compared to acute stress effects, only a weak decrease in the levels of GR and Hsp70 was demonstrated in chronic stress models. Chronically stressed rats, which were subsequently exposed to novel acute stressors (immobilization or cold), showed a lower extent of GR down-regulation when compared to acute stress. The exception was swimming, which partially restores this down-regulation. The observed changes in the levels of these major stress-related cellular proteins in liver cytosol lead to the conclusion that chronic stressors compromise intracellular GR down-regulation in the liver.     

Effect of stress exposure on the activation pattern of enkephalin-containing perikarya in the rat ventral medulla

We examined the effects of acute and chronic psychogenic stress on the activation pattern of enkephalin-containing perikarya in the rat ventrolateral medulla. Rats allocated to the chronic stress groups were subjected to 90 min of immobilization for 10 days. On the 11th day, the chronically stressed rats were exposed to homotypic (90-min immobilization) or to heterotypic but still psychogenic (90-min immobilization coupled to air jet stress) stress. The acute stress group was subjected once to an acute 90-min immobilization. For each group, the rats were anesthetized either before stress (time 0) or 90, 180, and 270 min after the onset of stress. Brain sections were then processed using immunocytochemistry (Fos protein) followed by radioactive in situ hybridization histochemistry (enkephalin mRNA). Following immobilization, the acute group displayed a marked increase in the number of activated enkephalin-containing perikarya within the paragigantocellularis and lateral reticular nuclei. This level of activation was sustained up to 180 min following the onset of the immobilization stress and had returned to baseline levels by 270 min from the initiation of the stress. However, this stress-induced activation of enkephalin-containing perikarya of the ventrolateral medulla was not seen following either homotypic or heterotypic stress in the chronically stressed group. These results provide evidence that enkephalin-containing perikarya of the ventrolateral medulla may constitute a potential circuit through which they regulate some aspect of the stress responses. Conversely, this enkephalinergic influence from the ventrolateral medulla was shown to be absent following chronic stress exposure. This would suggest a decrease in enkephalin inhibitory input originating from the ventrolateral medulla, thereby allowing a neuroendocrine and/or autonomic response to chronic stress.     

Gastro-protective and Anti-stress Efficacies of Monomethyl Fumarate and a <Emphasis Type="Italic">Fumaria indica</Emphasis> Extract in Chronically Stressed Rats

Results of the very first experiments conducted to evaluate therapeutic potentials of a fumarate containing Fumaria indica extract and of fairly low daily oral doses of monomethyl fumarate for prevention of chronic unavoidable foot-shock stress-induced gastric ulcers, and possible involvement of diverse neuro-hormonal and oxidative process in their stress response desensitizing effects are reported and discussed in this article. Preventive effects of 21 daily oral 60, 120, and 240 mg/kg doses of a standardized 50 % methanolic F. indica extract (MFI) and 1.25, 2.50, and 5.00 mg/kg/day of pure monomethyl fumarate (MMF) were compared in rats subjected to one hour daily unavoidable foot-shocks. A pharmaceutically well-standardized Withania somnifera (WS) root extract was used as a reference herbal anti-stress agent in all experiments. Effects of the treatments on stress-induced alterations in body weight, adrenal and spleen weights, gastric ulcer and ulcer index, weight of glandular stomach, protective mucosal glycoprotein content, cellular proliferation, oxidative stress on stomach fundus, and brain tissues of male rats were quantified. Other parameters quantified were plasma corticosterone levels, brain monoamine levels, and expressions of the cytokines TNF-α, IL-10, and IL-1β in blood and brain of stressed and treated rats. Most but not every observed stress-induced anomalies were suppressed or completely prevented by both MFI and pure MMF treatments in dose-dependent manner. Qualitatively, the observed activity profiles of both of them were similar to those of WS dose tested. These results reveal that both MFI and MMF are potent gastro-protective agents against chronic unavoidable stress-induced ulcers and strongly suggest that they act as regulators or modulators of monoamine, corticosterone, and cytokine homeostasis.     

Long-term effects of stress in critical periods of development on reactivity of adult female rats

Effects of stress during different periods of ontogeny, namely, the prenatal, prepubertal, or their combination (prenatal+prepubertal), on the indices of psychoemotional and tonic pain-related behaviors, as well as corticosterone reactivity after pain behavior were investigated in adult 90-day-old female Wistar rats. Our data show for the first time, the similarity of effects of prenatal (immobilization stress of a rat dam during the last week of pregnancy) and prepubertal (forced swimming, pain-related response in the formalin test) stresses on the indices under study, an increase in the time of immobility and in licking duration, but the difference between effects of combined stress on these indices. Pain-related response increased corticosterone in prepubertally stressed rats while in prenatally stressed rats, decreased it. In rats experienced combined stress, formalin-induced pain increased corticosterone as compared with that in prenatally, but not in prepubertally stressed rats. A positive correlation between pain-related reaction and stressed hormonal response was revealed in prepubertally stressed animals. So, long-term effects of stress during critical periods of ontogeny determine stress reactivity of behavioral and hormonal responses in adult female rats.     

Effects of 5,7-dihroxytryptamine administered supraspinally or spinally on the blood glucose level in D-glucose-fed and immobilization stress models

5,7-Dihydroxytryptamine (5,7-DHT) is a neurotoxin which causes the depletion of serotonin. Moreover, the serotonergic system is the regulator of the blood glucose level. However, the role of centrally located serotonergic system in blood glucose regulation after D-glucose feed and immobilization (IMO) stress was not clearly characterized yet. Thus the present study was designed to examine the effect of 5,7-DHT administered intracerebroventricularly (i.c.v.) or intrathecally (i.t.) on the blood glucose level in D-glucose-fed and immobilization stress models. Mice were pretreated once i.c.v. or i.t. with 5,7-DHT (from 10 to 40?µg) for 3 days and D-glucose (2?g/kg) was fed orally. The blood glucose level was measured at 0, 30, 60 and 120?min after D-glucose feeding and immobilization stress initiation. We found that i.c.v. or i.t. pretreatment with 5,7-DHT attenuated the blood glucose level in both animal models. D-glucose feeding causes an increase in plasma insulin level, whereas the plasma corticosterone level was downregulated in the D-glucose-fed model. The i.c.v. or i.t. pretreatment with 5,7-DHT alone slightly increased the plasma corticosterone level. In addition, the i.c.v. or i.t. pretreatment with 5,7-DHT caused a reversal of the downregulation of plasma corticosterone level induced by D-glucose feeding, whereas immobilization stress causes an increase in plasma corticosterone and insulin levels. The i.c.v or i.t. pretreatment with 5,7-DHT attenuated the immobilization stress-induced plasma corticosterone and plasma insulin levels. Our results suggest that supraspinal and spinal depletion of serotonin appears to be responsible for the downregulation of blood glucose level in both D-glucose-fed and immobilization stress models.     

Protective effects of the volatile oil of Nigella sativa seeds on β-cell damage in streptozotocin-induced diabetic rats: a light and electron microscopic study

The aim of this study was to evaluate the possible protective effects of the volatile oil of Nigella sativa (NS) seeds on insulin immunoreactivity and ultrastructural changes of pancreatic β-cells in STZ-induced diabetic rats. STZ was injected intraperitoneally at a single dose of 50 mg/kg to induce diabetes. The rats in NS treated groups were given NS (0.2 ml/kg) once a day orally for 4 weeks starting 3 days prior to STZ injection. To date, no ultrastructural changes of pancreatic β-cells in STZ induced diabetic rats by NS treatment have been reported. Islet cell degeneration and weak insulin immunohistochemical staining was observed in rats with STZ-induced diabetes. Increased intensity of staining for insulin, and preservation of β-cell numbers were apparent in the NS-treated diabetic rats. The protective effect of NS on STZ-diabetic rats was evident by a moderate increase in the lowered secretory vesicles with granules and also slight destruction with loss of cristae within the mitochondria of β-cell when compared to control rats. These findings suggest that NS treatment exerts a therapeutic protective effect in diabetes by decreasing morphological changes and preserving pancreatic β-cell integrity. Consequently, NS may be clinically useful for protecting β-cells against oxidative stress.     

Subsensitivity to insulin in adipocytes from rats submitted to foot-shock stress

We examined the effect of three daily foot-shock stress sessions on glucose homeostasis, insulin secretion by isolated pancreatic islets, insulin sensitivity of white adipocytes, and glycogen stores in the liver and soleus muscle of rats. Stressed rats had plasma glucose (128.3 +/- 22.9 mg/dL) and insulin (1.09 +/- 0.33 ng/mL) levels higher than the controls (glucose, 73.8 +/- 3.5 mg/dL; insulin, 0.53 +/- 0.11 ng/mL, ANOVA plus Fisher's test; p < 0.05). After a glucose overload, the plasma glucose, but not insulin, levels remained higher (area under the curve 8.19 +/- 1.03 vs. 4.84 +/- 1.33 g/dL 30 min and 102.7 +/- 12.2 vs. 93.2 +/- 16.1 ng/mL 30 min, respectively). Although, the area under the insulin curve was higher in stressed (72.8 +/- 9.8 ng/mL) rats than in control rats (34.9 +/- 6.9 ng/mL) in the initial 10 min after glucose overload. The insulin release stimulated by glucose in pancreatic islets was not modified after stress. Adipocytes basal lipolysis was higher (stressed, 1.03 +/- 0.14; control, 0.69 +/- 0.11 micromol of glycerol in 60 min/100 mg of total lipids) but maximal lipolysis stimulated by norepinephrine was not different (stressed, 1.82 +/- 0.35; control, 1.46 +/- 0.09 micromol of glycerol in 60 min/100 mg of total lipids) after stress. Insulin dose-dependently inhibited the lipolytic response to norepinephrine by up to 35% in adipocytes from control rats but had no effect on adipocytes from stressed rats. The liver glycogen content was unaltered by stress, but was lower in soleus muscle from stressed rats than in control rats (0.45 +/- 0.04 vs. 0.35 +/- 0.04 mg/100 mg of wet tissue). These results suggest that rats submitted to foot-shock stress develop hyperglycemia along with hyperinsulinemia as a consequence of insulin subsensitivity in adipose tissue, with no alteration in the pancreatic sensitivity to glucose. Foot-shock stress may therefore provide a useful short-term model of insulin subsensitivity.     

Modification of expression of neurohormones in hypothalamus of prenatally stressed male rats in model of posttraumatic stress disorder

By the method of quantitative immunohistochemistry there has been studied expression of corticotrophin-releasing hormone (CRH) and vasopressin in hypothalamic paraventricular nucleus (PVN) of prenatally stressed rats in the experimental model of the posttraumatic stress disorder-the paradigm “stress-restress”. The prenatal stress was modeled by immobilization of pregnant female rats for 1 h from the 15th to the 19th day of pregnancy. It has been shown that in sexually mature males-descendants of stressed mothers-a decrease in immunoreactivity to CRH and vasopressin is observed in the parvocellular and magnocellular PVN areas 10 days after the restress. In the control group males born by intact mothers the level of immunoreactivity to CRH was increased in both PVN areas, whereas with respect to vasopressin-in the magnocellular area. Only in the prenatally stressed males there is detected a decrease in the corticosterone level in the blood plasma 10 days after the restress. It is concluded that in the control group males the manifestation of the pathological state in the paradigm “stress-restress” consists in hyperactivation of the hypothalamic chain of regulation of the hypothalamus-pituitary-adrenocortical system, whereas in the prenatally stressed animals, on the contrary, there is observed a decrease in activity both of the central (PVN) and of the peripheral (adrenal cortex) chain of this hormonal axis.     

Stress- and cold-induced adrenocortical responses in repetitively immobilized or cold-acclimated rats

To evaluate the role of adrenocortical hormones in stress- or cold-induced nonshivering thermogenesis, plasma corticosterone (CS) and deoxycorticosterone (DOCS) were measured with the aid of HPLC under various conditions. Repetitive immobilization stress (3 h/day, for 1 or 4 weeks) elevated the resting level (24 h after the last immobilization) of CS, but not DOCS. Acute stress (immobilization for 30 min) or cold exposure (-5 degrees C for 15 min) caused marked increases of CS and DOCS in both nonstressed naive controls and repetitively stressed rats. Four weeks, but not 1 week, of repetitive immobilization stress potentiated the responsiveness of CS to both acute stress and cold, and that of DOCS to acute stress, but not to cold. Cold acclimation (5 degrees C, 4 weeks) significantly elevated both corticosteroids but did not affect the resting levels (18 h after being transferred to 25 degrees C) or the responsiveness of both CS and DOCS to either acute stress or cold. These results suggest that repetitive immobilization stress, but not cold acclimation, could enhance nonshivering thermogenesis, at least in part, through an improvement in the responsiveness of adrenocortical hormone secretion to acute stress or cold.     

Roles of plasma interleukin-6 and tumor necrosis factor-alpha and FFA and TG in the development of insulin resistance induced by high-fat diet

The role of adipokines in development of insulin resistance still remains controversial. The purpose of the present study was to examine the dynamic changes of fasting plasma levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), free fatty acids (FFA) and insulin in a Sprague-Dawley rat insulin resistant model induced by high-fat diet. Heterotopic deposition of triglycerides (TG) in liver, skeletal muscles and pancreatic islet was also investigated. The fasting plasma level of insulin in rats in the high-fat diet group was significantly higher than that in the normal diet group on day 21 (P<0.01), suggesting that an increased insulin resistance developed in the high-fat diet group. However, no significant difference in the plasma IL-6 level was observed between the two groups (P>0.05), although in both groups, the plasma IL-6 level was significantly higher on day 21 than that of the day 0 (P<0.05). The plasma FFA level in the high-fat diet group began to increase significantly on day 21 (P<0.05), and elevated markedly on day 28, was positively correlated to the fasting plasma insulin level. Histological study revealed a more abundant TG deposition in liver and skeletal muscles (from quadriceps femoris) in the high-fat diet group than in the normal diet group on day 21, and the liver deposition was even higher on day 28. However, no deposition was observed in pancreatic islets. The plasma TNF-alpha level remained unchanged throughout the duration of the experiment. These results indicate that the progression of insulin resistance in high-fat diet rats is closely related to the plasma FFA elevation and the heterotopic deposition of TG in liver and skeletal muscles, but is unrelated to the plasma TNF-alpha and IL-6 levels.     

Somatostatin analogue,Octreotide, improves restraint stress-induced liver injury by ameliorating oxidative stress,inflammatory response,and activation of hepatic stellate cells

The aim of this study is to investigate the effect of somatostatin (SST) analogue, Octreotide, on some features of liver injury induced by immobilization stress (IS) in adult male albino rats. Eighteen adult male albino rats were randomly divided into three equal groups: control, IS, and Octreotide-treated stressed groups. Octreotide (40 μg/kg body weight, subcutaneously) was administrated twice daily for 8 days during the exposure to IS. Octreotide was found to reduce the IS significantly and induce elevations in the plasma level of corticosterone, liver transaminases, and tumor necrosis factor α (TNF-α) as compared with IS group. Furthermore, Octreotide administration has significantly elevated the decline in the total antioxidant capacities (TAC) and lowered the elevated malondialdehyde (MDA) levels observed with IS in the hepatic tissue. Additionally, Octreotide treatment provided protection against the histopathological changes in the stressed liver in the form of significant reduction in the mean number of degenerated hepatocytes, the area % of collagen fibers, and glial fibrillary acid protein (GFAP) immunostaining with a significant increase in the mean number of normal hepatocytes. In conclusion, stressed rats showed disturbed liver functions and its oxidant–antioxidant status with highly expression hepatic stellate cells (HSCs), which were all improved by Octreotide administration, SST analogue.     

Maternal glucocorticoid hormones as a factor mediating the effect of prenatal stress on offspring anxiety

The plus-maze behavior was studied in offsprings of female rats subjected to immobilization stress on the 15-18 days of pregnancy. Prenatal stress decreased the level of anxiety in males and increased in females. The blockade of the mother's stress-induced glucocorticoid secretion by prior adrenalectomy and subsequent corticosterone injection during immobilization in a low dose (0.3 mg/kg) prevented the behavioral disorders in offsprings. In case of a higher dose of corticosterone (3 mg/kg) injection, the behavior of offsprings was the same as that of offsprings of the intact mothers subjected to immobilization. The results suggest that the stress-induced increase in maternal glucocorticoid level may be the mechanism by which prenatal stress impairs the development of sex differences in rat anxiety behavior.     

Repeated immobilization stress alters rat hippocampal and prefrontal cortical morphology in parallel with endogenous agmatine and arginine decarboxylase levels

Agmatine, an endogenous amine derived from decarboxylation of l-arginine catalyzed by arginine decarboxylase, has been proposed as a neurotransmitter or neuromodulator in the brain. In the present study, we examined whether agmatine has neuroprotective effects against repeated immobilization-induced morphological changes in brain tissues and possible effects of immobilization stress on endogenous agmatine levels and arginine decarboxylase expression in rat brains. Sprague–Dawley rats were subjected to 2 h immobilization stress daily for 7 days. This paradigm significantly increased plasma corticosterone levels, and the glutamate efflux in the hippocampus as measured by in vivo microdialysis. Immunohistochemical staining with β-tubulin III showed that repeated immobilization caused marked morphological alterations in the hippocampus and medial prefrontal cortex that were prevented by simultaneous treatment with agmatine (50 mg/kg/day), i.p.). Likewise, endogenous agmatine levels measured by high-performance liquid chromatography in the prefrontal cortex, hippocampus, striatum and hypothalamus were significantly increased by immobilization, as compared to controls. The increased endogenous agmatine levels, ranging from 92 to 265% of controls, were accompanied by a significant increase of arginine decarboxylase protein levels in the same regions. These results demonstrate that the administration of exogenous agmatine protects the hippocampus and medial prefrontal cortex against neuronal insults caused by repeated immobilization. The parallel increase in endogenous brain agmatine and arginine decarboxylase protein levels triggered by repeated immobilization indicates that the endogenous agmatine system may play an important role in adaptation to stress as a potential neuronal self-protection mechanism.     

Effect of ginsenoside Re on depression- and anxiety-like behaviors and cognition memory deficit induced by repeated immobilization in rats

In this study, we assessed the effects of ginsenoside Re (GRe) administration on repeated immobilization stressinduced behavioral alterations using the forced swimming test (FST), the elevated plus maze (EPM), and the active avoidance conditioning test (AAT). Additionally, we examined the effect of GRe on the central adrenergic system by observing changes in neuronal tyrosine hydroxylase (TH) immunoreactivity and brain-derived neurotrophic factor (BDNF) mRNA expression in the rat brain. Male rats received 10, 20, or 50 mg/kg GRe (i.p.) 30 min before daily exposures to repeated immobilization stress (2 h/day) for 10 days. Activation of the hypothalamic-pituitary-adrenal (HPA) axis in response to repeated immobilization was confirmed by measuring serum levels of corticosterone (CORT) and the expression of corticotrophin-releasing factor (CRF) in the hypothalamus. Repeated immobilization stress increased immobility in the FST and reduced openarm exploration in the EPM test. It also increased the probability of escape failures in the AAT test, indicating a reduced avoidance response. Daily administration of GRe during the repeated immobilization stress period significantly inhibited the stress-induced behavioral deficits in these behavioral tests. Administration of GRe also significantly blocked the increase in TH expression in the locus coeruleus (LC) and the decrease in BDNF mRNA expression in the hippocampus. Taken together, these findings indicate that administration of GRe prior to immobilization stress significantly improved helpless behaviors and cognitive impairment, possibly through modulating the central noradrenergic system in rats. These findings suggest that GRe may be a useful agent for treating complex symptoms of depression, anxiety, and cognitive impairment.