Chronic Restraint Stress Model Research Articles

Activation of satellite glial cells in the trigeminal ganglion contributes to masseter mechanical allodynia induced by restraint stress in rats

It is commonly accepted that psychological stress contributes to the development of chronic orofacial pain. However, the neural mechanism underlying this process has remained unclear. The present study was performed to determine the involvement of satellite glia cells (SGCs) in the trigeminal ganglion (TG) in stress-induced increases in masseter muscle allodynia in rats. Using a chronic restraint stress model, we found that exposure to a 14-day stress but not a 3-day stress (6h/day) caused decreased body weight gain, behavioral changes and marked masseter allodynia in rats. SGCs were dramatically activated, and substance P (SP) expression was significantly increased in the TG. A further analysis was undertaken to investigate the contribution of SGCs; the expression of interleukin-1β (IL-1β) in SGCs and interleukin-1 receptor I (IL-1RI) in neurons was significantly increased after chronic restraint stress, whereas injection of L-α-aminoadipate (a SGC inhibitor, LAA) into the TG dramatically inhibited the overexpression of these proteins. In addition, LAA or interleukin-1 receptor antagonist (IL-1ra) administration into the TG could significantly attenuate the mechanical masseter allodynia and overexpression of SP in the TG induced by restraint stress. These results suggest that SGC activation in the TG may play a role in masseter allodynia induced by restraint stress. The over-release of IL-1β and excessive IL1-RI expressions have close relationship with the stress induced masseter allodynia.

Establishment of a chronic restraint stress model of depression with C57BL/6J mice.

To establish a chronic restraint stress (CRS) model of depression,using C57BL/6J mice. Totally 20 C57BL/6J mice were screened by weight,sucrose preference,and the results of open-field test. Then,they were equally randomized into two groups:normal control (NC) group and CRS group. Mice in the CRS group were under restraint 4 hours a day and their behavioral changes were evaluated after 21 days. The immobility time was significantly longer in CRS mice [(131.70 ± 21.65) s] compared with controls [(68.88 ± 8.43) s] (P=0.0304). CRS mice showed a significant decrease in sucrose preference during the time 0-24 h [(66.21 ±3.24)% vs.(79.46 ± 3.85)%, P=0.0196] and 0-48 h [(73.25 ± 1.50)% vs.(80.20 ± 2.26)%, P=0.0248] compared with controls. The C57BL/6J mice CRS models of depression were successfully established.

Antistress and antioxidant effects of virgin coconut oil in vivo.

Virgin coconut oil (VCO) has been consumed worldwide for various health-related reasons and some of its benefits have been scientifically evaluated. Medium-chain fatty acids were found to be a potential antidepressant functional food; however, this effect had not been evaluated in VCO, which is rich in polyphenols and medium-chain fatty acids. The aim of this study was to evaluate the antistress and antioxidant effects of VCO in vivo, using mice with stress-induced injury. The antistress effect of VCO (administered per os, at a dose of 10 ml/kg body weight) was evaluated using the forced swim test and chronic cold restraint stress models. VCO was able to reduce immobility time and restore oxidative stress in mice post-swim test. Furthermore, mice treated with VCO were found to exhibit higher levels of brain antioxidants, lower levels of brain 5-hydroxytryptamine and reduced weight of the adrenal glands. Consequently, the serum cholesterol, triglyceride, glucose and corticosterone levels were also lower in VCO-treated mice. These results suggest the potential value of VCO as an antistress functional oil.

Insulin-like growth factor 2 mitigates depressive behavior in a rat model of chronic stress

Depression is a common psychiatric disorder associated with chronic stress. Insulin-like growth factor 2 (IGF2) is a growth factor that serves important roles in the brain during development and at adulthood. Here, the role of IGF2 expression in the hippocampus was investigated in a rat model of depression. A chronic restraint stress (CRS) model of depression was established in rats, exhibiting depression-like behavior as assessed with the sucrose preference test (SPT) and forced swimming test (FST), and with evaluation of the corticosterone levels. Hippocampal IGF2 levels were significantly lower in rats suffering CRS than in controls, as were levels of pERK1/2 and GluR1. Lentivirus-mediated hippocampal IGF2 overexpression alleviated depressive behavior in restrained rats, elevated the levels of pERK1/2 and GluR1 proteins, but it did not affect the expression of pGSK3β, GluR2, NMDAR1, and NMDAR2A. These results suggest the chronic restraint stress induces depressive behavior, which may be mediated by ERK-dependent IGF2 signaling, pointing to an antidepressant role for this molecular pathway.

Essential role of IL-10/STAT3 in chronic stress-induced immune suppression

Stress can either enhance or suppress immune functions depending on a variety of factors such as duration of stressful condition. Chronic stress has been demonstrated to exert a significant suppressive effect on immune function. However, the mechanisms responsible for this phenomenon remain to be elucidated. Here, male C57BL/6 mice were placed in a 50-ml conical centrifuge tube with multiple punctures to establish a chronic restraint stress model. Serum IL-10 levels, IL-10 production by the splenocytes, and activation of STAT3 in the mouse spleen were assessed. We demonstrate that IL-10/STAT3 axis was remarkably activated following chronic stress. Moreover, TLR4 and p38 MAPK play a pivotal role in the activation of IL-10/STAT3 signaling cascade. Interestingly, blocking antibody against IL-10 receptor and inhibition of STAT3 by STAT3 inhibitor S3I-201 attenuates stress-induced lymphocyte apoptosis. Inhibition of IL-10/STAT3 dramatically inhibits stress-induced reduction in IL-12 production. Furthermore, disequilibrium of Th1/Th2 cytokine balance caused by chronic stress was also rescued by blocking IL-10/STAT3 axis. These results yield insight into a new mechanism by which chronic stress regulates immune functions. IL-10/STAT3 pathway provides a novel relevant target for the manipulation of chronic stress-induced immune suppression.

Chronic Restraint Stress Upregulates Erythropoiesis through Glucocorticoid Stimulation

In response to elevated glucocorticoid levels, erythroid progenitors rapidly expand to produce large numbers of young erythrocytes. Previous work demonstrates hematopoietic changes in rodents exposed to various physical and psychological stressors, however, the effects of chronic psychological stress on erythropoiesis has not be delineated. We employed laboratory, clinical and genomic analyses of a murine model of chronic restraint stress (RST) to examine the influence of psychological stress on erythropoiesis. Mice exposed to RST demonstrated markers of early erythroid expansion involving the glucocorticoid receptor. In addition, these RST-exposed mice had increased numbers of circulating reticulocytes and increased erythropoiesis in primary and secondary erythroid tissues. Mice also showed increases in erythroid progenitor populations and elevated expression of the erythroid transcription factor KLF1 in these cells. Together this work reports some of the first evidence of psychological stress affecting erythroid homeostasis through glucocorticoid stimulation.

Reversal of chronic stress-induced pain by transcranial direct current stimulation (tDCS) in an animal model

Transcranial direct current stimulation (tDCS) has been suggested as a therapeutic tool for pain syndromes. Although initial results in human subjects are encouraging, it still remains unclear whether the effects of tDCS can reverse maladaptive plasticity associated with chronic pain. To investigate this question, we tested whether tDCS can reverse the specific behavioral effects of chronic stress in the pain system, and also those indexed by corticosterone and interleukin-1β levels in serum and TNFα levels in the hippocampus, in a well-controlled rat model of chronic restraint stress (CRS). Forty-one adult male Wistar rats were divided into two groups control and stress. The stress group was exposed to CRS for 11 weeks for the establishment of hyperalgesia and mechanical allodynia as shown by the hot plate and von Frey tests, respectively. Rats were then divided into four groups control, stress, stress+sham tDCS and stress+tDCS. Anodal or sham tDCS was applied for 20min/day over 8 days and the tests were repeated. Then, the animals were killed, blood collected and hippocampus removed for ELISA testing. This model of CRS proved effective to induce chronic pain, as the animals exhibited hyperalgesia and mechanical allodynia. The hot plate test showed an analgesic effect, and the von Frey test, an anti-allodynic effect after the last tDCS session, and there was a significant decrease in hippocampal TNFα levels. These results support the notion that tDCS reverses the detrimental effects of chronic stress on the pain system and decreases TNFα levels in the hippocampus.

Role of Leaky Neuronal Ryanodine Receptors in Stress- Induced Cognitive Dysfunction

The type 2 ryanodine receptor/calcium release channel (RyR2), required for excitation-contraction coupling in the heart, is abundant in the brain. Chronic stress induces catecholamine biosynthesis and release, stimulating β-adrenergic receptors and activating cAMP signaling pathways in neurons. In a murine chronic restraint stress model, neuronal RyR2 were phosphorylated by protein kinase A (PKA), oxidized, and nitrosylated, resulting in depletion of the stabilizing subunit calstabin2 (FKBP12.6) from the channel complex and intracellular calcium leak. Stress-induced cognitive dysfunction, including deficits in learning and memory, and reduced long-term potentiation (LTP) at the hippocampal CA3-CA1 connection were rescued by oral administration of S107, a compound developed in our laboratory that stabilizes RyR2-calstabin2 interaction, or by genetic ablation of the RyR2 PKA phosphorylation site at serine 2808. Thus, neuronal RyR2 remodeling contributes to stress-induced cognitive dysfunction. Leaky RyR2 could be a therapeutic target for treatment of stress-induced cognitive dysfunction.

Electroconvulsive stimulations prevent chronic stress-induced increases in L-type calcium channel mRNAs in the hippocampus and basolateral amygdala

Although affective disorders have high prevalence, morbidity and mortality, we do not fully understand disease etiopathology, nor have we determined the exact mechanisms by which treatment works. Recent research indicates that intracellular calcium ion dysfunction might be involved. Here we use the chronic restraint stress model of affective disorder (6h restraint per day for 21 days) in combination with electroconvulsive stimulations to examine the effects of stress and an effective antidepressive treatment modality on L-type voltage gated calcium channel subunit mRNA expression patterns in the brain. We find that stress tended to upregulate Cav1.2 and Cav1.3 channels in a brain region specific manner, while ECS tended to normalise this effect. This was more pronounced for Cav1.2 channels, where stress clearly increased expression in both the basolateral amygdala, dentate gyrus and CA3, while stress only upregulated Cav1.3 channel expression significantly in the dentate gyrus. ECS effects on Cav1.2 channel expression were generally specific to stressed animals. Our findings are consistent with and extent previous studies on the involvement of intracellular calcium ion dysfunction in affective disorders. Selective modulation of neuronal L-type voltage gated calcium channels appears to be a promising target for the development of novel antidepressive treatment modalities.

Prenatal stress alters hippocampal synaptic plasticity in young rat offspring through preventing the proteolytic conversion of pro‐brain‐derived neurotrophic factor (BDNF) to mature BDNF

Prenatal stress (PS) has been associated with a higher risk of development of various neurological and psychiatric disorders later in life, but the underlying mechanisms are not yet fully understood. Here, using a chronic prenatal restraint stress model where the rat dams were immobilized for 45 min three times per day during the last week of pregnancy, we explored the long-lasting effects of PS on hippocampal synaptic plasticity in the offspring of both sexes. We found that PS switched the direction of synaptic plasticity in hippocampal CA1 region, favouring low-frequency stimulation-induced long-term depression (LTD) and opposing the induction of long-term potentiation (LTP) by high-frequency stimulation in young (5-week-old) rat offspring, but these changes disappeared at adult age (8 weeks old). Fostering of PS offspring to control dams did not alter the effects of PS on LTP and LTD. In addition, PS-induced changes in LTP and LTD induction were correlated with increasing endogenous pro-brain-derived neurotrophic factor (pro-BDNF) and decreasing of the mature form of BDNF (mBDNF) levels. Furthermore, PS resulted in a significant decrease in the activity and expression of tissue plasminogen activator (tPA), a key serine protease involved in the extracellular conversion of pro-BDNF to mBDNF. No significant differences were observed between the sexes for the effects of PS on hippocampal synaptic plasticity, the levels of pro-BDNF and mBDNF, and tPA expression. These results suggest that PS downregulates tPA levels within the hippocampus, inhibiting the proteolytic conversion of pro-BDNF to mBDNF, thereby leading to long-lasting alterations of the properties of synaptic plasticity.

Chronically stressed female rats show increased anxiety but no behavioral alterations in object recognition or placement memory: A preliminary examination

Stress, depending on intensity and duration, elicits adaptive or maladaptive physiological effects. Increasing evidence shows those patterns of advantageous versus deleterious physiologic stress effects also exist for some brain functions, including learning and memory. For example, short stress enhances, while chronic stress impairs, performance on numerous cognitive tasks in male rats. In contrast, performance of female rats is enhanced, or not altered, following both short-term and long-term stress exposure on the same behavioral tasks. The current study was designed to better characterize the behavioral effects of sustained chronic restraint stress in female rats. Female Sprague Dawley rats were assigned to a stress (restraint, 6 h/day, 35 days) or control (no stress) condition, weighed weekly, and then tested on open field (OF), object recognition (OR) and object placement (OP) tasks. Stressed females gained less weight during stress than controls. On the OF, there were no group differences in locomotor activity, but stressed females made fewer inner visits than controls, indicating increased anxiety. Both groups successfully performed the OP and OR tasks across all inter-trial delays, indicating intact non-spatial and spatial memory in both control and stress females. The current results provide preliminary evidence that the commonly used chronic restraint stress model may not be an efficient stressor to female rats.

Change in the expression of hippocampal neuronal 5-hyroxytryptamine1A receptor in a mouse model of chronic restraint stress

Objective To investigate the change in expression of hippocampal neuronal 5-hyroxytryptamine1A(5-HT1A) receptor in a mouse model of chronic restraint stress.Methods Forty BALB/c male mice aged 6-9 months weighing 25-35 g were randomly divided into 2 groups ( n =20 each): normal control group (group C) and chronic restraint stress group( group S).In group S,the model of chronic restraint stress was established described by Wood et al.Tail suspension test,light-dark test and Morris water maze test were performed respectively at 1 d after successful establishment of the model.Immobility time,staying time in light compartment,and escape latency and frequency of crossing the original platform were recorded respectively in tail suspension test,light-dark test and Morris water maze test.Then the animals were sacrificed,hippocampi were removed for determination of the expression of 5-HT1A receptor in CA1 and CA3 regions of hippocampal neurons by immuno-histochemistry.Results Compared with group C,immobility time and escape latency were significantly prolonged,staying time in light compartment was shortened,frequency of crossing the original platform was decreased,and the expression of 5-HT1A receptor in hippocampal neurons was down-regulated in group S ( P ＜ 0.05 or 0.01 ).Conclusion Chronic restraint stress can induce cognitive impairment in mice by down-regulating the expression of 5-HT1A receptor in hippocampal neurons. Key words: Stress ; Receptor, serotonin, 5- HT1 A ; Hippocampus; Neurons

Profiling of hypothalamic and hippocampal gene expression in chronically stressed rats treated with St. John’s wort extract (STW 3-VI) and fluoxetine

Hypericum perforatum L., known as St. John's wort (SJW), is used as a phytotherapeutic agent for the treatment of mild to moderate forms of depression. The aim of the present study was to evaluate the effect of SJW extract (STW 3-VI; 250 and 500 mg/kg; p.o.) and fluoxetine (10 mg/kg, p.o.) on genes involved in the pathogenesis of depression using a chronic restraint stress (CRS) model in rats. Of particular interest was the assessment of similarities and differences between SJW extract and fluoxetine on the gene expression level in two different brain regions. Hypothalamic and hippocampal tissues were analyzed using the Affymetrix gene chip Rat Genome 230 2.0 Array, which comprises more than 30,000 rat transcripts. Limma program and PANTHER database were used to evaluate the microarray data. Genes involved in the pathways of inflammatory processes (Mapk8), oxidative stress (Gpx3, Gstm3, Sod3) or Alzheimer's disease (Sncb, Apbb1ip) were altered by both fluoxetine and SJW extract. For all groups, several signaling pathways were identified which could provide a link between the various hypotheses of depression. In conclusion, microarray analysis proved to be a valuable tool to identify a large number of genes and resulting pathways that may serve as novel drug targets or predict drug responsiveness for SJW or fluoxetine. Based on our comprehensive analysis, it was possible to identify similarities and differences between SJW and fluoxetine which may help to better understand their molecular action and, in addition, help to find novel treatment strategies for stress-related depression.

Microarray Analysis as a Tool to Elucidate the Mechanism of Action of St. John's Wort

Hypericum perforatum L., known as St. John's wort (SJW) is indicated as phytotherapeutic agent for the treatment of mild to moderate forms of depression. Data from literature support the hypothesis that chronic stress is a major risk factor for psychiatric illnesses. The aim of the present study was to evaluate the effect of SJW extract (STW3-VI; 250 and 500mg/kg; p.o.) and fluoxetine (10mg/kg, p.o.) on genes involved in the pathogenesis of depression using a chronic restraint stress (CRS) model in rats. Hypothalamic and hippocampal tissues were analyzed using the Affymetrix gene chip Rat Genome 230 2.0 Array, which comprises more than 30,000 rat transcripts. Limma analysis and PANTHER database were used to evaluate the microarray data. Treatment with SJW extract in both concentrations and fluoxetine reversed expression levels of several genes changed by CRS. Genes involved in pathways of inflammatory processes (Mapk8) oxidative stress (Gpx3, Gstm3, Sod3) or Alzheimer's disease (Sncb, Apbb1ip) were altered by both, fluoxetine and SJW. In all groups several pathways were identified which provide a link between the various hypotheses of depression. Gene expression results for both brain regions were verified using quantitative rPCR. In conclusion, Microarray analysis prooved to be a valuable tool to identify a large number of genes and resulting pathways that may serve as novel drug targets or predict drug responsiveness. Based on our results it was possible to identify new candidate pathways that help to understand molecular principles of depression and in addition help to find novel treatment strategies for neuropsychiatric disorders.

Mechanism of St. John's wort extract (STW3-VI) during chronic restraint stress is mediated by the interrelationship of the immune, oxidative defense, and neuroendocrine system

Chronic stress is a contributing risk factor for the development of psychiatric illnesses such as anxiety and depression disorders. The aim of the present study was to evaluate the mechanisms of action of the standardized St. John's wort extract (STW3-VI; SJW) in a chronic restraint stress model. Markers of antioxidant capacity such as superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT) in the hippocampus and hypothalamus, and plasma levels of ACTH and corticosterone as well as the inflammatory markers IL-6 and TNF-alpha were determined in rats exposed to chronic restraint stress for 21 consecutive days. In addition, total body and relative organ weights as well as behavioral changes in the open field test were evaluated on the last day. The results show that stressed animals decreased in open field activity compared to unstressed animals, which could be reversed by fluoxetine (10mg/kg, p.o.) and SJW (125-750mg/kg, p.o.) treatment. In addition, chronic restraint stress significantly decreased thymus and spleen indices in the stressed control group. However, treating stressed rats with fluoxetine or STW3-VI produced a significant and dose dependent increase in both thymus and spleen indices compared to stressed controls. Additionally, SJW and fluoxetine significantly reduced stress-induced increases in plasma ACTH and corticosterone levels. Furthermore, the administration of SJW significantly reduced the stress-induced increase in TNF-alpha levels. Our data provide new evidence for the hypothesis that the mechanism of action of STW3-VI is mediated by the interrelationship between the immune, oxidative defense and neuroendocrine system.

Gene expression analysis of hypothalamic and hippocampal tissues of rats treated with St. John's wort extract or fluoxetine in a chronic restraint stress model

Hypericum perforatum L., known as St. John's wort (SJW) is indicated as phytotherapeutic agent for the treatment of mild to moderate forms of depression. Data from literature support the hypothesis that chronic stress is a major risk factor for psychiatric illnesses. The aim of the present study was to evaluate the effect of SJW extract (STW3-VI; 250 and 500mg/kg; p.o.) and fluoxetine (10mg/kg, p.o.) on genes involved in the pathogenesis of depression using a chronic restraint stress (CRS) model in rats (1h for 21 consecutive days). Hypothalamic and hippocampal tissues were analyzed using the Affymetrix gene chip Rat Genome 230 2.0 Array, which comprises more than 30,000 rat transcripts. Limma analysis and PANTHER database were used to evaluate the microarray data. Our first results show that chronic stress for 21 days differentially regulated 256 genes in the control group, whereas treatment with fluoxetine in stressed animals influenced 43 genes in the hippocampus. However, in stressed animals treated with 250mg/kg of the SJW extract 140 genes were altered and 223 genes in the 500mg/kg group. In all groups several pathways were identified which provide a link between the various hypotheses of depression. Gene expression profiles for hypothalamic tissues will provide additional information about brain circuits involved in depression.

Possible therapeutic effect of a Traditional Chinese Medicine, Sinisan, on chronic restraint stress related disorders

According to Traditional Chinese Medicine (TCM), the liver is the origin or most associated with stress related disorders such as depression. Sinisan, a TCM prescription, has been used as a hepatic protectant. We examined whether Sinisan exerts therapeutic effects in an experimental animal model: the chronic restraint stress (CRS) model. Sinisan was administered in the animal's drinking water at a concentration of 100mg/kg for 21 days (7 days pre-CRS and 14 days during the CRS). Spatial learning and memory were measured 24h after the CRS procedures using the Morris Water Maze (MWM). Aggressive behavior and body weight were determined as well. The Sinisan treatment decreased aggressive behaviors and reversed CRS-induced impairment of spatial learning and memory as well as decreased rate of growth. In conclusion, our results suggest that Sinisan does exert measurable therapeutic effects in an experimental chronic stress model.

Potential of St. John's wort as antistress medication

Chronic stress is thought to be a risk factor for psychosomatic psychiatric illnesses, such as anxiety and depression disorders [1]. The aim of the present study was to evaluate the mechanisms of action of St. John's wort (SJW) extract (STW 3-VI) in a chronic restraint stress (CRS) model using male Sprague-Dawley rats. Markers of antioxidant capacity, such as SOD, GPx and catalase (CAT) in brain tissues, and plasma hormone levels (ACTH, corticosterone), as well as inflammatory markers such as IL-6, TNF-α and C-reactive protein were determined in addition to behavioral changes. Our first results show that CRS (1h for 21 consecutive days) significantly decreased open field activity in chronically stressed rats, which could be reversed by fluoxetine and SJW treatment (Control unstressed: 3349±433mm/5min; Control stressed: 1740±283mm/5min, p<0.01; fluoxetine 10mg/kg stressed 2949±443mm/5min, p<0.05; SJW 250mg/kg stressed: 2630±390mm/5min, p<0.05; SJW 500mg/kg stressed: 2615±358mm/5min, p<0.05). In addition, CRS significantly decreased thymus and spleen indices in CRS treated controls (Control unstressed: 1.64±0.07; 2.41±0.09 vs. Control stressed: 1.21±0.03; 2.10±0.06, p<0.01). However, treating stressed rats with fluoxetine or SJW extract produced a significant and dose dependent increase in both thymus and spleen indices. In addition, SJW or fluoxetine significantly reduced stress-induced increases in plasma corticosterone and ACTH levels. Furthermore, the administration of fluoxetine prevented the stress-induced increase in IL-6 levels. Compared to fluoxetine, SJW resulted in a small but significant decrease in IL-6 levels. Our data provide new insight into the effects of stress on neuroimmunological and antioxidative parameters as well as into the mechanisms of action of St. John's wort.