Immobilization Stress Rats Research Articles

Electroacupuncture intervention on stress-induced cardiac autonomic imbalance in rats involves corticotropin-releasing hormone system activity.

Autonomic imbalance is a core aspect of stress response that strongly correlates to cardiovascular diseases. Enhanced activity of the central corticotropin-releasing hormone (CRH) system may result in autonomic imbalance to cause cardiovascular responses in a stress state. Electroacupuncture at PC6 acupoints has been demonstrated to prevent and treat cardiovascular diseases. In this study, we aim to demonstrate the protective role of electroacupuncture at PC6 in ameliorating cardiac autonomic imbalance and investigate the underlying mechanisms in immobilization stress rats. Four groups were subjected. Immobilization stress was applied to three groups. And the rats in two electroacupuncture-intervened groups exerted electroacupuncture at PC6 or tail respectively. Then, we performed ECG recording for heart rate variability (HRV) analysis, and rats were sacrificed after experiments for biological analysis. HRV analysis indicated that electroacupuncture at PC6 improved the enhanced low-frequency band of the power spectrum (LF), the reduced high-frequency band of the power spectrum (HF), and the enhanced LF/HF ratio caused by immobilization stress. Besides, electroacupuncture at PC6 significantly decreased phosphorylated tyrosine hydroxylase expression and increased acetylcholine esterase expression in heart of immobilization stress rats. Furthermore, electroacupuncture at PC6 significantly decreased CRH level and CRH 1 type receptor and CRH 2 type receptor (CRHR2) expressions in the rostral ventrolateral medulla (RVLM), and CRH level and CRHR2 expression in the nucleus of the solitary tract (NTS) of immobilization stress rats. Our findings suggest that electroacupuncture at PC6 can ameliorate stress-induced cardiac autonomic imbalance by modulating the CRHergic input in the RVLM and NTS.

Protective effect of hydrogen sulfide against stress-induced lung injury: involvement of Nrf2, NFκB/iNOS, and HIF-1α signaling pathways

Stress is a common phenomenon that is attracting increasing attention. Hydrogen sulfide (H2S) is a gasotransmitter that plays an important role in many physiological and pathological events. Our study aimed to estimate the effect and the underlying mechanisms of the H2S donor, sodium hydrosulfide (NaHS), against immobilization stress (IS)-induced lung injury. Forty adult male rats were classified into control group, NaHS group, and IS groups with and without NaHS treatment. Serum was obtained to determine corticosterone (CORT), total antioxidant capacity (TAC), tumor necrosis factor-α (TNF-α), and interleukin-10 (IL-10) levels. Lung H2S, nitric oxide (NO), inducible nitric oxide synthase (iNOS), and malondialdehyde (MDA) levels were measured. Lung expressions of H2S synthesizing enzymes and Western blot analysis of nuclear factor erythroid 2-related factor 2 (Nrf2) and hypoxia-inducible factor 1 alpha (HIF 1α) were estimated. Histopathological changes and immunohistochemical assessment of nuclear factor kappa B (NF-κB) and caspase-3 were also done. Pretreatment with NaHS led to marked histological protection from lung damage seen in IS rats. Furthermore, pretreatment with NaHS before IS protected lung H2S levels and expressions of H2S-synthesizing enzymes. Similarly, the levels of CORT, TNF-α, IL-10, MDA, TAC, NO, iNOS, HIF-1 α, and nuclear Nrf2 and expressions of NF-kB and caspase 3 were all maintained at near control levels in contrast to that in the IS rats. In conclusion, NaHS is protective against stress-induced lung injury due to its antioxidant, anti-inflammatory, anti-fibrotic, and antiapoptotic effects. Thus, NaHS can be used to minimize stress complications on lung.

Behavioral and neurological improvement by Cydonia oblonga fruit extract in chronic immobilization stress rats.

It is known that chronic stress is a contributing factor to several physical and mental diseases. In this study, we examined the effect of hydroethanolic extract of Cydonia oblonga fruit (HECO, 300 mg/kg) in chronically immobilized rats on physiological and behavioral parameters by the open field test (OFT), sucrose preference test (SPT), and forced swimming test (FST) and on neurological alterations by analysis of the hippocampal neurogenesis. A daily 6 hr exposure to chronic immobilization stress (CIS) for 21 consecutive days induced anxiety- and depressive-like behaviors in rats' concomitant with decreased weight gain and increased plasma corticosterone (CORT) levels, rats also showed atrophy in the CA3 subregion of the hippocampus and a decreased number of Ki67 and DCX positive cells in the dentate gyrus (DG). Treatment with HECO successfully suppressed the physiological and behavioral markers of the CIS and prevents the structural abnormality and the impaired cell proliferation in the hippocampus. Moreover, the daily administration of HECO improved the mood function in normal rats. Taking together, our findings demonstrate, for the first time, the anti-depressive effect of C. oblonga fruit by enhancing the hippocampal neurogenesis in the rat model of depression.

Evaluation of the adaptogenic activity of Tecoma stans flowers extract

Aim: The present investigation aimed to screen the adaptogenic activity of the Tecomastans flower extract. Methods: Anoxia and immobilization stress models were used in the study. Results: Anoxia stress tolerance time in mice In the anoxia stress tolerance test, the time taken for the mice to exhibit clonic convulsions was taken as the endpoint. The graded doses (125, 250, 500 mg/kg) of the test extract demonstrated dose and duration dependent significant delay in clonic convulsions on the 7th, 14th and 21st days compared to the control group. The anti-stress effect of the higher dose (500 mg/kg) of the test extract was found closer to that of the standard drug. Immobilization Stress Effect on Biochemical Parameters: Immobilization stress significantly elevated the serum cholesterol, glucose, triglycerides, and BUN levels in stress control rats compared to the normal control group. Animals pretreated for ten days with test extract at different dose levels (125, 250 and 500 mg/kg) showed dose-dependent falls in all the biochemical parameters, as compared to the stress control rats. Effect on the Weight of Organs: An increase in liver, adrenal glands weight and decrease in spleen weight were seen in Immobilization stressed rats. Ten days pretreatment with graded doses of METSF significantly and dose-dependently ameliorated the Immobilization stress-induced altered organs weight. Conclusion: In conclusion, the methanolic extract of Tecomastans flowers exhibited dose-dependent significant antistress activity against stress-induced animal models.

Involvement of Hepatic SHIP2 and PI3K/Akt Signalling in the Regulation of Plasma Insulin by Xiaoyaosan in Chronic Immobilization-Stressed Rats.

Background: Long-term exposure to chronic stress is thought to be a factor closely correlated with the development of metabolic disorders, such as diabetes mellitus and metabolic syndrome. Xiaoyaosan, a Chinese herbal formula, has been described in many previous studies to exert anxiolytic-like or antidepressant effects in chronically stressed rats. However, few studies have observed the effects of Xiaoyaosan on the metabolic disorders induced by chronic stress. Objective: We sought to investigate the effective regulation of Xiaoyaosan on 21-day chronic immobility stress (CIS, which is 3 h of restraint immobilization every day)-induced behavioural performance and metabolic responses and to further explore whether the effects of Xiaoyaosan were related to SHIP2 expression in the liver. Methods: Sixty male Sprague Dawley rats were randomly divided into a control group, a CIS group, a Xiaoyaosan group and a rosiglitazone group. The latter three groups were subjected to 21 days of CIS to generate the stress model. After 21 days of CIS, the effects of Xiaoyaosan on body weight, food intake, and behaviour in the open field test, the sucrose preference test and the forced swimming test were observed following chronic stress. Plasma insulin, cholesterol (CHOL), triglyceride (TG), low-density lipoprotein (LDL-C) and high-density lipoprotein (HDL-C) concentrations and blood glucose were examined, and the protein and mRNA expression levels of SHIP2, p85 and Akt in the liver were measured using RT-qPCR and immunohistochemical staining. Results: Rats exposed to CIS exhibited depression-like behaviours, decreased levels of plasma insulin, CHOL, LDL-C, TG and HDL-C, and increased blood glucose. Increased SHIP2 expression and reduced Akt, p-Akt and p85 expression were also observed in the liver. Xiaoyaosan exerted antidepressant effects and effectively reversed the changes caused by CIS. Conclusions: These results suggest that Xiaoyaosan attenuates depression-like behaviours and ameliorates stress-induced abnormal levels of insulin, blood glucose, CHOL, LDL-C and HDL-C in the plasma of stressed rats, which may be associated with the regulation of SHIP2 expression to enhance PI3K/Akt signalling activity in the liver.

High Hydrostatic Pressure Extract of Ginger Exerts Antistress Effects in Immobilization-Stressed Rats.

Stress contributes to physiological changes such as weight loss and hormonal imbalances. The aim of the present study was to investigate antistress effects of high hydrostatic pressure extract of ginger (HPG) in immobilization-stressed rats. Male Sprague-Dawley rats (n = 24) were divided into three groups as follows: control (C), immobilization stress (2 h daily, for 2 weeks) (S), and immobilization stress (2 h daily, for 2 weeks) plus oral administration of HPG (150 mg/kg body weight/day) (S+G). Immobilization stress reduced the body weight gain and thymus weight by 50.2% and 31.3%, respectively, compared to the control group. The levels of serum aspartate transaminase, alanine transaminase, and corticosterone were significantly higher in the stress group, compared to the control group. Moreover, immobilization stress elevated the mRNA levels of tyrosine hydroxylase (Th), dopamine beta-hydroxylase (Dbh), and cytochrome P450 side-chain cleavage (P450scc), which are related to catecholamine and corticosterone synthesis in the adrenal gland. HPG administration also increased the body weight gain and thymus weight by 12.7% and 16.6%, respectively, compared to the stress group. Furthermore, the mRNA levels of Th, Dbh, phenylethanolamine-N-methyltransferase, and P450scc were elevated by the HPG treatment when compared to the stress group. These results suggest that HPG would have antistress effects partially via the reversal of stress-induced physiological changes and suppression of mRNA expression of genes related to corticosterone and catecholamine synthetic enzymes.

Change of Rin1 and Stathmin in the Animal Model of Traumatic Stresses.

The molecular mechanism of fear memory is poorly understood. Therefore, the pathogenesis of post-traumatic stress disorder (PTSD), whose symptom presentation can enhance fear memory, remains largely unclear. Recent studies with knockout animals have reported that Rin1 and stathmin regulate fear memory. Rin1 inhibits acquisition and promotes memory extinction, whereas stathmin regulates innate and basal fear. The aim of our study was to examine changes in the expression of Rin1 and stathmin in different animal models of stress, particluarly traumatic stress. We used three animal traumatic stresses: single prolonged stress (SPS, which is a rodent model of PTSD), an immobilization-stress (IM) and a Loud sound stress (LSS), to examine the change and uniqueness in Rin1/stathmin expression. Behavioral tests of SPS rats demonstrated increased anxiety and contextual fear-conditioning. They showed decreased long-term potentiation (LTP), as well as decreased stathmin and increased Rin1 expression in the hippocampus and the amygdala. Expression of the stathmin effector, tubulin, and downstream molecules Rin1, Rab5, and Abl, appeared to increase. Rin1 and EphA4 were endogenously coexpressed in primary neurons after SPS stimulation. IM rats exhibited increased anxiety behavior and enhanced fear-conditioning to contextual and auditory stimuli. Similar changes in expression of Rin1/stathmin were observed in IM rats whereas no changes were observed in rats exposed to a loud sound. These data suggest that changes in expression of the Rin1 and stathmin genes may be involved in rodents with SPS and IM stresses, which provide valuable insight into fear memories under abnormal conditions, particularly in PTSD.

Impact of Noni Juice on Myelin Components, Neurotransmittory and Behavioural Status in Rats Exposed to Immobilization Stress

Several reports indicate that psychological stress and depression are detrimental to health and that chronic stress implicates pathophysiology of mood and anxiety- related disorders, thus leading to several stressrelated complications. The present study focuses on behavioural status and neurochemical variations in myelin of rat brain exposed to chronic immobilization stress and evaluates the effect of fruit juice of noni over changes in the myelin content of forebrain (FB) and midbrain (MB) regions of rats exposed to stress. Immobilization stress (IS) strategy was utilized to induce stress in Wistar rats. Myelin protein was isolated from the MB and FB regions of rats. Assessment of activities of membrane bound enzymes, levels of neurotransmitters (dopamine, serotonin and glutamate of FB and MB) and lipid profile of myelin in addition to behavioural analysis were carried out. The membrane- bound enzymes such as ATPases, 5'-nucleotidase and acetylcholinesterase exhibit significant decrease in their activities both in the FB and MB regions on stress induction, when compared to that of control. The neurotransmitters and lipid profile also show similar pattern among the experimental group. However, administration of noni juice (NJ) in ISexposed rats can significantly alter the activities of myelin-associated enzymes and levels of neurotransmitters and lipid content of myelin (P < 0.05) along with improvement in the behavioural pattern when compared to those of IS rats. These preliminary results set targets for further authentication of the use of NJ against stress. This NJ could become one of the ideal supplements for management of stress-induced neurological disorders.

Anti-stress effects of ginseng via down-regulation of tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DBH) gene expression in immobilization-stressed rats and PC12 cells

Catecholamines are among the first molecules that displayed a kind of response to prolonged or repeated stress. It is well established that long-term stress leads to the induction of catecholamine biosynthetic enzymes such as tyrosine hydroxylase (TH) and dopamine β-hydroxylase (DBH) in adrenal medulla. The aim of the present study was to evaluate the effects of ginseng on TH and DBH mRNA expression. Repeated (2 h daily, 14 days) immobilization stress resulted in a significant increase of TH and DBH mRNA levels in rat adrenal medulla. However, ginseng treatment reversed the stress-induced increase of TH and DBH mRNA expression in the immobilization-stressed rats. Nicotine as a ligand of the nicotinic acetylcholine receptor (nAChR) in adrenal medulla stimulates catecholamine secretion and activates TH and DBH gene expression. Nicotine treatment increased mRNA levels of TH and DBH by 3.3- and 3.1-fold in PC12 cells. The ginseng total saponin exhibited a significant reversal in the nicotine-induced increase of TH and DBH mRNA expression, decreasing the mRNA levels of TH and DBH by 57.2% and 48.9%, respectively in PC12 cells. In conclusion, immobilization stress induced catecholamine biosynthetic enzymes gene expression, while ginseng appeared to restore homeostasis via suppression of TH and DBH gene expression. In part, the regulatory activity in the TH and DBH gene expression of ginseng may account for the anti-stress action produced by ginseng.

Changes of glucocorticoid receptor and levels of CRF mRNA, POMC mRNA in brain of chronic immobilization stress rats.

The effect of chronic immobilization stress (CIS) on the biochemical parameters has been one of the hot topics in neuroscience. The aim of this study was to investigate the effects of CIS on the levels of glucocorticoid receptor (GR), corticotrophin-releasing factor (CRF) mRNA and proopiomelanocortin (POMC) mRNA in brains of rats. The rats were randomly divided into stressed and control groups. The stressed group was given CIS 3 h a day for 21 days continuously. GR of rats' hippocampus and prefrontal cortex (PFC) were detected by immunohistochemistry method. In addition, the CRF mRNA and POMC mRNA of rats' brain regions (hypothalamus, pituitary, hippocampus, and PFC) were detected by reverse transcription-polymerase chain reaction (RT-PCR). After exposure to CIS for 21 days, the GR immuno staining (the gray values) of the stressed group was less than that of the control group in hippocampal CA(1), dentate gyrus, and PFC (P < 0.01). Quantitative analysis indicated the presence of CRF mRNA in hypothalamus and pituitary, while POMC mRNA in PFC, hippocampus and pituitary of the stressed group was less than that of the control group (P < 0.01). The decreased levels of GR, CRF mRNA, and POMC mRNA in different brain regions may contribute to explanation of the CIS induced mechanism.

P-CPA Pretreatment Reverses the Changes in Sleep and Behavior Following Acute Immobilization Stress Rats

The effects of p-CPA (para-chlorophenylalanine) pretreatment was studied on the sleep-wake parameters and patterns of behavioral activities in an animal model of acute immobilization stress. For the experiments, young male Charles Foster rats were divided into three groups, subjected to (i) acute immobilization stress for four hours on specially designed wooden boards, (ii) a similar model of acute immobilization stress after pretreatment of p-CPA (injected through i.p. route), and (iii) control rats (p-CPA untreated and unstressed). Three channels of electrographic signals, i.e., EEG (electroencephalogram), EOG (electrooculogram), and EMG (electromyogram) were recorded continuously for four hours for all three groups of rats to analyze the changes in sleep-wake stages. The assessment of behavior was performed just after the stress on separate groups of rats in Open-Field (OF) and Elevated Plus-Maze (EPM) apparatuses. The significant changes in total sleep time (P < 0.05), total time for rapid eye movement sleep (P < 0.01), and total time in wakefulness (P < 0.01) following acute immobilization stress were found reversed in the p-CPA (a serotonin inhibitor) pretreated group of rats. Simultaneously, the results of the present work also revealed that the changes in grooming behavior (P < 0.05) in OF and the total time spent on the center of EPM (P < 0.05) were observed altered in p-CPA pretreated group of rats.

Anti-Stress Effects of Ginseng in Immobilization-Stressed Rats

Stress is a global menace exacerbated by the advancement of industrialization. Failure of stress management is to a breakdown of the psychological and physiological protection mechanisms against stress. The aim of present study was to investigate the anti-stress potential of ginseng against immobilization stress. Male Sprague-Dawley rats (n=24) were divided into three groups; (ⅰ) control, (ⅱ) immobilization stress (2 hr daily, for 2 weeks), and (ⅲ) immobilization stress (2 hr daily, for 2 weeks) plus oral administration of ginseng (200 mg/kg BW/d). Immobilization stress resulted in a significant inhibition of body weight gain by 45% and a significant decrease in the tissue weights of thymus and spleen (p＜0.05). The concentrations of blood GOT and GPT were significantly increased in the immobilization-stressed group compared to the control group (p＜0.05). There were no differences in the blood cholesterol levels among groups. Ginseng administration in the immobilization-stressed group tended to reverse the lack of body weight gain and food intake, though not significantly. The ginseng-administered group showed a significant reversal in the stress-induced effect on spleen and thymus weight, increasing the tissue weights by 16% and 20%, respectively, compared to immobilization-stressed group (p＜0.05). The plasma corticosterone level was significantly increased in the stressed group by 39% compared to the control group (p＜0.05), but ginseng administration significantly reversed the stress-induced increase in plasma corticosterone by 15% compared to the immobilization-stressed group. The present study suggests that the anti-stress effect of ginseng is mediated by normalization of stress-induced changes in the circulating hormones and a reversal of tissue weight loss, thereby returning the body to normal homeostasis.

Repeated Immobilization Stress Increases Uncoupling Protein 1 Expression and Activity in Wistar Rats.

Repeat immobilization-stressed rats are leaner and have improved cold tolerance due to enhancement of brown adipose tissue (BAT) thermogenesis. This process likely involves stress-induced sympathetic nervous system activation and adrenocortical hormone release, which dynamically enhances and suppresses uncoupling protein 1 (UCP1) function, respectively. To investigate whether repeated immobilization influences UCP1 thermogenic properties, we assessed UCP1 mRNA, protein expression, and activity (GDP binding) in BAT from immobilization-naive or repeatedly immobilized rats (3 h daily for 4 weeks) and sham operated or adrenalectomized (ADX) rats. UCP1 properties were assessed before (basal) and after exposure to 3 h of acute immobilization. Basal levels of GDP binding and UCP1 expression was significantly increased (140 and 140%) in the repeated immobilized group. Acute immobilization increased GDP binding in both naive (180%) and repeated immobilized groups (220%) without changing UCP1 expression. In ADX rats, basal GDP binding and UCP1 gene expression significantly increased (140 and 110%), and acute immobilization induced further increase. These data demonstrate that repeated immobilization resulted in enhanced UCP1 function, suggesting that enhanced BAT thermogenesis contributes to lower body weight gain through excess energy loss and an improved ability to maintain body temperature during cold exposure.

Allosteric Modulation of the GabaA Receptor In Rat Hypothalamus By Somatostatin Is Altered By Stress

1. This autoradiographic study was conducted to investigate somatostatin modulation of GABA(A) receptor binding in hypothalamic structures of immobilization-stressed rats. 2. GABA(A) receptor binding was labelled with [35S]-t- butylbicyclophosphorothionate (TBPS), which binds in or near the chloride channel. 3. Several structures of the rat hypothalamus (i.e. the peri- and paraventricular nuclei) display an increase in [35S]-TBPS binding as well as an alteration of the modulatory effect of somatostatin on the GABA(A) receptor complex under stress. Furthermore, these results demonstrate for the first time that somatostatin is particularly effective in modifying [35S]-TBPS binding to the GABA(A) receptor in rat hypothalamus.

Renal Excretion And Saline Intake During Post-Stress Immobilization Period In Rats

An experiment in which the rats access either to 0.5% or 1.5% saline was designed in order to further characterise the relationship between sodium intake and renal excretion after acute immobilization stress. A saline solution for 3 days was provided to the rats previous to the experimental day. On that day, after finishing acute immobilization stress, all variables under observation were measured every 6 h for 24 h. These periods were denominated as follows: T1 (12.00 to 18.00 h), T2 (18.00 to 24.00 h), T3 (24.00 to 06.00 h) and T4 (06.00 to 12.00 h). IMO reduced sodium renal excretion in both T1 and T2. Sodium intake in acute immobilization stress rats was lower than in control rats during all observed periods, while the urine volume was only reduced in the stressed animals in T1. These results were similar in both saline solution concentrations. A good correlation was observed between sodium intake and sodium excretion in control rats having access to either 0.5% or 1.5% saline as well as in stressed r...

Renal Excretion And Saline Intake During Post-Stress Immobilization Period In Rats

An experiment in which the rats access either to 0.5% or 1.5% saline was designed in order to further characterise the relationship between sodium intake and renal excretion after acute immobilization stress. A saline solution for 3 days was provided to the rats previous to the experimental day. On that day, after finishing acute immobilization stress, all variables under observation were measured every 6 h for 24 h. These periods were denominated as follows: T1 (12.00 to 18.00 h), T2 (18.00 to 24.00 h), T3 (24.00 to 06.00 h) and T4 (06.00 to 12.00 h). IMO reduced sodium renal excretion in both T1 and T2. Sodium intake in acute immobilization stress rats was lower than in control rats during all observed periods, while the urine volume was only reduced in the stressed animals in T1. These results were similar in both saline solution concentrations. A good correlation was observed between sodium intake and sodium excretion in control rats having access to either 0.5% or 1.5% saline as well as in stressed rats having access to 0.5% saline, this correlation was not observed in stressed rats with 1.5% saline. This suggests that stress impaired the renal capability of rats to handle high sodium but not a slight sodium overload. The inability of the kidney to excrete sodium may be critical to reduce sodium intake after acute immobilization stress.

Indication for a granule-free form of vasopressin in immobilization-stressed rats

Following immobilization stress the supraoptic nucleus exhibits an increased number of coarse, heavily immunostained fibers in the basal glia labyrinth. Ultrastructural immunocytochemistry demonstrates a labeling of the rough endoplasmic reticulum in the neurosecretory perikarya and granule-free, immunoreactive material in the axons adjacent to the basal glia labyrinth. Furthermore, a labeling of the intercellular clefts of the neuropil is demonstrable in the supraoptic nucleus. These results lead to the hypothesis that 1) vasopressin is synthesized and released in two forms, in a granule-bound form and in a granule-free, probably more soluble form, and that 2) the latter might be released already in the nuclear area into the intercellular clefts from where it may reach its target cells via the cerebrospinal fluid of the subarachnoid space.