四逆散有效组分拮抗空瓶刺激所致大鼠慢性情绪应激的作用

目的:探讨四逆散有效组分拮抗慢性情绪应激大鼠的作用。方法:利用连续21 d空瓶刺激所致大鼠慢性情绪应激模型,观察四逆散有效组分(450 mg/kg/day,连续21 d)对模型大鼠的体重、行为学、血清皮质酮含量及大鼠海马组织病变的影响。结果:四逆散有效组分能够有效拮抗空瓶刺激诱导的大鼠慢性情绪应激反应,表现为大鼠体重明显升高、攻击和探究行为减少、修饰行为增加、皮质酮含量降低、改善情绪应激导致的海马损伤。结论:四逆散有效组分可能是通过抑制皮质酮的含量升高,减少海马损伤而发挥其拮抗慢性情绪应激的作用。     

Inflammatory mediators involved in the nociceptive and oedematogenic responses induced by Tityus serrulatus scorpion venom injected into rat paws

The present study investigated the role of kinins, prostaglandins (PGs) and nitric oxide (NO) in mechanical hypernociception, spontaneous nociception and paw oedema after intraplantar (ipl) injection of Tityus serrulatus venom (Tsv) in male Wistar rats. Tsv was ipl-injected in doses of 0.01-10microg/paw. Pre-treatment (30min prior) with DALBK (100nmol/paw) and icatibant (10nmol/paw), B1 and B2 selective kinin receptor antagonists, L-NAME (50mg/kg, i.p., a non-selective nitric oxide synthase inhibitor) or celecoxib, selective COX-2 inhibitor, was given 1h prior per os (5mg/kg, p.o.), significantly reduced the hypernociceptive response (Von Frey method), the spontaneous nociception (determined by counting the number of flinches) and paw oedema (plethysmometer method) induced by Tsv at doses of 1.0 and 10microg/paw for both nociceptive and oedematogenic responses, respectively. Nevertheless, indomethacin (5mg/kg, i.p., 30min prior) was ineffective in altering all of these events. The results of the present study show that Tsv, injected ipl into the rat paw, causes a dose-dependent paw oedema, mechanical hypernociception and flinches (a characteristic biphasic response) in which kinins and NO are substantially involved. Although celecoxib was effective against the oedema and pain caused by Tsv, COX-2 does not seem to be involved in the inflammatory response caused by Tsv.     

五指毛桃水提物对拘束应激性肝损伤的保护作用

目的:研究五指毛桃水提物对拘束负荷诱发小鼠应激性肝损伤的保护作用.方法:将雄性昆明种小鼠随机分为正常对照组,拘束应激模型组,破壁灵芝孢子粉(GL)组(500 mg·kg^-1)和五指毛桃水提物(RFH)低、中、高剂量组(125,250及500 mg·kg^-1),共6组.连续灌胃给药4 d后,除正常对照组外,其余各组小鼠拘束负荷18 h诱发小鼠应激性肝损伤,分别用赖氏法测定小鼠血浆丙氨酸氨基转移酶(ALT)活性、硫代巴比妥酸法测定肝组织丙二醛(MDA)含量、Griess化学法测定一氧化氮(NO)含量、荧光酶标仪测定肝组织抗氧化能力指数(ORAC)、HPLC法测定谷胱甘肽(GSH)含量、比色法测定谷胱甘肽过氧化物酶(GSH-Px)、谷胱甘肽硫转移酶(GST)活性.结果:与拘束应激模型组相比,五指毛桃水提物可以明显降低拘束负荷小鼠血浆ALT活性、肝组织MDA和NO含量,有效提高肝组织的ORAC指数、GSH含量、GSH-Px和GST活性.结论:五指毛桃水提物对拘束负荷诱发小鼠应激性肝损伤有一定的保护作用,其作用可能与缓解拘束负荷小鼠的氧化应激状态相关.     

Effect of L-arginine on restraint stress induced modulation of immune responses in rats and mice.

The present study investigates the role of nitric oxide (NO) on restraint stress (RS)-induced modulation of humoral and cell-mediated immune responses in rats and mice. RS produced suppression of humoral immune response, i.e., anti-SRBC antibody titre ( 7.38 +/- 0.32 versus 4.13 +/- 0.30; mean +/- S.E.M., P < 0.001). In case of cell-mediated immunity, in delayed type hypersensitivity (DTH) response the change in paw volume decreased from 0.069 +/- 0.003 mm (mean +/- S.E.M.) in control non-stressed group to 0.038 +/- 0.002 mm in the stressed group (P < 0.001) while percentage leucocyte migration inhibition (% LMI) decreased from 39.7 +/- 1.95 in control non-stressed animals to 15.2 +/- 1.07 in animals subjected to stress (P < 0.01). Pretreating the animals with an NO precursor, L-arginine (1000 mg kg-1, i.p.) antagonized the effect of RS on humoral (anti-SRBC antibody titre 6.50 +/- 0.27 versus 4.13 +/- 0.30, P < 0.001 ) and cell-mediated (DTH response 0.066 +/- 0.002 mm versus 0.038 +/- 0.002 mm, P < 0.001; % LMI 41.5 +/- 1.46 versus 15.2 +/- 1.07, P < 0.01) immune responses. Administration of 7-nitroindazole (7-NI, 50 mg kg-1, i.p.), an inhibitor of neuronal NO synthase, alone further enhanced the immunosuppressive effect of RS (anti-SRBC antibody titre 2.75 +/- 0.25 versus 4.13 +/- 0.30, P < 0.001; DTH response 0.019 +/- 0.002 mm versus 0.038 +/- 0.002 mm, P < 0.001; % LMI 5.0 +/- 1.08 versus 15.2 +/- 1.07, P < 0.01). However, when given before L-arginine treatment, 7-NI reversed the effect of the latter drug on stress-induced immunomodulation (anti-SRBC antibody titre 3.00 +/- 0.27 versus 6.5 +/- 0.27, P < 0.001; DTH response 0.043 +/- 0.003 mm versus 0.066 +/- 0.002 mm, P < 0.001; % LMI 12.0 +/- 0.93 versus 41.5 +/- 1.46, P < 0.01). Unlike its effect on RS-induced immune responsiveness, L-arginine (250, 500, 1000 mg kg-1) when given for 5-7 days to naive non-stressed animals produced dose dependent suppression of both humoral (anti-SRBC antibody titre 6.4 +/- 0.32 versus 5.4 +/- 0.32, 4.0 +/- 0.27, 3.1 +/- 0.30, respectively) and cell-mediated (DTH 0.065 +/- 0.003 mm versus 0.064 +/- 0.004 mm, 0.039 +/- 0.003 mm, 0.020 +/- 0.002 mm, respectively and % LMI 37.52 +/- 1.58 versus 30.48 +/- 1.07, 28.18 +/- 1.22, 19.76 +/- 0.83, respectively) immune responses. 7-NI significantly blocked these immunosuppressive effects of L-arginine (anti-SRBC antibody titre 6.0 +/- 0.38 versus 3.1 +/- 0.030, P < 0.01; DTH response 0.056 +/- 0.004 mm versus 0.020 +/- 0.002 mm, P < 0.001; % LMI 34.76 +/- 1.31 versus 19.76 +/- 0.83, P < 0.01). However, 7-NI when given to non-stressed animals failed to modulate immune responsiveness. Thus, NO appears to play an important role in RS-induced immunomodulation and these effects are different from its effect on immune responsiveness in non-stressed animals.     

The effects of restraint stress on voluntary ethanol consumption in rats

Sixty Wistar rats (Rattus norvegicus) were assigned to 4 groups of 15 rats each: ethanol stress (ES), ethanol no-stress (EN), isocaloric stress (IS) and isocaloric no-stress (IN). The effect of restraint stress on daily intake of ethanol and a 0.72% solution of glucose was examined in an ABA design (stress-no stress-stress). During the stress phases, 2 groups were subjected to daily 15-min restraint stress, whereas 2 groups were placed in different cages for 15 min as a control. All 4 groups were then given 6-hr access to their assigned liquid alone for 4 days followed by a choice between their assigned liquid and water on the 5th day. The ES group significantly increased their ethanol intake (g/kg) compared to the EN group on choice days but not on forced days. Percentage preference for ethanol was significantly greater and increased at a faster rate over the 75-day testing period compared with the EN group. However, total ethanol consumption (g/kg) and percentage preference did not vary as a function of phase. It is notable that the effects of restraint stress on ethanol self-administration persisted even after the stress schedule was removed.     

High-intensity nociceptive stimuli minimize behavioral effects induced by restraining stress during the tail-flick test.

Analgesia following exposure to various stressors is a well-documented phenomenon. Restraint of an animal during the tail-flick test (TFT) represents a potent stressor that can induce both altered baseline latencies and enhanced response to opioids. The present study shows that the use of higher stimulus intensities during TFT minimizes the stress influences produced by restraint on the animal's response rendering the test more sensitive to the pharmacological action of analgesic drugs.     

Gastric mucosal protection induced by restraint and water-immersion stress in rats.

We found that the gastric mucosal lesion induced by 60% ethanol containing 150 mM HCl was reduced by pre-loading the rat with restraint and water-immersion stress (22 degrees C). The resistance to ethanol injury was maximal in 1-hr stress loaded rats and gradually decreased with increasing time of stress (2-6 hr). The protective effect of stress was markedly decreased by subdiaphragmatic truncal vagotomy, and electrical stimulation of vagal nerves afforded similar protection as observed after stress. In contrast, pretreatment with atropine markedly reduced ethanol injury in both the control and 1 hr stress-loaded rats. One-hour stress produced surface epithelial cell damage in sham vagotomized rats, but the surface cells were almost intact in vagotomized rats. Pretreatment with indomethacin significantly mitigated the protective effect of stress against ethanol injury. However, the level of mucosal prostaglandin E2 was not changed 1 hr after stress, and it tended to decrease 6 hr after stress. Pretreatments with 1-hr stress and vagal stimulation weakly reduced localized staining of gastric mucosa with gentian violet. We conclude that adaptive protection can be achieved by restraint and water-immersion stress.     

The effects of inflammation and inflammatory mediators on nociceptive behaviour induced by ATP analogues in the rat

1. We have studied the behavioural effects of intraplantar injections of adenosine 5'-triphosphate (ATP) and related compounds in freely moving rats and investigated whether these nociceptive effects are augmented in the presence of inflammatory mediators. 2. We find that in normal animals ATP and analogues produce dose-dependent nocifensive behaviour (seen as bursts of elevation of the treated hindpaw), and localized thermal hyperalgesia. The rank order of potency was: alpha,beta-methyleneadenosine 5'-triphosphate (alpha,beta-methylene ATP) > 2-methylthioadenosine triphosphate (2-methylthio ATP) > ATP. After neonatal treatment with capsaicin, to destroy small calibre primary sensory neurones, nocifensive behaviour was largely absent. 3. The effects of ATP analogues were assessed in three models of peripheral sensitization: 2 h after dilute intraplantar carrageenan (0.25% w v(-1)); 24 h after irradiation of the hindpaw with ultraviolet (U.V.) B; immediately following prostaglandin E2 (PGE2) treatment. In all models the effect of alpha,beta-methylene ATP was greatly augmented. After carrageenan, significant hindpaw-lifting behaviour activity was induced by injection of only 0.05 nmol of alpha,beta-methylene ATP, some 100 times less than necessary in normal skin. 4. Our data suggest that it is much more likely that endogenous levels of ATP will reach levels capable of exciting nociceptors in inflamed versus normal skin. Our data also suggest the involvement of P2X3 receptor subunits in ATP-induced nociception.     

Influence of maternal restraint stress on the long-lasting effects induced by prenatal exposure to perfluorooctane sulfonate (PFOS) in mice

The behavioral effects of concurrent maternal exposure to restraint stress and perfluorooctane sulfonate (PFOS) were assessed in the offspring of mice at 3 months of age. Plug positive females were divided into two groups. Animals were given by gavage 0 and 6mg PFOS/kg/day on gestation days 12-18. One-half of the animals in each group were subjected to restraint stress (30min/session, three sessions per day) during the same period. At 3 months, mice were evaluated for general activity in an open-field, and for learning and memory in a water maze task. The group prenatally exposed to PFOS and restraint presented a reduced mobility in the open-field. In the water maze, an interaction between sex and restraint was observed. Delayed task learning was also detected in females prenatally exposed to PFOS and restraint. An overall effect of restraint was observed in mice on retention of the task, suggesting a better retention in restrained animals. On the other hand, corticosterone levels were lower in animals prenatally subjected to restraint stress. The current results suggest interactive effects between PFOS and maternal stress.     

The effects of noradrenaline on rat's behaviour

Summary The behavioural effects of NA injected without narcosis into the lateral brain ventricle of the rats were studied with two different techniques. Rats were classified according their normal level of exploratory activity into three groups: high, medium and low. It was shown that NA in a dose of 10 g increased locomotor activity only in animals of low activity; a dose of 50 g increased locomotor activity in all the animals; and a dose of 200 g induced a complete abolition of locomotor activity and a stuporose syndrome lasting 2 hours. The evidence that NA in some experimental conditions increases locomotor activity of rats supports the hypothesis that NA regulates processes in the central nervous system which stimulate behaviour.     

The inflammatory reaction induced by formalin in the rat paw

The involvement of bradykinin and some other inflammatory mediators in formalin-induced oedema and plasma extravasation was examined. Formalin was injected in rat paws at two doses, 1.75% or 5%. The lower dose induced the development of an immediate oedema associated with a progressive accumulation of ¹²⁵I-labelled albumin in the paws. These changes were suppressed by pretreatment with capsaicin or xylocaine. They were abolished by RP67580, a NK₁ receptor antagonist, and increased by phosphoramidon or diprotin A. They were not affected by HOE140, a bradykinin B₂ antagonist, captopril, methysergide, mepyramine, indomethacin, ketoprofen or l-N ^G-nitroarginine. The higher dose of formalin induced a swelling of the paws which took place in two phases associated with two periods of increase in vascular permeability. This oedema was reduced by pretreatment with capsaicin but not with xylocaine. It was reduced by RP67580 injected before or 30 min after formalin. It was inhibited by mepyramine, methysergide, indomethacin and NS-398, a cyclooxy-genase-2 inhibitor. It was not modified by HOE140. Its development was similar in normal and kininogen-deficient rats. We concluded that formalin administered at a low dose induces an oedema which mainly results from a neurogenic inflammation mediated by neuropeptides such as substance P. At higher doses, formalin induces an oedema which mainly depends on the release of substance P, prostanoids, 5-hydroxytryptamine and histamine. Bradykinin plays no significant role in the vascular changes whereas this peptide has been reported to participate in the stimulation of nociceptive afferent neurons. This discrepancy could be explained by a difference in the threshold of stimulation of the nociceptive neurons and that of the cells of the vascular walls, or by a formation of kinins in close contact of the neurons. Received: 29 June 1998 / Accepted: 20 November 1998     

Mechanisms underlying the nociceptive and inflammatory responses induced by trypsin in the mouse paw

It has been demonstrated that trypsin is able to evoke the classical signals of inflammation, mainly via the activation of proteinase-activated receptor-2 (PAR-2). This study was designed to evaluate the inflammatory and nociceptive responses caused by trypsin injection in the mouse paw. Trypsin produced a dose- and time-related paw edema, a response that was markedly reduced in PAR-2-deficient mice compared to wild-type mice, particularly at the early time-points after trypsin injection. In addition, trypsin produced an increase in myeloperoxidase (MPO) activity, which was significantly reduced in PAR-2-deficient mice. The injection of trypsin into the mouse paw also elicited a dose- and time-dependent spontaneous nociception, as well as thermal and mechanical hypernociceptive responses, which were consistently decreased in mice with genetic deletion of PAR-2. Pharmacological evaluation revealed that edema formation and spontaneous nociception caused by trypsin injection in the mouse paw are mediated by a complex range of mediators. Both edema and nociception seem to rely on the production of neuropeptides, probably involving C-fibre activation and vanilloid receptor-1 (TRPV1), besides the stimulation of kinin B(2) receptors. Edematogenic response is also likely related to the production of cyclooxygenase (COX) metabolites, whereas the mast cell activation appears to be greatly associated to spontaneous nociception. Altogether, the present results indicate that trypsin-induced edema and nociception in the mouse paw represent multi-mediated responses that are largely, but not exclusively, related to the activation of PAR-2. These pieces of evidence provide new insights on the role of trypsin in pain and inflammation.     

Estrous cycle modulation of nociceptive behaviors elicited by electrical stimulation and formalin

The impact of circulating ovarian hormones on nociceptive behaviors elicited by phasic and tonic stimuli was evaluated in rats using two behavioral tests: an operant escape task and the formalin test. The operant escape task was structured to separately evaluate hindlimb flexion reflexes, the latency of escape, and the amplitude of peak vocalization to a series of phasic electrocutaneous stimuli (0.05-0.8 mA), whereas the formalin test evaluated nociceptive behaviors elicited by tonic stimulation following a subcutaneous injection of dilute formalin (1%). Hindlimb reflex amplitude, escape latency, and peak vocalization varied across the estrous cycle, such that rats were most sensitive to electrical stimuli during proestrus (reflex and escape latency) and diestrus (vocalization). Furthermore, morphine-induced (3 mg/kg sc) attenuation of hindlimb reflex amplitude was sensitive to estrous cycling. During proestrus, morphine produced less attenuation of hindlimb reflex amplitude than during nonproestrus phases. However, estrous cycling did not alter nociceptive behaviors elicited by 1% formalin. These data support the notion that circulating ovarian hormones may differentially modulate behaviors associated with phasic and tonic pain.     

Behavioral effects in the elevated plus maze of an NMDA antagonist injected into the dorsal hippocampus: influence of restraint stress

The objective of the study was to investigate the influence of restraint stress on the effects of 2-amino-7-phosphonoheptanoic acid (AP7), an NMDA receptor antagonist, injected into the hippocampus of rats submitted to the elevated plus maze (EPM). Male Wistar rats with cannulas aimed to the dorsal hippocampus were forced immobilized for 2 h. Twenty four hours later they received bilateral injections of saline or AP7 (10 nmol/0.5 microl), and were tested in the EPM. In another experiment the animals received the treatment immediately before or after the restraint period, and were tested in the EPM 24 h later. AP7 had no effect in any anxiety measure in non-stressed rats. In stressed animals the drug increased the percentage of open arm entries when injected before the test in the EPM. When administered immediately after the restraint period, AP7 increased the percentage of time spent in the open arms and tended to do the same with the percentage of entries in these same arms. The results suggest that interference with hippocampal NMDA receptors modify the anxiogenic effect of restraint stress in an EPM.     

Developmental effects of maternal stress in the CD-1 mouse induced by restraint on single days during the period of major organogenesis

Maternal stress during gestation can produce significant fetal and/or postnatal effects, and can enhance the teratogenicity of other agents. We have previously shown that restraint stress on gestational day 8 in CD-1 mice produces significant increases in encephaloceles and supernumerary and fused ribs. In the present study we have examined the effects of stress induced by restraint on individual days during the period of major organogenesis (days 6-14). Weight loss and stress-induced analgesia as assessed by the tail-flick method were used to determine the degree of stress induced by a 12-h restraint period. Restrained animals lost significantly more weight and had longer tail-flick latencies than the concurrent food and water deprived controls on all gestational days. Significant increases in embryo/fetal mortality were also observed in the offspring of restrained animals. An increased incidence of supernumerary ribs was found in mice restrained on days 7 and 8. Since maternal toxicity induced by chemical teratogens may be accompanied by a general increase in maternal stress, our data suggest that such stress may be an etiological factor in teratology bioassays in which dose levels are sufficiently high to induce overt maternal toxicity.     

银杏叶提取物对大鼠冷应激引起的胃肠动力紊乱及NO含量变化的影响

目的探讨银杏叶提取物对冷束缚应激引起的胃肠动力紊乱及NO含量变化的影响。方法采用冷束缚应激的方法建立肠功能紊乱模型,应用葡聚糖蓝2000(DB2000)作为染料观察EGb和冷束缚应激状态对胃排空率、小肠推进率的影响,并利用比色法观察大鼠胃肠组织、血浆中NO含量的变化。结果冷束缚应激可抑制大鼠胃排空速度(P<0.05)及小肠推进率(P<0.01),EGb干预可明显拮抗冷束缚应激引起的胃排空速度及小肠推进率降低(P<0.05);EGb可以降低冷束缚应激引起的血浆中NO含量的升高(P<0.01)。结论EGb对冷束缚应激所诱发的肠道功能紊乱具有正向调解作用,NO可能在这一过程中发挥了作用。     

Behavioral and accumbens synaptic plasticity induced by cues associated with restraint stress

Exposure to acute stress can increase vulnerability to develop or express many psychiatric disorders, including post-traumatic stress disorder. We hypothesized that stress-induced psychiatric vulnerability is associated with enduring neuroplasticity in the nucleus accumbens core because stress exposure can alter drug addiction-related behaviors that are associated with accumbens synaptic plasticity. We used a single 2-h stress session and 3 weeks later exposed male and female rats to stress-conditioned odors in a modified defensive burying task, and quantified both active and avoidant coping strategies. We measured corticosterone, dendritic spine and astrocyte morphology in accumbens, and examined reward sensitivity using a sucrose two-bottle choice and operant sucrose self-administration. Exposure to stress odor increased burying (active coping) and immobility (avoidant coping) in the defensive burying task in female and male rats. Systemic corticosterone was transiently increased by both ongoing acute restraint stress and stress-conditioned odors. Three weeks after administering acute restraint stress, we observed increased dendritic spine density and head diameter, and decreased synaptic association with astroglia and the astroglial glutamate transporter, GLT-1. Exposure to conditioned stress further increased head diameter without affecting spine density or astroglial morphology, and this increase by conditioned stress was correlated with burying behavior. Finally, we found that stress-exposed females have a preference for sweet solutions and higher motivation to seek sucrose than stressed male rats. We conclude that acute stress produced enduring plasticity in accumbens postsynapses and associated astroglia. Moreover, conditioned stress odors induced active behavioral coping strategies that were correlated with dendritic spine morphology.Subject terms: Synaptic plasticity, Stress and resilience