Indicators Of Stress Response Research Articles

Problematic Internet use and associated mental health issues in South Korean Internet users

IntroductionThe Internet is commonly used in modern society; however, Internet use may become a problematic behaviour. There is an increasing need for research on problematic Internet use (PIU) and its’ associated risk factors.ObjectivesThis study aims to explore the prevalence and health correlates of problematic Internet use among South Korean adults.MethodsWe recruited the participants aged between 18 and 84 years old among the online panel of an online research service. The sample size of the survey was 500. Of these 500 participants, 51.4% (n = 257) were men and 48.6% (n = 243) were women. A participant was classified as a problematic Internet use (PIU) if his/her total score of Young's Internet Addiction Scale (YIA) was above 50. Stress Response Index (SRI), Fagerstrom test for nicotine dependence, lifetime average caffeine consumption, and sociodemographic query form were used in the collection of data. The t test and chi-square test were used for data analysis.ResultsOne hundred ninety-seven (39.4%) of the participants was classified into the PIU group. There was no difference of gender and education between PIU and normal users. However, PIU group was younger (mean 39.5 years) than normal users (mean 45.8 years). PIU group was more likely to have high levels of perceived stress, nicotine dependence, and drink more often caffeinated beverages (P < 0.05).ConclusionsThese data indicate that problematic Internet use is associated with perceived stress level, nicotine and caffeine use in South Korean Internet users. More research is needed to better understand the relationship between Internet use and mental health issues.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Protective effect of N,N'-dimethylthiourea against stress-induced gastric mucosal lesions in rats.

In the present study, we examined the protective effect of N,N'-dimethylthiourea (DMTU), a scavenger of hydroxyl radical (·OH), against water-immersion restraint stress (WIRS)-induced gastric mucosal lesions in rats. When male Wistar rats fasted for 24 h were exposed to WIRS for 3 h, gastric mucosal lesions occurred with increases in the levels of gastric mucosal myeloperoxidase (MPO), an index of tissue neutrophil infiltration, pro-inflammatory cytokines (tumor necrosis factor alpha and interleukin 1beta), lipid peroxide (LPO), and nitrite/nitrate (NOx), an index of nitric oxide synthesis, and decreases in the levels of gastric mucosal nonprotein SH and vitamin C and gastric adherent mucus. DMTU (1, 2.5, or 5 mmol/kg) administered orally at 0.5 h before the onset of WIRS reduced the severity of gastric mucosal lesions with attenuation of the changes in the levels of gastric mucosal MPO, pro-inflammatory cytokines, LPO, NOx, nonprotein SH, and vitamin C and gastric adherent mucus found at 3 h after the onset of WIRS in a dose-dependent manner. Serum levels of corticosterone and glucose, which are indices of stress responses, increased in rats exposed to WIRS for 3 h, but DMTU pre-administered at any dose had no effect on these increases. These results indicate that DMTU protects against WIRS-induced gastric mucosal lesions in rats by exerting its antioxidant action including ·OH scavenging and its anti-inflammatory action without affecting the stress response.

Effects of Optogenetic inhibition of BLA on Sleep Brief Optogenetic Inhibition of the Basolateral Amygdala in Mice Alters Effects of Stressful Experiences on Rapid Eye Movement Sleep.

Stressful events can directly produce significant alterations in subsequent sleep, in particular rapid eye movement sleep (REM); however, the neural mechanisms underlying the process are not fully known. Here, we investigated the role of the basolateral nuclei of the amygdala (BLA) in regulating the effects of stressful experience on sleep. We used optogenetics to briefly inhibit glutamatergic cells in BLA during the presentation of inescapable footshock (IS) and assessed effects on sleep, the acute stress response, and fear memory. c-Fos expression was also assessed in the amygdala and the medial prefrontal cortex (mPFC), both regions involved in coping with stress, and in brain stem regions implicated in the regulation of REM. Compared to control mice, peri-shock inhibition of BLA attenuated an immediate reduction in REM after IS and produced a significant overall increase in REM. Moreover, upon exposure to the shock context alone, mice receiving peri-shock inhibition of BLA during training showed increased REM without altered freezing (an index of fear memory) or stress-induced hyperthermia (an index of acute stress response). Inhibition of BLA during REM under freely sleeping conditions enhanced REM only when body temperature was high, suggesting the effect was influenced by stress. Peri-shock inhibition of BLA also led to elevated c-Fos expression in the central nucleus of the amygdala and mPFC and differentially altered c-Fos activity in the selected brain stem regions. Glutamatergic cells in BLA can modulate the effects of stress on REM and can mediate effects of fear memory on sleep that can be independent of behavioral fear.

Cortisol stress response and histopathological alteration index in Clarias gariepinus exposed to sublethal concentrations of Qua Iboe crude oil and rig wash

The histological effect on and stress response of post juvenile Clarias gariepinus exposed to Qua Iboe crude oil and rig wash were investigated. Fish weighing 60–90 g and measuring 16–18 cm were exposed for 7–28 days to 8.00 ml−1 Qua Iboe crude oil and 0.0018 ml–1 rig wash, both being 0.1 of the 96 hr LC50. Blood samples of C. gariepinus were collected every seven days and evaluated for stress by measuring cortisol concentration. The gills and liver were studied and scored for Gill Alteration Index (GAI) and Hepatic Alteration Index (HAI), respectively. There was an increase in cortisol level up to the 7th and 14th day among the group exposed to Qua Iboe crude oil, with a decrease on the 21st and 28th day. The rig wash group increased in cortisol level up to the 7th day and decreased slightly on the 14th day, after which the trend became irregular. The toxic effects of the Qua Iboe crude oil and rig wash were time dependent, as shown by the histopathological alteration index (HAI) of gill and liver. After 28 days of exposure, the gills had irreparable damage due to high frequency of cellular necrosis and degeneration, whereas the liver had from moderate to severe damage due to the high frequency of cellular degeneration and inflammation. Qua Iboe crude oil and rig wash are both toxic to C. gariepinus, therefore their indiscriminate discharge to the environment must be discouraged.

Personality, Stress and Resilience

Personality traits are consistently correlated with various indices of acute psychological stress response, including negative emotions and performance impairment. However, resilience is a complex personal characteristic with multiple neural and psychological roots. This article advocates a multifactorial approach to understanding resilience that recognizes the complexity of the topic both empirically and theoretically. The Trait-Stressor-Outcome (TSO) framework for organizing empirical data recognizes the multiplicity of traits, stressors and outcome metrics that may moderate stress response. Research requires a fine-grained data collection approach that discriminates multiple stress factors. Also, multiple layers of theory are necessary to explain individual differences in stress response, including biases in neural functioning, attentional processing, as well as styles of coping and emotion-regulation. Cognitive science differentiates multiple levels of explanation and allows for the integration of mechanisms at multiple levels of abstraction from the neural substrate. We illustrate the application of the multifactorial approach to collecting interpreting data on operator stress resulting from interaction with technology.

Cortisol stress responses and children's behavioral functioning at school

The present study investigated whether cortisol stress responses of 6‐year‐olds were associated with their behavioral functioning at school. Additionally, the moderating role of stress in the family environment was examined. To this end, 149 healthy children (M age = 6.09 years; 70 girls) participated in an age‐appropriate innovative social evaluative stress test. Saliva cortisol samples were collected six times during the stress test to calculate two indices of the cortisol stress response: cortisol stress reactivity and total stress cortisol. Teachers assessed children's internalizing, externalizing, and prosocial behaviors. Stress in the family environment was operationalized as maternally reported parenting stress. Results indicated a significant increase in cortisol concentrations in response to the stressor. No significant associations were found between cortisol stress responses and behavioral functioning at school and there was no evidence for moderation by maternal parenting stress. Potential theoretical and methodological explanations for these results are discussed.

Interactive effects on CO2, drought, and ultraviolet-B radiation on maize growth and development

Crop growth and development are highly responsive to global climate change components such as elevated carbon dioxide (CO2), drought, and ultraviolet-B (UV-B) radiation. Plant tolerance to these environmental stresses comprises its genetic potential, physiological changes, metabolism, and signaling pathways. An inclusive understanding of morphological, physiological, and biochemical responses to these abiotic stresses is imperative for the development of stress tolerant varieties for future environments. The objectives of this study were to characterize the changes in vegetative and physiological traits in maize hybrids in their response to multiple environmental factors of (CO2) [400 and 750μmolmol−1 (+(CO2)], irrigation treatments based evapotranspiration (ET) [100 and 50% (−ET)], and UV-B radiation [0 and 10kJm−2d−1 (+UV-B)] and to identify the multiple stress tolerant hybrids aid in mitigating projected climate change for shaping future agriculture. Six maize hybrids (P1498, DKC 65–81, N75H-GTA, P1319, DKC 66–97, and N77P-3111) with known drought tolerance variability were grown in eight sunlit, controlled environment chambers in which control treatment consisted of 400μmolmol−1 [CO2], 100% ET-based irrigation, and 0kJ UV-B. Plants grown at +UV-B alone or combination with 50% ET produced shorter plants and smaller leaf area while elevated CO2 treatments ameliorated the damaging effects of drought and higher UV-B levels on maize hybrids. Plant height, leaf area, total dry matter chlorophyll, carotenoids, and net photosynthesis measured were increased in response to CO2 enrichment. Total stress response index (TSRI) for each hybrid, developed from the cumulative sum of response indices of vegetative and physiological parameters, varied among the maize hybrids. The hybrids were classified as tolerant (P1498), intermediate (DKC 65–81, N75H-GTA, N77P-3111) and sensitive (P1319 and DKC 66–97) to multiple environmental stresses. The positive correlation between TSRI and vegetative and physiological index developed in this study demonstrates that a combination of vegetative and physiological traits is an effective screening tool to identify germplasm best suited to cope with future changing climates. Furthermore, the tolerant hybrids identified in this study indicate that the possibility of cultivar selection for enhanced agronomic performance and stability in a water limited environment with higher UV-B, anticipated to occur in future climates.

Are novel objects perceived as stressful? The effect of novelty on heart rate

Neophobia, or the fear of novel objects, is a behavior that is often found in wild animals. Neophobia appears to be related to the physiological stress response because individuals with higher glucocorticoid responses to stress often are more neophobic. The relationship between the heart rate response and novelty, however, has not been tested in a wild species. We implanted heart rate transmitters in captive European starlings (Sturnus vulgaris) to measure increases in heart rate as an index of the adrenomedullary stress response. Specifically, we measured heart rate in animals encountering novel objects on or near their food dishes using a system to display the novel objects while the experimenters remained outside the room, thereby minimizing the confounding effects of experimenter presence on heart rate. We analyzed three conditions: the period of adjustment to the experimental setup before any exposure to novelty, novel object trials, and no object controls (presented in a random order after 0–5 novel objects). Birds approached their food dishes faster during the adjustment period than during novel object trials. Although they demonstrated a behavioral aversion to novelty, the effect on heart rate was unexpected. Heart rate increased sharply when the food dishes were displayed. The duration of the startle response was longer during no object controls than during novel object exposure, the opposite of the anticipated result. There were no correlations between behavior and metrics of the heart rate response. Novel object exposure does not cause an increase in heart rate.

Heat tolerance evaluation in commercial African violet cultivars using physiological and pollen parameters

High temperatures negatively affect the vegetative and reproductive growth of African violets thus decreasing their aesthetic and commercial values. No scientific information is currently available on cultivar tolerance to high temperatures in this plant. This study was conducted with the objective of evaluating heat tolerance in commercial African violet cultivars using a combination of physiological and pollen parameters and ranking the cultivars based on their cumulative temperature response index (CTRI). Physiological parameters including cell membrane thermostability (CMT), canopy temperature depression (CTD) and chlorophyll stability index (CSI) were analyzed using fully expanded leaves. In vitro pollen germination percentage (PG) and pollen tube length (PTL) were estimated at between 10 and 40°C. Cardinal temperatures (Tmin, Topt, and Tmax) of PG and PTL, as well as maximum PG percentage (PGmax) and maximum PTL (PTLmax), were estimated using the modified bilinear model. Results showed the different cultivars varied significantly for their CMT (5.39–74.07%), CTD (−1.65 to 0.61°C) and CSI (70.16–81.06%). They also differed for PG (mean of 54.43%), PTL (mean of 3109.08μm), and cardinal temperatures (Tmin=−2.5°C, Topt=24.9°C, and Tmax=49.9°C for PG; Tmin=3.4°C, Topt=26.0°C, and Tmax=43.1°C for PTL). The CTRI of each cultivar was calculated as the sum of individual stress response index (ISRI) derived from CMT, CTD, CSI, and PGmax, PTLmax, Tmin, Topt, and Tmax for PG and PTL. Among the thirty cultivars screened, the cultivars ‘Rob's Ooey Gooey’ and ‘Mac's Stop Sign’ had high CTRI values for the physiological and pollen parameters, singly or in combination, so are potential candidates to be used for the development of novel heat tolerant genotypes.

Increased stocking density causes changes in expression of selected stress- and immune-related genes, humoral innate immune parameters and stress responses of rainbow trout (Oncorhynchus mykiss).

The present study investigated the effects of various stocking densities on the health status (stress and immune responses) of rainbow trout (Onchorhynchus mykiss). Juvenile rainbow trout were acclimated, placed in circular tanks under stocking densities of 10, 40 and 80kgm(-3) and reared for 30 days. The relative expression of genes involved in stress and immunity such as HSP70, LyzII, TNF-1α, IL-1β, IL-8 and IFN-γ1 in the head kidney was determined. Serum cortisol, ACTH, total antioxidant capacity, osmolality and lactate were measured after 30 days of culture at different stocking densities (D1:10kgm(-3), D2: 40kgm(-3) and D3: 80kgm(-3)) as indices of stress responses. In addition, the effects of stocking densities on serum complement, bactericidal activity, agglutinating antibody titers, serum IgM, anti-protease activity, serum total protein and alkaline phosphatase of the fish were measured. HSP70 gene expression was significantly density-dependent upregulated in D2 and D3 densities compared to D1 (P<0.05). Also, there was significant downregulation in expression of LyzII, TNF-1α, IL-1β, IL-8 and IFN-γ1 in fish reared at density of either D2 or D3 (P<0.05). In terms of stress responses, serum ACTH, cortisol and lactate level showed significant density-dependent increase (P<0.05) while serum osmolality and total antioxidant capacity showed significant decline (P<0.05) in fish reared at higher densities (D2 and D3) compared to fish reared at lower density (D1) (P<0.05). Concordant with the expression of the immune-related genes, the serum complement and bactericidal activity as well as specific antibody titer against Aeromonas hydrophila, IgM and anti-protease activity decreased along with elevation of stocking density from D1 to D3 (P<0.05). However, different stocking densities had no significant effect on serum total protein level and alkaline phosphatase activity. These results suggested that elevation of stocking densities and crowding resulted in the increase in HSP70 gene expression and the levels of selected stress responses in the serum. However, there was down-regulation of immune genes expression and decreased innate immune responses in the fish. The mRNA expression of the genes and immune parameters that were measured in this study could be helpful in monitoring the health status and welfare of the fish in aquaculture systems particularly in relation to increased stocking densities.

Exclusion of solar UV radiation improves photosynthetic performance and yield of wheat varieties

Field studies were conducted to determine the potential for alterations in photosynthetic performance and grain yield of four wheat (Triticum aestivum) varieties of India- Vidisha, Purna, Swarna and Naveen Chandausi by ambient ultraviolet radiation (UV). The plants were grown in specially designed UV exclusion chambers, wrapped with filters that excluded UV-B (<315 nm), UV-A/B (<400 nm) or transmitted ambient UV or lacked filters. The results indicated that solar UV exclusion increased the leaf mass per area ratio, leaf weight ratio and chlorophylls per unit area of flag leaves in all the four varieties of wheat. Polyphasic chlorophyll a fluorescence transients from the flag leaves of UV excluded wheat plants gave a higher fluorescence yield. Exclusion of solar UV significantly enhanced photosynthetic performance as a consequence of increased efficiency of PS II, performance index (PIABS) and rate of photosynthesis in the flag leaves of wheat varieties along with a remarkable increase in carbonic anhydrase, Rubisco and nitrate reductase activities. This additional fixation of carbon and nitrogen by exclusion of UV was channelized towards the improvement in grain yield of wheat varieties as there was a decrease in the UV-B absorbing substances and an increase in soluble protein content in flag leaves of all the four varieties of wheat. The magnitude of response for UV exclusion for all the measured parameters was higher in two varieties of wheat Vidisha and Purna as compared to Swarna and Naveen Chandausi. Cumulative stress response index (CSRI) for each variety was developed from the cumulative sum of physiological and yield parameters such as leaf mass area ratio of flag leaf, total chlorophyll content, performance index at absorption basis, rate of photosynthesis and grain yield. All the varieties had a negative CSRI, demonstrating a negative impact of ambient UV radiation. Naveen Chandausi and Swarna are less sensitive to ambient UV radiation; Vidisha is more sensitive to both UV-A and UV-B and Purna is more sensitive to ambient UV-B radiation.

Effect of elevated ultraviolet-B on four tropical soybean cultivars: quantitative and qualitative aspects with special emphasis on gas exchange, chlorophyll fluorescence, biomass and yield

Four Indian soybean cultivars (Glycine max L. cv. JS-335, JS 97-52, PK-416 and PS-1042) were grown under field conditions in suburban area of Varanasi to evaluate the varietal differences against ambient and elevated ultraviolet-B (ambient + 7.2 kJ m−2 day−1) for two consecutive years. Elevated UV-B caused negative impact on the assessed parameters with varied magnitude amongst the test cultivars. Reductions in rate of photosynthesis and stomatal conductance were observed maximum in JS-335 and minimum in PS-1042. Elevated UV-B also affected the plant abilities to utilize sunlight and increase the photoinhibitory response, which was displayed by reduced F v/F m in tested cultivars. Similar results were also observed for the biomass, yield and seed quality with maximum reduction in JS-335 followed by PK-416, JS 97-52 and PS-1042. Decline in the rate of photosynthesis, extra allocation of photosynthates for repairing and change in translocation pattern of solute and nutrients are mainly responsible for the deterioration in seed quality. Cumulative stress response index (CSRI) and quality response index (QRI) also revealed the sensitivity of soybean cultivars against elevated UV-B. Indexing of cultivars suggests that JS-335 was most sensitive whereas PS-1042 was resistant amongst cultivars.

Different Responses to Acupuncture in Electroencephalogram according to Stress Level: A Randomized, Placebo-Controlled, Cross-Over Trial

Objectives : The purpose of this randomized, placebo-controlled, cross-over trial was to examine how acupuncture treatment at Shinmun(HT7) affects the brain activity and the autonomic nervous system(ANS), using electroencephalograms(EEG) and heart rate variability(HRV). Methods : Eighteen healthy volunteers participated in two separate experiments: in each experiment, either real acupuncture(RA) or non-penetrating sham acupuncture(SA) was applied at HT7 in random sequences to each person. The EEG and HRV measurements were conducted simultaneously before and during the acupuncture stimulation for5 minutes, respectively. Resulting EEG and HRV parameters were compared between RA and SA groups. To assess differences according to the stress levels for participants, subgroup analysis was performed based on the results of the stress response index questionnaire. Results : In the results, acupuncture stimulation at HT7 increased α band in EEG. In the HRV analysis, heart rate was decreased significantly but HF and RMS-SD were increased in the RA group, compared with those of the SA group. In the subgroup analysis by stress level, participants in the RA group with high stress exhibited an increased in α band in their EEG while the low stress participants showed decrease or little increase in the band. For the SA group, α band reported relatively moderate changes in all channels. Conclusions : Our results showed that acupuncture induces changes in brain activation and the ANS. Acupuncture was related to the activation of the parasympathetic nervous system. The brain activities of the participants were different depending on the stress level.

Co-bedding Between Preterm Twins Attenuates Stress Response After Heel Lance

To examine the effect of co-bedding between preterm twins on stress response after heel lance. Using a multisite randomized controlled trial design, stable preterm twins (67 sets, N=134 infants) between 28 and 36 completed weeks' gestational age, stratified by gestational age (≤ and >32 weeks) and site, were randomly assigned to a co-bedding group, cared for continuously in the same incubator or crib or a standard care group, cared for in a separate incubator or crib, and underwent a medically indicated heel lance after at least 24 hours and no greater than 10 days of group allocation. The reported outcome was cortisol from saliva samples from 89 twins (n=49 co-bedding, n=40 standard care) collected immediately before the heel lance (baseline levels) and 113 twins (n=58 co-bedding, n=55 standard care) collected 20 minutes after heel lance (stress levels) as an index of stress response. No group differences were noted in baseline salivary cortisol levels: 0.36 μg/dL (SD 0.25) in the co-bedding group and 0.43 μg/dL (SD 0.50) in the standard care group. Twenty minutes after lance, levels were significantly lower in the co-bedding group, 0.28 μg/dL (SD 0.25) versus 0.50 μg/dL (SD 0.73) in the standard group (P=0.04). Similarly, the mean of paired changes in salivary cortisol from baseline was lower in the co-bedding group (-0.06 μg/dL) compared with the standard care group (0.14 μg/dL, P<0.05). Co-bedding attenuates the stress response of preterm twins undergoing heel lance. clinicaltrials.gov Identifier: NCT009176.

옥상텃밭을 이용한 약초재배 시험

ABSTRACTThis study was carried out to investigate the growth responses of medicinal plants such as Glehnia littoralis, Cryptotaenia japonica, Angelica gigas, Reynoutria japonica, Saururus chinensis, Houttuynia cordata, Ligularia fischeri, and Aralia cordata under 70%-shading and full sunlight conditions on a rooftop condition using artificial soil as a growth media. Glehnia littoralis, Cryptotaenia japonica, Ligularia fischeri, Saururus chinensis, and Houttuynia cordata showed better growth on plant height, leaf length, leaf width, petiole length and leaf number under full sunlight conditions on a rooftop condition. Cryptotaenia japonica and Houttuynia cordata had high value of Hunter's a (red-green) under full sunlight, while had lower value of L(lightness) and b(blue-yellow) than those of 70% shading condition. As an index of plant stress response, Glehnia littoralis, Reynoutria japonica, Houttuynia cordata, Ligularia fischeri showed Fv/Fm values 0.79∼0.84 under full sunlight in August, indicating low stress on plant growth. Therefore they seemed to be suitable medicinal plats for rooftop conditions. Ligularia fischeri and Reynoutria japonica showed better growth under 70% shading treatment in August, while showed high growth response under full sunlight conditions in September. The 70% shading treatment was effective for the growth of Angelica gigas, Reynoutria japonica, and Aralia cordata. Angelica gigas and Reynoutria japonica, however, showed better plant growth under

Acute stress impairs the retrieval of extinction memory in humans

Extinction training is a form of inhibitory learning that allows an organism to associate a previously aversive cue with a new, safe outcome. Extinction does not erase a fear association, but instead creates a competing association that may or may not be retrieved when a cue is subsequently encountered. Characterizing the conditions under which extinction learning is expressed is important to enhancing the treatment of anxiety disorders that rely on extinction-based exposure therapy as a primary treatment technique. The ventromedial prefrontal cortex, which plays a critical role in the expression of extinction memory, has been shown to be functionally impaired after stress exposure. Further, recent work in rodents has demonstrated that exposure to stress leads to deficits in extinction retrieval, although this has yet to be tested in humans. To explore how stress might influence extinction retrieval in humans, participants underwent a differential aversive learning paradigm, in which one image was probabilistically paired with an aversive shock while the other image denoted safety. Extinction training directly followed, at which point reinforcement was omitted. A day later, participants returned to the lab and either completed an acute stress manipulation (i.e., cold pressor), or a control task, before undergoing an extinction retrieval test. Skin conductance responses and salivary cortisol concentrations were measured throughout each session as indices of fear arousal and neuroendocrine stress response, respectively. The efficacy of our stress induction was established by observing significant increases in cortisol for the stress condition only. We examined extinction retrieval by comparing conditioned responses during the last trial of extinction (day 1) with that of the first trial of re-extinction (day 2). Groups did not differ on initial fear acquisition or extinction, however, a day later participants in the stress group (n=27) demonstrated significantly lower extinction retrieval (i.e., greater fear recovery) than those in the control group (n=25). Our results suggest that acute stress impairs the retrieval of extinction learning and offers insight into why treatment strategies used in the clinic may be challenging to recruit in daily life where stress is pervasive.

Effects of repeated tooth pulp stimulation on concentrations of plasma catecholamines, corticosterone, and glucose in rats

In this study, we examined whether tooth pulp stimulation (TPS) affects the stress responses in anesthetized rats. As for stress response indices, we monitored changes in the concentrations of plasma catecholamines (CAs) (adrenaline, noradrenaline, and dopamine), corticosterone (CS), and glucose (Glu). We observed that repeated TPS attenuated plasma adrenaline, dopamine, CS, and Glu levels compared with those of sham-TPS. After administering naloxone, an opioid antagonist, repeated TPS reversed the decreases in plasma CAs, CS, and Glu. These findings showed that the effects of repeated TPS may be mediated by endogenous opioid administration. Our findings suggest that repeated TPS can induce stress-analgesia and that an endogenous descending pain modulation system exists.

Hyperbaric Oxygen Treatment Produces an Antinociceptive Response Phase and Inhibits Astrocyte Activation and Inflammatory Response in a Rat Model of Neuropathic Pain

Hyperbaric oxygen (HBO) treatment has been proven to be a promising candidate for protection of the nervous system after acute injury in animal models of neuropathic pain. The purposes of this study were to examine the antinociceptive response phase induced by HBO treatment in a model of neuropathic pain and to determine the dependence of the treatment's mechanism of alleviating neuropathic pain on the inhibition of spinal astrocyte activation. Neuropathic pain was induced in rats by chronic constriction injury of the sciatic nerve. Mechanical threshold and thermal latency were tested preoperatively and for 1week postoperatively, four times daily at fixed time points. Methane dicarboxylic aldehyde (MDA) and superoxide dismutase (SOD) parameters were used as indices of oxidative stress response and tested before and after the treatment. The inflammatory cytokines interleukin (IL)-1β and IL-10 were assayed in the sciatic nerve were with enzyme-linked immunoassay. Glial fibrillary acidic protein activation in the spinal cord was evaluated immunohistochemically. The rats exhibited temporary allodynia immediately after HBO treatment completion. This transient allodynia was closely associated with changes in MDA and SOD levels. A single HBO treatment caused a short-acting antinociceptive response phase. Repetitive HBO treatment led to a long-acting antinociceptive response phase and inhibited astrocyte activation. These results indicated that HBO treatment played a dual role in the aggravation and alleviation of neuropathic pain, though the aggravated pain effect (transient allodynia) was far less pronounced than the antinociceptive phase. Astrocyte inhibition and anti-inflammation may contribute to the antinociceptive effect of HBO treatment after nerve injury.

Cardiac Perception Enhances Stress Experience

In the present study we aimed to investigate the impact of the ability to perceive bodily changes as indexed by the perception of one’s heartbeat (cardiac perception) on emotional experience when being confronted with a mental stressor. To induce stress, participants high and low in cardiac perception performed a computerized mental arithmetic test while listening to a white noise increasing in volume. Emotional experience and heart rate were assessed as indices of stress response. Our results show that participants high in cardiac perception reported more negative emotions during the stress period compared to participants low in cardiac perception, though heart rate did not differ between the groups. Our findings suggest that cardiac perception moderates the stress experience by enhancing the perceived emotion. Thus we were able to demonstrate that cardiac perception contributes as a factor explaining the variance in individuals’ emotional response to a stressor.

The effects of dissolved oxygen and triploidy on critical thermal maximum in brook charr (Salvelinus fontinalis)

This study examined the effect of dissolved oxygen (DO) level on critical thermal maximum (CTMax) in diploid and triploid brook charr (Salvelinus fontinalis) exposed to a temperature increase of 3°C/h. Because gas solubility is inversely proportional to temperature, DO declines during standard CTMax tests. With this treatment as a baseline, oxygen or nitrogen injection was used to provide three other DO conditions during CTMax tests: two hyperoxic (maintenance at initial 10mg/L and increase from 10mg/L at 2mg/L/h) and one hypoxic (decrease from 10mg/L at 2mg/L/h). Hyperoxia had no effect on temperature at CTMax or time taken to reach CTMax. Hypoxia, on the other hand, resulted in a significantly lower CTMax and shorter time to CTMax than under standard or hyperoxic conditions, with both indices affected by triploidy but not in a consistent fashion: in one experiment triploids had a lower CTMax and shorter time to CTMax than diploids and in a second experiment they had a higher CTMax and longer time to CTMax than diploids. Indices of the secondary stress response (plasma glucose and ions) during CTMax tests under hypoxia responded as would be predicted for an acute stress, with no difference between triploids and diploids.