Exercise preconditioning reduces neonatal incision surgery-induced enhanced hyperalgesia via inhibition of P38 mitogen-activated protein kinase and IL-1β, TNF-α release

Neonatal surgery leads to enhanced hyperalgesia to noxious stimulation in adulthood via a mechanism caused by enhanced phosphorylated (p)-p38 expression in microglia. We tested the effect of exercise on reducing enhanced hypersensitivity primed by neonatal incision surgery. Adult female Wistar rats, with or without neonatal incision surgery at postnatal day (P) 3, received right hind paw plantar incision surgery under anesthesia at P44. The rats performed wheel-running exercise from P22 to P41. Paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were measured and ipsilateral spinal cords were collected for protein quantification. For PWT and PWL, exercise reduced the pain index after incision surgery at P44 in rats with neonatal surgery (P < 0.01). Western blots showed that exercise suppressed P-p38 expression relative to adult rats without neonatal surgery (P < 0.05). Results of ELISA showed that exercise reduced IL-1β and TNF-α (P < 0.05) concentration in the ipsilateral spinal cord. Exercise preconditioning is an effective approach to reducing enhanced adult hyperalgesia primed by neonatal surgery. The mechanism may be explained by exercise-induced inhibition of P-p38 activation and IL-1β, TNF-α release.     

Neuroprotective effects of tamoxifen on experimental spinal cord injury in rats

The aim of this study was to evaluate the effects of tamoxifen on tumor necrosis factor α (TNF-α) and interleukin 1β (IL-1β) levels and ultrastructural changes in rats with spinal cord injury. Rats were divided into four groups: control group (laminectomy only), trauma group (laminectomy + spinal trauma), tamoxifen group (laminectomy + spinal trauma + tamoxifen), and vehicle group (laminectomy + spinal trauma + vehicle). Spinal cords were extirpated at the T₇–T₁₂ level and tissue samples from the spinal cords were gathered for TNF-α and IL-1β measurements at 1 and 6 hours. Spinal cords harvested at 6 hours were evaluated for ultrastructural changes. TNF-α and IL-1β levels at 6 hours were significantly lower in the tamoxifen group than in the trauma group. Electron microscopic examination of tissue from the trauma group revealed gross cell deformities with widespread edema of all structures as well as severe edema in the neuropil. At 6 hours after trauma, these ultrastructural changes were less marked in the tamoxifen group. Our findings support a neuroprotective and restorative role for tamoxifen in the context of secondary pathological biochemical events after SCI.     

Evaluation of periodontitis in hospital outpatients with major depressive disorder. A focus on gingival and circulating cytokines

An imbalance in stimulated cytokine production is associated with the etiopathogenesis of numerous diseases such as major depressive disorder (MDD) and periodontal disease. Increased cytokine levels have been reported in the gingival crevicular fluid (GCF) of patients with MDD. Thirty-six outpatients with MDD participated in this study. Each outpatient was age-matched (±3 years) with a healthy control (n = 36). The patients were controlled for race and smoking habits. Unstimulated and stimulated interleukin 6 (IL-6), interleukin 1β (IL-1β), and interferon-γ (INF-γ) production in whole blood culture (WBC) and IL-6 and IL-1β levels in the GCF were evaluated. Circulating levels of IL-6 and IL-1β (unstimulated) as well as GCF IL-1β were modestly lower in MDD patients, compared to the levels in age-matched controls (Mann–Whitney, p = 0.002, 0.0075, ANCOVA, p = 0.025, respectively). In the unstimulated group, there was no correlation between the levels of circulating IL-6 and GCF IL-6 (r = 0.07, p = 0.67), and between the levels of circulating IL-1β and the IL-1β level in the CGF (r = −0.08, p = 0.63). In the LPS stimulation group, there was no correlation between the levels of circulating levels of IL-6 and GCF IL-6 (r = 0. 02, p = 0.91) or between the circulating IL-1β and GCF IL-1β (r = 0.13, p = 0.42). We observed modest immunosuppression in MDD patients (evaluated by no stimulation whole blood culture [WBC]), especially in patients with melancholic depression, chronic depression, and severe depression.     

Emotions,immunity and sport: Winner and loser athlete’s profile of fighting sport

Several studies have focused on the relationship between hormonal changes and affective states in sporting contexts relating to an agonistic outcome. More recently, pro-inflammatory cytokines have also been successfully associated with affective state modulation.The aim of this study was to investigate whether athletes who won or lost show different levels of steroid hormones (testosterone and cortisol), pro-inflammatory cytokine IL-1β, or expressions of anger and anxiety during six training fights in seasonal competitions down to the main seasonal competition.In 25 male kick-boxing athletes (age ± SD, 28.68 ± 5.34), anger states (RS score) and anxiety states (AS score) were assessed by STAXI-2 and STAI-Y, respectively. Cortisol (C), testosterone (T) and IL-1β salivary levels were measured by the ELISA method. The saliva samples were taken in the afternoon, 30 min prior to the start and 30 min from the end of both simulated and official competitions.The results showed that the RS score, T, T/C ratio salivary levels increased during the season, whereas the AS score, C and IL-1β suggested an opposite trend. Close to an official competition, the RS score, T, T/C ratio and IL-1β salivary concentrations were significantly higher, and then decreased during competition. By contrast, the AS score and C levels significantly increased throughout the official competition.In addition, significant differences were found for hormones and IL-1β concentrations as well as psychometric assessment close to the outcome of an official match. Athletes who lost showed an higher AS score and C level, while those who won were characterized by an higher level during the pre-competition RS score, T, T/C ratio, and IL-1β. Note that these factors were positively and significantly correlated at the pre-official competition time, while in a linear regression analysis, IL-1β, T and T/C ratio concentrations explained 43% of the variance in the RS score observed at the same time (adjusted R(2) = 0.43, ANOVA P < .05).Our data suggest that the beginning of an agonistic event could trigger emotional responses which correspond to different biological processes instead that of a simulated fight. In particular, IL-1β could be a potential new biological marker of anger and the combined measurement of these factors may be a useful way of understanding athletes’ change in relation to their performance.     

Evidence for a novel,neurohumoral antinociceptive mechanism mediated by peripheral capsaicin-sensitive nociceptors in conscious rats

Stimulation of capsaicin-sensitive peripheral sensory nerve terminals induces remote anti-inflammatory effects throughout the body of anesthetized rats and guinea-pigs mediated by somatostatin. As somatostatin has also antinociceptive effects, the study aimed at investigating whether similar remote antinociceptive effects can be demonstrated in awake animals.In conscious rats, nociceptive nerve endings of the right hind paw decentralized by cutting the sciatic and saphenous nerves 18 h before were chemically stimulated, and drop of the noxious heat threshold (heat hyperalgesia) induced by prior (18 h before) plantar incision was measured on the contralateral, left hind paw using an increasing-temperature water bath. 18 h after nerve transection, mustard oil-evoked plasma extravasation was not significantly reduced in the right hind paw as tested by in vivo fluorescence imaging. Applying agonist of either transient receptor potential vanilloid 1 (TRPV1) or transient receptor potential ankyrin 1 (TRPA1) receptor (capsaicin or mustard oil, respectively) to the nerve-transected paw inhibited the plantar incision-induced drop of the noxious heat threshold on the contralateral paw. The onset of these remote antihyperalgesic effects was 10–20 min. A similar contralateral inhibitory effect of capsaicin or mustard oil treatment was observed on neuropathic mechanical hyperalgesia evoked by partial sciatic nerve injury 2 days before nerve transection and measured by a Randall–Selitto apparatus. The remote thermal antihyperalgesic effect was prevented by chronic (5 days) denervation or local capsaicin desensitization of the stimulated paw; reduced by intraperitoneally applied antagonist of somatostatin (cyclosomatostatin) or opioid receptors (naloxone). The response was mimicked by intraperitoneally applied somatostatin and associated with a 72 ± 27% increase in plasma somatostatin-like immunoreactivity that was absent after chronic (5 days) denervation.In conclusion, chemical activation of decentralized peripheral capsaicin-sensitive nociceptors evokes remote antihyperalgesic responses initiated outside the central nervous system and mediated by somatostatin and endogenous opioids.     

The role of IL-6 and IL-1β in painful perineural inflammatory neuritis

Inflammation along a nerve trunk (perineural inflammation), without detectable axonal damage, has been shown to induce transient pain in the organ supplied by the nerve. The aims of the present study were to study the role IL-6 and IL-1β, in pain induced by perineural inflammation.MethodsIL-6 and IL-1β secretion from rat’s sciatic nerves, L-5 Dorsal Root Ganglia (DRG), and the hind paw skin, 3 and 8 days following exposure of the nerve to Complete Freund’s Adjuvant (CFA), were measured using ELISA method. Hind paw tactile-allodynia, mechano-hyperalgesia, heat-allodynia and electrical detection thresholds were tested up to 8 days following the application of CFA, IL-6 or IL-1β adjacent to the sciatic nerve trunk. Employing electrophysiological recording, saphenous nerve spontaneous activity, nerve trunk mechano-sensitivity and paw tactile detection threshold (determined by recording action potential induced by the lowest mechanical stimulus) were assessed 3 and 8 days following exposure of the nerve trunk to CFA, IL-6, or IL-1β.ResultsIL-6 and IL-1β secretion from the nerve was significantly elevated on the 3rd day post-operation (DPO). On the 8th DPO, IL-6 levels returned to baseline while IL-1β levels remained significantly elevated. The DRG cytokine’s level was increased on the 3rd and 8th DPOs, contralateral cytokine’s level was increased on the 3rd DPO. The skin IL-6 level was increased bilaterally on the 3rd DPO and returned to baseline on the 8th DPO. IL-1β levels increased in the affected side on the 3rd and bilaterally on the 8th DPO. Direct application of IL-6 or CFA on the sciatic nerve induced significant hind paw tactile-allodynia from the 1st to 5th DPOs, reduced electrical detection threshold from the 1st to 3rd DPOs, mechano-hyperalgesia from 3rd to 5th DPOs and heat-allodynia on the 3rd DPO. Direct application of IL-1β induced paw tactile and heat-allodynia on the 7–8th DPOs and mechano-hyperalgesia on the 5–8th DPOs.Perineural inflammation significantly increased spontaneous activity myelinated fibres 3 and 8 days following the application. Direct application of IL-6 induced elevation of spontaneous activity on the 3rd while IL-1β on the 8th DPO.Nerve mechano-sensitivity was significantly increased on the 3rd day following exposure to CFA and IL-6 and on the 8th following CFA application. The rat’s paw lowest mechanical force necessary for induction of action potential, was significantly reduced 3 days following CFA application.ConclusionIL-6 and IL-1β play an important role in pain induced by perineural inflammation. IL-6 activity is more prominent immediately following application (2–5th DPOs), while IL-1β, activity is more significant in a later stage (5–8th DPOs).     

Role of brain macrophages on IL-1β and fatigue following eccentric exercise-induced muscle damage

Fatigue associated with recovery from muscle damage has recently been linked to increases in brain and muscle proinflammatory cytokines. However, little is known regarding the origin of these cytokines. Since macrophage-like cells in the brain are a primary source of cytokines, we used a brain specific macrophage depletion technique involving liposome encapsulated clodronate (CLD) to examine the role of macrophages on brain IL-1β and fatigue following eccentric exercise-induced muscle damage. Mice were assigned to six groups: Downhill saline (DWNSAL), downhill clodronate (DWNCLD), uphill saline (UPSAL), uphill clodronate (UPCLD), non-running saline (CONSAL) or non-running clodronate (CONCLD). Mice were given intracerebroventricular (ICV) (10 μL) injections of clodronate-filled liposomes (CLD) to deplete macrophages, or saline-filled liposomes (SAL) and run on a treadmill at 22 m/min and ?14% (DWN) or 14% (UP) grade for 150 min. A subset of uphill and downhill running mice (n = 40) was then run to fatigue on a treadmill at 36 m/min, 8% grade at 24 h after the uphill and downhill runs. A second subset of uphill, downhill, and control mice (n = 30) was sacrificed 24 h after the run for analysis of brain IL-1β concentration. Histological examination confirmed previous reports that CLD administration reduced perivascular and meningeal macrophage subsets in the brain. CLD reduced IL-1β concentration in the cortex of DWN mice (P < 0.05), which was associated with enhanced treadmill performance 24 h after both uphill and downhill runs (P < 0.05) although the magnitude was greater following the downhill run. These results suggest that brain macrophages can contribute to the increase in brain IL-1β and fatigue that are associated with recovery from exercise-induced muscle damage.     

Interleukin-1β enhances susceptibility to hyperthermia-induced seizures in developing rats

Cytokines have been shown to influence susceptibility to febrile seizures and epilepsy. In this study, the role of interleukin-1β (IL-1β) was examined in developing rats. IL-1β and interleukin-1 receptor antagonist (IL-1ra) were administered to developing rats, and seizures were induced by moist warm air. Twenty male Lewis rats (21–23 days old) were divided into two groups (IL-1β and saline control groups) and two holes were made in the skull for EEG electrodes. We applied human recombinant IL-1β intra-nasally 1 h before seizures induced by moist warm air. The brain temperature at the appearance of seizure discharges on EEG, and the latency time from the hyperthermia onset until the appearance of seizure discharges on EEG were measured. And the same study using IL-1ra was performed. The median brain temperature for the IL-1β group, 42.6 °C (range: 41.8–43.0), was significantly lower than that for the control, 42.9 (42.3–43.4) (P = 0.043). The brain temperature for the IL-1ra group, 43.3 (42.8–43.7), was significantly higher than that for the control, 42.9 (42.2–43.5) (P = 0.011), and the latency time for the IL-1ra group, 398 s (270–561), was significantly longer than that for the control, 325 (252–462) (P = 0.035). These results demonstrate that IL-1β promotes hyperthermia-induced seizures in developing rats.     

Intrathecal injection of an alpha seven nicotinic acetylcholine receptor agonist attenuates gp120-induced mechanical allodynia and spinal pro-inflammatory cytokine profiles in rats

Nicotinic acetylcholine receptors (nAchRs) are not only key receptors in the autonomic nervous system, but also are present on immune cells. The alpha seven subunit of nAchR (α7nAchR) suppresses pro-inflammation in peripheral monocytes by decreasing pro-inflammatory cytokine production. In spinal cord, α7nAchRs are found on microglia, which are known to induce and maintain pain. We predicted that α7nAchR agonists might attenuate intrathecal HIV-1 gp120-induced, pro-inflammatory cytokine- and microglia-dependent mechanical allodynia. Choline, a precursor for acetylcholine and selective agonist for α7nAchR, was administered intrathecally either with, or 30 min after, intrathecal gp120. Choline significantly blocked and reversed gp120-induced mechanical allodynia for at least 4 h after drug administration. In addition, intrathecal choline, delivered either with or 30 min after gp120, reduced gp120-induced IL-1β protein and pro-inflammatory cytokine mRNAs within the lumbar spinal cord. A second α7nAchR agonist, GTS-21, also significantly reversed gp120-induced mechanical allodynia and lumbar spinal cord levels of pro-inflammatory cytokine mRNAs and IL-1β protein. A role of microglia is suggested by the observation that intrathecal choline suppressed the gp120-induced expression of, cd11b, a macrophage/microglial activation marker. Taken together, the data support that α7nAchR may be a novel target for treating pain where microglia maintain the pro-inflammatory state within the spinal cord.     

Interaction of endokinin A/B and (Mpa6)-γ2-MSH-6–12 in pain regulation in mice

The present study focused on the interactive effects of (Mpa⁶)-γ2-MSH-6–12 (Mpa, spinal level) and endokinin A/B (EKA/B, supraspinal level) on pain regulation in mice. EKA/B (30 pmol) only weakened 100 pmol Mpa-induced hyperalgesia at 5 min, but could enhance it during 20–30 min. However, EKA/B (100 pmol) antagonized all dose levels of Mpa significantly at 5 min and blocked them completely at 10 min. EKA/B (3 nmol) co-injected with Mpa presented marked analgesia at 5 min and enduring hyperalgesia within 20–60 min. To investigate the underlying mechanisms between Mpa and EKA/B, SR140333B and SR142801 (NK₁ and NK₃ receptor antagonists, respectively) were utilized. SR140333B had no influence on Mpa, while SR142801 potentiated it during 20–30 min. Whereas, SR140333B and SR142801 could block the co-administration of Mpa and EKA/B (30 pmol) separately at 5 min and 30 min. These phenomena might attribute to that these two antagonists promoted the antagonism of EKA/B (30 pmol) at the early stage, while antagonized EKA/B preferentially in the latter period. SR140333B weakened the analgesia of EKA/B (3 nmol), but produced no effect on Mpa. However, SR140333B failed to affect the co-injection of Mpa and EKA/B, which implied that EKA/B cooperated with Mpa prior to SR140333B. These results could potentially help to better understand the interaction of NK and MrgC receptors in pain regulation in mice.     

A parametric study of electroacupuncture on persistent hyperalgesia and Fos protein expression in rats

We previously reported the anti-hyperalgesia of electroacupuncture (EA) on persistent inflammatory pain in an unrestrained, unsedated, and conscious rat model. Using this model, induced by injecting complete Freund's adjuvant (CFA) into one hind paw, we systematically evaluated the anti-hyperalgesia of EA stimulation parameters (frequency, intensity, treatment duration, and pulse width). We assessed hyperalgesia by paw withdrawal latency (PWL) to a noxious thermal stimulus and found that 10- and 100-Hz EA frequencies at a current intensity of 3 mA produced the greatest anti-hyperalgesia, when compared to other parameters. Both frequencies significantly increased PWL in the early phases of hyperalgesia (2.5 and 24 h; p < 0.05), and 10 Hz EA also significantly increased PWL in later phases (5 to 7 days; p < 0.05). A sufficient but tolerable intensity of 3 mA was more effective than lower intensities (1-2 mA). A 20-min treatment produced better anti-hyperalgesia than longer and shorter (10 and 30 min) treatments. Acupoint specificity study demonstrated that GB30 produced significant EA anti-hyperalgesia, while Waiguan (TE5) and sham points, an abdominal point and a point at the opposite aspect of GB30, did not. The spinal Fos protein expression study demonstrated that the optimal EA selectively suppressed Fos expression in superficial laminae (I/II) and activated it in deeper laminae (III/IV) of the spinal dorsal horn. The results suggest that the EA anti-hyperalgesia is parameter-dependent and point-specific, and they provide important information for designing further clinical acupuncture research on persistent inflammatory pain.     

Interleukin-1β plasma levels are associated with depression in temporal lobe epilepsy

Inflammatory mediators such as cytokines are likely to contribute to the pathophysiology of epilepsy. Proinflammatory cytokines are also associated with mood disorders, such as major depression. As people with temporal lobe epilepsy (TLE) are at an increased risk of mood disorders, we attempted to evaluate peripheral levels of IL-1β in people with TLE with depression and people with TLE without depression and in healthy controls. In a cross-sectional study, we compared three groups: 21 people with TLE without depression (TLE D −), 18 people with TLE with depression (TLE D +), and 31 controls without depression. A structured clinical interview (MINI-Plus) was used to diagnose current depression, and the Hamilton Depression Rating Scale (HAM-D) was used to quantify depressive symptoms. Plasma levels of IL-1β were significantly higher in people with TLE with depression than in controls (p = 0.004) or people with TLE without depression (p = 0.006). Interleukin-1beta levels positively correlated with HAM-D scores (Spearman's rho = 0.381, p = 0.017) in people with TLE. Higher levels of IL-1β in TLE seem to be associated with depression.     

The role of thrombospondin-1 and transforming growth factor-β after spinal cord injury in the rat

Spinal cord injury (SCI) continues to result in high morbidity and mortality throughout the world. An effective neuroprotective agent is still not available to counteract secondary damage caused by traumatic injury. Thrombospondin-1 (TSP-1) and transforming growth factor-β (TGF-β) have a role in angiogenesis, scar deposition, inflammation and may affect astrocyte phenotype and mobility. We investigated the role of TSP-1 and TGF-β in a model of spinal cord injury in rats. Forty female Sprague-Dawley rats were randomly divided into two equal groups: the experimental group was subject to SCI using an impactor and the sham-operated group was not subject to SCI. These animals were sacrificed at 12 h and 24 h after SCI for immunochemistry and Western blot analysis of the injured spinal segment for the expression of the TSP-1 and TGF-β proteins. We found that TSP-1 and TGF-β expression increased immediately after SCI in the injured segment. After 12 h, TSP-1 concentrations increased more rapidly and dramatically than TGF-β in the injured segment of the spinal cord. Elevations in TSP-1 and TGF-β concentrations persisted for 24 h after injury. These results show that elevated expression of TSP-1 and TGF-β can be detected in the injured segment of the spinal cord 12 and 24 h after injury. Thus, TSP-1 and TGF-β may have a role in SCI.     

Central inhibition of interleukin-1β ameliorates sickness behavior in aged mice

In elderly individuals high levels of interleukin-1β (IL-1β) in the brain have been implicated in infection-related behavioral pathologies but this has not been directly tested. Therefore, the current study investigated if sickness behavior in aged animals elicited by peripheral injection of lipopolysaccharide (LPS) is mediated through central IL-1β. Adult and aged mice were injected intracerebroventricularly with either saline or IL-1ra (4 μg) immediately prior to intraperitoneal administration of saline or LPS (10 μg) and locomotor and social behaviors were assessed. As anticipated, LPS depressed locomotor activity and social behavior in both adult and aged mice but the behavioral deficits were markedly greater in the aged at 24 h. Pretreatment with IL-1ra did not affect LPS-induced sickness behavior in adults; however, in aged mice IL-1ra attenuated LPS-induced sickness behavior, restoring it to the level exhibited by young adults. Twenty-four hours post-injection hippocampal and hypothalamic tissues were collected to determine IL-1β mRNA expression. Neither LPS nor IL-1ra affected IL-1β mRNA levels in adults, presumably because any effect of LPS had dissipated by 24 h. In contrast, IL-1β mRNA was markedly higher in aged mice 24 h after LPS, and prior treatment with IL-1ra either blocked or attenuated this effect in the hippocampus and hypothalamus, respectively. Taken together these data provide the first direct evidence that central IL-1β is responsible for the severe sickness behavior observed in aged animals after LPS treatment. Thus, inhibiting the central actions of IL-1β may be useful for minimizing behavioral complications in older individuals with an infection.     

Discharge rates and discharge variability of muscle spindle afferents in human chronic spinal cord injury

ObjectivesTo test the hypothesis that the firing rates and discharge variability of human muscle spindles are not affected by spinal cord injury.MethodsTungsten microelectrodes were inserted into muscle fascicles of the peroneal nerve in six individuals with complete paralysis of the lower limbs following spinal cord injury: 12 afferents were spontaneously active at rest and 7 were recruited during passive muscle stretch. For comparison, recordings were made from 17 spontaneously active and 9 stretch-recruited afferents in 12 intact subjects.ResultsFiring rates for the spontaneously active muscle spindles were not significantly different between the spinal (9.8 ± 1.6 Hz) and intact (10.2 ± 1.3 Hz) subjects; the same was true for the stretch-recruited afferents – static firing rates, measured over the final 1 s of a ramp-and-hold stretch, were not different between the spinal and intact groups (13.1 ± 3.1% vs 10.0 ± 2.5 Hz). There were also no differences in discharge variability between the spinal and intact subjects, either for the spontaneously active spindles (8.1 ± 2.0% vs 5.7 ± 0.9%) or for the stretch-activated spindles, calculated over the final 1 s of static stretch (19.7 ± 5.6% vs 17.0 ± 1.9%). In addition, the responses to stretch imposed manually by the experimenter provided no evidence for an increase in the dynamic response to stretch in the patients.ConclusionsThe static stretch sensitivity of human muscle spindles is not affected by chronic spinal cord injury, suggesting that there is no difference in static (and possibly dynamic) fusimotor drive to paralyzed muscles in chronic spinal cord injury.SignificanceThis study provides no evidence for an increase in fusimotor drive as a mechanism for the spasticity associated with chronic spinal injury, though further studies using controlled stretch would be required before it can be concluded that dynamic fusimotor drive is “normal” in these patients.     

Cadmium-induced IL-6 and IL-8 expression and release from astrocytes are mediated by MAPK and NF-κB pathways

Chronic exposure to cadmium has been linked to brain cancers, learning disabilities and memory deficits. Previous studies of cadmium toxicity in the central nervous system report cadmium induces oxidative stress in neurons and astrocytes. In the peripheral system, cadmium promotes interleukin-6 (IL-6) and IL-8 production and release. Elevation of IL-6 expression is linked to the pathogenesis of neurodegenerative diseases and astrogliosis. IL-8 plays a role in angiogenesis of gliomas and neurodegenerative diseases. Herein, the effects of non-toxic concentrations of cadmium on the production of IL-6 and IL-8 and the underlying mechanisms were investigated. U-87 MG human astrocytoma cells and primary human astrocytes were exposed to cadmium chloride. At 24 h post-exposure to 1 and 10 μM, levels of intracellular cadmium in U-87 MG cells were 11.89 ± 3.59 and 53.08 ± 7.59 μg/g wet weight, respectively. These concentrations had minimal effects on cell morphology and viability. IL-6 and IL-8 mRNA levels and secretion increased in dose- and time-dependent manners post cadmium exposure. Acute exposure to cadmium increased phosphorylation of ERK1/2, p38 MAPK, and p65 NF-κB. Pretreatment with U0126–an inhibitor of MEK1 and MEK2 kinases–SB203580–a p38 MAPK inhibitor–and SC-514–an IKKβ inhibitor–suppressed cadmium-induced IL-8 expression and release. Upregulation of cadmium-induced IL-6 was inhibited by U0126 and SC-514, but not SB203580. On the other hand, SP600125–a JNK inhibitor–and celecoxib–a selective COX-2 inhibitor–had no effect on production of both cytokines. In conclusion, non-toxic concentrations of cadmium can stimulate IL-6 and IL-8 release through MAPK phosphorylation and NF-κB activation. Suppressing IL-6 and IL-8 production could be novel approaches to prevent cadmium-induced angiogenesis in gliomas and inflammation in the brain.     

Nitrous oxide related behavioral and histopathological changes may be related to oxidative stress

Nitrous oxide (N₂O) toxicity can result in myelin loss and hyperhomocysteinemia similar to cobalamin (Cbl) deficiency. Studies on N₂O exposure can help in understanding the mechanism of demyelination. In view of paucity of studies on N₂O toxicity in rats this study was undertaken. Six male wistar rats were exposed to 1.5 L/min N₂O with 1:1 O₂ for 90 min daily for 1 month. After 1-month exposure blood homocysteine (HCY) and oxidative stress parameters glutathione (GSH) and total antioxidant capacity (TAC) were measured. Brain and spinal cord was subjected to histopathological examination. The neurobehavioral changes, oxidative stress parameters and histopathological changes were correlated with serum B12 and HCY level. After 1-month exposure, the rats appeared sluggish, lethargic and developed predominantly hind limb weakness for 1–1.5 h. In the exposed group, the total distance traveled (2001.66 ± 118.27 cm; p = 0.037), time moving (80.16 ± 5.7 s; p = 0.028), number of rearing (10.33 ± 1.45; p = 0.014) and grip strength (1042.40 ± 51.3 N; p = 0.041) were significantly decreased whereas, resting time significantly increased (219.83 ± 5.7 s; p = 0.030) compared to controls. Serum HCY level was significantly increased (20.56 ± 1.296 μm/ml; p = 0.0007) in the exposed group. However, serum B12 and folic acid levels were not significantly different. GSH significantly decreased (2.21 ± 0.60 mg/dl; p = 0.018) along with TAC (0.76 ± 0.16 Trolox_Eq_mmol/l; p = 0.036). The histopathological studies revealed shrinkage and vacuolation of neurons in cerebral cortex, focal myelin loss, vacuolation in subcortical white matter and spinal cord. N₂O exposure results in behavioral alterations, hyperhomocysteinemia, cortical and spinal cord demyelination which were associated with decrease GSH and TAC highlighting pathophysiological role of oxidative stress.     

Serum and gene expression profile of cytokines in first-episode psychosis

An inflammatory syndrome has been previously reported in chronic schizophrenia. The aims of this study were to investigate: (1) serum levels and leukocyte gene expression of cytokines in patients with first-episode psychosis and controls; and (2) possible causes of abnormal cytokine levels in first-episode psychosis, testing their association with psychosocial stressors, current nicotine and cannabis use, and duration of antipsychotic treatment. We recruited 24 first-episode psychosis patients and 24 healthy controls matched for age, gender, ethnicity and body mass index. Serum interleukin(IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, Tumour Necrosis Factor- α (TNF-α), Interferon- γ (IFN-γ), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), and monocyte chemotactic protein-1 (MCP-1) were analysed in all subjects. Leukocyte gene expression analyses were conducted only for those cytokines that were different between-groups in the serum analyses. Patients had significantly higher serum levels of IL-1α (effect size d = 0.6, p = 0.03), IL-1β (d = 0.4, p = 0.01), IL-8 (d = 0.6, p = 0.01) and TNF-α (d = 0.7, p = 0.05) and a trend for higher IL-6 serum levels (d = 0.3, p = 0.09) when compared with controls. Leukocyte m-RNA levels of IL-1α (d = 0.6, p = 0.04), IL-6 (d = 0.7, p = 0.01) and TNF-α (d = 1.6, p < 0.001), but not IL-1β and IL-8, were also significantly higher in patients. A history of childhood trauma was associated with higher TNF-α serum levels (p = 0.01), while more recent stressful life-events were associated with higher TNF-α mRNA levels in leukocytes (p = 0.002). In conclusion, first-episode psychosis is characterised by a pro-inflammatory state supported, at least in part, by activation of leukocytes. Past and recent stressors contribute to this pro-inflammatory state.     

Spinal CCL2 and microglial activation are involved in paclitaxel-evoked cold hyperalgesia

The antineoplastic paclitaxel induces a sensory neuropathy that involves the spinal release of neuroinflammatory mediators and activation of glial cells. Although the chemokine CCL2 can evoke glial activation and its participation in neuropathic pain has been demonstrated in other models, its involvement in paclitaxel-evoked neuropathy has not been previously explored. Paclitaxel-evoked cold hypernociception was assessed in mice by the unilateral cold plate test and the effects on cold hyperalgesia of the CCR2 antagonist RS 504393, the CCR1 antagonist J113863, the microglial inhibitor minocycline or an anti-CCL2 antibody were tested. Furthermore, ELISA measurements of CCL2 concentration and immunohistochemical assays of Iba-1 and GFAP, markers of microglial and astroglial cells respectively, were performed in the lumbar spinal cord.Cold hypernociception measured 3 days after the administration of paclitaxel (10 mg/kg) was inhibited by the s.c. (0.3–3 mg/kg) or i.t. (1–10 μg) administration of RS 504393 but not of J113863 (3–30 mg/kg). CCL2 levels measured by ELISA in the lumbar spinal cord were augmented in mice treated with paclitaxel and the i.t. administration of an anti-CCL2 antibody completely suppressed paclitaxel-evoked cold hyperalgesia, strongly suggesting that CCL2 is involved in the hypernociception evoked by this taxane. Besides, the implication of microglial activation is supported by the increase in the immunolabelling of Iba-1, but not GFAP, in the spinal cord of paclitaxel-treated mice and by the inhibition of cold hyperalgesia produced by the i.t. administration of the microglial inhibitor minocycline (1–10 nmol). Finally, the neutralization of spinal CCL2 by the i.t. administration of a selective antibody for 3 days almost totally inhibited paclitaxel-evoked microglial activation.In conclusion, our results indicate that paclitaxel-evoked cold hypernociception depends on the activation of CCR2 due to the spinal release of CCL2 and the subsequent microglial activation.