Neonatal brain inflammation enhances methamphetamine-induced reinstated behavioral sensitization in adult rats analyzed with explainable machine learning.

Neonatal brain inflammation produced by intraperitoneal (i.p.) injection of lipopolysaccharide (LPS) results in long-lasting brain dopaminergic injury and motor disturbances in adult rats. The goal of the present work is to investigate the effect of neonatal systemic LPS exposure (1 or 2 mg/kg, i.p. injection in postnatal day 5, P5, male rats)-induced dopaminergic injury to examine methamphetamine (METH)-induced behavioral sensitization as an indicator of drug addiction. On P70, subjects underwent a treatment schedule of 5 once daily subcutaneous (s.c.) administrations of METH (0.5 mg/kg) (P70-P74) to induce behavioral sensitization. Ninety-six hours following the 5th treatment of METH (P78), the rats received one dose of 0.5 mg/kg METH (s.c.) to reintroduce behavioral sensitization. Hyperlocomotion is a critical index caused by drug abuse, and METH administration has been shown to produce remarkable locomotor-enhancing effects. Therefore, a random forest model was used as the detector to extract the feature interaction patterns among the collected high-dimensional locomotor data. Our approaches identified neonatal systemic LPS exposure dose and METH-treated dates as features significantly associated with METH-induced behavioral sensitization, reinstated behavioral sensitization, and perinatal inflammation in this experimental model of drug addiction. Overall, the analysis suggests that the implementation of machine learning strategies is sensitive enough to detect interaction patterns in locomotor activity. Neonatal LPS exposure also enhanced METH-induced reduction of dopamine transporter expression and [3H]dopamine uptake, reduced mitochondrial complex I activity, and elevated interleukin-1ß and cyclooxygenase-2 concentrations in the P78 rat striatum. These results indicate that neonatal systemic LPS exposure produces a persistent dopaminergic lesion leading to a long-lasting change in the brain reward system as indicated by the enhanced METH-induced behavioral sensitization and reinstated behavioral sensitization later in life. These findings indicate that early-life brain inflammation may enhance susceptibility to drug addiction development later in life, which provides new insights for developing potential therapeutic treatments for drug addiction.

Pioglitazone Ameliorates Lipopolysaccharide-Induced Behavioral Impairment, Brain Inflammation, White Matter Injury and Mitochondrial Dysfunction in Neonatal Rats.

Previous studies have demonstrated that pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, inhibits ischemia-induced brain injury. The present study was conducted to examine whether pioglitazone can reduce impairment of behavioral deficits mediated by inflammatory-induced brain white matter injury in neonatal rats. Intraperitoneal (i.p.) injection of lipopolysaccharide (LPS, 2 mg/kg) was administered to Sprague-Dawley rat pups on postnatal day 5 (P5), and i.p. administration of pioglitazone (20 mg/kg) or vehicle was performed 5 min after LPS injection. Sensorimotor behavioral tests were performed 24 h after LPS exposure, and changes in biochemistry of the brain was examined after these tests. The results show that systemic LPS exposure resulted in impaired sensorimotor behavioral performance, reduction of oligodendrocytes and mitochondrial activity, and increases in lipid peroxidation and brain inflammation, as indicated by the increment of interleukin-1ß (IL-1ß) levels and number of activated microglia in the neonatal rat brain. Pioglitazone treatment significantly improved LPS-induced neurobehavioral and physiological disturbances including the loss of body weight, hypothermia, righting reflex, wire-hanging maneuver, negative geotaxis, and hind-limb suspension in neonatal rats. The neuroprotective effect of pioglitazone against the loss of oligodendrocytes and mitochondrial activity was associated with attenuation of LPS-induced increment of thiobarbituric acid reactive substances (TBARS) content, IL-1ß levels and number of activated microglia in neonatal rats. Our results show that pioglitazone prevents neurobehavioral disturbances induced by systemic LPS exposure in neonatal rats, and its neuroprotective effects are associated with its impact on microglial activation, IL-1ß induction, lipid peroxidation, oligodendrocyte production and mitochondrial activity.

Mu-opioid receptor knockout mice are more sensitive to chlordiazepoxide-induced anxiolytic behavior.

We have previously demonstrated benzodiazepine binding in the cortex and hippocampus of mu-opioid receptor knockout (KO) mice. It is known that benzodiazepine receptors are involved in regulating anxiety-like behaviors. Thus, the present study was designed to examine whether there are changes in anxiety-like behavior in mice lacking mu-opioid receptors. To produce anxiolytic activity (less anxiety), the prototype benzodiazepine receptor agonist chlordiazepoxide (CDP, 5 mg/kg) was intraperitoneally administered in wild type (WT) and mu-opioid receptor KO mice. We found that compared to WT mice, mu-opioid receptor KO mice showed enhanced anxiolytic activity to CDP, including increased number of entries into open arm, increased percentage of the time spent in open arms, and decreased percentage of the time spent in enclosed arms in the elevated plus-maze test. We also assessed protein expression of the gamma-aminobutyric acid (GABA) synthetic enzyme (glutamic acid decarboxylase; GAD). Western blotting data indicated that neither the lack of mu-opioid receptors nor CDP treatment altered cortical or hippocampal GAD65 or GAD67 protein expression. These data indicate that compared with WT, mu-opioid receptor KO mice experienced less anxiety and exhibited enhanced anxiolytic activity to CDP treatment, and these effects were not dependent on GAD65 or GAD67 protein expression. Our previous and present data suggest that the anxiolytic activity displayed in mu-opioid receptor KO mice is associated with upregulation of the benzodiazepine receptor system.

Distribution-based classification method for baseline correction of metabolomic 1D proton nuclear magnetic resonance spectra.

Baseline distortion in 1D (1)H NMR data complicates the quantification of individual components of biofluids in metabolomic experiments. Current 1D (1)H NMR baseline correction methods usually require manual parameter and filter tuning by experienced users to obtain desirable results from complex metabolomic spectra, thus becoming prone to correction variation and biased quantification. We present a novel alternative method, BaselineCorrector, for automatically estimating the baselines of 1D (1)H NMR metabolomic data. By collecting the standard deviations of spectral intensities, using a moving window to slide through a spectrum, BaselineCorrector can model the distribution of noise standard deviation as a derived chi-squared distribution in each window and then determine optimal parameters for least-error classification of signal and noise. Due to the universal property of noise distributions, BaselineCorrector can robustly recognize the baseline segments in various spectra. In addition to the commonly used 1D NOESY and CPMG pulse sequences, BaselineCorrector also provides an algorithm for correcting diffusion-edited NMR spectra. Using its classification model, BaselineCorrector is able to preserve low signal peaks and correctly handle wide, overlapping peaks in complex metabolomic spectra.

Metabolomic characterization of laborers exposed to welding fumes.

The complex composition of welding fumes, multiplicity of molecular targets, diverse cellular effects, and lifestyles associated with laborers vastly complicate the assessment of welding fume exposure. The urinary metabolomic profiles of 35 male welders and 16 male office workers at a Taiwanese shipyard were characterized via (1)H NMR spectroscopy and pattern recognition methods. Blood samples for the same 51 individuals were also collected, and the expression levels of the cytokines and other inflammatory markers were examined. This study dichotomized the welding exposure variable into high (welders) versus low (office workers) exposures to examine the differences of continuous outcome markers-metabolites and inflammatory markers-between the two groups. Fume particle assessments showed that welders were exposed to different concentrations of chromium, nickel, and manganese particles. Multivariate statistical analysis of urinary metabolomic patterns showed higher levels of glycine, taurine, betaine/TMAO, serine, S-sulfocysteine, hippurate, gluconate, creatinine, and acetone and lower levels of creatine among welders, while only TNF-α was significantly associated with welding fume exposure among all cytokines and other inflammatory markers measured. Of the identified metabolites, the higher levels of glycine, taurine, and betaine among welders were suspected to play some roles in modulating inflammatory and oxidative tissue injury processes. In this metabolomics experiment, we also discovered that the association of the identified metabolites with welding exposure was confounded by smoking, but not with drinking, which is a finding consistent with known modified response of inflammatory markers among smokers. Our results correspond with prior studies that utilized nonmetabolomic analytical techniques and suggest that the metabolomic profiling is an efficient method to characterize the overall effect of welding fume exposure and other confounders.

Interleukin-1 receptor antagonist ameliorates neonatal lipopolysaccharide-induced long-lasting hyperalgesia in the adult rats.

An increasing amount of data show that central inflammation contributes to many debilitating diseases and produces spontaneous pain and hyperalgesia (an increased sensitivity to painful stimuli), and these processes may be associated with the production of proinflammatory cytokines by activated microglia. In the present study, we demonstrate that neonatal intracerebral injection of lipopolysaccharide (LPS) (1mg/kg) in postnatal day 5 (P5) rats produced hyperalgesia that lasted into adulthood as indicated by decreased latency in the tail-flick test. Neonatal LPS administration resulted in a long-lasting increase in the number of activated microglial in the P70 rat brain. The effects of interleukin-1beta (IL-1ß) and IL-1 receptor antagonists on hyperalgesia were determined to examine the possible role of inflammatory cytokines in LPS-induced hyperalgesia. Our data show that neonatal intracerebral injection of IL-1ß (1 µg/kg) produced a hyperalgesic tendency similar to that induced by LPS. Neonatal administration of an IL-1 receptor antagonist (0.1mg/kg) significantly attenuated long-lasting hyperalgesia induced by LPS and reduced the number of activated microglia in the adult rat brain. These data reveal that neonatal intracerebral LPS exposure results in long-lasting hyperalgesia and an elevated number of activated microglia in later life. This effect is similar to that induced by IL-1ß and can be prevented by an IL-1 receptor antagonist. The present study suggests that an IL-1 receptor antagonist effectively attenuates or blocks long-lasting hyperalgesia and microglia activation produced by LPS exposure in the neonatal period of rats.

Bisphenol-A interferes with estradiol-mediated protection in osteoarthritic chondrocytes.

Aged women have a higher risk of osteoarthritis (OA) due to estrogen (E2) loss at menopause. Studies suggested that E2 inhibits nuclear factor (NF)-kappaB activity which is increased in arthritis pathogenesis. Other studies revealed that external E2 reduces the expression of matrix metalloproteinases (MMPs) in osteoarthritic chondrocytes, and attenuates the pathogenesis of OA. Bisphenol-A (BPA) is an important industrial material, and an endocrine-disrupting chemical (EDC) that binds E2 receptors and interrupts the hormone signaling. It is unknown how BPA affects E2 functions and influences E2-mediated protections in OA. In this study, we investigated the effects of E2 and BPA on nitric oxide (NO) production, NF-kappaB activation, and MMP-1 expression in chondrosarcoma SW1353 cells and primary human osteoarthritic chondrocytes. Among the tested chemicals, BPA reduced NO production and cell viability of chondrosarcoma cells, but had little effects on osteoarthritic chondrocytes. Using HPLC-UV, we observed BPA in the serum and synovial fluid of OA patients. In primary chondrocytes, modest concentrations of E2 reduced interleukin (IL)-1beta-dependent NF-kappaB activation and MMP-1 expression. BPA antagonized these protective effects of E2 in a concentration-dependent manner. In conclusion, BPA interferes with E2's functions in chondrocytes and may promote OA.

Tracheal ring fracture as a consequence of external laryngeal manipulation during endotracheal intubation.

We report a case of tracheal ring fracture after external laryngeal manipulation for assisting intubation because of difficult laryngoscopy during induction of anesthesia. The patient was a 64-year-old female suffering from a large multinodular goiter scheduled to undergo general anesthesia with endotracheal intubation for thyroidectomy. Laryngoscopy was performed, which did not visualize the glottis. With application of forceful external laryngeal manipulation, intubation was successfully achieved on the third attempt. But on skin incision and tissue exposure, a single fractured site on the second tracheal ring was noted. Fiberoptic bronchoscopy was performed and showed the tracheal mucosa remaining unmolested without endotracheal lesion or cartilage dislodgement into the trachea. The operation was carried out uneventfully and the fracture was treated conservatively. After extubation, the patient recovered smoothly and had no symptoms suggestive of tracheal narrowing or hoarseness of voice. Neck computed tomography and fiberoptic bronchoscopy were performed postoperatively, both of which showed normal tracheal ring alignment without evidence of edema or hematoma. The patient was discharged 3 days after operation. At the 3-month follow-up, she displayed good airway function and phonation. After review of her clinical history, we speculated that the tracheal ring fracture was caused by forced external compression of the tracheal cartilage during endotracheal intubation.

Activation of p38 mitogen-activated protein kinase in spinal microglia contributes to incision-induced mechanical allodynia.

BACKGROUND: Recent studies have implicated the activation of stress-activated mitogen-activated protein kinase (MAPK) p38 in spinal microglial cells for development of neuropathic and inflammatory pain. The aim of the present study was to investigate whether phosphorylation of p38 (p-p38) also mediates mechanical allodynia and thermal hyperalgesia induced by plantar incision. METHODS: After rats received a plantar incision surgery, mechanical allodynia and thermal hyperalgesia were determined by von Frey filaments and radiant heat, respectively, and the number of p-p38 immunoreactive cells in the dorsal horn was quantified to determine p38 activation at different time points after incision. The p38 inhibitor FR167653 was administered intrathecally 30 min before hind paw plantar incision to determine the role of p38 in postoperative pain. RESULTS: A significant increase in number of p-p38 immunoreactive cells was observed in the ipsilateral L4-5 spinal dorsal horn from 1 h to 3 days after the incision. p-p38 was found predominantly in microglia. However, microglial activation (assessed by OX-42 upregulation) was not evident until 3 days after plantar incision. Intrathecal pretreatment of FR167653 attenuated incision-induced mechanical allodynia from 1 h to day 2 and significantly reduced activation of p38 in the dorsal horn 1 day after plantar incision. However, FR167653 only inhibited heat hyperalgesia at an early time point. CONCLUSIONS: Plantar incision-induced mechanical allodynia can be prevented by the p38 inhibitor. Our results suggest that p38 activation in spinal microglia play a role in incision-induced mechanical allodynia in rats. Therefore, p38 inhibition may be useful in treating postsurgical pain.

A minimal stress model for the assessment of electroacupuncture analgesia in rats under halothane.

The use of anesthetics in acupuncture analgesia is controversial. We evaluate a steady-state light anesthesia model to test whether minimal stress manipulation and reliable measurement of analgesia could be simultaneously achieved during electroacupuncture (EA) in animals. A series of experiments were performed. Firstly, EA compliance and tail-flick latencies (TFL) were compared in rats under 0.1%, 0.3%, 0.5%, 0.7%, or 1.1% halothane for 120min. Under 0.5% halothane, TFL were then measured in groups receiving EA at intensity of 3, 10 or 20 volt (V), 1 or 2mg/kg morphine, 20V EA plus naloxone, or control. Subsequently, the effect of EA on formalin-induced hyperalgesia was tested and c-fos expression in the spinal dorsal horn was analyzed. Rats exhibited profound irritable behaviors and highly variable TFL under 0.1% or 0.3% halothane, as well as a time-dependent increase of TFL under 0.7% or 1.1% halothane. TFL remained constant at 0.5% halothane, and needle insertion and electrical stimulation were well tolerated. Under 0.5% halothane, EA increased TFL and suppressed formalin-induced hyperalgesia in an intensity-dependent and naloxone-reversible manner. EA of 20V prolonged TFL by 74%, suppressed formalin-induced hyperalgesia by 32.6% and decreased c-fos expression by 29.7% at the superficial and deep dorsal horn with statistically significant difference. In conclusion, 0.5% halothane provides a steady-state anesthetic level which enables the humane application of EA stimulus with the least interference on analgesic assessment. This condition serves as a minimal stress EA model in animals devoid of stress-induced analgesia while maintaining physiological and biochemical response in the experiment.

Lingual nerve injury following the use of an oropharyngeal airway under endotracheal general anesthesia.

We report a patient who presented for elective myomectomy. Laryngoscopy and endotracheal intubation were achieved smoothly without unduly force. An oropharyngeal airway was inserted after endotracheal intubation for biting and was left in the oral cavity until the end of surgery. Two days after surgery, the patient complained of numbness on the right side of her tongue. Neurological examination revealed an area of hypesthesia about 1 cm in diameter on the right side of the tongue tip. The motor function, taste perception, and speech articulation were all intact. A right lingual nerve lesion with terminal branch involvement was diagnosed. The patient was then reassured and discharged home. At the 4-week follow-up, spontaneous resolution occurred. After reviewing the history, we speculated that the mechanism of nerve injury in this case was a direct compression of the tongue tip by the oropharyngeal airway. This is the first report of lingual nerve injury caused by improper placement of the oropharyngeal airway. We recommend careful manipulation in the use of the oropharyngeal airway and vigilant surveillance being undertaken when an oropharyngeal airway is left in place for a prolonged period.