[Research progress on Mycobacterium tuberculosis acetyltransferase].

The protein acetylation of Mycobacterium tuberculosis(MTB) plays an important role in virulence, drug resistance, regulation of metabolism and host anti-tuberculosis immune response. The proteins acetylation of MTB and host protein could be induced by the MTB acetyltransferase, which is related to the occurrence, development and prognosis of tuberculosis (TB). A clear understanding of the function of MTB acetyltransferase and identification of its targeted regulatory protein acetylation modification is critical to elucidate the pathogenic mechanism and drug resistance mechanism of TB, and then this could then provide new targets for the development of anti-tuberculosis drugs. This article systematically reviewed the research progress on MTB acetyltransferase related functions, which will provide a theoretical basis for further research on its mediated protein acetylation modification, further development of new anti-tuberculosis drugs and elucidation of drug resistance mechanism.

[Mechanism of Mycobacterium tuberculosis on interleukin-6 receptor 3'-untranslated region methylation in CD4+T cells].

Objective: To investigate the role and mechanism of DNA methylation in Mycobacterium tuberculosis (MTB lysate) -induced downregulation of interleukin-6 receptor(IL-6R) expression in CD4+T cells. Methods: A prospective study was conducted. Bisulfite sequencing (BSP) was applied to determine the methylation levels of CpG island in IL-6R promoter region and 3'untranslated region (3'UTR) region in CD4+T cells from peripheral blood mononuclear cells (PBMC) of control group (healthy person, n=10) and TB group (tuberculosis patients, n=10) in Shenzhen Third People's Hospital between 2019 and 2020. Quantitative reverse transcription-PCR (RT-qPCR) and Western blotting were used to detect the expression of IL-6R, DNMT1, DNMT3A and DNMT3B in MTB lysate-stimulated CD4+T cells and Jurkat E6-1 cells. Furthermore, PBMC in control group and Jurkat E6-1 cells activated by anti-CD3/CD28 antibody were stimulated by MTB lysates to detect the methylation levels of CpG island and IL-6R and DNMT expression. Transcriptional activity of differently methylation regions of IL-6R 3'UTR was detected by using luciferase reporter gene system. Results: IL-6R expression in TB group was lower than that in control group, but DNMT1 and DNMT3B expressions were higher than those in control group in CD4+T cells isolated from PBMC. There was no significant difference in the methylation rate of IL-6R promoter CpG island of CD4+T cells between control and TB group. However, the methylation rates of CpG island in 3'UTR region were significantly higher (P<0.001) in TB (69.5%±3.4%), compared with control (54.3%±4.7%). Besides, IL-6R expression was lower than unstimulated, while DNMT1 and DNMT3B expression was higher than unstimulated after MTB lysate-stimulation of activated control PBMC in vitro. The methylation rate of CpG island in IL-6R 3'UTR region of CD4+T cells increased from 58.8%±11.6% to 79.4%±10.9% (P<0.001) after MTB lysate-stimulated PBMC of the control. The same results were observed in the MTB lysate-stimulated CD4+T cells isolated from PBMC in control and Jurkat E6-1 cell line. Furthermore, IL-6R expression after co-treatment of the DNA methyltransferase inhibitor decitabine (5-aza) with MTB lysate was higher than that stimulated by MTB lysate alone. In addition, the methylation levels of CpG islands in the 3' UTR region of IL-6R were lower than those stimulated by MTB lysates alone after co-treatment of the DNA methyltransferase inhibitor decitabine (5-aza) with MTB lysates. The transcriptional activity of the fully unmethylated IL-6R 3'UTR CpG island reporter gene was higher than that of the fully methylated IL-6R 3'UTR CpG island. Conclusions: MTB lysates stimulation inhibited IL-6R expression transcriptionalely as well as on the protein level by inducing hypermethylation of CpG island in IL-6R 3'UTR region of CD4+T cells. The hypermethylation of CpG island in IL-6R 3'UTR region of CD4+T cells induced by MTB may be related to the increased expression of DNMT1 and DNMT3B.

[The role and significance of digital reconstruction technique in liver segments based on portal vein structure].

Objective: To study the segment of liver according to the large amount of three-dimensional(3D) reconstructive images of normal human livers and the vascular system, and to recognize the basic functional liver unit based on the anatomic features of the intrahepatic portal veins. Methods: The enhanced CT primitive DICOM files of 1 260 normal human livers from different age groups who treated from October 2013 to February 2017 provided by 16 hospitals were analyzed using the computer-aided surgery system.The 3D liver and liver vascular system were reconstructed, and the digital liver 3D model was established.The vascular morphology, anatomical features, and anatomical distributions of intrahepatic portal veins were statistically analyzed. Results: The digital liver model obtained from the 3D reconstruction of CAS displayed clear intrahepatic portal vein vessels of level four.Perform a digital liver segments study based on the analysis of level four vascular distribution areas.As the less anatomical variation of left hepatic portal vein, the liver was classified into four types of liver segmentation mainly based on right hepatic portal vein.Type A was similar to Couinaud or Cho's segmentation, containing 8 segments(537 cases, 42.62%). Type B contained 9 segments as there are three ramifications of right-anterior portal vein(464 cases, 36.82%). The main difference for Type C was the variation of right-posterior portal vein which was sector shape(102 cases, 8.10%). Type D contained the cases with special portal vein variations, which needs three-dimensional simulation to design individualized liver resection plan(157 cases, 12.46%). These results showed that there was no significant difference in liver segmental typing between genders(χ(2)=2.179, P=0.536) and did not reveal any significant difference in liver segmental typing among the different age groups(χ(2)=0.357, P=0.949). Conclusions: The 3D digital liver model can demonstrate the true 3D anatomical structures, and its spatial vascular variations.The observation of anatomic features, distribution areas of intrahepatic portal veins and individualized liver segmentation achieved via digital medical 3D visualization technology is of great value for understand the complexity of liver anatomy and to guide the precise hepatectomy.

[Transanal drainage tube for prevention of anastomotic leak after anterior resection for rectal cancer: a meta-analysis].

Objective: To assess the effectiveness of transanal drainage tube (TDT) in reducing the incidence of anastomotic leak following anterior resection in patients with rectal cancer. Methods: We conducted a systematic search for relevant studies published from inception to October 2022 across multiple databases, including PubMed, Embase, Web of Science, Cochrane Library, CNKI, Wanfang, and VIP. Meta-analysis was performed using Review Manager 5.4 software. The primary outcomes included total incidence of anastomotic leak, grade B and C anastomotic leak rates, reoperation rate, anastomotic bleeding rate, and overall complication rate. Results: Three randomized controlled trials involving 1115 patients (559 patients in the TDT group and 556 in the non-TDT group) were included. Meta-analysis showed that the total incidences of anastomotic leak and of grade B anastomotic leak were 5.5% (31/559) and 4.5% (25/559), respectively, in the TDT group and 7.9% (44/556) and 3.8% (21/556), respectively, in the non-TDT group. These differences are not statistically significant (P=0.120, P=0.560, respectively). Compared with the non-TDT group, the TDT group had a lower incidence of grade C anastomotic leak (1.6% [7/559] vs. 4.5% [25/556]) and reoperation rate (0.9% [5/559] vs. 4.3% [24/556]), but a higher incidence of anastomotic bleeding (8.2% [23/279] vs. 3.6% [10/276]). These differences were statistically significant (P=0.003, P=0.001, P=0.030, respectively). The overall complication rate was 26.5%(74/279) in the TDT group and 27.2% (75/276) in the non-TDT group. These differences are not statistically significant (P=0.860). Conclusions: TDT did not significantly reduce the total incidence of anastomotic leak but may have potential clinical benefits in preventing grade C anastomotic leak. Notably, placement of TDT may increase the anastomotic bleeding rate.

Differential effects of cannabinoid receptor agonists on regional brain activity using pharmacological MRI.

BACKGROUND AND PURPOSE: Activation of cannabinoid CB1 and/or CB2 receptors mediates analgesic effects across a broad spectrum of preclinical pain models. Selective activation of CB2 receptors may produce analgesia without the undesirable psychotropic side effects associated with modulation of CB1 receptors. To address selectivity in vivo, we describe non-invasive, non-ionizing, functional data that distinguish CB1 from CB2 receptor neural activity using pharmacological MRI (phMRI) in awake rats. EXPERIMENTAL APPROACH: Using a high field (7 T) MRI scanner, we examined and quantified the effects of non-selective CB1/CB2 (A-834735) and selective CB2 (AM1241) agonists on neural activity in awake rats. Pharmacological specificity was determined using selective CB1 (rimonabant) or CB2 (AM630) antagonists. Behavioural studies, plasma and brain exposures were used as benchmarks for activity in vivo. KEY RESULTS: The non-selective CB1/CB2 agonist produced a dose-related, region-specific activation of brain structures that agrees well with published autoradiographic CB1 receptor density binding maps. Pretreatment with a CB1 antagonist but not with a CB2 antagonist, abolished these activation patterns, suggesting an effect mediated by CB1 receptors alone. In contrast, no significant changes in brain activity were found with relevant doses of the CB2 selective agonist. CONCLUSION AND IMPLICATIONS: These results provide the first clear evidence for quantifying in vivo functional selectivity between CB1 and CB2 receptors using phMRI. Further, as the presence of CB2 receptors in the brain remains controversial, our data suggest that if CB2 receptors are expressed, they are not functional under normal physiological conditions.

In vitro and in vivo characterization of A-796260: a selective cannabinoid CB2 receptor agonist exhibiting analgesic activity in rodent pain models.

BACKGROUND AND PURPOSE: Selective cannabinoid CB2 receptor agonists have demonstrated analgesic activity across multiple preclinical pain models. AM1241 is an indole derivative that exhibits high affinity and selectivity for the CB2 binding site and broad spectrum analgesic activity in rodent models, but is not an antagonist of CB2 in vitro functional assays. Additionally, its analgesic effects are mu-opioid receptor-dependent. Herein, we describe the in vitro and in vivo pharmacological properties of A-796260, a novel CB2 agonist. EXPERIMENTAL APPROACH: A-796260 was characterized in radioligand binding and in vitro functional assays at rat and human CB1 and CB2 receptors. The behavioural profile of A-796260 was assessed in models of inflammatory, post-operative, neuropathic, and osteoarthritic (OA) pain, as well as its effects on motor activity. The receptor specificity was confirmed using selective CB1, CB2 and mu-opioid receptor antagonists. KEY RESULTS: A-796260 exhibited high affinity and agonist efficacy at human and rat CB2 receptors, and was selective for the CB2 vs CB1 subtype. Efficacy in models of inflammatory, post-operative, neuropathic and OA pain was demonstrated, and these activities were selectively blocked by CB2, but not CB1 or mu-opioid receptor-selective antagonists. Efficacy was achieved at doses that had no significant effects on motor activity. CONCLUSIONS AND IMPLICATIONS: These results further confirm the therapeutic potential of CB2 receptor-selective agonists for the treatment of pain. In addition, they demonstrate that A-796260 may be a useful new pharmacological compound for further studying CB2 receptor pharmacology and for evaluating its role in the modulation of pain.

Gastric Stump Cancer Following Gastrectomy After Renal Transplantation: A Case Report.

A patient who had previously undergone a gastrectomy due to gastric ulcer perforation was admitted to our hospital. He presented with epigastric pain and poor oral intake accompanied with gastrointestinal bleeding, and was diagnosed with gastric stump cancer. He had a history of renal transplantation and was administered immunosuppressive agents. To alleviate the obstructive symptom and cure the gastrointestinal bleeding, the patient underwent surgical resection of the malignant tumor, with stable kidney function during the perioperative period. To the best of our knowledge, this is the first case reported in the English literature concerning gastric stump cancer that developed after renal transplantation. We speculate that the long-term use of immunosuppressants concomitant with gastrointestinal disorders after gastric surgery was an important causative factor in its etiology. We also investigated the possible treatment for it.

P2X7-related modulation of pathological nociception in rats.

Growing evidence supports a role for the immune system in the induction and maintenance of chronic pain. ATP is a key neurotransmitter in this process. Recent studies demonstrate that the glial ATP receptor, P2X7, contributes to the modulation of pathological pain. To further delineate the endogenous mechanisms that are involved in P2X7-related antinociception, we utilized a selective P2X7 receptor antagonist, A-438079, in a series of in vivo and in vitro experiments. Injection of A-438079 (10-300 micromol/kg, i.p.) was anti-allodynic in three different rat models of neuropathic pain and it attenuated formalin-induced nocifensive behaviors. Using in vivo electrophysiology, A-438079 (80 micromol/kg, i.v.) reduced noxious and innocuous evoked activity of different classes of spinal neurons (low threshold, nociceptive specific, wide dynamic range) in neuropathic rats. The effects of A-438079 on evoked firing were diminished or absent in sham rats. Spontaneous activity of all classes of spinal neurons was also significantly reduced by A-438079 in neuropathic but not sham rats. In vitro, A-438079 (1 microM) blocked agonist-induced (2,3-O-(4-benzoylbenzoyl)-ATP, 30 microM) current in non-neuronal cells taken from the vicinity of the dorsal root ganglia. Furthermore, A-438079 dose-dependently (0.3-3 microM) decreased the quantity of the cytokine, interleukin-1beta, released from peripheral macrophages. Thus, ATP, acting through the P2X7 receptor, exerts a wide-ranging influence on spinal neuronal activity following a chronic injury. Antagonism of the P2X7 receptor can in turn modulate central sensitization and produce antinociception in animal models of pathological pain. These effects are likely mediated through immuno-neural interactions that affect the release of endogenous cytokines.

Comparison of antinociceptive actions of standard analgesics in attenuating capsaicin and nerve-injury-induced mechanical hypersensitivity.

Intradermal capsaicin injection produces immediate spontaneous pain behaviors, and a secondary mechanical hypersensitivity (SMH) that is employed in the clinic as a model potentially predictive of human neuropathic pain. Presently, we have characterized capsaicin-induced SMH in rats, and compared pharmacological actions of standard analgesics in this and two nerve injury models, the L5/L6 spinal nerve ligation (SNL) and sciatic nerve chronic constriction injury (CCI) models. Intraplantar capsaicin produced dose-related SMH (enhanced paw withdrawal response to von Frey monofilament stimulation at an area away from injection site) that lasted for over 4 h. While pretreatment with a potent selective transient receptor potential vanilloid receptor-1 (TRPV1) antagonist A-425619 (1-isoquinolin-5-yl-3-(4-trifluoromethyl-benzyl)-urea) prevented development of acute nocifensive (flinching) behavior immediately following capsaicin injection (ED(50)=4.9 mg/kg), the compound failed to attenuate the SMH when administered 2 h following capsaicin (10 microg/10 microl). Additional standard analgesics were also tested 3 h following intraplantar capsaicin in the SMH model. Comparison of their potencies in attenuating mechanical hypersensitivity in capsaicin, SNL and CCI models revealed similar ED(50)s for morphine (2.3 mg/kg, 1.6 mg/kg and 3.2 mg/kg, respectively), gabapentin (33.1 mg/kg, 33.9 mg/kg and 26.3 mg/kg, respectively) and lamotrigine (9.1 mg/kg, 8.9 mg/kg and 15.5 mg/kg, respectively). Duloxetine produced 50-65% effect at the highest tested dose (50 mg/kg), whereas the highest tested doses of morphine (10 mg/kg), gabapentin (85.5 mg/kg) and lamotrigine (30 mg/kg) all produced >70% efficacy in capsaicin SMH, SNL and CCI models. In contrast, celecoxib and ibuprofen showed weak effects in all three models. All standard analgesics generally had weak efficacy in attenuating capsaicin-induced immediate acute flinching behavior when administered before capsaicin. These results provide further support to the suggestions that distinct pharmacological mechanisms underlie capsaicin-induced acute nocifensive and SMH behaviors, and certain neuronal mechanisms underlying neuropathic pain states are also contributory to capsaicin-induced SMH.

Diffusion tensor imaging in the assessment of normal-appearing brain tissue damage in relapsing neuromyelitis optica.

BACKGROUND AND PURPOSE: Normal-appearing brain tissue (NABT) damage was established in multiple sclerosis by histology, MR spectroscopy, magnetization transfer imaging and diffusion tensor imaging (DTI). However, whether this phenomenon can be detected in relapsing neuromyelitis optica (RNMO) remains unclear. The aim of this study was to use DTI to investigate the presence of NABT damage in RNMO patients and its possible mechanism. METHODS: Conventional MR imaging and DTI scans were performed in 16 patients with RNMO without visible lesions on brain MR imaging and in 16 sex- and age-matched healthy control subjects. Histogram analysis of mean diffusivity (MD) and fractional anisotropy (FA) was performed in the entire brain tissue (BT), white matter (WM), and gray matter (GM). Region of interest (ROI) analysis of MD and FA was also performed in WM regions connected with the spinal white matter tracts or optic nerve (including medulla oblongata, cerebral peduncle, internal capsule, and optic radiation), in corpus callosum without direct connection with them, and in some GM regions. RESULTS: From histogram analysis, we found the RNMO group had a higher average MD of the BT, WM, and GM, a lower average MD peak height and a higher average MD peak location of the GM, and a higher average FA peak height of the WM than did the control group. From ROI analysis, compared with control subjects, RNMO patients had a higher average MD and a lower average FA in ROIs of WM connected with the spinal white matter tracts or optic nerve and a normal average MD and FA in corpus callosum without direct connection with them. In addition, a high average MD was found in parietal GM in these patients. CONCLUSIONS: Our findings confirm the presence of abnormal diffusion in brain tissue in patients with RNMO and suggest that secondary degeneration caused by lesions in the spinal cord and optic nerve might be an important mechanism for this abnormality.

Complete Freund's adjuvant-induced reduction of exploratory activity in a novel environment as an objective nociceptive endpoint for sub-acute inflammatory pain model in rats.

BACKGROUND: Hind paw injection of complete Freund's adjuvant (CFA) is a commonly used sub-acute inflammatory pain model in rodents with typical subjective endpoint measurements of paw withdrawal to thermal or mechanical stimuli. METHODS: Here, we assessed CFA-induced reduction of exploratory activity in a novel environment (CRANE) as an objective nociceptive endpoint in rats. CFA (50%) was subcutaneously injected into the plantar aspect of the hind paw either unilaterally or bilaterally (150 µL/paw). Exploratory activity was recorded using an automated locomotor activity system. RESULTS: Bilateral CFA injection reduced exploratory activity 4-48 h following injection, compared to sham controls. Unilateral CFA injection produced less reduction of exploratory activity, compared to bilateral injection. Effects of orally dosed standard analgesics on CRANE were examined 48 h following bilateral CFA injection. Diclofenac treatment produced dose-related reversal of CRANE at 0.03-1.0 mg/kg with a plateau effect observed at higher doses (up to 30 mg/kg). Ibuprofen also produced dose-related reversal CRANE at 0.3-3.0 mg/kg with a plateau effect at higher doses (up to 60 mg/kg). Similarly, celecoxib produced dose-related reversal CRANE at 3-10 mg/kg, but not 30 mg/kg. Gabapentin (up to 100 mg/kg) and duloxetine (up to 30 mg/kg) produced no reversal of CRANE. CONCLUSIONS: The results presented here demonstrate that CRANE provides an objective assessment of pain behaviours for sub-acute inflammatory pain in rats. The pharmacological profile of standard analgesics supports that CRANE model may potentially be used to identify novel analgesic agents for the treatment of sub-acute inflammatory pain.

Intraventricular administration of insulin and IGF-1 in transient forebrain ischemia.

A beneficial effect of insulin in reducing cerebral ischemic damage has been recently demonstrated, and a direct central mechanism of insulin action in cerebral ischemia has been proposed. To test the hypothesis that one of the neuroprotective mechanisms of insulin action involves a direct interaction with CNS tissue via a growth factor effect, a continuous intraventricular infusion of two doses of insulin and of insulin-like growth factor 1 (IGF-1) was given to fed Wistar rats subjected to 10 min, 15 s of transient forebrain ischemia. Quantitative neuropathology after 1-week survival showed that low-dose insulin (7 IU/rat/day; n = 10) reduced selective necrosis in the striatum (p = 0.015) and one level of the hippocampus (p = 0.023) as compared with animals infused with phosphate-buffered saline (200 microliters/rat/day; n = 8). IGF-1 (50 micrograms/rat/day; n = 8) significantly ameliorated hippocampal damage in four of the six hippocampal levels (p < 0.05). High-dose insulin infusion (23 IU/rat/day; n = 8) produced a robust reduction in cortical (p = 0.0108), striatal (p = 0.003), and hippocampal (p < 0.05) necrosis at all coronal levels. However, this high-dose insulin reduced the blood sugar significantly (p < 0.01), from 11.8 to 7.8 mM, probably by virtue of centrally administered insulin reaching the periphery. We conclude that insulin and IGF-1 offer a moderate, centrally mediated, neuroprotective effect, likely mediated at least in part via a growth factor mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

Graded hypotension and MCA occlusion duration: effect in transient focal ischemia.

The first 2 h of middle cerebral artery occlusion (MCAO) are likely critical in determining the final outcome in ischemic stroke. To study this early postischemic period, male Wistar rats (n = 161) were subjected to right MCAO with closely spaced step variations in both duration of MCAO and blood pressure (BP), using the intraluminal suture technique. Quantitative neuropathology was performed at 25 coronal planes of the brain after 1-week survival. Atrophy was measured as the difference between the two hemispheres and was added to cortical and striatal necrosis to obtain total tissue loss. Damage consistently increased monotonically with increasing duration of occlusion only when infarct size was expressed as percentage of the contralateral hemisphere, but not when expressed as mm3, because of variable tissue size. The results showed that already at 1 week, the quantity of tissue loss due to resorption and transsynaptic effects approached the quantity of geographically traceable necrosis in cortex and striatum. Minimum brain damage (5%) occurred after 60 min at a BP of 80 mm Hg, with almost no cortical necrosis. Damage was extremely sensitive to hypotension and MCAO duration. At a BP of 40 mm Hg, 60 min of MCAO produced 25% damage, accelerating every 20 min during the 2-h period studied. At BP 80 mm Hg, 120 min of MCAO produced the same damage as only 80 min of MCAO at BP 60 mm Hg. At 60-, 80-, 100-, and 120-min duration of MCAO, infarct size was significantly reduced with increasing BP.(ABSTRACT TRUNCATED AT 250 WORDS)

A-134974: a novel adenosine kinase inhibitor, relieves tactile allodynia via spinal sites of action in peripheral nerve injured rats.

Extracellular levels of adenosine (ADO) can be raised through inhibition of adenosine kinase (AK), a primary metabolic enzyme for ADO. AK inhibitors have shown antinociceptive activity in a variety of animal models of nociception. The present study investigated the antinociceptive actions of a novel and selective AK inhibitor, A-134974 (IC(50)=60 pM), in a rat model of neuropathic pain (ligations of the L5/L6 spinal nerves) and explored the relative contributions of supraspinal, spinal and peripheral sites to the actions of A-134974. Systemic A-134974 dose-dependently reduced tactile allodynia (ED(50)=5 micromol/kg, i.p.) for up to 2 h. Fall latencies in the rotorod test of motor coordination were unaffected by systemic administration of A-134974 (at doses up to 30 micromol/kg, i.p.). Administration of A-134974 intrathecally (i.t.) was more potent (ED(50)=10 nmol) in relieving tactile allodynia than delivering the compound by intracerebroventricular (ED(50)>100 nmol, i.c.v.) or intraplantar (ED(50)>500 nmol) routes suggesting that spinal sites of action are the primary contributors to the anti-allodynic action of A-134974. The anti-allodynic effects of systemic A-134974 (10 micromol/kg, i.p.) were antagonized by the non-selective ADO receptor antagonist, theophylline (30-500 nmol) administered i.t. These data demonstrate that the novel AK inhibitor A-134974 potently reduces tactile allodynia through interactions with spinal sites and adds to the growing evidence that AK inhibitors may be useful as analgesic agents in a broad spectrum of pain states.

ABT-627, an endothelin ET(A) receptor-selective antagonist, attenuates tactile allodynia in a diabetic rat model of neuropathic pain.

Tactile allodynia, the enhanced perception of pain in response to normally non-painful stimulation, represents a common complication of diabetic neuropathy. The activation of endothelin ET(A) receptors has been implicated in diabetes-induced reductions in peripheral neurovascularization and concomitant endoneurial hypoxia. Endothelin receptor activation has also been shown to alter the peripheral and central processing of nociceptive information. The present study was conducted to evaluate the antinociceptive effects of the novel endothelin ET(A) receptor-selective antagonist, 2R-(4-methoxyphenyl)-4S-(1,3-benzodioxol-5-yl)-1-(N, N-di(n-butyl)aminocarbonyl-methyl)-pyrrolidine-3R-carboxylic acid (ABT-627), in the streptozotocin-induced diabetic rat model of neuropathic pain. Rats were injected with 75 mg/kg streptozotocin (i. p.), and drug effects were assessed 8-12 weeks following streptozotocin treatment to allow for stabilization of blood glucose levels (>/=240 mg/dl) and tactile allodynia thresholds (

Centrally administered insulin and IGF-1 in transient forebrain ischaemia in fasted rats.

Based on evidence for a direct central mechanism of insulin action in mitigating damage due to cerebral ischaemia, we have recently shown that centrally administered insulin, and to a lesser extent, insulin-like growth factor-1 (IGF-1), reduce ischaemic damage in fed rats. Because a portion of the neuroprotective effect of insulin may be due to peripheral hypoglycaemia, we undertook the present series of experiments to determine whether insulin or IGF-1 are neuroprotective in fasted rats, which already have low blood glucose values. Continuous minipump delivery of insulin (1 IU rat-1 day-1 n = 13), or IGF-1 (50 micrograms rat-1 day-1 n = 10) was compared to control rats treated with phosphate buffered saline (PBS 25 microliters rat-1 day-1 n = 10). Quantitative neuropathology was done one week after 10 min and 15 sec of transient forebrain ischaemia induced by bilateral carotid artery clamping at a mean arterial BP (MABP) of 50 mmHg. In all areas examined i.e. neocortex, striatum, and hippocampus, the three groups showed similar degrees of necrosis (p > 0.05), although there were insignificant trends for a beneficial effect of insulin in reducing selective neuronal necrosis in hippocampus. The results, in combination with previous studies, indicate that insulin is more effective in attenuating brain damage in fed rats.

Assessing carrageenan-induced locomotor activity impairment in rats: comparison with evoked endpoint of acute inflammatory pain.

BACKGROUND: Most animal models currently used to evaluate antinociceptive efficacy of analgesics rely on the assessment of evoked pain behaviours as primary endpoints. METHODS: Here, we have developed and characterized the carrageenan-induced locomotor activity impairment (CLAIM) model to objectively assess non-evoked inflammatory pain behaviour in rats. In this model, 100 µL of 1% carrageenan was subcutaneously injected into the plantar aspect of the right hind paw and exploratory behaviour in the novel testing chamber was recorded using an automated locomotor activity system. RESULTS: Carrageenan-injected animals exhibited an exploratory behavioural deficit 2-7 h following injection compared to saline-injected animals. The severity of impairment was carrageenan dose related, and sensitive to the light intensity in the testing room. The effects of standard analgesics on CLAIM were examined 2 or 3 h following carrageenan injection. Diclofenac and ibuprofen, in a dose range exerting no effect on locomotor activity in naïve rats, exhibited dose-related reversal of CLAIM (ED(50) = 1.5 and 5.0 mg/kg, respectively), with comparable efficacy on carrageenan-induced thermal hyperalgesia (ED(50) = 2.0 and 6.0 mg/kg, respectively). Gabapentin and duloxetine produced no reversal of CLAIM, or attenuation of thermal hyperalgesia. Efficacy discrepancy was noted for morphine on thermal hyperalgesia and CLAIM. Additionally, amphetamine dose dependently reversed CLAIM, and similarly increased locomotor activity in normal animals. DISCUSSION AND CONCLUSION: The results presented here demonstrate that CLAIM provides an objective assessment of non-evoked pain behaviours for acute inflammatory pain. The pharmacological profile of standard analgesics supports that CLAIM model can be used to identify agents to treat acute inflammatory pain in the clinic.

Decreased gray matter concentration and local synchronization of spontaneous activity in the motor cortex in Duchenne muscular dystrophy.

BACKGROUND AND PURPOSE: Patients with DMD have demonstrated functional abnormalities in the motor-related brain areas in previous PET, MRS, and TMS studies. We applied structural MR imaging and RS-fMRI in patients with DMD for the first time, and aimed to investigate the GMC and ReHo or local synchronization of spontaneous activity in the motor cortex. MATERIALS AND METHODS: Ten boys with DMD (6.4-14.0 years of age) and 15 healthy controls (7.9-15.1 years of age) underwent brain structural MR imaging and RS-fMRI scanning. GMC and local synchronization of spontaneous activity in the motor cortex were analyzed by using VBM and ReHo approaches, respectively. RESULTS: Compared with healthy controls, boys with DMD showed decreased GMC in the left PSMC and decreased ReHo in the bilateral PMSC as well as in the supplementary motor area (P < .05, corrected). CONCLUSIONS: The current results indicate that boys with DMD have both GMC loss and decreased local synchronization of spontaneous activity in the motor cortex, which might be due to the deficiency of dystrophin in the brain.

Peripheral and central sites of action for the non-selective cannabinoid agonist WIN 55,212-2 in a rat model of post-operative pain.

BACKGROUND AND PURPOSE: Activation of cannabinoid (CB) receptors decreases nociceptive transmission in inflammatory or neuropathic pain states. However, the effects of CB receptor agonists in post-operative pain remain to be investigated. Here, we characterized the anti-allodynic effects of WIN 55,212-2 (WIN) in a rat model of post-operative pain. EXPERIMENTAL APPROACH: WIN 55,212-2 was characterized in radioligand binding and in vitro functional assays at rat and human CB(1) and CB(2) receptors. Analgesic activity and site(s) of action of WIN were assessed in the skin incision-induced post-operative pain model in rats; receptor specificity was investigated using selective CB(1) and CB(2) receptor antagonists. KEY RESULTS: WIN 55,212-2 exhibited non-selective affinity and agonist efficacy at human and rat CB(1) versus CB(2) receptors. Systemic administration of WIN decreased injury-induced mechanical allodynia and these effects were reversed by pretreatment with a CB(1) receptor antagonist, but not with a CB(2) receptor antagonist, given by systemic, intrathecal and supraspinal routes. In addition, peripheral administration of both CB(1) and CB(2) antagonists blocked systemic WIN-induced analgesic activity. CONCLUSIONS AND IMPLICATIONS: Both CB(1) and CB(2) receptors were involved in the peripheral anti-allodynic effect of systemic WIN in a pre-clinical model of post-operative pain. In contrast, the centrally mediated anti-allodynic activity of systemic WIN is mostly due to the activation of CB(1) but not CB(2) receptors at both the spinal cord and brain levels. However, the increased potency of WIN following i.c.v. administration suggests that its main site of action is at CB(1) receptors in the brain.