内源性大麻素系统抗胶质瘤的作用机制

内源性大麻素系统是近年来研究较为深入的一个脂质信号和神经调节系统，广泛参与了体内一些生理或病理过程的调节。大量的研究表明，内源性大麻素系统及其相关药物能在体内外实验中抑制胶质瘤的生长，深入研究内源性大麻素系统抗胶质瘤的作用机制对改善胶质瘤的化疗效果具有重要的临床意义。     

CB2通过p38MAPK通路调控RAW264.7细胞ROS和NO的产生

目的研究大麻素受体2对氧化型低密度脂蛋白(oxidized low density lipoprotein,ox LDL)诱导后的RAW264.7巨噬细胞产生的一氧化氮(nitric oxide,NO)、活性氧(reactive oxygen species,ROS)、p38及磷酸化p38(phosphorylated p38,p-p38)的影响及其相关机制。方法使用MTT法检测大麻素受体激动剂WIN55,212-2和拮抗剂AM630对RAW264.7巨噬细胞的药物毒性;使用流式细胞仪技术检测ROS水平;采用Griess试剂盒法检测NO水平;Western blot检测p38丝裂原激活蛋白激酶类(mitogen-activated protein kinase,MAPK)通路中p38及p-p38的表达量。结果当WIN55,212-2及AM630浓度5μmol/L时,对RAW264.7巨噬细胞生存能力具有明显抑制作用;WIN55,212-2可有效降低ox LDL诱导的RAW264.7巨噬细胞NO、ROS的表达(t=2.36,P0.01;t=1.97,P0.01),AM630部分阻断了上述效应(t=2.01,P0.05;t=1.69,P0.05);WIN55,212-2可抑制ox LDL诱导的RAW264.7巨噬细胞p38的磷酸化水平(t=1.84,P0.01),加入AM630共孵育后使得p38磷酸化水平部分上升(t=1.72,P0.05)。结论大麻素受体2可通过p38 MAPK信号通路参与调控ox LDL诱导的RAW264.7巨噬细胞ROS和NO的产生。     

CB1 and TRPV1 receptors mediate protective effects on colonic electrophysiological properties in mice

CB1 and TRPV1 receptors modulate enteric neurotransmission and colonic inflammation. This study investigates early electrophysiological changes in distal colon of wild-type and receptor deficient mice after an inflammatory insult set by dinitrobenzene sulfonic acid (DNBS). Colitis was induced by DNBS in CB1^−/− mice, TRPV1^−/− mice, and their respective wild-type littermates. Electrophysiological properties consisting of membrane potentials and electrically induced inhibitory junction potentials (IJP) of circular smooth muscle cells were evaluated at different time points. Additionally a histological colitis severity score was evaluated in CB1^+/+ and CB1^−/− mice 24 h after DNBS. Inflammation caused spontaneous atropine insensitive rhythmic action potentials in CB1^−/− and TRPV1^−/− mice but not in wild-type animals. This indicates that membrane stability is disturbed, which in turn indicates a lack of protective mechanisms. Focal electrical neuronal stimulation of the myenteric plexus induced IJP in the smooth muscle cells. Twenty-four hours after initiation of inflammation, the duration of the IJP is prolonged in all animals, indicating disturbances within neuromuscular interaction. In CB1^−/− mice, it is interesting that the duration of IJP was significantly extended, as compared to CB1^+/+ mice pointing toward missing protective mechanisms in the CB1^−/− mice. Inflammatory insults in the mouse colon induce reproducible changes in the electrophysiological properties and such changes correlate with duration of colitis. In mutants, these electrophysiological changes display different patterns, suggesting the lack of protective properties for neuromuscular interactions and membrane stability.     

内源性大麻素抗肺纤维化的作用研究进展

肺纤维化作为临床常见的呼吸系统危重症,病因及发病机制复杂,最终导致呼吸衰竭,严重影响患者的生活质量。在肺组织、支气管平滑肌细胞、内皮细胞存在内源性大麻素和相应的大麻素受体,内源性大麻素与大麻素受体结合后可能通过磷脂酰肌醇-3激酶/蛋白激酶(PI3K/Akt)信号通路和TGF-β₁/Smad3信号通路参与调节免疫反应,抑制炎性细胞分泌细胞因子,减轻炎性反应,并且抑制血管内皮生长因子、基质金属蛋白酶等表达,抑制基底膜增生,发挥抗纤维化作用。文章就内源性大麻素在抗肺纤维化中的作用进行综述。     

隔三七饼灸对佐剂诱导型RA大鼠脊髓AST大麻素受体及P38MAPK表达的影响及机制探讨

目的:探讨隔三七饼灸对佐剂诱导型类风湿性关节炎(RA)大鼠脊髓星形胶质细胞(AST)大麻素受体及促分裂原活化蛋白激酶(P38MAPK)表达的影响及作用机制。方法:采用足垫部皮下注射弗式完全佐剂(FAC)复制RA大鼠模型,将大鼠随机分为假手术组、隔三七饼灸治疗组(艾灸组)、模型组和红外线照射(TDP)治疗组(TDP组),每组10只,艾灸组取内膝眼、外膝眼、血海、足三里穴,予以隔三七饼灸治疗,每次每穴灸五壮,隔日1次,10次为1个疗程;TDP组予以TDP照射治疗,每次30分钟,隔日1次,10次为1个疗程;模型组、假手术组平行饲养,只在鼠板上固定而不作其他处理。在造模成功后、治疗一个疗程后分别观察记录踝关节疼痛试验评分、热痛阈和机械性痛阈,并采用免疫组织化学技术,观察大麻素受体CB1、CB2在脊髓背角的表达及P38MAPK在脊髓AST内表达。结果:造模后,与假手术组比较,模型组、艾灸组和TDP组大鼠的疼痛试验评分显著升高(P<0.01),热痛阈和机械痛阈显著降低(P<0.01);治疗1个疗程后,与模型组比较,艾灸组和TDP组的疼痛试验评分和P38MAPK的表达降低(P<0.01,P<0.05),热痛阈、机械痛阈以及CB1、CB2表达升高(P<0.01,P<0.05);与TDP组比较,艾灸组的疼痛试验评分和P38MAPK的表达明显降低(P<0.05),热痛阈、机械痛阈以及CB1、CB2表达明显升高(P<0.05)。结论:隔三七饼灸对RA大鼠产生的疼痛有良好的改善作用,能增强脊髓大麻素受体CB1、CB2表达,抑制P38MAPK的表达,其机制可能是艾灸通过调控脊髓大麻素受体CB1、CB2的表达,抑制P38MAPK的通路而对佐剂性关节炎产生镇痛作用。     

Effect of observation combined with motor imagery of a skilled hand-motor task on motor cortical excitability: difference between novice and expert

The organization of developing auditory circuits depends on the elimination of aberrant connections and strengthening of appropriate ones. Endocannabinoid mediated plasticity is a proposed mechanism for this refinement. Here we investigated for the anatomical presence of cannabinoid receptors (CB1R) in the lateral superior olive (LSO) and medial nucleus of the trapezoid body (MNTB) of developing rats. We found that CB1R is present within the LSO and that it colocalized with vesicular glutamate transporter (VGLUT3), a presynaptic marker for MTNB terminals. Both before (P5) and around hearing onset (P12), the expression levels of CB1R were higher in the lateral limb of the LSO than in the medial limb. These results suggest that endocannabinoid signaling can modulate the strength of the developing MNTB-LSO synapse.     

Participation of cannabinoid receptors in peripheral nociception induced by some NSAIDs

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been used extensively to control inflammatory pain. Several peripheral antinociceptive mechanisms have been described, such as opioid system and NO/cGMP/KATP pathway activation. There is evidence that the cannabinoid system can also contribute to the in vivo pharmacological effects of ibuprofen and indomethacin. However, there is no evidence of the involvement of the endocannabinoid system in the peripheral antinociception induced by NSAIDs. Thus, the aim of this study was to investigate the participation of the endocannabinoid system in the peripheral antinociceptive effect of NSAIDs. All experiments were performed on male Wistar rats (160-200 g; N = 4 per group). Hyperalgesia was induced by a subcutaneous intraplantar (ipl) injection of prostaglandin E₂ (PGE₂, 2 µg/paw) in the rat''s hindpaw and measured by the paw pressure test 3 h after injection. The weight in grams required to elicit a nociceptive response, paw flexion, was determined as the nociceptive threshold. The hyperalgesia was calculated as the difference between the measurements made before and after PGE₂, which induced hyperalgesia (mean = 83.3 ± 4.505 g). AM-251 (80 µg/paw) and AM-630 (100 µg/paw) were used as CB₁ and CB₂ cannabinoid receptor antagonists, respectively. Ipl injection of 40 µg dipyrone (mean = 5.825 ± 2.842 g), 20 µg diclofenac (mean = 4.825 ± 3.850 g) and 40 µg indomethacin (mean = 6.650 ± 3.611 g) elicited a local peripheral antinociceptive effect. This effect was not antagonized by ipl CB₁ cannabinoid antagonist to dipyrone (mean = 5.00 ± 0.9815 g), diclofenac (mean = 2.50 ± 0.8337 g) and indomethacin (mean = 6.650 ± 4.069 g) or CB₂ cannabinoid antagonist to dipyrone (mean = 1.050 ± 6.436 g), diclofenac (mean = 6.675 ± 1.368 g) and indomethacin (mean = 2.85 ± 5.01 g). Thus, cannabinoid receptors do not seem to be involved in the peripheral antinociceptive mechanism of the NSAIDs dipyrone, diclofenac and indomethacin.     

Endocannabinoid-mediated enhancement of fear-conditioned analgesia in rats: Opioid receptor dependency and molecular correlates

The opioid and endocannabinoid systems mediate analgesia expressed upon re-exposure to a contextually aversive stimulus (fear-conditioned analgesia; FCA), and modulate the mitogen-activated protein kinase (MAPK) pathway. However, an interaction between the opioid and endocannabinoid systems during FCA has not been investigated at the behavioural or molecular level. FCA was modeled in male Lister-hooded rats by assessing formalin-evoked nociceptive behaviour in an arena previously paired with footshock. Administration of the fatty acid amide hydrolase and endocannabinoid catabolism inhibitor, URB597 (0.3 mg/kg, i.p.), enhanced expression of FCA. The opioid receptor antagonist, naloxone, attenuated FCA and attenuated the URB597-induced enhancement of FCA. SR141716A (CB₁ antagonist) and SR144528 (CB₂ antagonist) also attenuated the URB597-mediated enhancement of FCA. Expression of FCA was associated with increased relative phospho-ERK2 expression in the amygdala, an effect blocked by naloxone, SR141716A, and SR144528. Furthermore, URB597-mediated enhancement of FCA was associated with reduced phospho-ERK1 and phospho-ERK2 in the amygdala. Phospho-ERK1/2 expression in the hippocampus, prefrontal cortex, and thalamus was unchanged following FCA and drug treatment. None of the drugs affected formalin-evoked nociceptive behaviour or phospho-ERK1/2 expression in non-fear-conditioned rats. These data suggest that endocannabinoid-mediated enhancement of FCA is abolished by pharmacological blockade of opioid receptors as well as CB₁ or CB₂ receptors. Both pharmacological enhancement (with URB597) and attenuation (with naloxone) of this form of endogenous analgesia were associated with reduced expression of phospho-ERK1/2 in the amygdaloid complex arguing against a causal role for ERK1/2 signaling in the amygdala during expression of FCA or its modulation by opioids or cannabinoids.     

Intracerebral microinjections of Δ-tetrahydrocannabinol: search for the impairment of spatial memory in the eight-arm radial maze in rats

The purpose of this study was to identify brain sites that contribute to the delta(9)-tetrahydrocannabinol (delta(9)-THC)-induced impairment of spatial memory in rats. Rats were tested in the eight-arm radial maze after microinjections of delta(9)-THC into one of 14 different brain regions. The bilateral microinjection of delta(9)-THC (20 microg/side) impaired spatial memory when injected into the dorsal hippocampus (DH), ventral hippocampus (VH) or dorsomedial thalamus nucleus (DMT). However, rats treated with delta(9)-THC into DMT produced preseverative behavior which has not been observed by systemic administration of delta(9)-THC. On the other hand, spatial memory was unaffected by microinjections of delta(9)-THC into the other 11 areas examined: frontal (FC) and frontoparietal (FPC) cortex, central (ACE) and basolateral (ABL) amygdaloid nucleus, medial caudate putamen (CPM), lateral hypothalamus (LH), mammillary body (MB), basal forebrain (BF), medial septal nucleus (SEP) and dorsal (DR) and median (MR) raphe nucleus. These results suggest that DH and VH may be important brain sites for the delta(9)-THC-induced impairment of spatial memory.     

Down-regulation of cannabinoid-1 (CB-1) receptors in specific extrahypothalamic regions of rats with dietary obesity: a role for endogenous cannabinoids in driving appetite for palatable food?

Agonists at cannabinoid-1 (CB-1) receptors stimulate feeding and particularly enhance the reward aspects of eating. To investigate whether endogenous cannabinoids might influence appetite for palatable food, we compared CB-1 receptor density in the forebrain and hypothalamus, between rats fed standard chow (n=8) and others given palatable food (n=8) for 10 weeks to induce dietary obesity. CB-1 receptor density was significantly decreased by 30–50% (P<0.05) in the hippocampus, cortex, nucleus accumbens and entopeduncular nucleus of diet-fed rats. Furthermore, CB-1 receptor density in the hippocampus, nucleus accumbens and entopeduncular nucleus was significantly inversely correlated with intake of palatable food (r²=0.25–0.35; all P<0.05). By contrast, CB-1 receptor binding in the hypothalamus was low and not altered in diet-fed rats. CB-1 receptor down-regulation is consistent with increased activation of these receptors by endogenous cannabinoids. Acting in areas such as the nucleus accumbens and hippocampus, which are involved in the hedonic aspects of eating, cannabinoids may therefore drive appetite for palatable food and thus determine total energy intake and the severity of diet-induced obesity. However, cannabinoids in the hypothalamus do not appear to influence this aspect of eating behaviour.