Galeotti Nicoletta, Bartolini Alessandro, Ghelardini Carla
Department of Preclinical and Clinical Pharmacology, University of Florence, Viale G. Pieraccini 6, I-10539 Florence, Italy.
Neuropsychopharmacology. 2003 May;28(5):888-97. doi: 10.1038/sj.npp.1300111. Epub 2002 Nov 11.
The cellular events involved in muscarinic analgesia were investigated in the mouse hot-plate test. Intracerebroventricular (i.c.v.) pretreatment with antisense oligonucleotides (aODNs) against the alpha subunit of G(q) and G(11) proteins prevented the analgesia induced by physostigmine and oxotremorine. Furthermore, administration of the phospholipase C (PLC) inhibitor U-73122, as well as the injection of an aODN complementary to the sequence of PLCbeta(1), antagonized the increase of the pain threshold induced by both cholinomimetic drugs. In mice undergoing treatment with LiCl, which impairs phosphatidylinositol synthesis, or treatment with heparin, an IP(3) receptor antagonist, the antinociception induced by physostigmine and oxotremorine was dose-dependently antagonized. I.c.v. pretreatment with TMB-8, a blocker of Ca(2+) release from intracellular stores, prevented the increase of pain threshold induced by the investigated cholinomimetic drugs. Coadministration of Ca(2+) restored the muscarinic analgesia in LiCl, heparin, and TMB-8-preatreated mice. On the other hand, i.c.v. pretreatment with the selective protein kinase C (PKC) inhibitor calphostin C, resulted in a dose-dependent enhancement of physostigmine- and oxotremorine-induced antinociception. The administration of PKC activators, such as PMA and PDBu, dose dependently prevented the cholinomimetic drug-induced increase of pain threshold. Neither aODNs nor pharmacological treatments employed produced any behavioral impairment of mice as revealed by the rota-rod and hole-board tests. These results indicate a role for the PLC-IP(3) pathway in central muscarinic analgesia in mice. Furthermore, activation of PKC by cholinomimetic drugs may represent a pathway of negative modulation of muscarinic antinociception.
在小鼠热板试验中研究了毒蕈碱镇痛涉及的细胞事件。用针对G(q)和G(11)蛋白α亚基的反义寡核苷酸（aODN）进行脑室内（i.c.v.）预处理可预防毒扁豆碱和氧化震颤素诱导的镇痛作用。此外，给予磷脂酶C（PLC）抑制剂U-73122以及注射与PLCβ(1)序列互补的aODN，可拮抗两种拟胆碱药物诱导的痛阈升高。在用氯化锂处理（损害磷脂酰肌醇合成）或用肝素（一种IP(3)受体拮抗剂）处理的小鼠中，毒扁豆碱和氧化震颤素诱导的抗伤害感受呈剂量依赖性拮抗。用TMB-8（一种细胞内钙库钙释放阻滞剂）进行i.c.v.预处理可预防所研究的拟胆碱药物诱导的痛阈升高。在氯化锂、肝素和TMB-8预处理的小鼠中，同时给予钙可恢复毒蕈碱镇痛作用。另一方面，用选择性蛋白激酶C（PKC）抑制剂钙磷蛋白C进行i.c.v.预处理，可导致毒扁豆碱和氧化震颤素诱导的抗伤害感受呈剂量依赖性增强。给予PKC激活剂，如佛波酯（PMA）和二丁酰佛波酯（PDBu），可剂量依赖性地预防拟胆碱药物诱导的痛阈升高。如转棒试验和洞板试验所示，所用的aODN和药物处理均未对小鼠产生任何行为损害。这些结果表明PLC-IP(3)途径在小鼠中枢毒蕈碱镇痛中起作用。此外，拟胆碱药物激活PKC可能代表毒蕈碱抗伤害感受负调节的一条途径。
