Eyerman David J, Yamamoto Bryan K
Laboratory of Neurochemistry, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA 02118, USA.
J Pharmacol Exp Ther. 2005 Jan;312(1):160-9. doi: 10.1124/jpet.104.072264. Epub 2004 Aug 26.
L-Lobeline is an alkaloid that inhibits the behavioral effects of methamphetamine (METH) in rats. No studies have examined the effects of lobeline on the acute and long-term neurochemical changes produced by neurotoxic doses of METH. The effects of lobeline on METH-induced dopamine release, alterations in vesicular monoamine transporter 2 (VMAT-2) distribution, and long-term depletions of dopamine and serotonin (5-HT) content in the rat striatum were examined. METH increased body temperature and dopamine release, decreased VMAT-2 immunoreactivity at 1 and 24 h after METH, and decreased dopamine and 5-hydroxytryptamine (5-HT) content in striatum when examined 7 days later. Prevention of METH-induced hyperthermia attenuated the decrease in VMAT-2 as well as dopamine and 5-HT content. Lobeline pretreatment did not affect METH-induced dopamine release but attenuated the decreases in VMAT-2 after METH and the long-term decreases in striatal dopamine and 5-HT content. These effects of lobeline were due partly to the attenuation of METH-induced hyperthermia. The maintenance of hyperthermia during lobeline + METH exposure restored the effects of METH on decreases in VMAT-2 as well as dopamine and 5-HT content. To examine the effects of lobeline independent of its effects on METH-induced hyperthermia, lobeline was administered after METH when body temperature returned to normal. Lobeline treatment at 5 and 7 h after METH attenuated the METH-induced decreases in synaptosomal, membrane-associated, and vesicular VMAT-2 24 h after METH, as well as the METH-induced decreases in dopamine and 5-HT content 7 days later. Therefore, lobeline has both temperature-dependent and -independent neuroprotective effects against METH toxicity.
L-洛贝林是一种生物碱,可抑制大鼠体内甲基苯丙胺(METH)的行为效应。尚无研究考察洛贝林对神经毒性剂量的METH所产生的急性和长期神经化学变化的影响。本研究考察了洛贝林对METH诱导的多巴胺释放、囊泡单胺转运体2(VMAT-2)分布改变以及大鼠纹状体中多巴胺和5-羟色胺(5-HT)含量长期耗竭的影响。METH可升高体温并增加多巴胺释放,在METH给药后1小时和24小时降低VMAT-2免疫反应性,并在7天后检测时降低纹状体中的多巴胺和5-羟色胺(5-HT)含量。预防METH诱导的体温过高可减轻VMAT-2以及多巴胺和5-HT含量的降低。洛贝林预处理不影响METH诱导的多巴胺释放,但可减轻METH给药后VMAT-2的降低以及纹状体中多巴胺和5-HT含量的长期降低。洛贝林的这些作用部分归因于其对METH诱导的体温过高的减轻。在洛贝林 + METH暴露期间维持体温过高可恢复METH对VMAT-2以及多巴胺和5-HT含量降低的影响。为了考察洛贝林独立于其对METH诱导的体温过高的影响,在体温恢复正常后于METH给药后给予洛贝林。METH给药后5小时和7小时给予洛贝林可减轻METH给药后24小时METH诱导的突触体、膜相关和囊泡VMAT-2的降低,以及7天后METH诱导的多巴胺和5-HT含量的降低。因此,洛贝林对METH毒性具有温度依赖性和非依赖性神经保护作用。