Lambert Mads Ødum, Ipsen Theis Højland, Kohlmeier Kristi Anne
Department of Drug Design and Pharmacology Faculty of Health Sciences Universitetsparken 2 University of Copenhagen Copenhagen 2100 Denmark.
Pharmacol Res Perspect. 2016 Dec 23;5(1):e00282. doi: 10.1002/prp2.282. eCollection 2017 Feb.
Cocaine has strong reinforcing properties, which underlie its high addiction potential. Reinforcement of use of addictive drugs is associated with rises in dopamine (DA) in mesoaccumbal circuitry. Excitatory afferent input to mesoaccumbal circuitry sources from the laterodorsal tegmental nucleus (LDT). Chronic, systemic cocaine exposure has been shown to have cellular effects on LDT cells, but acute actions of local application have never been demonstrated. Using calcium imaging, we show that acute application of cocaine to mouse brain slices induces calcium spiking in cells of the LDT. Spiking was attenuated by tetrodotoxin (TTX) and low calcium solutions, and abolished by prior exhaustion of intracellular calcium stores. Further, DA receptor antagonists reduced these transients, whereas DA induced rises with similar spiking kinetics. Amphetamine, which also results in elevated levels of synaptic DA, but via a different pharmacological action than cocaine, induced calcium spiking with similar profiles. Although large differences in spiking were not noted in an animal model associated with a heightened proclivity of acquiring addiction-related behavior, the prenatal nicotine exposed mouse (PNE), subtle differences in cocaine's effect on calcium spiking were noted, indicative of a reduction in action of cocaine in the LDT associated with exposure to nicotine during gestation. When taken together, our data indicate that acute actions of cocaine do include effects on LDT cells. Considering the role of intracellular calcium in cellular excitability, and of the LDT in addiction circuitry, our data suggest that cocaine effects in this nucleus may contribute to the high addiction potential of this drug.
可卡因具有很强的强化特性,这是其高成瘾潜力的基础。成瘾性药物使用的强化与中脑伏隔核回路中多巴胺(DA)的增加有关。中脑伏隔核回路的兴奋性传入输入来自外侧背盖核(LDT)。慢性全身性可卡因暴露已被证明对LDT细胞有细胞效应,但局部应用的急性作用从未得到证实。使用钙成像技术,我们发现将可卡因急性应用于小鼠脑片可诱导LDT细胞中的钙峰发放。峰发放被河豚毒素(TTX)和低钙溶液减弱,并被细胞内钙储备预先耗尽所消除。此外,DA受体拮抗剂减少了这些瞬变,而DA诱导的增加具有相似的峰发放动力学。苯丙胺也会导致突触DA水平升高,但通过与可卡因不同的药理作用,诱导出具有相似特征的钙峰发放。尽管在与获得成瘾相关行为的更高倾向相关的动物模型(产前尼古丁暴露小鼠,PNE)中未观察到峰发放的巨大差异,但注意到可卡因对钙峰发放的影响存在细微差异,这表明与孕期尼古丁暴露相关的LDT中可卡因作用的降低。综合来看,我们的数据表明可卡因的急性作用确实包括对LDT细胞的影响。考虑到细胞内钙在细胞兴奋性中的作用以及LDT在成瘾回路中的作用,我们的数据表明可卡因在该核中的作用可能导致了这种药物的高成瘾潜力。