NEUROSCIENCE - SUBPROJECT 1: MODULATION OF MORPHINE TOLERANCE BY ANTI-OPIATE PEP

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。阿片类药物耐受的潜在机制仍有待阐明。神经肽FF （NPFF, ph - leu - ph - gln,Pro-Gln,Arg, ph - nh2）是一种哺乳动物八肽，已被证明可以减轻阿片类药物引起的各种效应，如抗痛觉和吗啡耐受和依赖的发展。据推测，吗啡释放抗阿片类药物是体内平衡机制的一部分。随着吗啡用量的增加，抗阿片类药物被释放到脑脊液中。直接结果是，mu阿片受体（MOR）复合物下调，逐渐产生更高程度的激动剂亚敏感性（耐受性）。本项目将研究NPFF通过G蛋白解偶联和/或改变NPFF和MOR之间共享的信号转导通路来减弱吗啡诱导的耐受性的机制。大鼠将通过Alzet 2001渗透微型泵在脑室内长期（13天）输注硫酸吗啡使其耐受。由于先前的研究结果表明，慢性静脉注射吗啡和NPFF单独能够下调MOR密度，因此本研究为进一步研究NPFF降低脊髓和与阿片类药物耐受性相关的分离脑区（大脑皮层、纹状体和丘脑）吗啡耐受性的机制提供了一个很好的模型。为了验证这一假设，研究人员将通过与MOR信号转导途径相关的几个指标（gtp - γ - s活性、cAMP水平、蛋白激酶A和C活性）来测试NPFF对吗啡耐受性的慢性影响。进一步的实验将确定NPFF在MOR受体密度上的调节是否与MOR和NPFF受体蛋白转录水平和/或表达的变化有关。这些发现有望通过对MOR系统信号转导通路中相互作用发生的位置提供更清晰的理解，来描述NPFF减弱吗啡耐受性的机制。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The underlying mechanism(s) of opiate tolerance remains to be elucidated. Neuropeptide FF (NPFF, Phe-Leu-Phe-Gln,Pro-Gln,Arg,Phe-NH2), is a mammalian octapeptide that has been shown to attenuate various opiate-induced effects, like antinociception and the development of morphine tolerance and dependence. It is hypothesized that the administration of morphine releases anti-opiates as part of a homeostatic mechanism. As greater quantities of morphine are administered, increasing quantities of anti-opiates are released into the cerebral spinal fluid. As a direct consequence mu opioid receptor (MOR) complex is down-regulated, producing progressively higher degrees of agonist subsensitivity (tolerance). The present project will examine the mechanism(s) by which NPFF attenuates morphine-induced tolerance via uncoupling of the G protein and/or altering a shared signaling transduction pathway between NPFF and MOR. Rats will be made tolerant by chronic (13 days) intraventricular infusion of morphine sulfate, via the Alzet 2001 osmotic mini-pumps. Because previous findings have shown that chronic i.c.v. infusion of morphine and NPFF alone were able to down-regulate MOR density, the present proposal represents an excellent model to further examine the mechanism(s) by which NPFF attenuates morphine tolerance in spinal cord and discrete brain regions (Cerebral Cortex, Striatum, and Thalamus) that are associated with opiate tolerance. To test this hypothesis, studies will be conducted to test the chronic effects of NPFF on morphine tolerance as measured at several indices related to the MOR signaling transduction pathway (GTP-gamma-S activity, cAMP levels, protein kinases A and C activities). Additional experiments will determine if NPFF modulation at the MOR receptor density is associated with changes at the transcriptional level and/or expression of MOR and NPFF receptor protein. These findings are expected to delineate the mechanism(s) by which NPFF attenuates morphine tolerance by providing a clearer understanding as to where the interaction is occurring within the signaling transduction pathway of the MOR system.