MORPHINE-6 GLUCURONIDE--DEVELOPMENT OF BREATHING CONTROL

本研究的总体目标是研究新生豚鼠脑干中mu阿片受体的发育，以便更好地了解子宫内慢性吗啡暴露对呼吸的影响以及吗啡的活性代谢物吗啡-6- β - d -葡萄糖醛酸盐（M6G）在呼吸抑制中的作用。这个关于mu阿片受体研究的提议有三个主要方面，当结合起来时，使其独特。它们是：1)位置，重点是脑干的呼吸核；2)发育，重点是出生后第一周的新生动物；3)治疗，重点是慢性间歇性与子宫内吗啡暴露的恒定速率。解剖研究包括利用免疫组织化学、放射自显像、原位杂交和逆转录聚合酶链反应（RT-PCR）对mu阿片受体及其mRNA进行定位和定量；药理学研究包括脑干膜和稳定转染的CHO细胞的结合谱的表征；功能研究包括测定阿片类药物诱导的GTPgammaS在组织和细胞中的结合。这些研究将提供关于mu受体在发育、吗啡诱导的呼吸抑制中的作用的新信息，重要的是，M6G结合（与mu和潜在的非典型位点）在吗啡诱导的呼吸效应中的关系。假设：1)出生后第一周，脑干呼吸核中D- Ala2-MePhe4-Gly-ol5-enkephalin （DAMGO）结合和阿片诱导的GTPgammaS结合发生了发育变化；2) mu阿片受体的发育变化受子宫内吗啡暴露的影响；3) [3H]-DAMGO和[3H]-M6G结合与阿片类药物诱导的脑干GTPgammaS结合在出生后发育和子宫吗啡暴露后存在定量和定性差异。与呼吸核相关的阿片受体的变化与吗啡和M6G对呼吸的影响有关。本研究对因母体药物滥用而在子宫内暴露于海洛因或其他阿片类药物的胎儿和新生儿、前阿片类药物滥用孕妇的维持治疗或疼痛治疗具有重要意义。

The overall goal of this research is to examine the development of mu opioid receptors in the brainstem of the neonatal guinea pig in order to better understand the respiratory effects of chronic in utero morphine exposure and the role of morphine's active metabolite, morphine-6-beta-D-glucuronide (M6G), in respiratory depression. There are three main aspects to this proposal on the study of the mu opioid receptor that, when combined, make it unique. They are: 1) location, with the emphasis on the respiratory nuclei of the brainstem; 2) development, with the emphasis on the neonatal animal during the first week after birth; and 3) treatment, with the emphasis on chronic intermittent versus a constant rate of in utero morphine exposure. The anatomical studies include the localization and quantitation of mu opioid receptors and receptor mRNA using immunohistochemistry, autoradiography, in situ hybridization and reverse transcriptase polymerase chain reaction (RT-PCR); the pharmacological studies include characterization of binding profiles of brainstem membranes and stably transfected CHO cells; and the functional studies include the determination of opioid-induced GTPgammaS binding in tissue and cells. These studies will provide new information about the role of mu receptors in development, morphine-induced respiratory depression, and importantly, the relationship of M6G binding (to mu and to a potential atypical site) in morphine-induced respiratory effects. The hypotheses are: 1) that there are developmental changes in D- Ala2-MePhe4-Gly-ol5-enkephalin (DAMGO) binding and opioid-induced GTPgammaS binding in brainstem respiratory nuclei during the first week of life; 2) that developmental changes in the mu opioid receptor are affected by in utero morphine exposure; and 3) that there are quantitative and qualitative differences between [3H]-DAMGO and [3H]-M6G binding and opioid-induced GTPgammaS binding in the brainstem during postnatal development and following in utero morphine exposure. Changes in opioid receptors associated with respiratory nuclei have consequences for the effects of morphine and M6G on breathing. This study is of significance for the fetus and neonate who are exposed in utero to heroin or other opioids because of maternal drug abuse, maintenance therapy of pregnant former opioid abusers or pain therapy.