Optimization of non-peptide probes for the NPFF receptor system

项目描述（由申请人提供）：本项目根据项目公告（PA）提交，编号：PAR-12-060，标题：征求体内化学探针发现的验证Hits （R01）。众所周知，阿片受体与调节疼痛的感知密切相关。纵观历史，阿片类药物制剂已被用来有效地管理疼痛，并继续作为主流治疗，由于其功效。然而，这些药物与剂量限制的副作用、耐受性和成瘾性有关。尽管如此，它们仍然是治疗急性和慢性剧烈疼痛最广泛的处方药。寻找一种没有副作用的有效镇痛化合物，仍然是医疗机构的一大目标。直到最近，人们才意识到内源性阿片调节肽的存在，可以作为一种额外的治疗手段来减轻这些负担。这些阿片类药物调节肽（特别是胆囊收缩素和神经肽FF）能够根据剂量和作用部位减少和增强阿片类药物的药理作用。更有趣的是，它们被认为对阿片类药物治疗相关的耐受性和依赖性具有作用和可能的责任。具体来说，神经肽FF （NPFF）已被报道作为内源性抗阿片系统存在，并阻断阿片诱导的耐受性和痛觉过敏的发展。该系统中有两种公认的受体，NPFF1和NPFF2。目前，针对NPFF系统建立的（亚型选择性或非选择性）小分子、非肽探针尚不存在。缺乏合适的非肽探针阻碍了对NPFF作用的充分理解，以及该受体系统如何参与阿片类药物的作用以及其他提出的药理学。这是我们的目标

DESCRIPTION (provided by applicant): This project is submitted under Program Announcement (PA) Number: PAR-12-060 and Title: Solicitation of Validated Hits for the Discovery of in vivo Chemical Probes (R01). Opioid receptors are well known to be intimately involved with modulating the perception of pain. Throughout history, opioid preparations have been utilized to effectively manage pain and have continued to be the mainstay of therapy due to their efficacy. However, these drugs are associated with the liabilities of dose-limiting side-effects, tolerance and addiction. Still they are the most widely prescribed medications to treat acute and chronic severe pain. The search for an effective analgesic compound devoid of side-effects, is still a large goal of the medical establishment. Only recently in history was it realizd that endogenous opioid-modulating peptides exist that can be utilized as a means of additional therapy to attenuate these liabilities. These opioid modulating peptides (specifically cholecystokinin and Neuropeptide FF) are able to both reduce and potentiate the pharmacological effects of opioids depending on the dose and site of action. More interestingly, they have been proposed to have a role and possible responsibility for tolerance and dependence associated with opioid therapy. Specifically, Neuropeptide FF (NPFF) has been reported to exist as an endogenous anti-opioid system and block the development of tolerance and opioid-induced hyperalgesia. There are two recognized receptors in this system, NPFF1 and NPFF2. Currently, established (subtype selective or non-selective) small molecule, non-peptide probes for the NPFF system do not exist. This lack of a suitable non-peptide probe has hampered the full understanding of the actions of NPFF and how this receptor system is involved in the actions of opioids as well as other proposed pharmacologies. It is the goal of this project to identify one or more suitable non-peptide probes to serve the research community in an effort to further characterize the NPFF system. Our lead molecules, generated under our project R03 DA029738, show that we have both angonists and antagonists for this system and have begun to understand selectivity issues yet they need to be optimized for in vivo approaches. This work will be carried out through the following specific aims: AIM 1 - To prepare through chemical synthesis, novel non-peptidic NPFF1 and NPFF2 ligands, agonists or antagonists with selectivity for NPFF1, NPFF2, or a combination of affinities at each receptor; AIM 2 - To investigate the physiochemical properties of high affinity NPFF ligands through a variety of in vitro assays that will assess solubility, stability, membrane permeability, protein binding, microsomal stability and metabolic profiling; AIM 3 - To perform in vivo pharmacokinetics in rats to determine half-life, bioavailability and brain to plasma ratios. Those compounds that show activity will be subjected to full PK workup in rats to ultimately determine their suitability as potential in vivo probes and to understand their dosing requirements (peak time, brain:plasma, half-life, clearance); AIM 4 - To evaluate novel NPFF ligands in vivo for hyperalgesic activity. Compounds will be evaluated in a warm-water tail-withdrawal hyperalgesia model to confirm and further determine pharmacological profiles of those compounds identified in Aims 2 and 3. Overall, with our expertise through this project, we will provide the research community with suitable in vivo non-peptide probes to further characterize the NPFF system. These will be new tools as currently, non-peptide NPFF ligands with favorable affinities, activities, and in vivo properties do not exist.