From the ‡State Key Laboratory of Natural Medicines, Key Lab of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Tongjiaxiang #24, Nanjing 21009, China.
§School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705.
Mol Cell Proteomics. 2017 Nov;16(11):1922-1937. doi: 10.1074/mcp.RA117.000057. Epub 2017 Sep 1.
Endogenous neuropeptides are important signaling molecules that function as regulators of food intake and body weight. Previous work has shown that neuropeptide gene expression levels in a forebrain reward site, the nucleus accumbens (NAc), were changed by feeding. To directly monitor feeding-induced changes in neuropeptide expression levels within the NAc, we employed a combination of cryostat dissection, heat stabilization, neuropeptide extraction and label-free quantitative neuropeptidomics via a liquid chromatography-high resolution mass spectrometry platform. Using this methodology, we described the first neuropeptidome in NAc and discovered that feeding caused the expression level changes of multiple neuropeptides derived from different precursors, especially proSAAS-derived peptides such as Big LEN, PEN and little SAAS. We further investigated the regulatory functions of these neuropeptides derived from the ProSAAS family by performing an intra-NAc microinjection experiment using the identified ProSAAS neuropeptides, 'Big-LEN' and 'PEN'. Big LEN significantly increased rats' food and water intake, whereas both big LEN and PEN affected other behaviors including locomotion, drinking and grooming. In addition, we quantified the feeding-induced changes of peptides from hippocampus, hypothalamus and striatum to reveal the neuropeptide interplay among different anatomical regions. In summary, our study demonstrated neuropeptidomic changes in response to food intake in the rat NAc and other key brain regions. Importantly, the microinfusion of ProSAAS peptides into NAc revealed that they are behaviorally active in this brain site, suggesting the potential use of these peptides as therapeutics for eating disorders.
内源性神经肽是重要的信号分子，作为调节食物摄入和体重的调节剂。以前的工作表明，进食会改变前脑奖励部位伏隔核（NAc）中的神经肽基因表达水平。为了直接监测 NAc 中神经肽表达水平的进食诱导变化，我们采用了冷冻切片、热稳定、神经肽提取和无标记定量神经肽组学相结合的方法，通过液相色谱-高分辨率质谱平台。使用这种方法，我们描述了 NAc 中的第一个神经肽组，并发现进食导致来自不同前体的多种神经肽的表达水平发生变化，特别是前 SAAS 衍生的肽，如 Big LEN、PEN 和 little SAAS。我们通过使用鉴定出的 ProSAAS 神经肽“Big-LEN”和“PEN”在 NAc 内进行微注射实验，进一步研究了这些源自 ProSAAS 家族的神经肽的调节功能。Big LEN 显著增加了大鼠的食物和水摄入量，而 Big LEN 和 PEN 都影响了其他行为，包括运动、饮水和梳理。此外，我们还定量了来自海马体、下丘脑和纹状体的进食诱导的肽变化，以揭示不同解剖区域之间的神经肽相互作用。总之，我们的研究表明，大鼠 NAc 和其他关键脑区对食物摄入的神经肽组学变化。重要的是，将 ProSAAS 肽微注入 NAc 表明它们在该脑区具有行为活性，这表明这些肽作为治疗进食障碍的潜在用途。
