Neuroscience Graduate Program, University of California Riverside, Riverside, California, United States of America.
Graduate Program in Genetics, Genomics & Bioinformatics, University of California Riverside, Riverside, California, United States of America.
PLoS One. 2020 Nov 25;15(11):e0241758. doi: 10.1371/journal.pone.0241758. eCollection 2020.
Ethologically relevant chemical senses and behavioral habits are likely to coadapt in response to selection. As olfaction is involved in intrinsically motivated behaviors in mice, we hypothesized that selective breeding for a voluntary behavior would enable us to identify novel roles of the chemosensory system. Voluntary wheel running (VWR) is an intrinsically motivated and naturally rewarding behavior, and even wild mice run on a wheel placed in nature. We have established 4 independent, artificially evolved mouse lines by selectively breeding individuals showing high VWR activity (High Runners; HRs), together with 4 non-selected Control lines, over 88 generations. We found that several sensory receptors in specific receptor clusters were differentially expressed between the vomeronasal organ (VNO) of HRs and Controls. Moreover, one of those clusters contains multiple single-nucleotide polymorphism loci for which the allele frequencies were significantly divergent between the HR and Control lines, i.e., loci that were affected by the selective breeding protocol. These results indicate that the VNO has become genetically differentiated between HR and Control lines during the selective breeding process. Although the role of the vomeronasal chemosensory receptors in VWR activity remains to be determined, the current results suggest that these vomeronasal chemosensory receptors are important quantitative trait loci for voluntary exercise in mice. We propose that olfaction may play an important role in motivation for voluntary exercise in mammals.
行为相关的化学感觉和行为习惯很可能会共同适应选择。由于嗅觉参与了老鼠的内在动机行为，我们假设选择性繁殖一种自愿行为将使我们能够确定化学感觉系统的新作用。自愿轮跑（VWR）是一种内在动机和自然奖励的行为，即使是野生老鼠也会在自然界中放置的轮子上奔跑。我们通过选择性繁殖表现出高 VWR 活性的个体（高跑步者；HRs），以及 4 个未选择的对照线，在 88 代以上建立了 4 个独立的、人工进化的老鼠系。我们发现，HRs 和对照的犁鼻器（VNO）中特定受体簇中的几种感觉受体表达不同。此外，其中一个簇包含多个单核苷酸多态性位点，其等位基因频率在 HR 和对照系之间存在显著差异，即受选择性繁殖方案影响的位点。这些结果表明，在选择性繁殖过程中，VNO 在 HR 和对照系之间发生了遗传分化。虽然犁鼻化学感觉受体在 VWR 活性中的作用仍有待确定，但目前的结果表明，这些犁鼻化学感觉受体是老鼠自愿运动的重要数量性状位点。我们提出嗅觉可能在哺乳动物自愿运动的动机中发挥重要作用。
