Department of Anthropology and School of Biomedical Sciences, Kent State University, Kent, Ohio, USA.
Brain Health Research Institute, Kent State University, Kent, Ohio, USA.
J Comp Neurol. 2021 May 1;529(7):1659-1668. doi: 10.1002/cne.25048. Epub 2020 Oct 19.
The genus Macaca is an ideal model for investigating the biological basis of primate social behavior from an evolutionary perspective. A significant amount of behavioral diversity has been reported among the macaque species, but little is known about the neural substrates that support this variation. The present study compared neural cell density and serotonergic innervation of the amygdala among four macaque species using histological and immunohistochemical methods. The species examined included rhesus (Macaca mulatta), Japanese (M. fuscata), pigtailed (M. nemestrina), and moor macaques (M. maura). We anticipated that the more aggressive rhesus and Japanese macaques would have lower serotonergic innervation within the amygdala compared to the more affiliative pigtailed and moor macaques. In contrast to our prediction, pigtailed macaques had higher serotonergic innervation than Japanese and moor macaques in the basal and central amygdala nuclei when controlling for neuron density. Our analysis of neural cell populations revealed that Japanese macaques possess significantly higher neuron and glia densities relative to the other three species, however we observed no glia-to-neuron ratio differences among species. The results of this study revealed serotonergic innervation and cell density differences among closely related macaque species, which may play a role in modulating subtle differences in emotional processing and species-typical social styles.
猕猴属是从进化角度研究灵长类动物社会行为生物学基础的理想模型。猕猴物种之间存在大量的行为多样性，但对于支持这种变化的神经基质知之甚少。本研究使用组织学和免疫组织化学方法比较了四种猕猴物种杏仁核的神经细胞密度和 5-羟色胺能神经支配。所检查的物种包括猕猴（Macaca mulatta）、日本猕猴（M. fuscata）、豚尾猴（M. nemestrina）和食蟹猴（M. maura）。我们预计，与更具亲和力的豚尾猴和食蟹猴相比，更具攻击性的猕猴和日本猕猴的杏仁核内 5-羟色胺能神经支配较低。与我们的预测相反，当控制神经元密度时，豚尾猴的基底核和中央杏仁核核内的 5-羟色胺能神经支配高于日本猕猴和食蟹猴。我们对神经细胞群体的分析表明，与其他三个物种相比，日本猕猴具有显著更高的神经元和神经胶质密度，但我们没有观察到物种间神经胶质与神经元比率的差异。这项研究的结果揭示了密切相关的猕猴物种之间的 5-羟色胺能神经支配和细胞密度差异，这可能在调节情绪处理和物种典型社会行为的细微差异中发挥作用。
