Neuroinflammation and social behavior across the lifespan

描述(申请人提供)：衰老是一个多因素的过程，其中包括社会动机和社会识别能力在内的各种神经行为功能以不同的速度下降，但人们对这些有害变化的神经基础知之甚少。这项建议的首要目标是以大鼠为模型系统，评估自然衰老过程中社会行为瓦解的神经机制(S)。我们假设，在衰老过程中社会行为的逐渐下降既是对社会刺激的动机动力减弱的症状，也是对社会刺激的认识受损的症状。我们认为，衰老的两个既定后果--循环雄激素水平的进行性下降，称为雄停顿，以及中枢神经系统逐渐向促炎状态的高度转变--在衰老过程中社会行为的瓦解中发挥了关键作用。其机制是循环中雄激素的逐渐丢失导致促炎症细胞因子如白介素1的去抑制，从而使催产素(OT)在下丘脑室旁核(PVN)和杏仁内侧核(MEA)的表达短路，这是社会动机/认知过程的关键要素。因此，特定目标1将通过一系列社会行为任务来表征与年龄相关的社会行为缺陷的性质，同时确定MEA中OT神经元在老年大鼠社会行为退化中的作用。目的2检测中枢神经系统促炎状态对老年大鼠社会行为回路钝化反应的影响及抗炎药的治疗作用。具体目标3将确定性腺激素在中枢神经系统向促炎状态转变过程中的作用及其对社会行为的影响及其各自的作用机制。这项拟议工作的成果将把衰老过程的几个核心特征(雄激素减少、炎症加剧、神经肽调节改变)整合到一个有意义的机制画像中，描绘出社会行为如何在整个生命周期中受到侵蚀，并为逆转这一过程提供几个具体的治疗目标。因此，目前的研究很有希望将啮齿动物模型的发现转化为老龄人口生活质量的直接改善。

DESCRIPTION (provided by applicant): Aging is a multifactorial process, in which a variety of neurobehavioral functions including social motivation and social recognition abilities decline at different rates, yet very little is known about the neural basis of these deleterious changes. The overarching goal of this proposal is to evaluate the neural mechanism(s) underlying the disintegration of social behavior during the natural course of aging, using rats as a model system. We hypothesize that the gradual decline in social behavior during senescence is symptomatic of both reduced motivational drive toward, and impaired recognition of, social stimuli. We argue that two established consequences of aging - a progressive decline in circulating androgen levels, termed andropause, and a gradual transition of the CNS toward a heightened state of pro-inflammation - play a key role in the disintegration of social behavior during senescence. The proposed mechanism is that gradual loss of circulating androgens leads to disinhibition of pro-inflammatory cytokines such as interleukin-1, which short-circuits th release of oxytocin (OT) expression in the paraventricular nucleus (PVN) of the hypothalamus and release in the medial amygdala (MeA), a key requisite for social motivation/recognition processes. Thus, Specific Aim 1 will characterize the age-related nature of social behavior deficits using a series of social behavior tasks, while at the same time determining the role of OT neurons in the MeA on the degradation of social behavior in aged rats. Specific Aim 2 will test the impact of the CNS pro-inflammatory state on the blunted response of social behavior circuitry and the therapeutic effect of administration of anti-inflammatory agents in aged rats. Specific Aim 3 will determine the role of gonadal hormones on the transition of the CNS toward a pro-inflammatory state and its impact on social behavior and their respective mechanisms of action. The outcome of the proposed work will integrate several core features of the aging process (declining androgens, heightened inflammation, altered neuropeptide regulation) into a meaningful mechanistic portrait of how social behavior erodes across the lifespan, and offer several specific therapeutic targets for reversing this process. As a result, the present studies hold great promise for translating findings from rodent models into direct improvements in the quality of life for aging populations.