Protective effect of cannabinoid CB1 receptor signalling on noradrenergic neurons of the locus coeruleus

我们在假设1中提出的研究旨在回答细胞群大麻素CB1受体信号传导保护蓝斑中去肾上腺素能神经元的问题。为了阐明这种保护作用是细胞自主的还是全身性的，我们将比较野生型和去甲肾上腺素能神经元或星形胶质细胞特异性CB1受体敲除小鼠在LC中线粒体缺陷和神经元损失的发生和严重程度，以及前脑去甲肾上腺素能末端的减少。此外，我们将比较对照组和条件CB1敲除动物的注意力、工作和恐惧记忆认知功能模型，这些认知功能已知受衰老和去甲肾上腺素能系统的影响。作为胶质活性、小胶质细胞和星形胶质细胞的密度和形态的读数，将评估LC中促炎细胞因子TNFa的表达。为了验证我们的结果，我们将在CB1STOP组成性敲除和CB1受体在去甲肾上腺素能神经元和星形胶质细胞上表达恢复的小鼠之间进行同样的比较。在假设2中，我们询问是否有可能通过CB1受体信号的升高来保护LC去肾上腺素能神经元免受年龄相关变化的影响。为此，我们将在（预防性治疗）前用低剂量的d9 -四氢大麻酚（THC）长期治疗小鼠，并在（治疗性治疗）发生显著神经元损失后单独治疗一组动物。治疗的效果将分析为老年动物的注意力，记忆和LC去肾上腺素能神经元基因表达的变化到年轻动物的典型水平。

Our proposed studies in Hypothesis 1 aim to answer the question in which cell population cannabinoid CB1 receptor signalling protects noradrenergic neurons in the locus coeruleus. To clarify whether the protective effect is cell autonomous or systemic, we will compare the onset and severity of mitochondrial deficits and neuronal loss in the LC, as well as the reduction of noradrenergic terminals in the forebrain between wild-type and noradrenergic neuron or astrocyte specific CB1 receptor knockout mice. Additionally, we will compare control and conditional CB1 knockout animals in models of attention, working- and fear-memory – cognitive functions known to be influenced by ageing and also by noradrenergic system. As a readout for glial activity, the density and morphology of microglia and astrocytes, expression of the pro-inflammatory cytokine TNFa in LC will be assessed. To validate our results, we will do the same comparison between CB1STOP constitutive knockouts and mice with restoration of CB1 receptor expression on noradrenergic neurons and astrocytes. In Hypothesis 2 we ask if it is possible to protect LC noradrenergic neurons from age-related changes through an elevation of CB1 receptor signalling. For that, we will treat mice chronically with a low dose D9-tetrahydrocannabinol (THC) before (preventive treatment) and a separate groups of animals after (curative treatment) the onset of significant neuronal loss. Efficacy of treatment will be analysed as a change in attention, memory and gene expression of LC noradrenergic neurons in old animals to a level typical to young ones.