Gene x environment interactions on brain and behaviour in the Cacna1c genetic rat model: Calcium signalling, microRNAs, and immune activation

情感性障碍（AD），即重度抑郁症（MDD）和双相情感障碍（BD），是遗传和环境风险因素导致的表型。这些因素相互作用的潜在神经生物学机制以及它们如何对大脑结构和功能施加影响尚不清楚。WP2是FOR2107的动物骨干，通过在Cacna1c遗传大鼠模型中应用基因x环境（GxE）方法解决了这些问题。在第一个资助期，我们获得了Cacna1c+/-大鼠多种行为改变的大量证据，包括焦虑相关行为升高、阿吗啡刺激下声惊吓的脉冲前抑制缺陷、空间导航任务中的逆转学习障碍、社会行为和声音交流缺陷。与双相障碍特别相关的是，在Cacna1c+/-大鼠中，锂对安非他明引起的躁狂样表型的抑制作用几乎减弱。行为表型的环境调节与GxE在神经生物学测量、免疫激活和表观遗传修饰水平上的相互作用是平行的。例如，作为虐待模型，在Cacna1c+/+大鼠的断奶后社会隔离（SI）反应中，在海马中检测到成熟microRNA （miRNA）水平的广泛降低。有趣的是，在Cacna1c+/-大鼠中，这种作用在很大程度上减弱了。具体来说，绝大多数mirna （bbb80 %）受到GxE相互作用的影响，这表明大多数海马mirna受到遗传和环境因素的联合调节(collab。WP3)。此外，虽然断奶后SI在Cacna1c+/+大鼠中引起了以促炎细胞因子升高为特征的免疫反应，但在Cacna1c+/-大鼠中没有发现这种反应，提示有恢复力（collab）。WP4)。在第二个资助期，我们将在我们建立的GxE Cacna1c大鼠模型中进行五条研究。我们将(1)确定社会行为和声音沟通缺陷背后的生物心理学机制；(2)开发一种新的bd样情感循环行为测定方法；(3)将前额皮质和海马钙信号成分的改变与AD相关的行为表型联系起来。与WP3一起，我们将(4)通过脑内注射重组腺相关病毒颗粒（rAAV）进一步探索miRNA操纵对前额叶皮层和海马的影响，目的是通过恢复miRNA的生物发生来挽救断奶后SI后与AD相关的行为表型。最后，利用WP3和WP4，我们将(5)评估这种miRNA生物发生操作对免疫特征的影响，反之亦然，免疫挑战对ad相关表型的影响。通过这种高度互联的方法，该项目有望对AD病因和治疗中的miRNA生物发生和免疫系统有新的见解。

Affective disorders (AD), i.e. major depressive disorder (MDD) and bipolar disorder (BD), are phenotypes to which genetic and environmental risk factors contribute. The underlying neurobiological mechanisms by which such factors interact and how they exert their influence on brain structure and function are yet poorly understood. WP2, animal backbone of the FOR2107, addresses these questions by applying a gene x environment (GxE) approach in the Cacna1c genetic rat model. In the first funding period, we obtained substantial evidence for multiple behavioural alterations in Cacna1c+/- rats, including elevated anxiety-related behaviour, deficits in pre-pulse inhibition of acoustic startle under apomorphine challenge, reversal learning impairments in a spatial navigation task, and social behaviour and acoustic communication deficits. Of particular relevance for BD, the effectiveness of lithium in inhibiting mania-like phenotypes evoked by amphetamine was almost blunted in Cacna1c+/- rats. Environmental modulation of behavioural phenotypes was paralleled by GxE interactions at the level of neurobiological measures, immune activation, and epigenetic modifications. For instance, a widespread reduction in mature microRNA (miRNA) levels was detected in the hippocampus of Cacna1c+/+ rats in response to post-weaning social isolation (SI), as a model of maltreatment. Intriguingly, this effect was largely blunted in Cacna1c+/- rats. Specifically, the vast majority of miRNAs (>80%) was affected by the GxE interaction, indicating that most hippocampal miRNAs are subject to regulation by a combination of genetic and environmental factors (collab. WP3). Moreover, while post-weaning SI evoked immune reactivity characterized by elevated pro-inflammatory cytokines in Cacna1c+/+ rats, no such reactivity was seen in Cacna1c+/- rats, suggesting resilience (collab. WP4). In the second funding period, we will follow five lines of research in our established GxE Cacna1c rat model. We will (1) identify biopsychological mechanisms underlying social behaviour and acoustic communication deficits; (2) develop a novel behavioural assay for BD-like affective cycling; and (3) link alterations in calcium signalling components in prefrontal cortex and hippocampus to behavioural phenotypes with relevance to AD. Together with WP3, we will (4) further explore the impact of miRNA manipulations in prefrontal cortex and hippocampus by means of intracerebral injection of recombinant adeno-associated virus particles (rAAV), with the aim to rescue behavioural phenotypes relevant to AD after post-weaning SI through restoring miRNA biogenesis. Finally, with WP3 and WP4, we will (5) assess the impact of such miRNA biogenesis manipulations on immune signatures and, vice versa, the impact of immune challenges on AD-relevant phenotypes. Through this highly interconnected approach, the project promises novel insight regarding miRNA biogenesis and immune system in AD aetiology and treatment.