Quinpirole (QNP) sensitization is a well-established model of stereotypical checking relevant to obsessive-compulsive disorder. Previously, we found that QNP-treated rats display deficits in hippocampus-dependent tasks. The present study explores the expression of immediate early genes (IEG) during QNP-induced stereotypical checking in the hippocampus, anterior cingulate cortex (ACC), orbitofrontal cortex (OFC), and medial prefrontal cortex (mPFC). Adult male rats were injected with QNP (0.5 mg/mL/kg; n = 15) or saline (n = 14) daily for 10 days and exposed to an arena enriched with two objects. Visits to the objects and the corners of the arena were recorded. QNP-treated rats developed an idiosyncratic pattern of visits that persisted across experimental days. On day 11, rats were exposed to the arena twice for 5 min and sacrificed. The expression of IEGs Arc and Homer1a was determined using cellular compartment analysis of temporal activity by fluorescence in situ hybridization. IEG-positive nuclei were counted in the CA1 area of the hippocampus, ACC, OFC, and mPFC. We found significantly fewer IEG-positive nuclei in the CA1 in QNP-treated rats compared to controls. The overlap between IEG expressing neurons was comparable between the groups. We did not observe significant differences in IEG expression between QNP treated and control rats in ACC, OFC, and mPFC. In conclusion, treatment of rats with quinpirole decreases plasticity-related activity in the hippocampus during stereotypical checking.

中文翻译：

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D2/D3 激动剂喹吡罗重复治疗后海马、前扣带皮层、眶额叶和前额叶皮层的可塑性相关活动


喹吡罗 (QNP) 致敏是与强迫症相关的一种成熟的刻板检查模型。此前，我们发现 QNP 治疗的大鼠在海马依赖性任务中表现出缺陷。本研究探讨了 QNP 诱导的海马、前扣带皮层 (ACC)、眶额皮层 (OFC) 和内侧前额叶皮层 (mPFC) 刻板检查过程中立即早期基因 (IEG) 的表达。成年雄性大鼠连续 10 天每天注射 QNP（0.5 mg/mL/kg； n = 15）或生理盐水（ n = 14），并暴露在充满两种物体的环境中。记录对物体和竞技场角落的访问。接受 QNP 治疗的老鼠形成了一种特殊的访问模式，这种模式在整个实验期间持续存在。第11天，将大鼠暴露于场地两次，每次5分钟并处死。 IEGs Arc和Homer1a的表达是通过荧光原位杂交对时间活性进行细胞区室分析来确定的。对海马 CA1 区、ACC、OFC 和 mPFC 中的 IEG 阳性细胞核进行计数。我们发现，与对照组相比，QNP 治疗的大鼠 CA1 区 IEG 阳性细胞核明显减少。各组之间表达 IEG 的神经元之间的重叠程度相当。我们没有观察到 QNP 治疗组大鼠和对照大鼠 ACC、OFC 和 mPFC 中 IEG 表达的显着差异。总之，用喹吡罗治疗大鼠会降低刻板检查过程中海马可塑性相关的活动。