Xiang Dan, Wang Huiling, Sun Siqi, Yao Lihua, Li Ruiting, Zong Xiaofen, Wang Gaohua, Liu Zhongchun
Department of Psychiatry, Renmin Hospital of Wuhan University, Wuhan, China.
Front Psychiatry. 2020 Jan 28;10:1020. doi: 10.3389/fpsyt.2019.01020. eCollection 2019.
Accumulating evidences indicate that gastrin-releasing peptide receptor (GRPR) may contribute to the pathophysiology of depression. However, the mechanism of the involvement of GRPR in the progression of depression remains unclear. Here, we showed the extent to which stress and antidepressant treatment impact GRPR expression, and explored the interactions between 5-HT2a receptor (5-HT2aR) and GRPR at the cellular level.
The rat depression models were created with chronic unpredictable mild stress (CUMS). Then, these rats were treated with fluoxetine for 4 weeks after CUMS. We measured body weight and performed behavioral tests to determine the effects of stress and fluoxetine on depressive-like behaviors. Real-time PCR and western blotting were used to measure the mRNA and protein expression levels of GRPR in the hypothalamus. Then, Flag-tagged protein (pcmv-Flag-5HT2aR) and Myc-tagged protein (pcmv-Myc-GRPR) expression vectors were constructed, identified, and transfected into human embryo kidney 293 (HEK293) cells. The interaction between 5-HT2aR and GRPR was detected by coimmunoprecipitation and double-label immunofluorescence.
The rats subjected to 4 weeks of CUMS showed depressive-like behaviors, including decreased body weight, sucrose preference, and distance traveled, rearing frequency and velocity in the open field test and increased immobility time in the forced swimming test. Fluoxetine treatment reversed CUMS-induced depressive-like behavior. The mRNA and protein expression of GRPR in the hypothalamus was significantly increased after 4 weeks CUMS exposure, and treatment with fluoxetine reversed these changes. Coimmunoprecipitation showed that 5-HT2aR and GRPR combine with each other . Immunofluorescence revealed that the 5-HT2aR and GRPR were colocalization in both the cell membrane and cytoplasm.
Our study enhances the understanding of the involvement of GRPR in depression. This study also provides experimental evidence of the interaction between 5-HT2aR and GRPR, which may play an important role in the pathogenesis of depression.
越来越多的证据表明胃泌素释放肽受体（GRPR）可能与抑郁症的病理生理学有关。然而，GRPR参与抑郁症进展的机制仍不清楚。在此，我们展示了应激和抗抑郁治疗对GRPR表达的影响程度，并在细胞水平上探索了5-羟色胺2A受体（5-HT2aR）与GRPR之间的相互作用。
采用慢性不可预测轻度应激（CUMS）建立大鼠抑郁症模型。然后，在CUMS后对这些大鼠进行4周的氟西汀治疗。我们测量体重并进行行为测试，以确定应激和氟西汀对抑郁样行为的影响。采用实时聚合酶链反应（PCR）和蛋白质免疫印迹法检测下丘脑GRPR的信使核糖核酸（mRNA）和蛋白表达水平。然后，构建、鉴定带有Flag标签的蛋白（pcmv-Flag-5HT2aR）和带有Myc标签的蛋白（pcmv-Myc-GRPR）表达载体，并将其转染到人胚肾293（HEK293）细胞中。通过免疫共沉淀和双标免疫荧光检测5-HT2aR与GRPR之间的相互作用。
接受4周CUMS的大鼠表现出抑郁样行为，包括体重下降、蔗糖偏好降低、旷场试验中行进距离、竖毛频率和速度降低，以及强迫游泳试验中不动时间增加。氟西汀治疗逆转了CUMS诱导的抑郁样行为。暴露于CUMS 4周后，下丘脑GRPR的mRNA和蛋白表达显著增加，氟西汀治疗逆转了这些变化。免疫共沉淀显示5-HT2aR与GRPR相互结合。免疫荧光显示5-HT2aR和GRPR在细胞膜和细胞质中均共定位。
我们的研究增进了对GRPR参与抑郁症的理解。本研究还提供了5-HT2aR与GRPR之间相互作用的实验证据，这可能在抑郁症的发病机制中起重要作用。
