Prelimbic α1-adrenoceptors are involved in the regulation of depressive-like behaviors in the hemiparkinsonian rats

Publication date: Available online 14 July 2017
Source:Brain Research Bulletin
Author(s): Zhong Heng Wu, Qiao Jun Zhang, Cheng Xue Du, Yue Xi, Wen Juan Li, Fang Yuan Guo, Shu Qi Yu, Ya Xin Yang, Jian Liu
At present, it is not clear whether α1-adrenoceptors in the prelimbic cortex (PrL) are involved in Parkinson's disease-related depression. Here we examined effects of PrL α1-adrenoceptors on depressive-like behaviors in rats with unilateral 6-hydroxydopamine lesions of the medial forebrain bundle. The lesion induced depressive-like responses as measured by the sucrose preference and forced swim tests compared to sham-operated rats. Intra-PrL injection of α1-adrenoceptor agonist phenylephrine induced or increased the expression of depressive-like behaviors in sham-operated and the lesioned rats. Further, intra-PrL injection of α1-adrenoceptor antagonist benoxathian produced antidepressant effects in two groups of rats. Intra-PrL injection of phenylephrine increased the mean firing rate of PrL pyramidal neurons in both sham-operated and the lesioned rats, while benoxathian decreased the mean firing rate of the neurons. Compared to sham-operated rats, the duration of phenylephrine and benoxathian action on the firing rate of the pyramidal neurons was shortened in the lesioned rats. Neurochemical results showed that intra-PrL injection of phenylephrine or benoxathian increased or decreased dopamine and noradrenaline and serotonin levels in the medial prefrontal cortex, ventral hippocampus and habenula in sham-operated and the lesioned rats, respectively. Altogether, these results suggest that activation and blockade of α1-adrenoceptors in the PrL change the firing activity of the pyramidal neurons, and then increase or decrease levels of three monoamines in the limbic and limbic-related brain regions, which are involved in the regulation of depressive-like behaviors. Additionally, the results also suggest that the dopaminergic lesion leads to hypofunctionality of α1-adrenoceptors on pyramidal neurons of the PrL.



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