Dopaminergic Neurons in the Ventral Tegmental-Prelimbic Pathway Promote the Emergence of Rats from Sevoflurane Anesthesia / 神经科学通报·英文版

Dopaminergic neurons in the ventral tegmental area (VTA) play an important role in cognition, emergence from anesthesia, reward, and aversion, and their projection to the cortex is a crucial part of the "bottom-up" ascending activating system. The prelimbic cortex (PrL) is one of the important projection regions of the VTA. However, the roles of dopaminergic neurons in the VTA and the VTADA-PrL pathway under sevoflurane anesthesia in rats remain unclear. In this study, we found that intraperitoneal injection and local microinjection of a dopamine D1 receptor agonist (Chloro-APB) into the PrL had an emergence-promoting effect on sevoflurane anesthesia in rats, while injection of a dopamine D1 receptor antagonist (SCH23390) deepened anesthesia. The results of chemogenetics combined with microinjection and optogenetics showed that activating the VTADA-PrL pathway prolonged the induction time and shortened the emergence time of anesthesia. These results demonstrate that the dopaminergic system in the VTA has an emergence-promoting effect and that the bottom-up VTADA-PrL pathway facilitates emergence from sevoflurane anesthesia.

Prelimbic α2-adrenoceptors are involved in the regulation of depressive-like behavior in hemiparkinsonian rats / 西安交通大学学报(医学版)

Objective: To observe the depressive-like behavior in hemiparkinsonian rats and the effects of activation or blockade of prelimbic (PrL) α2-adrenoceptors on depressive-like behavior in sham-operated and the parkinsonian rats. Methods: The rat model of Parkinson's disease (PD) was established by injection of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle (MFB). Then the depressive-like behavior in rats was detected by the sucrose preference test and forced swim test (FST). In addition, changes in depressive-like behavior in the rats were also observed after local injection of a selective α2-adrenoceptor agonist or antagonist into the PrL. Results: The unilateral lesion of MFB by 6-OHDA induced depressive-like behavior as measured by the sucrose preference test and the FST compared to the sham-operated rats. Intra-PrL injection of selective α2-adrenoceptor agonist clonidine induced depressive-like behavior in the sham-operated and the lesioned rats. However, intra-PrL injection of α2-adrenoceptor antagonist idazoxan elicited anti-depressant effects in both the sham-operated and the lesioned groups. Moreover, the effective doses for behavior produced by clonidine and idazoxan in the lesioned rats were higher than those in the sham-operated rats. Conclusion: The α2-adrenoceptors in the PrL play an important role in the regulation of depressive-like behavior in PD.

Prelimbic α1-Adrenoceptors are involved in regulation of neural activities in the amygdala in a rat model of Parkinson's disease with anxiety / 西安交通大学学报(医学版)

Objective: To observe the effects of activation or blockade of the prelimbic (PrL) α1-adrenoceptors on anxiety-like behaviors and amygdaloid neural activities in rats with Parkinson's disease (PD). Methods: The rat model of PD was established by 6-hydroxydopamine (6-OHDA) unilateral lesion of the medial forebrain bundle (MFB). Then the anxiety-like behavior of rats was detected by the open field test. In addition, the changes of anxiety-like behavior, the effects of PrL α1-adrenoceptor stimulation on monoamines and c-Fos expression in the amygdala were also observed after local injection of the selective α1-adrenoceptor agonist or antagonist into the PrL by guided cannula. Results: Unilateral 6-OHDA lesions of the MFB in rats induced anxiety-like behaviors (P<0.001). Furthermore, activation of the PrL α1-adrenoceptors significantly induced or enhanced anxiety-like behaviors in the rats (sham group: P<0.001; lesion group: P<0.05), while blockade of the α1-adrenoceptors produced anxiolytic effects (sham group: P<0.001; lesion group: P<0.05). Then activation of the PrL α1-adrenoceptors increased the levels of DA and 5-HT while blockade of the PrL α1-adrenoceptors decreased DA and 5-HT levels in the amygdala in sham-operated rats (DA & 5-HT: P<0.001). However, compared to those of sham-operated rats, activation of the PrL α1-adrenoceptors increased the levels of NA and 5-HT while blockade of the PrL α1-adrenoceptors decreased NA and 5-HT levels in the amygdala in the lesioned rats (NA & 5-HT: P<0.001). In addition, the density of c-Fos immunoreactive positive neurons in the amygdala increased after intra-PrL injection α1-adrenoceptors agonist phenylephrine (sham group & lesion group: P<0.001). Conclusion: These findings indicate that changed neural activities in the amygdala after activation or blockade of the PrL α1-adrenoceptors are involved in regulating anxiety-like behaviors in PD rats.