Serotonergic interaction between medial prefrontal cortex and mesotelencephalic DA system underlies cognitive and affective deficits in hemiparkinsonian rats

Acupuncture activates IRE1/XBP1 endoplasmic reticulum stress pathway in Parkinson's disease model rats

Acupuncture has demonstrated its efficacy as a treatment for Parkinson's disease (PD). Thus, the objective of this study was to investigate the potential mechanisms underlying acupuncture's effects on PD treatment. Our approach involved several steps. Firstly, we assessed the behavioral changes in PD rats, the modulation of dopamine (DA) and 5-hydroxytryptamine (5-HT) levels in the striatum, as well as the alteration in α-synuclein (α-syn) levels in the midbrain, aiming to evaluate the efficacy of acupuncture in PD treatment. Secondly, we selected endoplasmic reticulum (ER) stress inhibitors and activators to assess the impact of ER stress on PD rats. Lastly, we utilized an IRE1 inhibitor to observe the influence of acupuncture on the IRE1/XBP1 pathway in PD rats. The findings of this study revealed that acupuncture improved the autonomous motor function, balance ability, coordination, and sensory motor integration function in the PD model rats. Additionally, it increased the levels of DA and 5-HT in the striatum while decreasing the levels of α-syn in the midbrain. Acupuncture also activated the expression of ER stress in the midbrain and upregulated the expression of IRE1/XBP1 in the striatum of PD model rats. Based on these results, we concluded that acupuncture may enhance the behavior of PD rats by activating the IRE1/XBP1 ER stress pathway, associated with the reduction of midbrain α-syn expression and the increase in striatal DA and 5-HT levels in unilateral 6-OHDA lesioned rats.

Application of Neurotoxin-Induced Animal Models in the Study of Parkinson's Disease-Related Depression: Profile and Proposal

Depression can be a non-motor symptom, a risk factor, and even a co-morbidity of Parkinson's disease (PD). In either case, depression seriously affects the quality of life of PD patients. Unfortunately, at present, a large number of clinical and basic studies focused on the pathophysiological mechanism of PD and the prevention and treatment of motor symptoms. Although there has been increasing attention to PD-related depression, it is difficult to achieve early detection and early intervention, because the clinical guidelines mostly refer to depression developed after or accompanied by motor impairments. Why is there such a dilemma? This is because there has been no suitable preclinical animal model for studying the relationship between depression and PD, and the assessment of depressive behavior in PD preclinical models is as well a very challenging task since it is not free from the confounding from the motor impairment. As a common method to simulate PD symptoms, neurotoxin-induced PD models have been widely used. Studies have found that neurotoxin-induced PD model animals could exhibit depression-like behaviors, which sometimes manifested earlier than motor impairments. Therefore, there have been attempts to establish the PD-related depression model by neurotoxin induction. However, due to a lack of unified protocol, the reported results were diverse. For the purpose of further promoting the improvement and optimization of the animal models and the study of PD-related depression, we reviewed the establishment and evaluation strategies of the current animal models of PD-related depression based on both the existing literature and our own research experience, and discussed the possible mechanism and interventions, in order to provide a reference for future research in this area.

Anxiogenic-like behavior and deficient attention/working memory in rats expressing the human DISC1 gene

In humans, mutations in the Disrupted-in-schizophrenia 1 (DISC1) gene have been related to psychiatric disorders, including symptoms of abnormal cognitive and emotional behaviors. In our previous studies, overexpression of the human DISC1 gene in rats resulted in schizophrenia-like phenotypes showing deficits in motor learning, impaired cognitive function and dysfunctions of the dopamine system. Here we asked, whether the DISC1 overexpression affects locomotor activity in the open field (OF), anxiety in the elevated plus-maze (EPM), depression-related behavior in the forced swim test (FST), and attention-like/short-term working-memory in the spontaneous alternation behavior (SAB) in the T-maze in transgenic DISC1 (tgDISC1) rats and littermate controls (WT). TgDISC1 rats showed enhanced anxiety behavior in the EPM and an impairment in attention-like/short-term working-memory in the SAB. However, tgDISC1 animals showed no locomotor impairments or depression-like behavior in the OF and FST. These results suggest that DISC1 overexpression leads to higher anxiety level and an attention-like/working-memory deficit. These findings may expand the causal role of DISC1 in its contribution to multiple symptom dimensions of psychiatric disorders.