The dorsal medial prefrontal cortex (dmPFC) has been recognized as a key cortical area for nociceptive modulation. However, the underlying neural pathway and the function of specific cell types remain largely unclear. Here, we show that lesions in the dmPFC induced an algesic and anxious state. Using multiple tracing methods including a rabies-based transsynaptic tracing method, we outlined an excitatory descending neural pathway from the dmPFC to the ventrolateral periaqueductal gray (vlPAG). Specific activation of the dmPFC/vlPAG neural pathway by optogenetic manipulation produced analgesic and antianxiety effects in a mouse model of chronic pain. Inhibitory neurons in the dmPFC were specifically activated using a chemogenetic approach, which logically produced an algesic and anxious state under both normal and chronic pain conditions. Antagonists of the GABA_A receptor (GABA_AR) or mGluR1 were applied to the dmPFC, which produced analgesic and antianxiety effects. In summary, the results of our study suggest that the dmPFC/vlPAG neural pathway might participate in the maintenance of pain thresholds and antianxiety behaviors under normal conditions, while silencing or suppressing the dmPFC/vlPAG pathway might be involved in the initial stages and maintenance of chronic pain and the emergence of anxiety-like behaviors.

Vitiligo, a depigmenting autoimmune skin disease characterized by melanocyte dysfunction or death, is known to be associated with an imbalance in gut microbiota. Oxidative stress plays a critical role in the pathogenesis of vitiligo. However, the complex promising interaction between abnormal accumulation of reactive oxygen species (ROS) in the skin and gut microbiota has remained unclear. Here, we compared transcriptome data of vitiligo lesions and normal skin and identified a high expression of oxidative stress-related genes in vitiligo lesions. We also established a vitiligo mouse model and found that the presence of gut microbiota influenced the expression of ROS-related genes. Depletion of gut microbiota reduced abnormal ROS accumulation and mitochondrial abnormalities in melanocytes, significantly improving depigmentation. Our findings from manipulating gut microbiota through cohousing, fecal microbiota transplantation (FMT), and probiotic supplementation showed that transferring gut microbiota from mice with severe vitiligo-like phenotypes exacerbated skin depigmentation while probiotics inhibited its progression. Targeted metabolomics of fecal, serum, and skin tissues revealed gut microbiota-dependent accumulation of hippuric acid, mediating excessive ROS in the skin. Elevated serum hippuric acid levels were also confirmed in vitiligo patients. Additionally, a microbiota-dependent increase in intestinal permeability in vitiligo mice mediated elevated hippuric acid levels, and we found that hippuric acid could directly bind to ROS-related proteins (NOS2 and MAPK14). Our results suggested the important role of gut microbiota in regulating vitiligo phenotypes and oxidative stress. We identified hippuric acid, a gut microbiota-host co-metabolite, as a critical mediator of oxidative stress in vitiligo skin and its binding targets (NOS2 and MAPK14), resulting in oxidative stress. Validation in a small human cohort suggested that hippuric acid could serve as a novel diagnostic biomarker and therapeutic target for vitiligo. These findings provided new insights into how gut microbiota regulates skin oxidative stress in vitiligo and suggested potential treatment strategies for the disease.

Pain and itch are intricately entangled at both circuitry and behavioral levels. Emerging evidence indicates that parvalbumin (PV)-expressing neurons in zona incerta (ZI) are critical for promoting nocifensive behaviors. However, the role of these neurons in itch modulation remains elusive. Herein, by combining FOS immunostaining, fiber photometry, and chemogenetic manipulation, we reveal that ZI PV neurons act as an endogenous negative diencephalic modulator for itch processing. Morphological data showed that both histamine and chloroquine stimuli induced FOS expression in ZI PV neurons. The activation of these neurons was further supported by the increased calcium signal upon scratching behavior evoked by acute itch. Behavioral data further indicated that chemogenetic activation of these neurons reduced scratching behaviors related to histaminergic and non-histaminergic acute itch. Similar neural activity and modulatory role of ZI PV neurons were seen in mice with chronic itch induced by atopic dermatitis. Together, our study provides direct evidence for the role of ZI PV neurons in regulating itch, and identifies a potential target for the remedy of chronic itch.

Neuropathic pain (NP) is a complex, chronic pain condition caused by injury or dysfunction affecting the somatosensory nervous system. This study aimed to identify crucial mRNAs and microRNAs (miRNAs) in the prelimbic cortex (PL) of NP rats. mRNA and miRNA microarrays were applied in the present study. The miRNA-mRNA regulatory network was constructed by using ingenuity pathway analysis (IPA). A total of 35 differentially expressed (DE) RNAs (24 miRNAs and 10 mRNAs) were identified in the spared nerve injury (SNI) group compared with the control group. The DE miRNA-mRNA network showed that IL-6 and tumor necrosis factor (TNF) were core components. Mir-30c-5p and mir-16-5p were the most connected miRNAs in the network. Interestingly, four mRNAs (Rnase 4, Egr2, Rexo4, and Klf2) with significantly increased expression were abundantly expressed in microglia, which was verified by the real-time quantitative polymerase chain reaction (qPCR). Furthermore, the expression of Rnase4 and Egr2 decreased in M1-polarized macrophages and increased in M2-polarized macrophages. In conclusion, we screened dozens of DE mRNAs and miRNAs in the PL of SNI rats. The core of the DE mRNA and miRNA network pointed to molecules associated with inflammation. Four mRNAs (Rnase4, Egr2, Rexo4, and Klf2) might be the potential markers of M2 polarization.

Astrocytic glycogen plays an important role in brain energy metabolism. However, the contribution of glycogen metabolism to stress-induced depression remains unclear. Chronic social defeat stress was used to induce depression-like behaviors in mice, assessed with behavioral tests. Glycogen concentration in the medial prefrontal cortex (mPFC) and the expression of key enzymes of the glycogen metabolism were investigated using Western blots, immunofluorescent staining, electron microscopy, and biochemical assays. Stereotaxic surgery and viral-mediated gene transfer were applied to knockdown or overexpress brain-type glycogen phosphorylase (PYGB) in the mPFC. The glycogen content increased in the mPFC after stress. Glycogenolytic dysfunction due to inactivation of PYGB was responsible for glycogen accumulation. Behavioral tests on astrocyte-specific PYGB overexpression mice showed that augmenting astrocytic PYGB reduces susceptibility to depression when compared with stress-susceptible mice. Conversely, PYGB genetic down-regulation in the mPFC was sufficient to induce glycogen accumulation and depression-like behaviors. Furthermore, PYGB overexpression in the mPFC decreases susceptibility to depression, at least partially by rescuing glycogen phosphorylase activity to maintain glycogen metabolism homeostasis during stress. These findings indicate that (1) glycogen accumulation occurs in mice following stress and (2) glycogenolysis reprogramming leads to glycogen accumulation in astrocytes and PYGB contributes to stress-induced depression-like behaviors. Pharmacological tools acting on glycogenolysis might constitute a promising therapy for depression.