Fibromyalgia (FM) is a complex, chronic, widespread pain syndrome that can cause significant health and economic burden. Emerging evidence has shown that neuroinflammation is an underlying pathological mechanism in fibromyalgia. Toll-like receptors (TLRs) are key mediators of the immune system. TLR4 is expressed primarily in microglia and regulates downstream signaling pathways, such as MyD88/NF-κB and TRIF/IRF3. It remains unknown whether electroacupuncture (EA) has therapeutic benefit in attenuating fibromyalgia pain and what role the TLR4 pathway may play in this effect. We compared EA with sham EA to eliminate the placebo effect due to acupuncture. We demonstrated that intermittent cold stress significantly induced an increase in mechanical and thermal FM pain in mice (mechanical: 2.48 ± 0.53 g; thermal: 5.64 ± 0.32 s). EA but not sham EA has analgesic effect on FM mice. TLR4 and inflammatory mediators-related molecules were increased in FM mice’s thalamus, medial prefrontal cortex, somatosensory cortex, and amygdala, indicating neuroinflammation and microglial activation. These molecules were reduced by EA but not sham EA. Furthermore, a new chemogenetics method was used to precisely inhibit SSC activity displayed an anti-nociceptive effect through TLR4 pathway. Our results imply that the analgesic effect of EA is associated with TLR4 downregulation. We provide novel evidence that EA can modulate the TLR4 signaling pathway, revealing potential therapeutic targets for FM pain.

Pain is unpleasant sensory and emotional experience accompanied by tissue injury. Often an indi-vidual experience, it can be influenced by different physiological, psychological, and social factors. Fibromyalgia, one of the most difficult-to-treat types of pain, is characterized by general muscle pain accompanied by obesity, fatigue, sleep, and memory and psychological concerns. Fibromyal-gia has increased nociceptive sensations via central sensitization in the brain and spinal cord level. We used intermittent cold stress to create a mouse fibromyalgia pain model (Day 0: 3.69  0.14 g; Day 5: 2.13  0.12 g). Mechanical pain could be reversed by eicosapentaenoic acid (EPA) admin-istration (Day 0: 3.72  0.14 g; Day 5: 3.69  0.13 g). A similar trend could be also observed for thermal hyperalgesia. The levels of elements in the transient receptor potential V1 (TRPV1) sig-naling pathway were increased in the ascending pain pathway, including the thalamus, medial prefrontal cortex, somatosensory cortex, anterior cingulate cortex, and cerebellum. EPA intake significantly attenuated this overexpression. Novel chemogenetics method was used to indeed in-hibit SSC to ACC activity presented an analgesic effect through TRPV1 downstream pathway. The present results provide insights as to the role of TRPV1 signaling pathway as in fibromyalgia and its potential as a clinical target.

Neuropathic pain is initiated by a malfunction of the somatosensory cortex system. Acupuncture had been shown to have therapeutic effects for neuropathic pain, although with uncertain mechanisms. We used electroacupuncture (EA) to treat mice spared nerve injury (SNI) model and explore the underlying molecular mechanisms through novel chemogenetic techniques. Both me-chanical and thermal pain were found in SNI mice till four weeks (mechanical: 3.23 ± 0.29 g; thermal: 4.9 ± 0.14 s). Hyperalgesia was attenuated by 2 Hz EA (mechanical: 4.05 ± 0.19 g; ther-mal: 6.22 ± 0.26 s) but not with sham EA (mechanical: 3.13 ± 0.23 g; thermal: 4.58 ± 0.37 s), sug-gesting EA’s specificity. In addition, animals with transient receptor potential V1 (Trpv1) deletion showed no significant induction of neuropathic pain (mechanical: 4.43 ± 0.26 g; thermal: 6.24 ± 0.09 s). Moreover, we found increased levels of inflammatory factors such as interleukin-1 beta (IL1-β), IL-3, IL-6, IL-12, IL-17, tumor necrosis factor alpha, and interferon gamma after SNI modeling, which decreased in EA and Trpv1-/- group rather than sham group. Western blot and immunofluorescence analysis showed similar tendency in the dorsal root ganglion, spinal cord dorsal horn, somatosensory cortex (SSC), and anterior cingulate cortex (ACC). In addition, a novel chemogenetics method was used to precisely inhibit SSC to ACC activity showed an analgesic effect through TRPV1 pathway. In summary, our findings indicate a novel mechanism underlying neuropathic pain as beneficial targets for neuropathic pain.

Obesity induces inflammation in the hypothalamus and adipose tissue, resulting in metabolic disorders. A novel hypothalamic neuropeptide, neurosecretory protein GM (NPGM), was previously identified in the hypothalamus of vertebrates. While NPGM plays an important role in lipid metabolism in chicks, its metabolic regulatory effects in mammals remain unclear. In this study, a novel Cre driver line, NPGM-Cre, was generated for cell-specific manipulation. Cre-dependent overexpression of Npgm led to fat accumulation without increased food consumption in NPGM-Cre mice. Chemogenetic activation of NPGM neurons acutely promoted feeding behavior and chronically resulted in a transient increase in body mass gain. Furthermore, the ablated NPGM neurons exhibited a tendency to be glucose intolerant, with infiltration of proinflammatory macrophages into the adipose tissue. These results suggest that NPGM neurons may regulate lipid storage and inflammatory responses, thereby maintaining glucose homeostasis.

Huntington’s disease (HD) causes progressive movement disorders and cognitive deficits. Besides, sleep disturbances and emotional distress are prominent clinical signatures of HD. The experimental subjects and HD human brains display altered regenerative plasticity resulting from aberrant neurogenic and nonneurogenic areas. Sleep disorders, emotional disruption, and cognitive deficits have been linked to impaired cell cycle events of neural stem cells (NSC) in neurodegenerative disorders. In a physiological state, circadian clock gene pathways play important roles in the regulation of the proliferation and differentiation of NSC, whereas the irregular circadian clock pathway is attributed to impairment in the neurogenic process. The recent advancement of chemogenetic-based approaches represents a potential scientific tool to rectify the abnormal circadian clock which may aid in mitigating neurogenic failure in the brain. Notably, GABAergic vasoactive intestinal peptide (VIP)-expressing neurons in the brain plays a key role in the regulation of neuroplasticity and circadian rhythm. Thus, this conceptual review article addresses the potential link between sleep disorder and aberrant neurogenic events in HD and proposes chemogenetic kindling of vasoactive intestinal peptide (VIP) -expressing GABAergic neurons in the brain as a therapeutic strategy for reprogramming the clock gene pathways in mitigating the neurodegenerative failure in HD.