Auricular Electrical Stimulation Alleviates Headache through CGRP/COX-2/TRPV1/TRPA1 Signaling Pathways in a Nitroglycerin-Induced Migraine Rat Model

Modulation of Glia Activation by TRPA1 Antagonism in Preclinical Models of Migraine

Preclinical data point to the contribution of transient receptor potential ankyrin 1 (TRPA1) channels to the complex mechanisms underlying migraine pain. TRPA1 channels are expressed in primary sensory neurons, as well as in glial cells, and they can be activated/sensitized by inflammatory mediators. The aim of this study was to investigate the relationship between TRPA1 channels and glial activation in the modulation of trigeminal hyperalgesia in preclinical models of migraine based on acute and chronic nitroglycerin challenges. Rats were treated with ADM_12 (TRPA1 antagonist) and then underwent an orofacial formalin test to assess trigeminal hyperalgesia. mRNA levels of pro- and anti-inflammatory cytokines, calcitonin gene-related peptide (CGRP) and glia cell activation were evaluated in the Medulla oblongata and in the trigeminal ganglia. In the nitroglycerin-treated rats, ADM_12 showed an antihyperalgesic effect in both acute and chronic models, and it counteracted the changes in CGRP and cytokine gene expression. In the acute nitroglycerin model, ADM_12 reduced nitroglycerin-induced increase in microglial and astroglial activation in trigeminal nucleus caudalis area. In the chronic model, we detected a nitroglycerin-induced activation of satellite glial cells in the trigeminal ganglia that was inhibited by ADM_12. These findings show that TRPA1 antagonism reverts experimentally induced hyperalgesia in acute and chronic models of migraine and prevents multiple changes in inflammatory pathways by modulating glial activation.

Effect of Xiongmatang Extract on Behavioral and TRPV1-CGRP/CGRP-R Pathway in Rats With Migraine

Migraine is a complex neurovascular disease, which seriously affects the quality of life in patients. This study aimed to evaluate the effect of Xiongmatang (XMT) extract on rats with migraine induced by inflammatory soup and the underlying mechanisms. First, 1 week after dural catheterization, inflammatory soup was injected through a microsyringe to stimulate the dura of rats for 6 times (12 days), once every 2 days, 10 μL each time, to establish a migraine model. According to pain threshold analysis, behavioral change detection, and pathological analysis, the effects of XMT extract on rats with migraine were evaluated. The positive, mRNA and protein expression of related factors were detected by immunohistochemistry, RT-QPCR, and Western blot analysis to elucidate the underlying mechanism. XMT extract improved the behavioral performance of rats, and improve the pathological changes in the trigeminal nerve in rats. Further experimental results show that XMT extract regulated the expression of migraine-related factors in the trigeminal nerve, manifested as transient receptor potential vanilloid 1 (TRPV1), calcitonin-gene-related peptide (CGRP), calcitonin receptor-like receptor (CRLR), and receptor activity-modifying protein 1 (RAMP1) positive expression, mRNA expression, and protein expression reduction. XMT extract can significantly improved the behavioral performance of rats with migraine, and its mechanism of action might involve regulating the activity of TRPV1-CGRP/CGRP-R pathway.

Involvement of TRPM2 in the Neurobiology of Experimental Migraine: Focus on Oxidative Stress and Apoptosis

Excessive Ca²⁺ influx and mitochondrial oxidative stress (OS) of trigeminal ganglia (TG) have essential roles in the etiology of migraine headache and aura. The stimulation of TRPM2 channel via the generation of OS and ADP-ribose (ADPR) induces pain, inflammatory, and oxidative neurotoxicity, although its inhibition reduces the intensity of pain and neurotoxicity in several neurons. However, the cellular and molecular effects of TRPM2 in the TG of migraine model (glyceryl trinitrate, GTN) on the induction of pain, OS, apoptosis, and inflammation remain elusive. GTN-mediated increases of pain intensity, apoptosis, death, cytosolic reactive oxygen species (ROS), mitochondrial ROS, caspase -3, caspase -9, cytosolic Ca²⁺ levels, and cytokine generations (TNF-α, IL-1β, and IL-6) in the TG of TRPM2 wild-type mouse were further increased by the TRPM2 activation, although they were modulated by the treatments of GSH, PARP-1 inhibitors (PJ34 and DPQ), and TRPM2 blockers (ACA and 2APB). However, the effects of GTN were not observed in the TG of TRPM2 knockout mice. The current data indicate that the maintaining activation of TRPM2 is not only important for the quenching OS, inflammation, and neurotoxicity in the TG neurons of mice with experimental migraine but also equally critical to the modulation of GTN-induced pain.

The Effectiveness of Scutellaria baicalensis on Migraine: Implications from Clinical Use and Experimental Proof

Background

Scutellaria baicalensis (SB), a traditional Chinese medicine, is commonly used for the treatment of inflammatory and painful conditions. The purpose of the present study was to examine the effects of SB on migraine.

Materials and Methods

We examined the clinical applications of SB based on the data obtained from Taiwan's National Health Insurance Research Database and confirmed that it was frequently used in Taiwan for the treatment of headaches. An experimental migraine model was established in rats by an intraperitoneal injection of nitroglycerin (NTG, 10 mg/kg). Pretreatment with SB was given orally 30 min before NTG administration. The rats were subjected to migraine-related behaviour tests that were video-recorded and analysed using EthoVision XT 12.0 software.

Results

The frequency of exploratory and locomotor behaviour was comparatively lower in the NTG group than that in the control group, while the frequency of resting and grooming behaviour increased. These phenomena were ameliorated by pretreatment with 1.0 g/kg SB. The total time spent on the smooth surface was longer in the NTG group than that in the control group, but the time was shortened by pretreatment with 1.0 g/kg SB.

Conclusions

Pretreatment with 1.0 g/kg SB relieved migraine-related behaviours in the experimental NTG-induced migraine model. The outcome therefore demonstrated that pretreatment with 1.0 g/kg SB is beneficial for migraine treatment.

Long-Term Beneficial Effects of Acupuncture with Reduced Risk of Depression Development Following Trigeminal Neuralgia: A Nationwide Population-Based Cohort Study

BACKGROUND

Existing evidence has shown that patients with trigeminal neuralgia (TN) have a higher risk of developing depression than the normal population. Clinically, acupuncture has been widely used to alleviate pain in TN. However, few studies have explored the use of acupuncture to prevent depression in TN. Therefore, this study aimed to apply national real-world data to investigate the long-term effect of acupuncture on the risk of depression in patients with TN.

METHODS

We recruited participants with newly diagnosed TN from the Taiwanese National Health Insurance Research Database between January 1, 2000 and December 31, 2010, and categorized them into either the acupuncture cohort or non-acupuncture cohort using the 1:1 propensity score-matched method. All patients in the two cohorts were followed up until the end of 2013. Cox proportional hazards regression analysis was used to compare the incidence of depression between the two cohorts.

RESULTS

In total, 776 patients with newly diagnosed TN in each cohort with similar baseline characteristics were enrolled in the study. The acupuncture cohort had a reduced risk of depression compared to the non-acupuncture cohort (adjusted hazard ratio, 0.47; 95% confidence interval, 0.31-0.70). Kaplan-Meier analysis also revealed that the cumulative incidence of depression was significantly lower in the acupuncture cohort during the 13-year follow-up period (Log rank test, p < 0.001). In particular, the beneficial effect of acupuncture was a decrease in the risk of depression among TN patients aged 50-69 years who had also used carbamazepine.

CONCLUSION

This study demonstrated that acupuncture is associated with a reduction in the risk of depression during long-term follow-up in patients with TN. The results provide new insights for clinical practitioners as well as for health resource allocation.