Mol Pain
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Chronic pain arising from degenerative diseases of the joint such as osteoarthritis (OA) has a strong peripheral component which is likely to be mediator driven. Current treatments which reduce the production of such mediators i.e. non-steroidal anti-inflammatory drugs (NSAIDs), can help to lessen pain in OA patients. However, this is not always the case and complete pain relief is rarely achieved, suggesting that additional unidentified mediators play a role. Here we have investigated the notion that chemokines might act as such pain mediators in OA. ⋯ Chemokines in general and CCL2, 7 and 9 in particular, represent promising targets for further studies into the identification of new pain mediators in chronic joint pain.
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Cadmium (Cd) is an environmental pollutant and acute exposure to it causes symptoms related to pain and inflammation in the airway and gastrointestinal tract, but the underlying mechanisms are still unclear. TRPA1 is a nonselective cation channel expressed in sensory neurons and acts as a nociceptive receptor. Some metal ions such as Ca, Mg, Ba and Zn are reported to modulate TRPA1 channel activity. In the present study, we investigated the effect of Cd on cultured mouse dorsal root ganglion neurons and a heterologous expression system to analyze the effect of Cd at the molecular level. In addition, we examined whether Cd caused acute pain in vivo. ⋯ Cd excites sensory neurons via activation of TRPA1 and causes acute pain, the mechanism of which may be similar to that of Zn. The present results indicate that TRPA1 is involved in the nociceptive or inflammatory effects of Cd.
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Effect of amitriptyline on tetrodotoxin-resistant Nav1.9 currents in nociceptive trigeminal neurons.
Amitriptyline (AMI) is tricyclic antidepressant that has been widely used to manage various chronic pains such as migraines. Its efficacy is attributed to its blockade of voltage-gated sodium channels (VGSCs). However, the effects of AMI on the tetrodotoxin-resistant (TTX-r) sodium channel Nav1.9 currents have been unclear to present. ⋯ These data suggest that AMI is a state-selective blocker of Nav1.9 channels in rat nociceptive trigeminal neurons, which likely contributes to the efficacy of AMI in treating various pains, including migraines.
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Resveratrol (3,5,4' - trihydroxy-trans-stilbene), a widely distributed natural stilbenoid, was proposed to account for the unique effects of red wine on life span and health. It has been reported to possess various biological and pharmacological activities, such as anti-oxidant, anti-inflammatory, and anti-carcinogenic effects. Here, using whole-cell patch-clamp techniques and behavioral analyses, we investigated whether resveratrol and other stilbenoids can modulate TRP channels in sensory neurons in vitro, and have analgesic effects in vivo. ⋯ These data suggest that resveratrol and other stilbenoids may have an inhibitory effect on TRP channels. In addition, these stilbenoids modulate TRP channel activity in different ways.
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This review aims to create an overview of the currently available results of site-directed mutagenesis studies on transient receptor potential vanilloid type 1 (TRPV1) receptor. Systematization of the vast number of data on the functionally important amino acid mutations of TRPV1 may provide a clearer picture of this field, and may promote a better understanding of the relationship between the structure and function of TRPV1. ⋯ The main goal of this paper is to publish the above mentioned data in a form that facilitates in silico molecular modelling of the receptor by promoting easier establishment of boundary conditions. The better understanding of the structure-function relationship of TRPV1 may promote discovery of new, promising, more effective and safe drugs for treatment of neurogenic inflammation and pain-related diseases and may offer new opportunities for therapeutic interventions.