Chronic pain is a substantial public health problem, and the current treatment modalities are insufficient. Cannabis and cannabis extracts have been used for thousands of years for medicinal purposes, and following its legalization in a number of states, is increasingly being used to manage neurological, psychological, and inflammatory conditions. However, research on the efficacy, mechanisms of action, and effects of cannabis and its components on human and health and disease in the United States has been limited by its DEA Schedule 1 classification. The principal components of cannabis, THC and CBD, are believed to have pain reducing effects. THC has been most extensively studied, and although it has analgesic properties, its psychotropic properties limit its utility for pain management. Notably the minor cannabinoids are emerging as potential natural compounds with anti-inflammatory and pain reducing effects, but without the unwanted psychotropic effects of THC. At the same time, anti-inflammatory strategies are being explored for treating chronic pain. We have found that the endocannabinoids anandamide, N-arachidonoyl dopamine and N-oleoyl dopamine, and the phytocannabinoid, ?-9-THC, all have anti-inflammatory effects and improve functional indices in mice treated with LPS. They each profoundly up-regulate plasma levels of IL-10 in LPS-treated mice. Using bone marrow chimeras, we determined that NADA mediates its anti-inflammatory effects in LPS-treated mice via the TRPV1 expressed by non-myeloid cell lineages. In contrast, our preliminary data suggest that ?-9- THC exerts its anti-inflammatory effects via cannabinoid receptor 1 (CB1R), rather than TRPV1. In preliminary studies we have found that Cannabidiol (CBD), Cannabinol (CBN), Cannabigerol (CBG) and Cannabichromene (CBC) modulate inflammatory activation of human microvascular endothelial cells. We broadly hypothesize that minor cannabinoids reduce inflammatory and neuropathic pain via anti-inflammatory mechanisms mediated through the activation of peripheral TRPV1 and CB1R in sensory neurons. We will leverage the expertise of the PIs in neurobiology, pain biology, TRPV1, immunology, vascular biology and injury to study the anti-inflammatory and pain reducing effects of CBD, CBN, CBG, and CBC, and other minor cannabinoids in vitro and in vivo in models of inflammatory and neuropathic pain.
In Aim #1 we will define the ability of minor cannabinoids to modulate inflammatory activation and function of nociceptors, leukocytes, and endothelial cells, and determine their dependence on TRPV1 and CB1R.
In Aim #2 we will determine the role of anti-inflammatory mechanisms in reducing pain behaviors in inflammatory and neuropathic pain models in mice.
In Aim #3 we will determine how minor cannabinoids reduce inflammatory and neuropathic pain behaviors through TRPV1- and CB1R- expressed in nociceptors. These studies will advance the understanding of the endovanilloid and endocannabinoid systems in pain, and will pave the way for future development of minor cannabinoid-based therapies targeting the endovanilloid and endocannabinoid systems for pain.
Chronic pain is a major public health problem in the United States, and current medically-approved options for the treatment of pain are rarely safe or effective. Cannabis and components of cannabis are used to treat chronic pain, but there are large gaps in the understanding of how cannabinoids reduce pain, and their effects on inflammation and responses to injury. We will study the effects and mechanisms of action of minor cannabinoids on behavioral models of pain caused by inflammation or nerve injury, focusing on their activation of two important receptors in pain biology, the transient receptor potential vanilloid 1 (TRPV1) and cannabinoid receptor 1 (CB1R).