The skin(ny) on the role of cannabinoids in dermatology

Written by Katherine Kramer, DVM, DAVBP (Canine & Feline Practice)

A 2019 survey among Canadian pet owners found that people who had tried hemp products on their pets did so for a variety of reasons. The main issues were to reduce pain & inflammation, anxiety, vomiting and to aid with sleep. Most veterinarians who are interested in veterinary cannabinoid medicine will agree that these are all common indications for the use of cannabis and will, most likely, add cancer and seizures to the list as well.

But what about cannabis for skin conditions? Records point to the ancient use of topical cannabis for wound healing, rashes and hair loss yet most of us today aren’t aware of these benefits. Investigating the role of cannabinoids in dermatology has been a growing field just over the last decade as scientists try to answer these questions: How does the endocannabinoid system (ECS) affect the largest mammalian organ and how this knowledge could translate into novel therapies for dermatologic disease?

Recent research has indicated that the ECS has a major role in the general skin homeostasis, epidermal permeability, hair growth, inflammation, pain, wound healing and skin tumors. Studies have demonstrated the presence of all the components of the ECS in the skin of multiple species, including the dog, cat and horse. These components, which include the endocannabinoids (primarily AEA and 2-AG), the receptors (Cb1, CB2, TRPV1, PPAR) and the necessary enzymes (such as FAAH and MAGL), have been found in keratinocytes, sebocytes, mast cells and adnexal skin tissues.

Particularly interesting are the findings of the interactions between mast cells, the ECS and N-acylethanolamines. Mast cells, of course, are multifunctional cells that play a huge role in the skin’s neuroimmune response in inflammatory and allergic reactions. They have been shown to metabolize endocannabinoids and express different types of cannabinoid receptors. N-acylethanolamines are a class of fatty acid amides that includes the endocannabinoid anandamide (AEA). This class also includes N-palmitoylethanolamine (PEA) which appears to be an ‘endocannabinoid-like mediator’. PEA has been shown to down-regulate mast cells and reduce mast cell degranulation in both canine and feline models. PEA also has the ability to increase the levels of 2-AG in keratinocytes and enhance the affinity of 2-AG for TRPV1 thus decreasing inflammation.

The therapeutic implications of all of these studies suggest that veterinary cannabinoid medicine may assist with dermatologic diseases involving inflammation and pruritus, hypersensitivity and wound healing. As usual, many more studies are needed to assess specific dermatologic indications and therapeutic dosages but the use of cannabinoids and endocannabinoid mediators appears to be extremely promising. The role of the ECS in dermatology definitely appears to be more than ‘skin deep’.

References

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