CBD Protects Kidney Function
The use of cannabis is shown to have no negative impact on kidney function and CBD, in the mouse model, actually protected it from damage.
Kidneys represent an important organ system for both cardiovascular function and the excretion of waste. As such, factors influencing renal (kidney) function can indirectly affect other physiological processes, such as control of blood pressure, heart rate, excretion of sodium and maintenance of water and salt balance in the body.
The kidneys are among the organ systems where CB1 and CB2 receptors are widely expressed, and therefore both endogenous and cannabis cannabinoids can alter their function. Unfortunately, there are very few clinical studies involving humans, therefore little is known about the effect of cannabinoids on both healthy kidneys and kidney function where there is a pre-existing renal disease. From the available pre-clinical and clinical data, the following is what we know about the effects of CB1 and CB2 receptor activation on the kidneys.
Distribution of CB1 and CB2 receptors throughout the kidney has shown to be perturbed in renal disease, such as the case of diabetic nephropathy. Biopsies from patients suffering from nephropathy showed increased expression of CB1 receptor, while in both humans and mouse models, decreased CB2 expression has been noted.
Indeed, studies conducted so far have shown that using pharmacological agents to reduce CB1 activity and increase CB2 activity is associated with improvement in renal structure and function in models of chronic kidney disease. In further support of this, administration of cannabidiol (CBD) has been shown to preserve renal structures when flow of oxygen was intermittently reduced in an animal model of acute kidney injury.
It seems that the CBD can exert direct effects that are protective to kidney structure and function. The final physiological effect of CB receptor activation however, is likely not easily predictable.
CBD may alter kidney function indirectly by dampening inflammation. Activation of CB2 receptors has an anti-inflammatory effect, resulting in reduction of inflammatory cell infiltration and reducing the production of cytokines (a molecule that increases inflammation). Conversely, in another study using a mouse model of acute kidney injury, activation of CB1 receptor was associated with increased oxidative stress, which stimulates inflammation, eventually initiating cell death. The benefit of reducing renal inflammation lies in the effects on the cardiovascular system, which is reducing overall risk of developing hypertension and vascular stiffness.
Information about the effects of smoked cannabis in healthy population and patients with CKD is very limited. One single study, involving 647 patients, found that smoking cannabis was not associated with a decline in kidney function. Markers of renal function were also unaltered in a small prospective trial in which medical cannabis was used for pain. Additionally, in 1225 patients who received a kidney transplant, using medical cannabis did not alter the function of the transplanted kidney at one year after they received it.
It is thus plausible that cannabinoid signaling may be used therapeutically in kidney diseases. Cannabis products richer in CBD seem to have greater pharmacological potential compared to THC. With the emergence of new knowledge about other cannabinoids present in the plant and their receptor activating profiles, it will be clearer as to which strains and products would be more beneficial for patients with kidney disease.