Type 2 diabetes is a metabolic disorder characterised by insulin resistance, inflammation and obesity (Donath and Shoelson, 2011). It is a worldwide pandemic, resulting in an estimated 1.5 million deaths each year, with 9 % of the global population being diagnosed as diabetic (World Health Organization, 2014)[LR((CS1] . Adipose tissue is an active organ which secretes hormones known as adipokines (leptin, Interluekin-6, Interleukin-1β, tumour necrosis factor-α), which mediate a number of metabolic functions. When adipose tissue expands to accommodate excess triacylglycerols, this results in a shift from an anti-inflammatory to a pro-inflammatory state. In this state, levels of pro-inflammatory adipokines increase, mediating a shift from an anti-inflammatory to a pro-inflammatory state that is accompanied by dysfunction and apoptosis of the pancreatic β-cells, resulting in the development of type 2 diabetes (Fantuzzi, 2005). Cannabis sativa L. and Leonotis leonurus L. have been traditionally used as anti-inflammatory and anti-diabetic agents in Southern Africa, as well as for treating snakebite, fever and malaria.  

Aim
Despite the link between inflammation, obesity and insulin resistance being well documented (Donath and Shoelson, 2011; Shoelson et al., 2006), no major investigations have been completed on the ability of cannabinoid-derived products to reduce diabetes-related inflammation. Chronic cannabis use has been associated with a lower body mass index (Rodondi et al., 2006; Warren et al., 2005) and increased pancreatic β-cell mass (Levendal et al., 2012), relative to non-cannabis users. The aim of this study assesses the effects of the cannabinoids, and the diterpenoid marrubiin, on adipokine and cytokine expression in pre- and differentiated 3T3-L1 cells. 

Method
To determine the effects of the various compounds, individually and in combination, on adipokine expression; mouse adipocytes were exposed to cannabinol (a non-psychoactive constituent of Cannabis), cannabidiol, ∆9-tetrahydrocannabinol, marrubiin (a terpenoid), anandamide (an endogenous endocannabinoid) and cannabis extract, individually and in combination, under normal glucose and hyperglycaemic conditions, for seven and fourteen-days, in pre-adipocytes and for seven days in differentiated mouse adipocytes (3T3-L1 cells). Levels of tumour necrosis factor-α, leptin, interleukin-6 and interleukin-1β were quantified using mouse enzyme-linked immunosorbent assay kits and Oil Red staining was carried out to determine lipid distribution and lipid droplet size. 

Results
Results indicated that cannabinol and ∆9-tetrahydrocannabinol, individually and in combination, exert an anti-inflammatory effect by significantly decreasing the expression of the pro-inflammatory cytokines under insulin-resistant and hyperglycaemic states. This study provides the first direct evidence that ∆9-tetrahydrocannabinol, cannabinol, cannabidiol and marrubiin decrease inflammation and lipid droplet content in pre-adipocytes, and differentiated adipocytes under both normal and high glucose conditions. The shift from a pro- to an anti-inflammatory state induced by these compounds may therefore provide a possible supplementary option to current treatment regimes.

Discussion
This study provides the first direct evidence that ∆9-tetrahydrocannabinol, cannabinol, cannabidiol and marrubiin decrease inflammation and lipid droplet content in pre-adipocytes, and differentiated adipocytes under both normal and high glucose conditions. The shift from a pro- to an anti-inflammatory state induced by these compounds may therefore provide a possible supplementary option to current treatment regimes.


References

Donath, M.Y., Shoelson, S.E., 2011. Type 2 diabetes as an inflammatory disease. Nature Reviews Immunology 11, 98-107.

Fantuzzi, G., 2005. Adipose tissue, adipokines, and inflammation. Journal of Allergy and Clinical Immunology 115, 911-919.

Levendal, R.A., Schumann, D., Donath, M., Frost, C.L., 2012. Cannabis exposure associated with weight reduction and β-cell protection in an obese rat model. Phytomedicine 19, 575-582.

Rodondi, N., Pletcher, M.J., Liu, K., Hulley, S.B., Sidney, S., 2006. Marijuana use, diet, body mass index, and cardiovascular risk factors (from the CARDIA study). The American Journal of Cardiology 98, 478-484.

Shoelson, S.E., Lee, J., Goldfine, A.B., 2006. Inflammation and insulin resistance. Journal of Clinical Investigation 116, 1793-1801.

Warren, M., Frost-Pineda, K., Gold, M., 2005. Body mass index and marijuana use. Journal of Addictive Diseases 24, 95-100.

World Health Organization, 2014. Global Health Estimates: Deaths by Cause, Age, Sex and Country, 2000-2012. Geneva, WHO.

Cannabinoids reduce inflammation in pre- and differentiated 3T3-L1 cells, under hyperglycaemic conditions