The development of a treatment that can delay the onset of diabetic neuropathy and slow its progression is urgently needed. In cell culture models of diabetic neuropathy, elevated glucose attenuates nerve growth factor (NGF)-induced neurite outgrowth (Lelkes et al., 2001). Jordan et al. (2005) demonstrated the synthetic cannabinoid CB1 receptor agonist HU210 triggers neurite outgrowth in cultured neurons, implicating a role for CB1 receptors in stimulating neurite outgrowth and regeneration after neuronal injury. In the present study, we investigated the neuroprotective effect of CB1 agonist treatment in a cell culture model of diabetic neuropathy, whereby neurite outgrowth of rat pheochromocytoma (PC12) cells was induced by NGF (50 ng/ml), in the presence of normal and high concentrations of glucose (5.5 and 50mM) to simulate normal and hyperglycaemic conditions in vivo. We examined whether impaired neurite outgrowth of PC12 cells cultured in high glucose can be “rescued” with HU210 (0.03-30µM). We observed a reduction in total neurite length induced by NGF in PC12 cells cultured in 50mM glucose on day 6 (P<0.01 versus 5.5mM; n=70-79 from 6 independent cultures). This effect was due to raised glucose levels, used to mimic diabetic conditions, rather than any hyperosmolality effects since mannitol (50mM) produced similar results to the physiological 5.5mM glucose control (P=0.79). When cells were cultured for six days in the presence of combined NGF/CB1 agonist, neurite measurement revealed the addition of HU210 (30nM-3µM) had no significant effect on total neurite length in cells cultured in 5.5mM glucose (P=0.17 versus the untreated/vehicle DMSO 1:1000; n=148-220 individual cells), whilst increased total neurite lengths were found in cells cultured in 50mM glucose in a HU210 concentration-dependent manner. Total neurite length of PC12 cells treated with 0.3and 3µM HU210 was longer than those in the untreated, 0.03µM HU210 and vehicle groups (P<0.01; n=112-216 individual cells). Cell viability assays showed there were no effects of glucose or mannitol on cell viability (P=0.86). Except for 30µM HU210 which was associated with a high occurrence of cell death (P<0.01), there was no significant difference in cell survival between the various concentrations of HU210 (30nM-3µM) in both normal and high glucose conditions (P=0.99 and P=0.91 respectively, versus each control, without HU210 and vehicle; n=4, in duplicate). These results demonstrate a neuroprotective role of the CB1 agonist HU210 (≤3µM) in PC12 cells cultured under conditions mimicking hyperglycaemia, and suggest CB1 receptors may be an appropriate therapeutic target in preventing the neurodegenerative process in diabetes.