Effects of Sonchus asper Extract on Diabetes-induced Learning and Memory Impairment in Rats

Cognitive impairment occurs in diabetes mellitus. Sonchus asper has been used in folk medicine to improve mental performance. Here it is hypothesized that chronic treatment with an extract of Sonchus asper (6, 12 and 25 mg/kg, p.o.) would have effects on passive avoidance learning (PAL) and memory in control and streptozotocin-induced diabetic rats. Treatments were begun at the onset of hyperglycaemia. PAL was assessed 30 days later. A retention test was done 24 h after training. At the end, the animals were weighed and blood samples were drawn for plasma glucose measurement. Diabetes caused impairment in acquisition and retrieval processes of PAL and memory. Sonchus asper treatment (12 and 25 mg/kg) improved learning and memory in control rats and reversed learning and memory deficits in diabetic rats. A dose of 6 mg/kg did not affect cognitive function. Sonchus asper administration did not alter the body weight and plasma glucose levels. These results show that Sonchus asper prevented the deleterious effects of diabetes on PAL and memory. As Sonchus asper would be free of major side effects compared with other nootropic medications, it may provide a new potential alternative for demented diabetic patients