n-3 Polyunsaturated fatty acids ameliorate cognitive age-related impairments and depressive behaviour in unchallenged aged prediabetic rats

• n-3 PUFA-rich oil treatments demonstrated significantly quicker MWM acquisition and shorter FST immobility time than did the control group.
• n-3 PUFA-rich oils present the protective effects by improving fasting blood sugar levels, reducing proinflammatory cytokine levels and nonesterified fatty acid, thus preventing cognitive age-related impairments and depression-like behaviour in aged prediabetic rats.

Epidemiological studies have reported that nutritional deficit of n-3 polyunsaturated fatty acids (PUFAs) is closely related to depression and cognitive impairment in middle and later life. This study investigated the preventive effects of n-3 PUFA-rich oils on the behavioural impairment of unchallenged aged prediabetic rats by using a Morris water maze (MWM) test and forced swimming test (FST). Twenty 102-wk-old male SD male rats received a 35% sucrose solution and were fed with fish oil or flaxseed oil diets for 8 wk. Both treatments reduced the production of IL-6 and non-esterified fatty acids significantly. Both treatments demonstrated significantly quicker MWM acquisition, shorter FST immobility time and higher levels of nerve growth factor than did the control group. Thus, n-3 PUFA-rich oil might produce protective effects by improving fasting blood sugar levels and reducing proinflammatory cytokine levels, thus preventing cognitive age-related impairments and depression-like behaviour in aged prediabetic rats.