OBJECTIVETo investigate the effects of chronic aluminum exposure on the learning and memory abilities and brain-derived nerve growth factor (BDNF) in Sprague-Dawley (SD) rats.

METHODSThirty-two male SD rats were randomly and equally divided into 4 groups: control group and high-, middle-, and low-dose exposure groups. The rats in high-, middle-, and low-dose exposure groups were fed with the feed mixed with AlCl(3) (120.0, 12.0, and 1.2 mg/kg, respectively), while the rats in control group were fed conventionally. After 6 months of feeding, brain aluminum levels were determined by inductively coupled plasma mass spectrometry; Morris water maze was employed to test the learning and memory abilities; the expression and content of BDNF in brain tissue were measured by Western blot and enzyme-linked immuno sorbent assay (ELISA).

RESULTSThe high- and middle-dose exposure groups had significantly higher brain aluminum levels than the control group (P<0.05). The Morris water maze test showed that the high- and middle-dose exposure groups had significantly prolonged escape latency (P<0.05), significantly prolonged time taken to first reach the target quadrant (P<0.01), and significantly decreased number of platform crossings and time spent in the target quadrant (P<0.05), as compared with the control group. The Western blot and ELISA showed that the expression and content of BDNF in brain tissue decreased as the dose of AlCl(3) increased, and they were significantly lower in the high- and middle-dose exposure groups than in the control group (P<0.05).

CONCLUSIONChronic aluminum exposure (12.0 and 120.0 mg/kg) can lead to cognitive dysfunction in rats, and the decreased expression of BDNF may be one of the mechanisms of learning and memory deficits induced by aluminum.