Abstract:
Background: Chronic stress causes memory impairment. Curcumin, main
secondary metabolite of Curcuma longa, has limited applications as a
neuroprotectant due to its low bioavailability. Vitamin D, a fat-soluble
secosteroid, has independently shown to improve cognitive functions.
Objective: To examine the synergistic effect of curcumin and vitamin D on
memory impairment caused by restrained stress.
Methods: Restraint stress was induced in BALB/c mice. 30 mg/kg of curcumin
and/or 1500 IU of vitamin D were administered orally. Learning and memory
were evaluated by behavior tests; novel object recognition, and Morris water
maze (MWM) test.
Results: Percentage recognition index which is a measure of animal’s ability to
discriminate between a familiar object and novel object, was decreased in stress
group (39.4±6.95) as compared to control (60.7±3.37). An improvement in
exploratory behavior and recognition memory was seen in stressed mice
following treatment with curcumin and/or vitamin D (stress + curcumin = stress
+ curcumin + vitamin D). For spatial memory, decreasing trend in escape
latencies was observed for all, with stress group performing equally well,
indicating that restrained stress might not cause a notable impairment of spatial
memory. On the other hand, reference memory, assessed from probe trial was
significantly impaired in stress group (10.33±1.33). Following treatment with
curcumin alone (31.33±2.02) or in combination with vitamin D (29.33±5.2) a
significant improvement was seen in stressed mice; however, a cumulative effect
was not observed.
Conclusion: Restraint stress model showed significant decline in cognitive
functions. Treatment with curcumin alone and in combination with vitamin D
counteracted stress and improved learning and memory, although a significant
cumulative effect was not seen. Further studies with focus on the molecular
aspects of learning and memory are needed.
