Impact of amitriptyline on learning and memory

Abstract

Background/aim: Amitriptyline belongs to class of known as tricycline antidepresant (TCA) that is being used to treat anxiety and depressive states. It may help improve mood and feelings of well-being, relieve anxiety and tension, help to improve sleep and increase energy level. The study investigated the effect of amitriptyline on learning and memory using eighteen (18) healthy Swiss mice of both sexes weighing 16 – 25 g. Method: The animals were divided into three (3) groups consisting of six (6) animals each. Group 1 served as the control group, Group 2 was administered with amitriptyline at a dose of 3 mg/kg body weight dissolved in 3 mls of distilled water, and used to test for learning, while Group three was also given similar administration like Group 2, but used to test for memory. All the animals were tested for learning and memory performance using Novel object recognition task and Morris water maze test. Results: The results obtained from the Novel object recognition task showed that there was a significant decrease (p < 0.05) in total object approach in acquisition trial of amitriptyline treated group when compared to the acquisition trial of the control group. There was a significant decrease (p < 0.05) in retention trial of amitriptyline group when compared to retention trial in the control group. There was a significant decrease (p < 0.05) in total duration exploring objects in acquisition trial of amitriptyline treated group when compared to the acquisition trial of the control group. There was a significant increase (p < 0.05) in total duration exploring objects in retention trial of amitriptyline treated group when compared to the retention trial of the control group. There was a significant decrease (p < 0.05) in the index of habituation of amitriptyline treated group when compared to the control group. The index of discrimination showed a significant increase (p < 0.05) in amitriptyline treated group when compared to the control group and a significant decrease (p < 0.05) in amitriptyline group when compared to the control group. In the Morris water maze test, Day 1 – 3 were for acquisition training, day 4 – 6 reversal training, day 7 the probe trial day and day 8 the visible platform day. During acquisition training in the Morris water maze test, there was no significant difference in Swim latencies in day 1 and 2. However in day 3, there was a significant increase (p < 0.05) in swim latency of group compared to control group and a significant decrease (p < 0.05) in swim latency of amitriptyline treated group compared to the control group. During reversal training in day 1, 2 and 3, there was no significant difference in swim latency among the three groups. Results for the retention quadrant in the probe trials showed a significant decrease (p < 0.01) in amitriptyline group when compared to the control group. Conclusion: Results suggest that amitriptyline impairs learning and memory functions.