Impact of amitriptyline on learning and memory

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.

Effect of Aqueous Extract ofCrocus sativusL. on Morphine-Induced Memory Impairment

In the present study, the effect of aqueous extracts of saffron on morphine-induced memory impairment was investigated. On the training trial, the mice received an electric shock when the animals were entered into the dark compartment. Twenty-four and forty-eight hours later, the time latency for entering the dark compartment was recorded and defined as the retention trial. The mice were divided into (1) control, (2) morphine which received morphine before the training in the passive avoidance test, (3–5) three groups treated by 50, 150 and 450 mg/kg of saffron extract before the training trial, and (6 and 7) the two other groups received 150 and 450 mg/kg of saffron extract before the retention trial. The time latency in morphine-treated group was lower than control (P< 0.01). Treatment of the animals by 150 and 450 mg/kg of saffron extract before the training trial increased the time latency at 24 and 48 hours after the training trial (P< 0.05 andP< 0.01). Administration of both 150 and 450 mg/kg doses of the extract before retention trials also increased the time latency (P< 0.01). The results revealed that the saffron extract attenuated morphine-induced memory impairment.

Cognitive-Enhancing Effects of Polygalasaponin Hydrolysate in Aβ25–35-Induced Amnesic Mice

Polygalasaponins are the major active constituents ofPolygala tenuifoliaexhibiting antiamnesic activity, but their applications are limited due to their toxicities. Evidence showed that the toxicities can be attenuated by hydrolysis. Herein, effects of a hydrolysate of polygalasaponins (HPS) on cognitive impairment induced by Aβ25−35were assessed by Morris water maze and step-through passive avoidance tests. The impaired spatial reference memory was improved by HPS (50 and 100 mg/kg). In the acquisition trial of step-through test, HPS (50 and 100 mg/kg) increased the latency into the dark chamber and decreased the error frequency significantly (). However, no significant change was observed during the retention trial. Additionally, HPS increased the corresponding SOD activities (62.34%, 22.09%) and decreased MDA levels (28.21%, 32.35%) in both cortex and hippocampus as compared to model animals. These results show that HPS may be a useful treatment against amnesia probably via its antioxidant properties.