Antidepressant and anti-amnesic effects of the aqueous lyophilisate of the leaves of Leptadenia arborea on an animal model of cognitive deficit associated depression.

Leptadenia arborea (Asclepiadaceae) is a plant used in traditional medicine to treat syphilis, migraine, and mental illnesses. The aim of our study was to investigate possible antidepressant and anti-amnesic effects of the aqueous lyophilisate of the leaves of Leptadenia arborea in an animal model of cognitive deficit associated depression. Swiss albino adult mice of both sexes were used for this study. A 14-day combined stress model was used to induce depression with early cognitive deficits. The forced swimming test, the open field test and plasma corticosterone level were used to assess antidepressant-like effect. The novel object recognition task (NORT), the Morris Water Maze (MWM) and neurochemical analysis of hippocampal acetylcholinesterase activity was also carried out to assess memory integrity. The aqueous lyophelisate of L. arborea increased swimming time and decreased immobility time in the forced swimming test. In the open field test they was no difference in the number of lines crossed between groups, and the lyophilisate-treated mice spent more time in the centre compared to the control. The lyophilisate decreased the plasma level of corticosterone compared to the control. The lyophilisate decreased the latency to reach the hidden platform and increased the time spent in the target quadrant in the MWM. The lyophilisate also increased the time of exploration of the novel object in the NORT and decreased the acetylcholinesterase activity in the hippocampus. L. arborea effects were decreased when it was co-administered with pCPA. Results suggest that the aqueous lyophilisate of the leaves of L. arborea possess antidepressant-like and anti-amnesic effects.

Combined corticosterone treatment and chronic restraint stress lead to depression associated with early cognitive deficits in mice.

Many models, such as chronic mild stress, chronic stress or chronic corticosterone injections are used to induce depression associated with cognitive deficits. However, the induction period in these different models is still long and face constraints when it is short such as in the chronic mild stress done in a minimum period of 21 days. This study aimed to characterize a model of depression with early onset cognitive deficit. 14 days combined chronic injection of corticosterone followed by 2 h restraint stress using a restrainer was used to induce depression with early cognitive deficit onset. The forced swim test, sucrose test and plasma corticosterone concentration were used to assess depression-like characteristics. The Morris water maze, novel object recognition task, as well as hippocampal acetylcholinesterase activity were used to assess cognitive deficit. The combined corticosterone injection + chronic restraint stress group presented with marked depression-like behaviour and a higher plasma corticosterone concentration compared to corticosterone injection alone and restraint stress alone. It also showed an alteration in the learning process, memory deficit as well as increased acetylcholinesterase activity compared to corticosterone injection and restraint stress alone groups. These findings suggest that the combined corticosterone administration and chronic restraint stress can be used not only as an animal model for severe depression, but also for depression with early onset cognitive deficit.