The brain endocannabinoid system has been shown to play a role in many physiological processes, including mood, learning and memory. It is also involved in the pathogenesis of anxiety, depression, mood disorders, as well as neurodegenerative disorders, although the exact mechanisms by which cannabinoid receptors interfere in these disorders are not well established. The aim of the present study was to evaluate the effects of cannabinoid ligands HU-210 (CB1 receptor agonist) and SR 141716A (CB1 receptor antagonist) on learning and memory processes of rats with depressive-like state, induced by bilateral olfactory bulbectomy. The bilateral olfactory bulbectomy (OBX) is a validated model of depression, which can be used also as an animal model of Alzheimer's disease. We found that the subchronic treatment of OBX rats with HU 210 and SR 141716A exerted modulatory effect on rat's performance in both active avoidance (shuttle box) and passive avoidance (step through) tests. HU 210 ameliorated the memory deficits of OBX rats; however, the scores of the sham-operated controls had not been reached. SR 141716A modified the avoidance performance in OBX rats and showed a memory enhancing effect in the sham-operated rats. Our findings suggest that CB1 receptors might be involved in avoidance learning and memory acquisition in OBX rats.
Olfactory bulbectomy (OBX) is an experimental model of depression, which has recently been used as a model of Alzheimer's disease due to the development of neurodegenerative changes in the brain. The OBX model in rodents is accompanied by biochemical, morphological and structural changes in the brain, as well
Dysfunction of the endocannabinoid system has been related to depressive-like behavior. In our study, bilateral olfactory bulbectomy (OBX) was used as an animal model of depression. We evaluated the effect of the selective CB1-antagonist SR-141716A (Rimonabant) on the exploratory and locomotor activity of OBX-rats. Rimonabant was administered intragastrically for 14 days to OBX-rats, divided into 3 experimental groups, where the drug was given before; immediately (1-14 days) after; or 14 days (14-28 day) after OBX. Exploratory and locomotor activity of OBX-rats was tested in an Opto-Varimex apparatus. SR-141716A, administered subchronically, intragastrically exerted locomotor stimulating effects in OBX- and sham-operated rats, while the exploratory activity was not affected. The time interval for the drug administration is of significance for the manifestation of the effects on locomotor activity in OBX-rats. SR-141716A applied 14 days before OBX or after the development of a depressive-like state (14-28 days after OBX), but not immediately after OBX (1-14 days) aggravated the OBX-induced hyperlocomotor state.
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