Involvement of the serotonergic system in the antidepressant-like effect of 1-(phenylselanyl)-2-(p-tolyl)indolizine in mice

Rationale Depression is a mental disorder that affects approximately 280 million people worldwide. In the search for new treatments for mood disorders, compounds containing selenium and indolizine derivatives show promising results. Objectives and methods To evaluate the antidepressant-like effect of 1-(phenylselanyl)-2-( p -tolyl)indolizine (MeSeI) (0.5–50 mg/kg, intragastric—i.g.) on the tail suspension test (TST) and the forced swim test (FST) in adult male Swiss mice and to elucidate the role of the serotonergic system in this effect through pharmacological and in silico approaches, as well to evaluate acute oral toxicity at a high dose (300 mg/kg). Results MeSeI administered 30 min before the FST and the TST reduced immobility time at doses from 1 mg/kg and at 50 mg/kg and increased the latency time for the first episode of immobility, demonstrating an antidepressant-like effect. In the open field test (OFT), MeSeI did not change the locomotor activity. The antidepressant-like effect of MeSeI (50 mg/kg, i.g.) was prevented by the pre-treatment with p -chlorophenylalanine ( p -CPA), a selective tryptophan hydroxylase inhibitor (100 mg/kg, intraperitoneally—i.p. for 4 days), with ketanserin, a 5-HT 2A/2C receptor antagonist (1 mg/kg, i.p.), and with GR113808, a 5-HT 4 receptor antagonist (0.1 mg/kg, i.p.), but not with WAY100635, a selective 5-HT 1A receptor antagonist (0.1 mg/kg, subcutaneous—s.c.) and ondansetron, a 5-HT 3 receptor antagonist (1 mg/kg, i.p.). MeSeI showed a binding affinity with 5-HT 2A , 5 -HT 2C , and 5-HT 4 receptors by molecular docking. MeSeI (300 mg/kg, i.g.) demonstrated low potential to cause acute toxicity in adult female Swiss mice. Conclusion In summary, MeSeI exhibits an antidepressant-like effect mediated by the serotonergic system and could be considered for the development of new treatment strategies for depression.