Serotonergic mechanisms are involved in antidepressant-like effects of bisbenzylisoquinolines liensinine and its analogs isolated from the embryo of Nelumbo nucifera Gaertner seeds in mice

Objectives We attempted to ascertain if bisbenzylisoquinoline alkaloids, liensinine and isoliensinine from Nelumbo nucifera Gaertner have antidepressant‐like effects and compare the effects with those previously obtained by their analogue neferine. Methods Using mice, the forced swimming test (FST) was carried out after treatment with liensinine, isoliensinine and neferine. Key findings Liensinine and isoliensinine elicited antidepressant‐like effects in mice after the FST. Anti‐immobility effects of liensinine and isoliensinine were antagonized by the 5‐hydroxytryptamine1A (5‐HT1A) receptor antagonist WAY 100635, but not by the α1‐adrenoceptor antagonist prazosin. The anti‐immobility effects of liensinine, isoliensinine and neferine were blocked by pretreatment with p‐chlorophenylalanine (PCPA), which depletes serotonin (5‐HT). Conclusions These data suggest that liensinine and isoliensinine from Nelumbo nucifera Gaertner have antidepressant‐like effects and that antidepressant‐like effects of liensinine and its analogues are closely related to serotonergic mechanisms.