The effect of paroxetine, venlafaxine and bupropion administration alone and combined on spatial and aversive memory performance in rats

Background: The use of antidepressants in combination is common practice following non-response to single antidepressant agents. Nevertheless, the scientific literature lacks preclinical studies regarding the combined administration of antidepressants across multiple behavioral measures including, but not limited to, cognition. Hence, we aimed to determine the effects of paroxetine (PAR), venlafaxine (VEN) and bupropion (BUP) alone or combined (PAR + BUP or VEN + BUP) on spatial and affective memory tasks to advance the knowledge about the combined use of antidepressants in cognition. Methods: Adult rats received daily injections (15 days) of PAR (20 mg/kg, ip), VEN (20 mg/kg, ip), BUP (20 mg/kg, ip) alone or combined and were submitted to behavioral measures of spatial memory (radial-arm maze — RAM), aversive memory (passive avoidance — PA), open field (OF) and forced swimming (FST) tests. Results: In the RAM, VEN or VEN + BUP impaired learning, while short-term memory (STM) was impaired by PAR, BUP and their combination. VEN + BUP improved STM as compared to BUP. PAR impaired long-term memory (LTM). VEN or BUP alone impaired STM and long-term fear memory, whilst PAR + BUP or VEN + BUP did not induce significant alterations. Conclusions: The effects of VEN, PAR or BUP alone and in combination on measures of memory are variable and vary as a function of the pharmacodynamics profile of each drug as well as the specific memory paradigm.