LAUSR

&NA; Previously the effects (0.01‐3.0 mg/kg) of post‐training SB‐699551 (a 5‐HT5A receptor antagonist) were reported in the associative learning task of autoshaping, showing that SB‐699551 (0.1 mg/kg) decreased lever‐press conditioned responses (CR) during short‐term (STM; 1.5‐h) or (3.0 mg/kg) long‐term memory (LTM; 24‐h); relative to the vehicle animals. Moreover, as pro‐cognitive efficacy of SB‐699551 was reported in the ketamine‐model of schizophrenia. Hence, firstly aiming improving performance (conditioned response, CR), in this work autoshaping lever‐press vs. nose‐poke response was compared; secondly, new set of animals were randomly assigned to SB‐699551 plus forgetting or amnesia protocols. Results show that the nose‐poke operandum reduced inter‐individual variance, increased CR and produced a progressive CR until 48‐h. After one week of no training/testing sessions (i.e., interruption of 216 h), the forgetting was observed; i.e., the CR% of control‐saline group significantly decreased. In contrast, SB‐699551 at 0.3 and 3.0 mg/kg prevents forgetting. Additionally, as previously reported the non‐competitive NMDA receptor antagonist dizocilpine (0.2 mg/kg) or the non‐selective cholinergic antagonist scopolamine (0.3 mg/kg) decreased CR in STM. SB‐699551 (0.3 mg/kg) alone also produced amnesia‐like effect. Co‐administration of SB‐699551‐dizocilpine or SB‐699551‐scopolamine reversed the SB‐699551 induced‐amnesic effects in LTM (24‐h). Nose‐poke seems to be a reliable operandum. The anti‐amnesic and anti‐forgetting mechanisms of amnesic SB‐699551‐dose remain unclear. The present findings are consistent with the notion that low doses of 5‐HT5A receptor antagonists might be useful for reversing memory deficits associated to forgetting and amnesia. Of course, further experiments are necessary.