ABSTRACT
RATIONALE: The serotonin (5-hydroxytryptamine (5-HT)) 5-HT7 receptor is localized in brain areas mediating memory; however, the role of this receptor on memory remains little explored. OBJECTIVE: First, demonstrating the associative nature of Pavlovian/instrumental autoshaping (P/I-A) task, rats were exposed (three sessions) to CS-US (Pavlovian autoshaping), truly random control, free operant, and presentations of US or CS, and they were compared with rats trained-tested for one session to the P/I-A procedure. Also, effects of the 5-HT7 receptor agonist LP-211 administered intraperitoneally after training was determined on short- (1.5 h) and long-term memory 24 and 48 h) and on scopolamine-induced memory impairment and cAMP production. METHODS: Autoshaping and its behavioral controls were studied. Other animals were subjected to an autoshaping training session and immediately afterwards were given (intraperitoneal) vehicle or LP-211 (0.1-10 mg/kg) and/or scopolamine (0.2 mg/kg) and tested for short-term memory (STM) and long-term memory (LTM); their brains were extracted for the cAMP ELISA immunoassay. RESULTS: P/I-A group produced the higher %CR. LP-211 did not affect STM; nonetheless, at 0.5 and 1.0 mg/kg, it improved LTM. The 5-HT7 receptor antagonist SB-269970 (SB; 10.0 mg/kg) alone had no effect; nevertheless, the LP-211 (1.0 mg/kg) LTM facilitation was reversed by SB. The scopolamine (0.2 mg/kg) induced-decrement in CR was accompanied by significant increased cAMP production. The scopolamine-induced decrement in CR and increments in cAMP were significantly attenuated by LP-211. CONCLUSIONS: Autoshaping is a reliable associative learning task whose consolidation is facilitated by the 5-HT7 receptor agonist LP-211.
Subject(s)
Amnesia/drug therapy , Association Learning/drug effects , Behavior, Animal/drug effects , Memory, Long-Term/drug effects , Memory, Short-Term/drug effects , Piperazines/pharmacology , Receptors, Serotonin/physiology , Animals , Male , Piperazines/administration & dosage , Rats , Rats, WistarABSTRACT
Diverse studies indicate that the attention deficit hyperactivity disorder (ADHD) is associated with alterations in encoding processes, including working or short-term memory. Some ADHD dysfunctional domains are reflected in the spontaneously hypertensive rat (SHR). Here SHR-saline group showed significantly poor STM and LTM relative to SD and WKY saline rats. SD and WKY rats treated with d-amphetamine displayed better STM and LTM, compared to SD-vehicle, WKY-vehicle or SHR-d-amphetamine groups.
