The 5-HT1A agonist 8-OH-DPAT dose-dependently interferes with the establishment and the expression of lithium-induced conditioned rejection reactions in rats

Rationale: The present experiments evaluated the potential of the 5-HT1A agonist, 8-OH-DPAT (DPAT), which reduces serotonin availability, to interfere with both the establishment and with the expression of lithium-induced conditioned rejection reactions (experiment 1) and lithium-induced taste avoidance (experiment 2). Objectives: To determine the effect of reduced serotonin availability on conditioned rejection reactions, a rat model of nausea. Methods: Rats were injected with 8-OH-DPAT [at doses of 0.0 (saline), 0.0 1 or 0.1 mg/kg, SC] 30 min prior to exposure to 0.1% saccharin solution by intra-oral infusion (experiment 1) or by bottle presentation (experiment 2). Immediately following saccharin exposure, rats were injected with 20 ml/kg lithium chloride (0.15 M) or 20 ml/kg saline solution. On each of three test trials, rats were injected with DPAT [0.0 (saline), 0.01 and 0.1 mg/kg, SC; counterbalanced order], 30 min prior to exposure to saccharin solution by intra-oral infusion (experiment 1) or by a two-bottle test (experiment 2: saccharin and water). Results: DPAT interfered with both the establishment (at a dose of 0.1 mg/kg, SC) and with the expression (at doses of 0.01 and 0.1 mg/kg, SC) of lithium-induced conditioned rejection reactions; however, DPAT did not modulate taste avoidance in a consumption test. Conclusions: These results indicate that conditioned rejection reactions, but not taste avoidance, can be attenuated by the anti-emetic agent, 8-OH-DPAT.