α‐Pinene Influence on Pulpal Pain‐Induced Learning and Memory Impairment in Rats Via Modulation of the GABAA Receptor

Background: This study investigated the effect of central administration of α‐pinene and the interaction of α‐pinene with GABAA receptor on pulpal nociception‐induced changes in learning and memory performances in rats. Materials and Methods: Sixty‐six adult male Wistar rats were used. Pulpal nociception was induced by intradental application of capsaicin (100 μg/rat). α‐pinene (0.1, 0.2, and 0.4 μg/rat) was injected centrally 10 min before the administration of capsaicin. In addition, α‐pinene (0.4 μg/rat) was co‐injected with bicuculline (0.5 μg/rat). Spatial and passive avoidance learning and memory were assessed using Morris water maze (MWM) and shuttle box tasks, respectively. Results: Experimental results of the MWM test showed that capsaicin increases escape latency and distance traveled to the hidden platform (P < 0.01). The effect was prohibited by α‐pinene at the dose of 0.4 μg/rat. Moreover, capsaicin‐treated animals spent less time in the target zone than capsaicin + α‐pinene (0.4 μg/rat)‐treated rats (P < 0.05). In the shuttle box test, α‐pinene (0.2 μg and 0.4 μg) prevented an increased number of acquisition trials and time spent in the dark chamber induced by capsaicin, whereas it increased step‐through latency (P < 0.01). However, the effects of α‐pinene (0.4 μg/rat) in both tests were prohibited by bicuculline (0.5 μg/rat). Conclusion: The data showed that central administration of α‐pinene might reduce pulpalgia‐induced learning and memory impairment, at least partially, via modulation of GABAA receptors.