Evaluation of neurotransmitters involved in the anxiolytic and panicolytic effect of the aqueous fraction of Paullinia cupana (guaraná) in elevated T maze

This study investigated the effects of repeatedly administration of an aqueous fraction of Paullinia cupana Kunth, Sapindaceae (guaraná) seeds (8 mg/kg) on rats submitted to the elevated T-maze, model of generalized anxiety and panic disorders. The selective serotonin reuptake inhibitor paroxetine (3 mg/kg), was used as a positive control. To evaluate possible neurotransmissions involvement, ineffective doses of metergoline (3 mg/kg - non-selective serotonin receptor antagonist), sulpiride (20 mg/kg - non-selective dopaminergic receptor antagonist) or ketamine (0.125 mg/kg - non-selective glutamate receptor antagonist) were acutely administered in association with the aqueous fraction of P. cupana. Both aqueous fraction and paroxetine decrease the inhibitory avoidance latencies of the elevated T-maze, indicating anxiolytic effect and increased one-way escape latencies from the open arm of the elevated T-maze, indicating a panicolytic effect. The pretreatment with metergoline, sulpiride and ketamine blocked the anxiolytic effect of aqueous fraction. The panicolytic effect of aqueous fraction was blocked by both metergoline and sulpiride. These results show that the serotonergic, dopaminergic and glutamatergic neurotransmission systems are involved in anxiolytic effect promoted by aqueous fraction, whereas only the serotonergic and the dopaminergic neurotransmission systems are involved in the panicolytic effect promoted by aqueous fraction of P. cupana. The effects produced by paroxetine, were blocked only by metergoline, validating this experimental procedure.