Essential oils from leaves of Pilocarpus pennatifolius and Cordia verbenacea in silver catfish (Rhamdia quelen): cardiovascular aspects and participation of the GABAergic system in the sedative and anesthetics effects

Abstract This study evaluated the heart rate of silver catfish (Rhamdia quelen) exposed to a sedative concentration of Cordia verbenacea (CVOL) and Pilocarpus pennatifolius (PPOL) leaves essential oils (EOs) using ultrasound device with color doppler. Furthermore, it aimed to establish the possible involvement of the GABAergic receptor complex benzodiazepine site (BDZ) in their sedative and/or anesthetic effects using juvenile silver catfish as experimental model. Fish were transfered to baths with 150 µM diazepam [DZP], DZP (150 µM) in association with EOs sedative and anesthetic concentrations, respectively, 20 and 300 mg L-1 of CVOL or PPOL, and the EOs alone. Juveniles were exposed to bath containing flumazenil [FLU] (5 µM) or water to recover. DZP showed a positive interaction with the EOs to achieve sedation and anesthesia. Fish exposed to DZP, DZP in association with EOs and EOs alone showed a higher recovery score when exposed to FLU, suggesting the participation of the benzodiazepine site of GABAa receptor complex in the effect of CVOL and PPOL. The major component of CVOL was α-pinene (34.8%) and of PPOL was 2-undecanone (57.2%). Both EOs showed sedative effect at 20 mg L-1 and PPOL induced anesthesia at 300 mg L-1, without adverse effects.