Akademik Veri Yönetim Sistemi
Aquaculture, cilt.560, 2022 (SCI-Expanded)
© 2022 Elsevier B.V.Menthol has been recommended for fish anaesthesia in recent studies. However, no observations of brain electrical activity, electromyography and electrocardiogram have been reported to date in in vivo experiments using menthol. In order to fill the gaps at the electrophysiological and behavioural levels, juveniles of tambaqui, Colossoma macropomum were used as live models and subjected to two experimental conditions: I - Behavioural assessment using menthol at 100 mg.L−1; II - Characterization of electroencephalography (EEG), electromyography (EMG), electrocardiography (ECG), and opercular beat rate (OBR) using menthol at 100 mg.L−1. The fish were assayed into three groups for all characterizations: (a) control; (b) ethanol (vehicle control); and (c) menthol at100 mg.L−1, nine animals per group were used for each marker, one fish being considered a replicate (n = 9) and used only once. On the EEG, it was observed that menthol induced decreased mean power in cerebral activity, indicating the deepening of the anaesthesia, showing that menthol led to reversible CNS depression, with the resumption of mean power after washout, devoid of seizures or any other observable alterations. The EMG showed a decreased skeletal muscle tone, with no excitability or muscle spasms. The ECG showed a reduced heart rate, however, menthol did not elicit important alterations during induction or recovery in the duration of the QRS complex (ventricular depolarization). For all records the sinus rhythm was maintained, menthol did not lead to deleterious QT interval (ventricular contraction) prolongation, and the RR interval (time between two successive QRS complexes) corroborated a reversible anaesthetic effect. OBR showed the maintenance of the ventilatory rate during induction and recovery, which indicates a reduced risk of causing severe hypoxia. Overall, the electrophysiological data reinforced the results observed in the behavioural assessment. The findings indicate that menthol proved to be an effective and safe anaesthetic for tambaqui juveniles, as it did not cause major changes in the pattern of tracings, and therefore, should be considered a standard chemical compound of plant origin for the purpose of full immobilization and general anaesthesia of C. macropomum.