Quelen Iane Garlet

Anesthetic activity of Brazilian native plants in silver catfish (Rhamdia quelen)

There is an increasing demand for inexpensive and safe anesthetics that can reduce fish stress caused by some procedures such as capture and handling. In this context, the present study evaluated the potential of essential oils (EO) of three Brazilian native plants (Hesperozygis ringens, Lippia sidoides and Ocotea acutifolia) as anesthetics for the silver catfish - Rhamdia quelen. Moreover, an analysis was made of the chemical composition of these oils and their influence on stress parameter. EO of H. ringens and O. acutifolia were effective as anesthetics, without behavioral side effects. EO of O. acutifolia (150 µL L-1) promoted an increase in blood glucose level. Regarding to the composition, pulegone accounts for 96.63% of the EO of H. ringens, and caryophyllene oxide amounts to 56.90% of the EO of O. acutifolia. Two chemotypes, thymol and carvacrol (68.40% and 67.89%, respectively) were verified for EO of L. sidoides. Both samples of EO of L. sidoides showed anesthetic activity in silver catfish, but exposure also caused loss of mucus and mortality. Thus, only the EO of H. ringens and O. acutifolia are advised for anesthetic use

Anesthesia and transport of fat snook Centropomus parallelus with the essential oil of Nectandra megapotamica(Spreng.) Mez

This study analyzed the chemical composition and anesthetic potential of essential oil (EO) of Nectandra megapotamica in fat snook (Centropomus parallelus). For the extraction of EO by hydrodistillation, leaves were separated in young (EO-Y) or old (EO-O), and the chemical composition of the EOs was determined by CG-MS. The anesthetic potential was assessed by the evaluation of induction and recovery time of anesthesia and stress response from anesthesia and transport. Three experiments were carried out: i) four different concentrations of each EO were tested to evaluate anesthesia induction and recovery time; ii) two concentrations of EO-O were tested for the evaluation of its effects on stress parameters (glucose, lactate, and Na+ and K+ plasma levels) caused by anesthesia; and iii) fish were transported in plastic bags, supplied with two concentrations of EO-O for the evaluation of water quality and mortality. All experiments were performed on fish acclimated to 0 and 33 ppt salinity. The main constituents of the Y and O-EOs were bicyclogermacrene (46.5/34.6%), α-pinene (26.8/26.2%), β-pinene (7.9/12.3%), and germacrene D (9.6/9.1%). Mild sedation was achieved at 30 °L L-1(1.3-3.2 min) and deep anesthesia at 150 °L L-1(5.6-8.0 min) with both EOs. The recovery time ranged from 1-10 min. The EO-O was not able to avoid the stress of anesthesia evidenced by elevated glucose and lactate plasma levels observed in all groups. Plasma levels of Na+ and K+ were not significantly affected by treatments. During transport, the use of EO-O did not prevent deterioration in water quality and the post-transport mortality. In conclusion, the EO of N. megapotamica has anesthetic activity in fat snook, but it was not able to prevent the stress of anesthesia and transport.

Sedative and anesthetic activities of the essential oils of Hyptis mutabilis (Rich.) Briq. and their isolated components in silver catfish (Rhamdia quelen)

This study evaluated the sedative and anesthetic effects of the essential oils (EO) of Hyptis mutabilis (Rich.) Briq. and their isolated components on silver catfish (Rhamdia quelen). Quantitative chemical differences between the EOs obtained from leaves and inflorescences were verified, and a new chemotype rich in globulol was described. Although there were no significant differences in the time of induction for sedation and anesthesia between the EOs, only the leaf EO at 344 mg/L anesthetized all fish without side effects. Fractionation of the leaf EO was carried out by column chromatography. The isolated compounds [(+)-1-terpinen-4-ol and (-)-globulol] showed different activity from that detected for the leaf EO in proportional concentrations and similar sedation to a eugenol control at 10 mg/L. However, fish exposed to 1-terpinen-4-ol (3 and 10 mg/L) did not remain sedated for 30 min. Anesthesia was obtained with 83-190 mg/L globulol, but animals showed loss of mucus during induction and mortality at these concentrations. Synergism of the depressor effects was detected with the association of globulol and benzodiazepine (BDZ), compared with either drug alone. Fish exposed to BDZ or globulol+BDZ association showed faster recovery from anesthesia in water containing flumazenil, but the same did not occur with globulol. In conclusion, the use of globulol in aquaculture procedures should be considered only at sedative concentrations of 10 and 20 mg/L, and its mechanism of action seems not to involve the GABAA-BDZ system.

Effects of anesthesia with the essential oil of Ocimum gratissimum L. in parameters of fish stress

The effects of anesthesia with the essential oil of Ocimum gratissimum (EOO) in parameters of stress after handling were investigated in silver catfish (Rhamdia quelen). EOO was obtained from the aerial parts by hydrodistillation. Juveniles were anesthetized with 70 or 300 mg L-1 EOO and submitted to air exposure for 1 minute. The fishes were sampled immediately or transferred to anesthetic-free aquaria until sampling. In the first experiment, juveniles had their blood collected at 0, 1, 4, and 8 h after handling to assay plasma cortisol and blood glucose levels. The unanesthetized animals were restrained manually for blood collection. In the second experiment, water samples of the recovery aquaria were collected to evaluate net ion fluxes at 0 - 4 h and 4 - 8 h. Water and ethanol controls were also performed under the same conditions. The results showed that the cortisol levels did not differ among the treatments. Hyperglycemia was verified in fish exposed to 70 and 300 mg L-1 EOO at 1 h and 4 h after handling. After 8 h, cortisol and glucose concentrations were lower or similar than those from immediately after handling for all treatments. EOO anesthesia prevented Na+ efflux observed in the control groups in both flux periods. There were net Cl- and K+ effluxes at 0 - 4 h and influxes at 4 - 8 h after handling in most treatments, and these fluxes did not differ among the treatments. The results suggest that EOO did not impair stress recovery and did not act as an additional handling stressor in silver catfish.

Effect of (+)-dehydrofukinone on GABAA receptors and stress response in fish model

(+)-Dehydrofukinone (DHF) is a major component of the essential oil of Nectandra grandiflora (Lauraceae), and exerts a depressant effect on the central nervous system of fish. However, the neuronal mechanism underlying DHF action remains unknown. This study aimed to investigate the action of DHF on GABAA receptors using a silver catfish (Rhamdia quelen) model. Additionally, we investigated the effect of DHF exposure on stress-induced cortisol modulation. Chemical identification was performed using gas chromatography-mass spectrometry and purity was evaluated using gas chromatography with a flame ionization detector. To an aquarium, we applied between 2.5 and 50 mg/L DHF diluted in ethanol, in combination with 42.7 mg/L diazepam. DHF within the range of 10-20 mg/L acted collaboratively in combination with diazepam, but the sedative action of DHF was reversed by 3 mg/L flumazenil. Additionally, fish exposed for 24 h to 2.5-20 mg/L DHF showed no side effects and there was sustained sedation during the first 12 h of drug exposure with 10-20 mg/L DHF. DHF pretreatment did not increase plasma cortisol levels in fish subjected to a stress protocol. Moreover, the stress-induced cortisol peak was absent following pretreatment with 20 mg/L DHF. DHF proved to be a relatively safe sedative or anesthetic, which interacts with GABAergic and cortisol pathways in fish.

Larvicidal activity of Brazilian plant essential oils against Coenagrionidae larvae.

ABSTRACT Odonate larvae can be serious pests that attack fish larvae, postlarvae, and fingerlings in fish culture tanks, causing significant loss in the supply and production of juveniles. This study reports a screen of the essential oils (EOs) of Nectandra megapotamica (Sprengel) Mez, Nectandra grandiflora Nees, Hesperozygis ringens (Bentham) Epling, Ocimum gratissimum L., Aloysia gratissima (Gillies & Hooker) Troncoso, and Lippia sidoides Chamisso against Coenagrionidae larvae. In addition, the most effective EO and its 50% lethal concentration (LC50) and chemical analysis are described. The larvae of Acanthagrion Selys, Homeoura Kennedy, Ischnura Charpentier, and Oxyagrion Selys were used to assess the EO effects. EO obtained from H. ringens, O. gratissimum, and L. sidoides showed the highest larvicidal effects at 19 h of treatment.Themajor constituents of theEOofH. ringens include pulegone and limonene, while eugenol and Z-&bgr;-ocimene predominate in the EO of O. gratissimum, and carvacrol and &pgr;-cymene were the major compounds of the EO of L. sidoides. Leaf EOs from H. ringens, O. gratissimum, and L. sidoides showed activity against Coenagrionidae larvae at similar concentrations with LC50s of 62.92, 75.05, and 51.65 µl liter-1, respectively, and these were considered the most promising treatments.

S-(+)- and R-(-)-linalool: a comparison of the in vitro anti-Aeromonas hydrophila activity and anesthetic properties in fish

Linalool is the main compound of many essential oils and occurs in two isomeric forms: S-(+)- and R-(-)-linalool. This study aimed to determine if linalool isomers have different antimicrobial and anesthetic properties in fish. For this purpose, these compounds were previously isolated from Lippia alba (Mill.)N. E. Brown and Ocimum americanum L. essential oils. Antimicrobial effects were evaluated through the microdilution test against Aeromonas hydrophila, an important fish disease etiologic agent. Induction time until sedation, anesthesia and recovery time were determined in silver catfish (Rhamdia quelen) through bath exposure (60, 180, 300 or 500 μL L-1). The results showed different biological properties for the isomers being S-(+)-linalool the only active against A. hydrophila at 3.2 mg mL-1. The sedation was induced without differences between the compounds, however R-(-)-linalool promoted faster anesthesia. There were no differences regarding the recovery time of the animals exposed to the linalool isomers. Although both S-(+)- and R-(-)-linalool can be used for sedative purposes, their use in A. hydrophila infection is inadvisable due to the high effective concentration. Considering anesthesia as the main objective, the R-(-)-linalool demonstrated clear advantages at lower concentration.

Anesthetic activity of the essential oil of Ocimum americanum in Rhamdia quelen (Quoy & Gaimard, 1824) and its effects on stress parameters

The aim of this study was to evaluate the anesthetic activity of the essential oil (EO) of Ocimum americanum L. in silver catfish (Rhamdia quelen ). In the first experiment, the depressor effects and chemical composition of the leaf EO (LEO) and inflorescence EO (IEO) were compared. Juveniles (n = 10) were placed in aquaria containing different concentrations of EO (25 - 500 mg L-1) to determine the point at which anesthesia was induced and the length of the recovery period. In the following experiment, the effects of 300 and 500 mg L-1 LEO exposure on stress parameters (plasma cortisol, glucose and sodium levels) after air exposure for 1 min were assayed. Fish (n = 10 per sampling time) were sampled immediately or transferred to anesthetic-free aquaria until sampling (15, 30, 60 or 240 min). LEO was composed mainly of β-linalool and 1,8-cineole in similar proportions, whereas IEO showed β-linalool as major compound. Anesthesia was obtained in silver catfish with 200-500 mg L-1 between 4-8 min for LEO and 6-16 min for IEO. Lower EO concentrations did not reach anesthetic stage up to 30 min. LEO used as anesthetic prevented the cortisol increase and sodium loss induced by aerial exposure. Glucose levels were raised in catfish exposed to LEO compared to basal group (not air exposed) in almost all observation times. EO of O. americanum obtained from leaves was considered suitable to anesthetic procedures due to its fast induction and handling-induced stress prevention.

(+)-Dehydrofukinone modulates membrane potential and delays seizure onset by GABAa receptor-mediated mechanism in mice

ABSTRACT (+)‐Dehydrofukinone (DHF), isolated from Nectandra grandiflora (Lauraceae) essential oil, induces sedation and anesthesia by modulation of GABAa receptors. However, no study has addressed whether DHF modulates other cellular events involved in the control of cellular excitability, such as seizure behavior. Therefore, the aim of the present study was to investigate the effect of DHF on cellular excitability and seizure behavior in mice. For this purpose, we used isolated nerve terminals (synaptosomes) to examine the effect of DHF on the plasma membrane potential, the involvement of GABAa receptors and the downstream activation of Ca2 + mobilization. Finally, we performed an in vivo assay in order to verify whether DHF could impact on seizures induced by pentylenetetrazole (PTZ) in mice. The results showed that DHF induced a GABA‐dependent sustained hyperpolarization, sensitive to flumazenil and absent in low‐[Cl−] medium. Additionally, (1–100 &mgr;M) DHF decreased KCl‐evoked calcium mobilization over time in a concentration‐dependent manner and this effect was prevented by flumazenil. DHF increased the latency to myoclonic jerks (10 mg/kg), delayed the onset of generalized tonic‐clonic seizures (10, 30 and 100 mg/kg), and these effects were also blocked by the pretreatment with flumazenil. Our data indicate that DHF has anticonvulsant properties and the molecular target underlying this effect is likely to be the facilitation of GABAergic neuronal inhibition. The present study highlights the therapeutic potential of the natural compound DHF as a suppressor of neuronal excitability. Graphical abstract Figure. No Caption available. Highlights(+)‐Dehydrofukinone blunted KCl‐evoked depolarization and calcium influx.(+)‐Dehydrofukinone effects on neuronal excitability are blocked by flumazenil.(+)‐Dehydrofukinone delays pentylenetetrazole‐induced seizures in mice.GABAa receptors play a role in the anticonvulsant effect of (+)‐dehydrofukinone.

Anesthesia of Epinephelus marginatus with essential oil of Aloysia polystachya: an approach on blood parameters

This study investigated the anesthetic potential of the essential oil (EO) of Aloysia polystachya in juveniles of dusky grouper (Epinephelus marginatus). Fish were exposed to different concentrations of EO of A. polystachya to evaluate time of induction and recovery from anesthesia. In the second experiment, fish were divided into four groups: control, ethanol and 50 or 300 µL L-1 EO of A. polystachya, and each group was submitted to induction for 3.5 min and recovery for 5 or 10 min. The blood gases and glucose levels showed alterations as a function of the recovery times, but Na+ and K+ levels did not show any alteration. In conclusion, the EO from leaves of A. polystachya is an effective anesthetic for dusky grouper, because anesthesia was reached within the recommended time at EO concentrations of 300 and 400 µL L-1. However, most evaluated blood parameters showed compensatory responses due to EO exposure.