| dc.description.abstract | The essential oil (EOs) extracted from plants Hesperozygis ringens and Lippia alba possess
anesthetic and sedative properties and is an alternative to traditional anesthetics used in
aquaculture for ease of handling and/or reduce stress. In this sense, the study aimed to
investigate the effects of these EOs on the physiology of fish, through physiological, biochemical
and endocrine indicators. In the article 1 was determined (a) the anesthetic activity of the EOs of
H. ringens (EOHR) and L. alba (EOLA) and (b) its effects on silver catfish (Rhamdia quelen) after
induction and recovery from anesthesia. Fish were subjected to one of the following treatments
for each EO: basal group, control or anesthetized (150, 300 or 450 uL L-1 EO), evaluating the
ventilatory rate (VR) during the induction period and thereafter transferred to anesthetics-free
tanks for recovery from anesthesia. At 0, 15, 30, 60 and 240 min of recovery, samples of plasma
and gills were collected to measure metabolic indicators and ionregulatory enzymes, respectively.
In the article 2, the effects of prolonged exposure to low EOHR concentrations were studied on
silver catfish. After 6 h of exposure to 0 (control), 30 or 50 uL L-1 EOHR added to water, it was
analyzed: VR, metabolic indicators of stress in plasma, enzyme activity in liver, and expression of
pituitary hormones (growth hormone - GH, prolactin - PRL and somatolactina - SL). In the
manuscript, (a) evaluated the effectiveness of anesthesia EOLA on gilthead sea bream (Sparus
aurata) and (b) we investigated the effects of 35 uL L-1 EOLA and 2-phenoxyethanol (2-PHE) on
the stress response in gilthead sea bream undergoing persecution. After 4 h of exposure, the
plasma was sampled (for the determination of cortisol, metabolites and osmolality), brain and
pituitary (to evaluate the expression of endocrine indicators). In the article 1, anesthesia with EOs
caused changes in some parameters measured in silver catfish, but did not prevent the
restoration of most of the indicators assessed after 240 min of recovery. In the article 2, 50 uL L-1
EOHR led to an increase of glucose, lactate, protein and osmolality, as well as an increase in
metabolic enzyme activity and reduced expression of GH and SL. In the manuscript, gilthead sea
bream exposed to EOLA, stressed or not, exhibited higher levels of cortisol, glucose, lactate and
osmolality. EOLA exposure added to the stress reduced the expression levels of CRH-BP
(corticotropin releasing hormone bound to protein). PRL expression was reduced in the stressed
control group and after exposure to EOLA and 2-PHE in fish not stressed. Higher expression of
pro-opiomelanocortin (POMC) "a" and "b" were observed in fish stressed and exposed to EOLA
and 2-PHE, respectively. We conclude that: (1) the EOLA is more efficient for silver catfish that
EOHR in anesthesia concentrations; (2) for sedating the fish, it is recommended 30 uL EOHR L-1
(or less); (3) the EOLA was effective as an anesthetic for gilthead sea bream at 100-300 uL L-1,
but for 4 h exposure, the 2-PHE was more effective in preventing the stress response. | |
