Astaxanthin helps increase physical stress resistance in baby black tiger shrimp
This study aimed to determine whether increasing astaxanthin content in the body through dietary supplementation in juvenile Penaeus monodon can enhance antioxidant capacity and resistance to heat and stress stress. osmotic capacity or not. Total blood antioxidant status (TAS) and superoxide dismutase (SOD) were chosen as indicators of the antioxidant capacity of shrimp. Resistance to heat stress and osmotic stress is demonstrated by shrimp resilience and hemolytic aspartate aminotransferase (AST) and alanine aminotransferase (ALT). After 5 days, black tiger shrimp were fed a diet supplemented with 0 or 80 mg astaxanthin/kg for 8 weeks so that the juveniles had two levels of astaxanthin. The shrimp are then subjected to rapid changes in water temperature (27 to 5o C) and/or salinity (32 ‰ to 0 ‰) for 5 minutes. Treated shrimp had significantly higher astaxanthin content in their bodies than control shrimp. The mean recovery rate in treated shrimp (56%) was significantly higher than that in control shrimp (48%) suggesting that astaxanthin supplementation improved resistance to heat and osmotic stress. Heat stress had a more profound effect than osmotic stress on shrimp recovery, as indicated by the difference in recovery, 73% versus 24%. TAS was improved and SOD was reduced thanks to the presence of astaxanthin in the diet. Enhancement of antioxidant capacity with dietary astaxanthin and, consequently, improved resilience to heat and osmotic stress demonstrated that astaxanthin is a ‘semi-essential’ nutrient for black tiger shrimp. The presence of astaxanthin may become important when animals are subjected to physiological stress caused by abiotic changes. However, complex interactions between thermal and osmotic stress as well as improvements in resistance brought about by dietary astaxanthin have been observed. The hepatopancreatic function of shrimp may have been improved by dietary astaxanthin because the hemolymph AST of control shrimp was significantly higher than that of treated shrimp. However, the hemolymph AST and ALT contents of shrimp did not reflect the improvement in health following thermal and osmotic stresses, respectively.
While an organism is subjected to stresses such as chemical, physical, biological (i.e. pathogen infection) due to sudden lack of oxygen, abnormal oxidative reactions during aerobic metabolism lead to formation of excess singlet oxygen (Ranby and Rabek, 1978) and free radicals are subsequently produced (sometimes called ‘‘free radicals’’). These radicals can weaken lipids, proteins, carbohydrates and nucleotides (Yu, 1994), which are important parts of cell components, including membranes, enzymes and DNA. Radical damage can be very significant as it can take place as a chain reaction. Therefore, mortality can occur due to severe damage by large free radicals generated from acute stresses or long-term chronic stress. Naturally occurring substances that neutralize the potential deleterious effects of singlet oxygen and free radicals are often grouped into antioxidant defense systems (Yu, 1994).
Carotenoids play an important role in animal health as antioxidants through neutralizing free radicals produced by normal cell activity and various stressors (Chew, 1995). h-Carotene is recognized as a lipid antioxidant, i.e. free radical trapping and singlet oxygen reduction. The lipid protective effect of h-carotene complements that of a-tocopherol, depending on tissue oxygen content (Bohm et al., 1997). Astaxanthin contains a long double bond system with relatively unstable electronic orbitals; it can remove oxygen radicals in cells (Stanier et al., 1971). The antioxidant activity of astaxanthin was found to be about 10 times stronger than h-carotene and 100 times greater than a-tocopherol (Shimidzu et al., 1996). Astaxanthin also shows potent activity as an inhibitor of lipid peroxidation mediated by reactive oxygen species and has been proposed as “super vitamin E” (Miki, 1991).
Among the functions of astaxanthin in aquaculture as suggested by Torrissen (1990) and Shimidzu et al. (1996), antioxidant properties may be closely related to stress resistance. Astaxanthin can help increase the survival rate of shrimp during farming. Chien and Jeng (1992) reported a positive correlation between tissue pigment concentration of kuruma shrimp Marsupenaeus japonicus and survival rate. Thongrod et al. (1995) also found that the survival rate of black tiger shrimp postlarvae increased through the addition of astaxanthin to the diet. Enhanced tolerance to salinity stress in penaeid shrimp postlarvae is associated with an increase in astaxanthin in the diet and body (Darachai et al., 1998; Mercchie et al., 1998).
In both studies, after 1 – 2 hours of exposure to stress with a 27-fold decrease in salinity, postlarvae maintained on diets supplemented with high levels of astaxanthin had a better survival rate or survival time than those that did not. diets containing little or no astaxanthin supplementation. Besides osmotic stress, Chien et al. (1999) demonstrated that under hypoxic stress (DO < 1 mg/l for 4 hours), juvenile black tiger shrimp fed a diet high in astaxanthin had a higher survival rate than animals companion. In those studies, a close relationship between the antioxidant properties of astaxanthin and stress resistance was indicated by an increase in shrimp survival. No biochemical evidence was provided.
Total antioxidant status (TAS) is an overall index of an individual’s antioxidant status. As the value increases, the antioxidant capacity against free radical reactions also increases. TAS is commonly used in clinical and pharmaceutical trials, serving as a valuable and reusable method for detecting actual antioxidant status in humans (Lantos et al., 1997). . However, its detection in fish is limited to an assessment of the effects of different dietary protein sources on cellular and humoral immune responses (Tulli et al., 2000). Do not use in crustaceans as described.
Superoxide dismutase (SOD), a specific cellular enzyme for scavenging superoxide radicals, is involved in protective mechanisms in tissue damage following oxidation and phagocytosis. The higher the SOD value, the more superoxide radicals need to be reacted. SOD has been widely used in finfish in relation to nutritional requirements, health promotion, monitoring of pollution stress, pesticide effects, signs of disease, and heat or osmotic stress. However, research on SOD in crustaceans is rare (Bell and Smith, 1993; Holmblad and Soderhall, 1999; Munoz et al., 2000; Neves et al., 2000). Aspartate aminotransferase (AST) or glutamate oxaloacetate transaminase (GOT) and alanine aminotransferase (ALT) or glutamate pyruvate transaminase (GPT) are enzymes involved in transferring amino groups from one specific amino acid to another.
Therefore, higher values indicate greater transfer of amino groups or greater tissue metabolic wasting of amino acids. AST and ALT activities are often used as general indicators of vertebrate liver function. High AST and ALT generally, but not definitively, indicate impaired or damaged normal liver function. AST and ALT may be indirectly related to oxidative metabolites so they serve as indicators of oxidative status. For finfish, AST and/or ALT have been widely used in studies evaluating the response of finfish to toxins (heavy metal pollutants and pesticides), stress due to temperature, low oxygen, starvation, pH, ammonia and nitrite, disease, health, treatment monitoring and nutrition. The crustacean hepatopancreas is thought to be homologous to the mammalian liver and pancreas (Gibson and Barker, 1979) and is responsible for major metabolic events, including enzyme secretion, absorption and nutrient storage, molting, and vitellogen formation (Chanson and Spray, 1992).
Several aminotransferases in various tissues and organs including the hepatopancreas of crustaceans have been studied, including AST and ALT in the lobster Homarus americanus (Devereaux, 1986), kynurenine aminotransferase in black tiger shrimp (Meunpol et al. ., 1998), and D-alanine oxidase and D-aspartate oxidase in some crustaceans (D’Aniello and Giuditta, 1980). In crustaceans, AST and ALT have only recently been used to study the effects of pesticides (Galindo-Reyes et al., 2000) and heavy metal pollution (Zhao et al., 1995; Li et al., 1998). This study is perhaps the first attempt to link AST and ALT to stress resistance in invertebrates.
Studies on the protection of antioxidants against oxidative damage can be conducted by pretreating animals with antioxidants and then subjecting them to oxidative stress caused by oxidants or chemicals. toxic effects (Shaikh et al., 1999). The objective of this study was to examine the effect of astaxanthin as an antioxidant in black tiger shrimp fingerlings as indicated by TAS and SOD values as well as shrimp responses in terms of resilience, AST and ALT to heat and osmotic stress.
Materials and methods
2.1. Feed
5-day-old black tiger shrimp (Penaeus monodon) postlarvae, with an average weight of 6.7 ± 1 mg, were raised indoors in 2 fiberglass-reinforced polyethylene tanks weighing 0.5 tons at a density of 500 shrimp/each. bellows. The tanks are covered with black curtains to prevent algae growth. Shrimp were fed one of two diets (Table 1) containing 0 or 80 mg astaxanthin/kg feed at 5% of body weight per day at 08:00, 16:00, and 20:00 h. Debris at the bottom of the tank was siphoned off daily, and approximately one-third of the water was replaced daily with UV-sterilized seawater and 1-µm filtration. Water quality remains relatively stable: 27 – 29 oC, salinity 30 – 32‰, pH 8.2 – 8.3 and DO 5.2 – 6.5 mg/l. Ammonia-N and nitrite-N are monitored and kept at safe levels (Chien, 1992). Feeding period is 8 weeks. Final shrimp weight and survival rate were recorded. Before and after rearing, the astaxanthin content of 5 fish in each tank was analyzed.
2.2. Analysis of astaxanthin concentration in whole body shrimp tissue
Shrimp were weighed, freeze-dried and weighed again to determine moisture. Then, the dry sample was ground using a ceramic mortar and pestle and placed into a 50 ml polypropylene centrifuge tube. Then, 20 ml of acetone (0.05% butylated hydroxytoluene, BHT) was added as a solvent (Schwartz and Patroni-Killam, 1985; Khachik et al., 1986; Barimalaa and Gordon, 1988), and the mixture was homogenized. homogenization (Polytron PT-MR3000) at 8000 rpm for 1 minute. The contents of each tube were centrifuged (Hitachi 18 PR52) under 4 oC at 12,700 g for 15 min. The pellet was resuspended and centrifuged with an additional 20 ml of acetone until the acetone extract was clear. The combined acetone extract was transferred to a 250 ml separating funnel, divided with 30 ml of nhexane, and washed three times with 10% NaCl to remove excess acetone. The extract volume was reduced to 10 ml using a rotary evaporator and then filtered through a 0.2-μm Millipore filter and stored in three 4-ml brown vials. Astaxanthin was analyzed by high performance liquid chromatography (HPLC), using a Hitachi L-6200 pump, silica column (Lichrosorb Si-60 column 5 micro 2504.6 mm ID, E. Merck), Hitachi L-4250 detector UV –VIS at 470 nm and Hitachi D-2000 Chromatography Integrator. The operating conditions were: mobile phase, 14% acetone in nhexane; solvent flow rate, 1.5 ml/min; injection volume, 100 Al; and pump program, the sequence was 0–20 min Mixture A and 20.5–40 min Mixture B; Mixture A is acetone:n-hexane, 14:86, and Mixture B is 100% n-heptane. The system is controlled by the chromatography data system (Scientific Information Services), which also integrates the areas under the peaks. The standard was chromatographically pure astaxanthin, a gift from Hoffman La Roche, Basel, Switzerland. Body astaxanthin was expressed on a dry weight basis to eliminate potential errors due to changes in shrimp moisture associated with different stages of the molting cycle (Pan et al., 1999).
2.3. Stress test
Shrimp from each astaxanthin treatment were collected, divided into 12 cups of 2000 ml at a density of 25 shrimp/cup and acclimated to a temperature of 27 0C and a salinity of 32‰ for 24 hours. All 24 cups were continuously aerated and not fed. Four temperature-controlled water tanks were preset to one of two temperature levels and contained one of two water salinities to form four temperature-salinity regimes: (1) no stress at control, 27 0C and salinity 32‰; (2) osmotic pressure only, 27 0 C and salinity 0‰; (3) thermal stress only, 5 0C and salinity 32‰; and (4) both osmotic and thermal stress, 5 0C and salinity 0‰. When the adaptation period ends, one or two shrimp die in a few cups. An unpaired t test (n = 12) showed no difference in mortality between control and treated shrimp. To keep the number of shrimp in each experimental unit equal and to facilitate recovery calculations, 20 active shrimp from each beaker were tested under pressure. They were collected with a small hand-held net and immediately dipped into the designated pressure tank for 5 minutes, then returned to the original beaker. Seawater of 27 0C and 32‰ was added to each beaker while the shrimp were returned. Recovery, defined as the ratio of the number of shrimp continuing to swim normally to the number of shrimp examined, was recorded 24 h after return. Exposure to each stress condition was repeated three times (shrimp cup). This procedure is performed to control and treat shrimp.
2.4. Biochemistry of blood
The blood of shrimp after stress was drawn by inserting a needle into the pericardial cavity through the intervening membrane between the cephalothorax and the abdomen. Hemolymph samples were prepared by mixing a 400 Al isotonic NaCl solution containing 0.94 m mol/l EDTA with 100 Al hemolymph immediately after hemolymph withdrawal. Samples were refrigerated if not used immediately for determination of TAS, SOD, AST, ALT and hemolytic proteins.
2.4.1. TAS and SOD
To measure hemolymph TAS and SOD, 20 and 25 Al of the hemolymph sample, respectively, were used and determined spectrophotometrically at wavelengths of 600 and 505 nm, respectively, with a U-2000 spectrophotometer (Hitachi, Tokyo, Japan) at 37o C. All tests were performed within 5 hours of sample collection using Randox Laboratories kits (Crumlin, Antrim, UK) according to the manufacturer’s instructions. Activity is expressed in international enzyme units (Ul 1).
2.4.2. AST and ALT
AST and ALT activities were determined spectrophotometrically at 340 nm using a U2000 spectrophotometer (Hitachi) at 37o C. 100 Al lymph samples were used for each sample. All tests were performed within 5 hours of sample collection using Randox Laboratories kits according to the manufacturer’s instructions. Activity is expressed in international enzyme units (Ul 1).
2.4.3. Hemolytic proteins
Hemolytic proteins were determined using a protein assay kit (no. 500-0006, Bio-rad laboratories, Richmond, CA, USA) and bovine serum albumin (BSA, 66 kDa, Sigma) as standards, a method derived from Bradford (1976). One analysis used a 200-Al hemolymph sample.
2.5. Statistical analysis
For heat and osmotic stress testing, a 3-way 2´2´2 ANOVA was used to determine the effects of astaxanthin in shrimp body, temperature stress and salinity stress on recovery capacity and parameters. biochemical numbers of shrimp. Because recovery data were expressed as percentages, an arcsine square root transformation was performed before analysis (Sokal and Rohlf, 1995; Ray et al., 1996).
results
In the absence of repetition, no statistical test could be performed to compare growth (Table 2). After 8 weeks of culture, the animal had grown more than 50,000%. Without dietary supplementation, the body astaxanthin concentration in control shrimp after rearing was only approximately 17% of the concentration before rearing. After farming, the astaxanthin concentration in treated shrimp was 72% compared to before farming. The increase in astaxanthin in the body due to astaxanthin supplementation was 334% ((45.6 – 10.5)/10.5). Ignoring both stresses, the mean recovery rate in control shrimp was significantly lower than in treated shrimp (Table 3).
Dietary supplementation with astaxanthin at 80 mg/kg improved shrimp resistance to osmotic stress by 19% and heat stress alone by 13% compared to control shrimp (Table 4). Ignoring the effects of astaxanthin in the body, the resilience to osmotic stress and heat stress is different. The pressure to reduce temperature of 22o C has a greater impact than the pressure to reduce salinity of 32‰ because the average recovery rate of shrimp is 16% and 40%, respectively. Without heat and osmotic stress, both control and treated shrimp had 100% recovery (Table 4). Regardless of the effects of astaxanthin in the body, the average recovery rates were 29% ((22 + 35%)/2) and 78% for heat stress only and 78% for heat stress and osmotic stress, respectively. understand. Under combined stress conditions, both control and treated shrimp had the same level of recovery, 3%, about 1/10 of the recovery level of each stress when applied alone. Control shrimp had significantly lower recovery than treated shrimp when exposed to heat stress or osmotic stress.
Among the interactions, only the third-order interaction effect, heat stress, body astaxanthin salinity, on recovery was significant (Table 5). Ignoring both stresses, the mean TAS values in control shrimp were significantly lower than in treated shrimp (Table 3). TAS is not influenced by osmotic stress or thermal stress but by the interaction of both (Table 5).
Ignoring both stresses, the mean SOD values in control shrimp were significantly higher than in treated shrimp (Table 3). Regardless of the body’s astaxanthin effects and heat stress, mean SOD increased by 45% ((0.175 – 0.121)/0.121) under osmotic stress conditions. Regardless of the body’s effects of astaxanthin and osmotic stress, heat stress also increased mean SOD by 79%. The average SOD value of both shrimp species not exposed to any stress was 0.028, approximately 17% of the value found in shrimp subjected to both stresses of 0.165 (Table 4). Significant interaction effects on SOD were found between salinity heat stress and between astaxanthin effects in salinity heat stress in vivo (Table 5).
Ignoring both stresses, mean AST values in control shrimp were significantly higher than in treated shrimp (Table 3). Regardless of the body’s astaxanthin effects and heat stress, AST activity decreased by 19% under osmotic stress. Regardless of the effects of astaxanthin in the body and osmotic stress, it means that AST is not affected by heat stress. While subjected to osmotic stress at both 27 and 5o C, the AST of control shrimp was significantly higher than that of treated shrimp (Table 4). Excluding osmotic stress, no difference in AST was found between control and treated shrimp. A significant interaction effect on SOD was found between salinity stress and heat stress (Table 5). Ignoring both stress factors, mean ALT values were not affected by in vivo astaxanthin (Table 3). Significantly higher ALT values in control shrimp compared with treated shrimp were found only when shrimp were not stressed (Table 4). Regardless of the body’s astaxanthin effects and heat stress, osmotic stress did not affect mean ALT. Regardless of the body’s astaxanthin effects and osmotic stress, average ALT decreased by 25% during heat stress. No interaction effects were found on ALT (Table 5).
discuss
4.1. Pigment
A dilution effect and a decrease in astaxanthin concentration in the shrimp body were observed as the shrimp grew, a condition that has been reported previously (Menasveta et al., 1993; Pan et al., 1999). Although the treated shrimp diet contained 113% (71.5/63.2) of the astaxanthin concentration in whole-body PL5 shrimp at the start of the trial, the body astaxanthin concentration of these shrimp remained decreased by 28% during the 8-week feeding trial. The decrease in astaxanthin concentration may be mainly due to shrimp weight gain, about 50,000%. Pigments obtained from food sources may vary depending on the species, size of the animal, growth rate, rearing conditions and duration, dietary astaxanthin level, pigment tissue, and other unknown factors (Pan et al., 2001), therefore, the pigmentation effect of this study is difficult to compare with others. ±
4.2. The recuperation
Resistance to osmotic stress has been used to evaluate postlarval shrimp quality (Tackaert et al., 1989) and postlarval nutritional status (Ree et al., 1994). The change in slope and time of osmotic pressure can be varied: 15 – 20‰ and 2 h (Bauman and Scura, 1990), 20 –40xand 2 h (Dura’n Go’mez et al., 1991 ), 20– 30‰ and 2 h (Ree et al., 1994), 27x and 1 h (Merchie et al., 1998), and 28 ‰ and 2 h (Darachai et al., 1998).
Considering that juveniles may be less hardy than postlarvae when subjected to large changes in salinity, we shortened the stress period to 5 min and used resilience, rather than survival in those studies, as reaction parameters. The use of heat stress or a combination of heat and osmotic stress to differentiate between weak and healthy postlarvae or crustacean juveniles has not been previously reported. Mercchie et al. (1998) and Darachai et al. (1998). In Mercie’s study, black tiger shrimp postlarvae were subjected to salinity stress including changing water salinity from 27‰ to 0‰ in 1 hour.
Shrimp supplemented with 810 mg astaxanthin/kg had a significantly lower cumulative stress index (Dhert et al., 1992) than postlarval shrimp fed a diet containing 230 mg astaxanthin/kg. Both diets contained 1700 mg ascorbic acid/kg and were fed to postlarvae for 4 weeks before exposure to salinity shock. In Darachai’s study, 15-day postlarvae of black tiger shrimp were transferred from 30 times the speed and soaked in water with 2 times the salinity for 2 hours. Larvae fed diets supplemented with synthetic astaxanthin or algal astaxanthin from zoea II showed an increase in time to 50% cumulative mortality (37–45 min) compared to time to cumulative mortality. Cumulatively 50% of larvae fed unpigmented diet (32 min). Darachai et al. (1998) concluded that astaxanthin appears to prolong the lifespan of postlarvae after acute environmental stress. In our study, we also confirmed that resistance to salinity stress (32‰ to 0‰ shock for 5 min) in black tiger shrimp fingerlings (PL61, 3.4–3.6 g) could be increased enhanced through supplementing astaxanthin in the diet (80 mg/kg) and simultaneously increasing astaxanthin in the body (45.6 Ag/g). In previous studies (Darachai et al., 1998; Mercchie et al., 1998), the animals were much younger (PL10; PL15), the stress duration was much longer (1 h; 2 h), the range of Astaxanthin levels in the diet were also higher. wider (230 and 810 mg/kg; 0, 189 and 209 mg/kg), and higher body astaxanthin concentrations (117 and 165 µg/g; 97, 109 and 123 µg carotenoid/g).
Besides the ability to withstand osmotic stress, the ability to withstand heat stress in black tiger shrimp breeds is also enhanced by supplementing astaxanthin in the diet. However, under complex stress conditions, treated shrimp did not improve their resistance compared to the control. This may be because the combined stress is too strong and exceeds the range of physiological tolerance. The cumulative effect of thermal and osmotic stress appears to be at work.
Mercie et al had no explanation for the enhancement of salt stress tolerance by dietary astaxanthin. (1998). Darachai et al. (1998) concluded that astaxanthin appears to be useful in extending the lifespan of black tiger shrimp postlarvae exposed to reduced salinity stress. They speculate that this change requires more energy expenditure to maintain osmotic stability. Under these conditions, there is the potential for the production of unusually high amounts of oxygen radicals. Because astaxanthin contains a long double bond system with relatively unstable electronic orbitals, it can scavenge oxygen radicals in cells (Stanier et al., 1971) and thus reduce cell damage and increase strengthen resistance. Similar speculation can be applied to thermal stress because thermal stress is also related to oxidation energy.
4.3. TAS and SOD
The inconsistency in response to thermal and osmotic stress between TAS and SOD can be explained as follows. Because of the specificity of SOD in catalyzing the conversion of O2 to hydrogen peroxide, it does not have a strictly inverse relationship with TAS, an indicator of the overall antioxidant defense status against oxygen species. reactive oxygen species (ROS) and reactive oxygen intermediates (ROI). When an organism is first exposed to stress, SOD will be able to react accordingly and immediately with the production of superoxide anion. Because TAS indicates the static potential of antioxidant capacity against all
free radicals, it may not show a discernible change under stress if the production of superoxide anion is negligible compared to the already existing radicals. The TAS and SOD of shrimp hemolytic disease were improved by dietary astaxanthin and were reflected in the observed recovery. Various antioxidants, such as vitamin C and/or vitamin E (Poston et al., 1976; Watanabe et al., 1981; Bell et al., 1985; Maage et al., 1990; Wahli et al. et al., 1998) and astaxanthin (Christiansen et al., 1995; Thompson et al., 1995), were added to diets to enhance the health and immunity of finfish. Yang et al. (1995) used SOD to evaluate algal toxins in rainbow trout and proposed that the toxicity of flagellated marine phytoplankton to salmon is due to the formation of toxic concentrations of superoxide, hydroxyl radicals and hydrogen peroxide.
Sakai et al. (1998) found that hepatic SOD in yellowtail Seriola quinqueradiata was lower than in controls and concluded that jaundice in fish may be the result of severe oxidative stress. Astaxanthin, which has strong 1 O2 quenching activity, is thought to play a role in protecting marine organisms from ROS (Shimidzu et al., 1996). However, among those studies, SOD is rarely used as one of the health indicators. Vitamin E and astaxanthin are both antioxidants, but their effects on oxidative enzymes are different. For post-molt Atlantic salmon, Lygren et al. (1999) found that vitamin E negatively affected both catalase activity and tissue SOD activity while astaxanthin only negatively affected catalase activity. Holmblad and Soderhall (1999) first linked SOD to immunity in crustaceans. They speculate that peroxinectin and extracellular SOD cooperate during respiration to kill ingested or encapsulated parasites.
SOD in the gills and liver of the fossil freshwater catfish Heteropneustes increased as the temperature increased from 25 to 37o C after 1–4 h (Parihar et al., 1996, 1997). Blood SOD increased in European seabass Dicentrarchus labrax when exposed to increased temperatures (13 to 23 jC for 1 h) (Roche and Boge, 1996). A sudden increase or decrease in temperature can lead to a sudden increase in metabolism or oxygen consumption and a concomitant increase in SOD. Neves et al. (2000) suggested that lower SOD activity in shrimp infected with gill parasites alters oxygen consumption as the respiration of parasite-infected animals is impaired. The effects of osmotic stress on fish SOD have rarely been studied. Roche and Boge (1996) suggested that the increase in SOD in the blood of European seabass when salinity decreased (37xto 5xin 2 h) was due to the ability of epinephrine to prevent natural oxidation, the concentration of which is usually increased in stressed fish. Our findings suggest that complex interactions on TAS and SOD exist between heat and osmotic stress as well as the body’s astaxanthin effect (Table 5). Roche and Boge (1996) Y.-H. Chien et al. / Aquaculture 216 (2003) 177–191 187 also showed that the response of fish blood parameters to heat stress and osmotic pressure is different. In their study, the increase in glycemic, cortisol, and peroxidase activities was greater for heat stress than for osmotic shock, while SOD and catalase activities were stimulated more by osmotic shock.
Yew-Hu Chien a,*, Chih-Hung Pan a , Brian Hunter b a Department of Aquaculture, National Taiwan Ocean University, Keelung 202, Taiwan b Roche Aquaculture Centre Asia Pacific, 11/F 2535 Sukhumvit Road, Bangchak Prakanong, Bangkok 10250, Thailand
