The Systemic Effects Of Low Doses Of Antibiotics On Health And Food Safety In Nile Tilapia (Oreochromis Niloticus) And Regulation By Dietary Compositions

Antibiotics are currently used to treat/prevent human and animal diseases including cultured fish globally.They exist ubiquitously in the environment at low doses because of misuse,overdose and poor absorption after ingestion,coupled with their high-water solubility and degradation resistance.On the one hand,antibiotics used in aquaculture help to improve fish health by killing or inhibiting pathogenic bacteria proliferation.However,on the other hand,they cause multiple side effects.To date,the systemic chronic effects of exposure to low environmental concentrations of antibiotics(LECAs)and legal aquaculture doses of antibiotics(LADAs)in fish and their human health risk risk remain elusive.In addition,the use of dietary compositions such as lipid and carbohydrate to attenuate the side effects induced by antibiotics remains unclear.In this study,we used Nile tilapia(Oreochromis niloticus)to study the systemic effects of LECAs and LADAs on the general fish health and human health risk.We further explored the role of high fat diet and high carbohydrate diet on modulating the adverse effects induced by dietary oxytetracycline.General physiological functions,biochemical analysis,metabolic activities,histological analysis,intestinal and hepatic health were evaluated.The possible human health risk resulting from consumption of the fish muscles treated with antibiotics in adults and children were assessed by using risk quotient.We first,investigated the in vivo chronic effects of exposure to LECAs and LADAs by using oxytetracycline(OTC)and sulfamethoxazole(SMZ)in fish and their human health risk.Secondly,we determined the ability of high fat diet to influence the adverse effects of oxytetracycline on O.niloticus.Lastly,we evaluated the ability of high carbohydrate diet to protect O.niloticus from oxytetracycline-induced side effects.1.Chronic exposure to low environmental concentrations and legal aquaculture doses of antibiotics cause systemic adverse effects in Nile tilapia(Oreochromis niloticus)and provoke differential human health riskAntibiotics used globally to treat human and animal diseases exist ubiquitously in the environment at low doses because of misuse,overdose and poor absorption after ingestion,coupled with their high-water solubility and degradation resistance.However,the systemic chronic effects of exposure to low environmental concentrations of antibiotics(LECAs)and legal aquaculture doses of antibiotics(LADAs)in fish and their human health risk are currently unknown.We investigated the in vivo chronic effects of exposure to LECAs and LADAs using oxytetracycline(OTC)and sulfamethoxazole(SMZ)in Nile tilapia,(Oreochromis niloticus)and their human health risk.Twenty O.niloticus weighing 27.73 ± 0.81 g were exposed to water containing LECAs(OTC at 420 ng/L and SMZ at 260 ng/L)and diets supplemented with LADAs(OTC 80 mg/kg/day and SMZ 100 mg/kg/day)for twelve weeks.The general physiological functions,metabolic activities,intestinal and hepatic health were studied and systemically analyzed.Moreover,risk assessment method was used to indicate the possible human health risk in adults and children after consumption of the experimental Nile tilapia fillets.After exposure,we observed retarded growth performance accompanied by reduced nutrients digestibility,feed efficiency,organ indices,and lipid body composition in treated fish.Antibiotics distorted intestinal morphological features,subsequently induced microbiota dysbiosis and suppressed intestinal tight junction proteins.Exposure of the fish to LECAs and LADAs induced oxidative stress,suppressed innate immunity,stimulated inflammatory and detoxification responses,concomitantly inhibited antioxidant capacity and caused lipid peroxidation in intestine and liver organs.Both LECAs and LADAs enhanced gluconeogenesis,inhibited lipogenesis and fatty acid beta oxidation in intestine and liver organs.The exposure of fish to LECAs and LADAs induced anaerobic glycolytic pathway and affected intestinal fat catabolism in intestine while halted aerobic glycolysis,increased hepatic fat catabolism,and induced DNA damage in the liver.The hazard risk quotient in children for fish treated with OTCD was > 1 indicating human health risk.Overall,both LECAs and LADAs impair general physiological functions,nutritional metabolism,and compromise fish immune system.Consumption of fish fed with legal dietary OTC provoke health risk in children.Global stringent prohibition policy for use of antibiotics in aquaculture production and strategies to limit their release into the environment are urgently required to protect human health.In addition,mechanisms are required to modulate the adverse effects caused by antibiotics in fish.2.High fat diet worsens the adverse effects of antibiotic on intestinal health in juvenile Nile tilapia(Oreochromis niloticus)Antibiotics and high fat diets are commonly used independently in global aquaculture production for fish health management and to spare the use of costly protein as energy source,respectively,causing relatively similar metabolic effects and stresses.However,it is unknown whether dietary high fat worsens or attenuates the adverse effects of antibiotics in fish.We determined the ability of high fat diet to influence the adverse effects of oxytetracycline on Nile tilapia,Oreochromis niloticus.Thirty Nile tilapia weighing 8.45?±?0.15?g were fed on medium fat(MF;70 g/kg)and high fat(HF;120 g/kg)diets and the same fat levels supplemented with 2.00 g/kg diet of OTC(80 mg/kg body weight/day)hereafter,MFO and HFO for 65 days.Afterwards,we evaluated growth performance,feed efficiency,and intestinal health of fish.The Nile tilapia fed on HFO diet had significantly lower growth rate,body protein content and feed efficiency compared to those fed on MFO diet.Dietary HFO diet affected the intestine histomorphology,which decreased dramatically the tight junction proteins of Nile tilapia and induced microbiota dysbiosis compared to MFO diet.The Nile tilapia fed on HFO diet had increased oxidative stress,which stimulated drug detoxification response,caused endoplasmic reticulum stress and apoptosis compared to those fed on MFO diet.The new findings from our study demonstrate that,the adverse effects of antibiotics in fish are different at medium and high fat contents.Feeding fish with high fat diets with antibiotics worsen the adverse effects.This study enlightens our understanding on the risks of antibiotics misuse and also suggests that antibiotics should be more strictly limited in aquaculture,in which high fat diets are currently widely used in fish production worldwide.Therefore,more options to reduce the adverse effects induced oxytetracycline are needed in fish.3.High carbohydrate diet partially protects Nile tilapia(Oreochromis niloticus)from oxytetracycline-induced side effectsAntibiotics used in global aquaculture production cause various side effects,which impair fish health.However,the use of dietary composition such as carbohydrate,which is one of the dominant components in fish diets to attenuate the side effects induced by antibiotics remains unclear.Therefore,we determined the ability of high carbohydrate diet to protect Nile tilapia(Oreochromis niloticus)from oxytetracycline-induced side effects.Triplicate groups of thirty O.niloticus(9.50 ± 0.08 g)were fed on medium carbohydrate(MC;335 g/kg)and high carbohydrate(HC;455 g/kg)diets without and with 2.00 g/kg diet of oxytetracycline(80 mg/kg body weight/day)hereafter,MCO and HCO for 35 days.Thereafter,we assessed growth performance,hepatic nutrients composition and metabolism,microbiota abundance,immunity,oxidative and cellular stress,hepatotoxicity,lipid peroxidation and apoptosis.To understand the possible mechanism of carbohydrate protection on oxytetracycline,we assessed the binding effects and efficiencies of mixtures of medium and high starch with oxytetracycline as well as the MCO and HCO diets.The O.niloticus fed on the MCO and HCO diets had lower growth rate,nutrients utilization and survival rate than those fed on the MC and HC diets,respectively.Dietary HCO increased hepatosomatic index and hepatic protein content of O.niloticus than MCO diet.The O.niloticus fed on the HCO diet had lower m RNA expression of genes related to protein,glycogen and lipid metabolism compared to those fed on the MCO diet.Feeding O.niloticus on the HCO diet increased innate immunity and reduced pathogenic bacteria,pro-inflammation,hepatotoxicity, cellular stress and apoptosis than the MCO diet.The high starch with oxytetracycline and HCO diet had higher-oxytetracycline binding effects and efficiencies than the medium starch with oxytetracyline and MCO diet,respectively.Our study demonstrates that,high carbohydrate diet binds the antibiotic,which partially protects O.niloticus from oxytetracycline-induced side effects.Therefore,adding high carbohydrate in diet formulation for omnivorous fish species alleviates some of the side effects caused by antibiotics.