Stimulants cocktail: Methylphenidate plus caffeine impairs memory and cognition and alters mitochondrial and oxidative status.

Methylphenidate (MPH) is a psychostimulant widely misused to increase wakefulness by drivers and students. Also, MPH can be found in dietary supplements in a clandestine manner aiming to burst performance of physical exercise practitioners. The abusive use of high doses of caffeine (CAF) in these contexts is equally already known. Here, we demonstrate the behavioral, oxidative and mitochondrial effects after acute exposure to high doses of MPH (80 mg/L) and CAF (150 mg/L), alone or associated (80 mg/L + 150 mg/L, respectively). We used zebrafish as animal model due to its high translational relevance. We evaluated the behavioral effects using the Novel Tank Test (NTT), Social Preference Test (SPT) and Y-maze Task and analyzed biomarkers of oxidative stress and activity of mitochondrial respiratory chain complexes. MPH alone induced antisocial behavior. MPH inhibited lipid peroxidation. The association of MPH + CAF presented memory impairment and anxiogenic behavior. In oxidative status, it inhibited lipid peroxidation, increased protein carbonylation and mitochondrial complex II, III and IV activity. Our results demonstrate that MPH and CAF alone negatively impact the typical behavioral of zebrafish. When associated, changes in cognition, memory, oxidative and mitochondrial status are more relevant.

Aloysia triphylla in the zebrafish food: effects on physiology, behavior, and growth performance.

Dietary supplements are commonly used by animals and humans and play key roles in diverse systems, such as the immune and reproductive systems, and in metabolism. Essential oils (EOs), which are natural substances, have potential for use in food supplementation; however, their effects on organisms remain to be elucidated. Here, we examine the effects of dietary Aloysia triphylla EO supplementation on zebrafish behavior, metabolism, stress response, and growth performance. We show that fish fed diets containing A. triphylla EO presented an anxiolytic response, with reduced exploratory activity and oxygen consumption; no changes were observed in neuroendocrine stress axis functioning and growth was not impaired. Taken together, these results suggest that the A. triphylla EO supplementation is a strong candidate for use in feed, since it ensures fish welfare (anxiolytic behavior) with decreased oxygen consumption. This makes it suitable for use in high-density production systems without causing damage to the neuroendocrine stress axis and without growth performance being impaired.

Anesthetic activity of the essential oil of Aloysia triphylla and effectiveness in reducing stress during transport of albino and gray strains of silver catfish, Rhamdia quelen.

This study investigated the efficacy of the essential oil (EO) of Aloysia triphylla as an anesthetic for albino and gray strains of silver catfish, Rhamdia quelen. Juveniles were exposed to concentrations between 20 and 800 µL L(-1) EO of A. triphylla to evaluate time of induction and recovery from anesthesia. In another experiment, both strains were divided into four groups such as 0 (control), 30, 40, or 50 µL L(-1) EO and transported for 5 h. The longest time for anesthetic induction and recovery was observed in the albinos. Both strains reached anesthesia in the 100-800 µL L(-1) (11.1-1.24 min) range, without mortality, being 200 µL L(-1) the best response considering time to anesthesia (5.35 min). Albinos transported with all EO concentrations showed higher values of carbon dioxide in the water of transport, but lower levels were observed in grays transported with 40 and 50 µL L(-1) EO when compared to control fish. The same concentrations did not prevent significant whole-body cortisol rise at the end of transport in the albino strain. Juveniles of both strains transported with EO presented lower ion loss to the water compared to control fish. The EO of A. triphylla is an effective anesthetic for albino and gray silver catfish. This EO increases whole-body cortisol levels in the albino strain, but as it reduces net ion loss as in the gray strain, it can be also recommended for transport.

Bee products prevent agrichemical-induced oxidative damage in fish.

In southern South America and other parts of the world, aquaculture is an activity that complements agriculture. Small amounts of agrichemicals can reach aquaculture ponds, which results in numerous problems caused by oxidative stress in non-target organisms. Substances that can prevent or reverse agrichemical-induced oxidative damage may be used to combat these effects. This study includes four experiments. In each experiment, 96 mixed-sex, 6-month-old Rhamdia quelen (118±15 g) were distributed into eight experimental groups: a control group that was not exposed to contaminated water, three groups that were exposed to various concentrations of bee products, three groups that were exposed to various concentrations of bee products plus tebuconazole (TEB; Folicur 200 CE™) and a group that was exposed to 0.88 mg L(-1) of TEB alone (corresponding to 16.6% of the 96-h LC50). We show that waterborne bee products, including royal jelly (RJ), honey (H), bee pollen (BP) and propolis (P), reversed the oxidative damage caused by exposure to TEB. These effects were likely caused by the high polyphenol contents of these bee-derived compounds. The most likely mechanism of action for the protective effects of bee products against tissue oxidation and the resultant damage is that the enzymatic activities of superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) are increased.

Nitrogenous and phosphorus excretions in juvenile silver catfish (Rhamdia quelen) exposed to different water hardness, humic acid, and pH levels.

This study examined ammonia, urea, creatinine, protein, nitrite, nitrate, and phosphorus (P) excretion at different water hardness, humic acid, or pH levels in silver catfish (Rhamdia quelen) juveniles. The fish were exposed to different levels of water hardness (4, 24, 50, or 100 mg L(-1) CaCO3), humic acid (0, 2.5, or 5.0 mg L(-1)), or pH (5.0, 6.0, 7.0, 8.0, or 9.0) for 10 days. The overall measured nitrogen excretions were 88.1% (244-423 µmol kg(-1 )h(-1)) for ammonia, 10.9% (30-52 µmol kg(-1 )h(-1)) for creatinine, 0.02% (0.05-0.08 µmol kg(-1 )h(-1)) for protein, 0.001 % (0.002-0.004 µmol kg(-1 )h(-1)) for urea, 0.5% (0.64-3.6 µmol kg(-1 )h(-1)) for nitrite, and 0.5% (0.0-6.9 µmol kg(-1 )h(-1)) for nitrate, and these proportions were not affected by water hardness or humic acid levels. The overall P excretion in R. quelen was 0.14-2.97 µmol kg(-1) h(-1). Ammonia excretion in R. quelen usually was significantly higher in the first 12 h after feeding, and no clear effect of water hardness, humic acid levels, and pH on this daily pattern of ammonia excretion could be observed. Water hardness only affected the ammonia and P excretion of R. quelen juveniles in the initial and fifth days after transfer, respectively. The exposure of this species to humic acid increased ammonia excretion after 10 days of exposure but did not affect P excretion. An increase in pH decreased ammonia and increased creatinine excretion but did not change P excretion in R. quelen. Therefore, when there is any change on humic acid levels or pH in the culture of this species, nitrogenous compounds must be monitored because their excretion rates are variable. On the other hand, P excretion rates determined in the present study are applicable to a wide range of fish culture conditions.

Antioxidant activity of bee products added to water in tebuconazole-exposed fish

An experiment was conducted to evaluate the potential of honey, propolis, and bee pollen for the reversal of lipid peroxidation induced by tebuconazole (TEB) in South American catfish (Rhamdia quelen), in which the concentration of thiobarbituric acid reactive substances (TBARS), the activity of the antioxidant enzyme glutathione-S-transferase (GST) and the concentrations of non-enzymatic antioxidants, reduced glutathione (GSH), ascorbic acid, and non-protein thiols were assessed. Honey (0.125 g L-1) and bee pollen (0.05 g L-1) added to the water reverse the production of TBARS induced by TEB, while propolis demonstrated a pro-oxidant effect, inducing an increase in TBARS production. The data presented herein suggest that the addition of water to honey and bee pollen potentially protects against the oxidative stress caused by agrichemicals.

Um experimento foi conduzido objetivando avaliar o potencial do mel, da própolis e do pólen apícola na reversão da peroxidação lipídica causada pelo fungicida tebuconazole (TEB) na espécie de peixe tropical Rhamdia quelen, avaliando a concentração das substâncias reativas ao ácido tiobarbitúrico (TBARS), a atividade da enzima glutationa-S-transferase (GST) e das concentrações dos antioxidantes glutationa reduzida (GSH), ácido ascórbico e dos tiois não proteicos. O mel adicionado à água na concentração de 0,125g L-1 e o pólen apícola na concentração de 0.05 g L-1reverteram a geração das TBARS causada pela exposição ao TEB, enquanto a própolis demonstrou efeito pró-oxidante, induzindo um aumento na geração das TBARS. Os dados apresentados neste trabalho sugerem o potencial do mel e do pólen apícola adicionados à água como substâncias protetoras contra o estresse oxidativo causado por agroquímicos.