Analyzing the impact of synthetic and natural steroids: a study of cytochrome P450 metabolism, morphological alterations through metabolomics, and histopathological Examination.

This study focuses on the comparative metabolic profiling and effects of two steroid types: natural and synthetic, specifically 17α-methyl testosterone (17α-MT) at varying concentrations (1.5, 2, and 3 mg/kg) in rainbow trout (Oncorhynchus mykiss). Over a 75-day feeding trial, growth metrics, such as feed efficiency, daily specific growth, live weight gain, total weight gain, and survival rate were systematically monitored every 15 days. At the end of the feeding trial, histopathology, immunohistochemistry, and metabolome analyses were performed in the high-concentration groups (3 mg/kg natural and 3 mg/kg synthetic), in which the lowest survival rate was determined. Key findings reveal that the type of hormone significantly influences growth parameters. While some natural steroids enhanced certain growth aspects, synthetic variants often yielded better results. The metabolomic analysis highlighted significant shifts in the metabolism of tryptophan, purine, folate, primary bile acids, phosphonates, phosphinates, and xenobiotics via cytochrome P450 pathways. Histopathologically, the natural hormone groups showed similar testicular, hepatic, muscular, gill, cerebral, renal, and intestinal tissue structures to the control, with minor DNA damage and apoptosis observed through immunohistochemistry. Conversely, the synthetic hormone groups exhibited moderate DNA damage and mild degenerative and necrotic changes in histopathology.

Effect of climate change on hematotoxicity/hepatoxicity oxidative stress, Oncorhynchus mykiss, under controlled conditions.

Described as the 'main ecological factor', temperature, strongly affects the physiological stress responses of fish. In order to evaluate the effects of temperature variations on fish culture and food value chain, the present study was designed as a climate change model. Furthermore, the present study provides a theoretical basis for a better understanding of the mechanisms of the environmentally induced changes. In this direction, we examined the blood physiology and oxidative stress responses induced by temperature variation in the rainbow trout, a temperature-sensitive cold-water fish. The obtained results showed that climate changes promoted the inhibited activities' expressions and the development of potential tissue and hematological defense mechanisms against temperature-induced toxic damage. This study showed that climate change could be a subset of the studies on the stress physiology in aquaculture, which can be developed for new experimental designs and research collaborations. Furthermore, it highlights knowledge gaps to guide future research in this emerging field.

Effect of dietary n-3 polyunsaturated fatty acids on antioxidant defense and sperm quality in rainbow trout (Oncorhynchus mykiss) under regular stripping conditions.

This study examined the effect of dietary n-3 polyunsaturated fatty acids (PUFA) on malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and reduced glutathione (GSH) levels; semen and liver fatty acid compositions; and spermatological values (semen volume and pH, sperm density, percentage and duration of sperm motility) in rainbow trout (Oncorhynchus mykiss) under regular stripping conditions. For this purpose, one control and two experimental diets were prepared as isonitrogenous and isocaloric. The control diet did not contain n-3 PUFA. However, the D1 and D2 diets were supplemented with n-3 PUFA concentrated anchovy oil at a 1% and 2% level, respectively. The n-3 PUFA content in the semen and liver, semen volume, initial sperm motility, duration of 50% sperm motility, total duration of sperm motility and sperm density values of the control fish fed the n-3 PUFA-deficient diet were decreased and were accompanied by a reduction of the antioxidant defense (SOD, CAT, GSH-Px and GSH) and an elevation of MDA in the blood, gonad, liver and kidney at all of the sampling periods (P<0.01 for each case). However, the effects of the sampling period on the MDA and antioxidant defense values in the blood, gonad, liver and kidney of the control diet fish (with the exception of the GSH and GSH-Px activities) and the D1 and D2 diet fish were not significant (P>0.01). However, supplementation with n-3 PUFA protected the fish from these adverse effects. The modulations were clearly observed in the fish fed the D2 diet because they were under lower oxidative stress, as indicated by MDA. The increased enzyme activity corresponds with the physiological mechanisms combating the elevation of free radicals under oxidative stress. The highest n-3 PUFA levels in the semen and liver and spermatological values were obtained from the fish fed the D2 diet at all of the sampling periods. On the other hand, the effects of the sampling stage on the spermatological values of the fish fed the D1 and D2 diets were not significant (P>0.01). However, the effects of the sampling stage in the fish fed the control diet on these values (with the exception of semen pH) were significant (P<0.01). In conclusion, the addition and balance of n-3 PUFA in the diet of broodstock fish can improve sperm quality and ultimately cause successful reproduction.