Oxidative status and histological changes in sea bass larvae muscle in response to high dietary content of docosahexaenoic acid DHA

Abstract

In previous studies, we observed dystrophic alterations in muscle of 48-day-old sea bass fed imbalanced docosahexaenoic acid (DHA) and vitamin E diets. To understand the whole pathological process associated with oxidative stress, a histological study was performed by feeding 14-day-old sea bass larvae with microdiets containing different ratios of DHA/vitamin E (1/150, 5/150 and 5/300) for a period of 21 days. Larvae fed diet 1/150 showed no lesions in contrast to larvae fed diets 5/150 and 5/300 where the highest incidence of muscle lesions and thiobarbituric acid reactive substances (TBARS) content was observed. Semithin sections revealed focal lesions consisting of degenerated fibres with hypercontracted myofilaments and extensive sarcoplasm vacuolization affecting both red and white muscle. Ultrathin sections of degenerating muscle fibres showed diffuse dilatation of sarcoplasmic reticulum, disorganized myofilaments and autophagic vacuoles containing myelin figures and dense bodies. Additionally, some macrophages were observed among injured fibres as numerous satellite cells. Results from the study agree with those obtained from previous work, proving the pathological potential of free radicals in sea bass larvae musculature. Moreover, high vitamin E inclusion could not completely protect cell membranes from free radicals action.

Selenium inclusion decreases oxidative stress indicators and muscle injuries in sea bass larvae fed high-DHA microdiets

“…As observed in our previous studies ( 12 , 24 ) , high dietary DHA levels caused pathological changes in sea bass larvae muscle. However, in the present study, inclusion of Se proved to be efficient in controlling the damage caused by ROS, reducing the incidence of muscle injury to almost half as compared with the 5/300 diet.…”

“…One of the most important factors that can lead to oxidative stress in fish is their high requirement for LC-PUFA, which are high in diets and, subsequently, in fish tissue ( 22 , 23 ) . For instance, severe dystrophic lesions in the epaxial musculature of sea bass larvae have been related to the deleterious effect of oxidative stress due to the high ingestion of LC-PUFA, particularly DHA ( 12 , 24 ) . Muscle growth is an essential process during larval stages, as a massive increment of muscle fibres takes place from hatching to maturity ( 25 ) with damage to the musculature appearing to compromise larval growth ( 12 , 24 ) .…”

Dietary n−3 LC-PUFA requirements in silvery-black porgy juveniles (Sparidentex hasta)

“…Although our findings were in accordance with previous results reported in European sea bass larvae fed with high dietary DHA levels (Betancor et al, 2013), we cannot conclude that our findings were mainly due to the higher levels of dietary LC-PUFAs or different peroxidation levels of oils used for diet formulations, as lipid peroxidation levels were not measured in experimental diets. In our study, the TAC was not correlated with lipid peroxidation levels in the liver and plasma samples, whereas TAC decreased with increasing MDA concentration in grass carp fed high levels of lipids (Jin et al, 2013).…”

Vitamin C Enhances Vitamin E Status and Reduces Oxidative Stress Indicators in Sea Bass Larvae Fed High DHA Microdiets

“…In previous studies we have shown the alteration of sea bass (Dicentrarchus labrax) larvae oxidative status when they were fed high levels of DHA (5%), with α-TOH having a limited effect in preventing alterations such as muscular dystrophy or hepatic ceroidosis (38,39). Therefore, the aim of the present study was to evaluate the combined effect of α-TOH and AA in preventing oxidative stress in sea bass larvae fed high levels of DHA in relation to larval performance or antioxidant status as well as the incidence of morphological alterations, including the expression of selected related genes.…”