Association of plasma and heart homocysteine and blood malondialdehyde with cardiovascular diseases induced by acute selenium deficiency in lambs

Effect of Macleaya cordata and Magnolia officinalis plant extracts on oxidative stress control in lambs fed a high-concentrate diet

Objective

The objective of this experiment was to compare conventional antioxidants and plant extracts for oxidative stress control in lambs fed a high-concentrate diet.

Methods

Forty-eight male Dorper×Santa Ines lambs with an initial weight of 20±1.49 kg and 60 days of age, were used to evaluate the effects of feeding a combination of Macleaya cordata and Magnolia officinalis plant extracts (0 vs 320 mg/kg dry matter [DM]) in combination with selenium+vitamin E (0 vs 100 IU/kg DM of vitamin E and 0.1 mg/kg DM of selenium) in a completely randomized block design in a 2×2 factorial arrangement. The animals were housed in individual pens and received a high-concentrate diet consisting of 80% whole corn and 20% protein pellet for 60 days. The animals were weighed at the beginning of the experiment and every 14 days for performance monitoring. Three blood samplings were performed during the experimental period for the evaluation of oxidative and protein parameters.

Results

The treatments with vitamin E and selenium as additives had a positive influence on final weight, daily weight gain, carcass weight, and selenium content in longissimus muscle (p = 0.01). Plant extracts tended to improve final weight (p = 0.064) and daily weight gain (p = 0.059), showing similar effect as selenium and vitamin E. There was no effect of treatment on blood proteins, indicating that the animals were healthy throughout the experiment.

Conclusion

The use of plant extracts had a similar effect as the addition of selenium and vitamin E, with dietary inclusion of additives resulting in better performance of lambs but both supplements did not have strong influence on oxidative stress.

Gene expression of selenoproteins can be regulated by thioredoxin(Txn) silence in chicken cardiomyocytes

Thioredoxin (Txn) system is the most crucial antioxidant defense mechanism in myocardium. The aim of this study was to clarify the effect of Txn low expression on 25 selenoproteins in chicken cardiomyocytes. We developed a Se-deficient model (0.033mg/kg) and Txn knock down cardiomyocytes model (siRNA) studies. Western Blot, Quantitative Real-time PCR (qPCR) were performed, and correlation analysis, heat map were used for further analysis. Both low expression of Txn models are significantly decreased (P<0.05) the mRNA levels of Deiodinase 1, 2 (Dio 1, 2), Glutathione Peroxidase 1, 2, 3, 4 (Gpx 1, 2, 3, 4), Thioredoxin Reductase 1, 2, 3 (TR 1, 2, 3), Selenoprotein t (Selt), Selenoprotein w (Selw), Selenoprotein k (Selk), selenoprotein x1 (Sepx1), and significantly increased (P<0.05) the mRNA levels of the rest of selenoproteins. Correlation analysis showed that Deiodinase 3 (Dio 3), Selenoprotein m (Selm), 15-kDa Selenoprotein (Selp15), Selenoprotein h (Selh), Selenoprotein u (Selu), Selenoprotein i (Seli), Selenoprotein n (Seln), Selenoprotein p1 (Sepp1), Selenoprotein o (Selo), Selenoprotein s (Sels), Selenoprotein synthetase 2 (Sels2) and Selenoprotein p (Selp) had a negative correlation with Txn, while the rest of selenoproteins had a positive correlation with Txn. Combined in vivo and in vitro we can know that hamper Txn expression can inhibit Gpx 1, 2, 3, 4, TR 1, 2, 3, Dio 1, 2, Selt, Selw, Selk, Sepx1, meanwhile, over expression the rest of selenoproteins. In conclusion, the different selenoproteins possess and exhibit distinct responses to silence of Txn in chicken cardiomyocytes.

Interplay between autophagy and apoptosis in selenium deficient cardiomyocytes in chicken

Dietary selenium (Se) deficiency can cause heart dysfunction, however the exact mechanism remains unclear. To understand this mechanism, 180day-old chicks, divided into two groups, C (control group) and L (low Se group), were fed with either a Se-sufficient (0.23mg/kg) or Se-deficient (0.033mg/kg) diets for 25days, respectively. Heart tissues and blood samples were collected. In L group, the activities of serum creatine kinase (CK) and creatine kinase-myoglobin (CK-MB) increased and typical ultrastructural apoptotic features were observed. Se deficiency up-regulated the mRNA levels of Cysteinyl aspartate specific proteinase 3 (Caspase-3), Cysteinyl aspartate specific proteinase 8 (Caspase-8), Cysteinyl aspartate specific proteinase 9 (Caspase-9), B cell lymphoma/leukemia 2 (Bcl-2), Bcl-2 Associated X Protein (Bax), (P<0.05), whereas, the mRNA levels of Microtubuleassociated protein light chains 3-1 (LC3-1), Autophagy associated gene 5 (ATG-5), Mammalian target of rapamycin (mTOR), Dynein and Becline-1 were down-regulated (P<0.05). Noticeably, Microtubuleassociated protein light chains 3-2 (LC3-2) mRNA level increased (P<0.05) by 20%. Western blot results showed that Se deficiency decreased the expression of Becline-1 and LC3-1 protein, however, the expression of Bax, Caspase-3 and Cysteinyl aspartate specific proteinase 12 (Caspase-12) increased at protein levels. The present study revealed that Se deficiency induced apoptosis while inhibited autophagy in chicken cardiomyocytes through Bax/Bcl-2 inhibition and caspases-mediated cleavage of Becline-1. Moreover, correlation analysis illustrates that apoptosis and autophagy might function contradictorily. Altogether we conclude that Se deficient chicken cardiomyocytes experienced apoptosis rather than autophagy which is considered to be more pro-survival.