Effect of anthocyanidins on myogenic differentiation in induced and non-induced primary myoblasts from rainbow trout (Oncorhynchus mykiss).

Authors: VILLASANTE, ALEJANDRO - University Of Idaho; POWELL, MADISON - University Of Idaho; MURDOCH, GORDON - University Of Idaho; Overturf, Kenneth - Ken; CAIN, KEN - University Of Idaho; WACYK, JURIJ - University Of Chile; HARDY, RON - University Of Idaho

Submitted to: Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/2016
Publication Date: 6/1/2016
Citation: Villasante, A., Powell, M., Murdoch, G., Overturf, K.E., Cain, K., Wacyk, J., Hardy, R. 2016. Effect of anthocyanidins on myogenic differentiation in induced and non-induced primary myoblasts from rainbow trout (Oncorhynchus mykiss). Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology. 196:102-108.

Interpretive Summary: Aquaculture has grown significantly in the last two decades. In the search for safer and more environmentally friendly feed ingredients, plant-derived extracts are being tested. Several of the phytochemicals found in plants have been reported to exert beneficial effects in fish, such as appetite stimulation, growth promotion and increased disease resistance. One such group of phytochemical called anthocynanins are a type of flavonoid that provide the red, blue, and purple pigmentation found in certain fruits and vegetables. Several health benefits have been observed from the dietary intake of food rich in anthocyanins in human and animal studies. Previously we showed that dietary inclusion of anthocyanins improves antioxidant capacity and fatty acid profiles in trout receiving these phytochemicals. Furthermore, we also showed that a mixture of anthocyanins enhances the expression of genes related to anti-oxidant mechanisms and triggers growth in cultured muscle cells obtained from trout. In this study we further explored the mechanisms behind anthocyanin regulation of muscle development in cultured rainbow trout muscle cells. We show that regulation of muscle cell development by anthocyanins is based upon both exposure time and the status of muscle cell differentiation when exposed. This work will help better understand the basis of phytochemical effects at the cellular level for improving muscle development in cultured fish.

Technical Abstract: A study was conducted to test whether an anthocyanidin mixture (peonidin, cyanidin and pelargonidin chloride) modulates myogenesis in both induced and non-induced myogenic cells from juvenile rainbow trout (Oncorhynchus mykiss). We evaluated three different anthocyanidin concentrations (1X, 2.5X and 10X) at two sampling times (24 and 36 hours). To test for treatment effects, we analyzed the expression of myoD and pax7 as well as two target genes of the Notch signaling pathway, hey2 and her6. In induced myogenic cells, the lowest and middle anthocyanidin doses caused significantly greater expression of myoD after 24 hours of treatment compared to control. A significantly higher expression of pax7 in cells exposed to either anthocyanidin treatment during 36 hours compared was observed. Similarly, the pax7/myoD ratio was significantly lower in cells exposed to the lowest anthocyanidin doses during 24 hours compared to control. No significant effect of anthocyanidin treatments on the expression of hey2 and her6 at either sampling point was detected. In non-induced cells, we observed no effect of anthocyanidins on myoD expression and significant down-regulation on pax7 expression in cells exposed to either anthocyanidin mixture concentrations after 24 and 36 hours of treatment compared to control. Further, the pax7/myoD ratio was significantly lower in cells exposed to either anthocyanidin doses at both sampling time. In non-induced cells, the highest anthocyanidin dose provoked significantly greater expression of hey2 after 24 hours of treatment compared to control. We detected no such effect in non-induced cells exposed to the lowest and middle anthocyanidin doses during 24 hours of treatment. The expression of her6 was unaffected by anthocyanidin treatments at either sampling time or doses compared to control. Collectively, these findings provide evidence that anthocyanidins modulate specific components of the myogenic programming in fish, thereby potentially affecting somatic growth in fish fed plant-derived extracts rich in this type of polyphenols. Moreover, in early differentiating myogenic cells, the anthocyanidin effect on myogenic programming appears to differ based upon the exposure time and the differentiation stage of the myogenic cells by boosting myogenic differentiation signaling after 24 hours treatment while pausing differentiation, potentially favoring cell survival after 36 hours treatment. Further research to determine whether plant-derived secondary metabolites including alkaloids, terpenoids, tannins, saponins, glycosides, flavonoids, phenolics, steroids and essential oils can modulate myogenic programming in myogenic cells isolated from finfish species is warranted.