Ayşe ÖLMEZ, Mehtap BAYIR, Chunfang WANG, Abdulkadir BAYIR

Effects of long-term starvation and refeeding on fatty acid metabolism-relatedgene expressions in the liver of zebrafish, Danio rerio

A 70-day starvation was conducted to determine the effects of long-term starvation on whole-body polyunsaturated fatty acid (PUFA) composition and fatty acid metabolism-related gene expression in the liver of zebrafish, Danio rerio. The starvation period was followed by a 15-day refeeding period to test recovery of both PUFA composition and gene expression levels. It was found that n-3 PUFA and arachidonic acid levels increased during starvation and returned to normal values after refeeding (P < 0.05). Expression of seven (elovl5, fads2, cpt1-β, acox1, acadvl, fabp1a, and fabp7a) of eight total genes downregulated significantly towards the end of the starvation. As a result of refeeding, gene expression of elovl5 and ppar-α returned to the normal levels. Therefore, it was concluded that, in general, mRNA expression of genes involved in fatty acid metabolism was negatively influenced by long-term starvation (70 days); there was no direct relationship between whole-body fatty acid composition and hepatic gene expressions; and 15-day refeeding was insufficient for recovery of starvation-based metabolic losses in zebrafish.

Anahtar Kelimeler:

Lipid metabolism, starvation, mRNA transcription, qPCR, zebrafish

Effects of long-term starvation and refeeding on fatty acid metabolism-relatedgene expressions in the liver of zebrafish, Danio rerio

Keywords:

Lipid metabolism, starvation, mRNA transcription, qPCR, zebrafish,

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Comoglio LI, Gaxiola G, Roque A, Cuzon G, Amin O. The effect of starvation on refeeding, digestive enzyme activity, oxygen consumption, and ammonia excretion in juvenile white shrimp Litapenaeus vannamei. I ShellŞsh Res 2004; 23: 243—249.
Machado CR, Garéfalo MAR, Roselino ]ES, Kettelhut IC, Migliorini RH. Effect of fasting on glucose turnover in a carnivorous Şsh (Hoplias sp). Am ] Physiol 1998; 256: R612— R615.
Navarro I, Gutierrez ]. Fasting and starvation. In: Hochachka P, Mommsen T, editors. Biochemistry and Molecular Biology of Fishes. New York, NY, USA: Elsevier; 1995. pp. 393—434.
Expression of both transport genes (fapra and fabp7a) was negatively aŞected by the starvation stress. fabp7a plays a role in the transportation of fatty acids such as DHA, which are essential for proper nervous system function (29). Rapid fat metabolism occurs in the intestine, liver, adipose tissue, and muscle. Therefore, high fabp gene expression levels are associated with the intake and use of fatty acids in these tissues (30). Hence, the decrease in fabp expressions in the liver is likely due to fatty acid levels that were too low to trigger fabp expressions.
In conclusion, it was determined that mRNA expressions of several genes involved in fatty acid metabolism in the liver of zebraŞsh were downregulated (except for ppm-oc) by long-term starvation; a 15-day refeeding period, in general, was insufficient for recovery of mRNA expressions; and there was no direct relationship between PUFA composition and fatty acid metabolism- related gene expressions. Finally, we think that more studies are needed to explain the molecular effects of starvation in teleost Şshes to better understand fatty acid metabolism.