One evidence of cocaine- and amphetamine-regulated transcript (CART) has the bidirectional effects on appetite in Siberian sturgeon (Acipenser baerii).

Cocaine- and amphetamine-regulated transcript (CART), discovered in 1995, with various biological functions, has received much attention recently due to its role in the regulation of appetite in mammals. However, the function of CART on the appetite control in fish species is still not very clear. In this study, Siberian sturgeon (Acipenser baerii Brandt) cart gene was cloned for the first time, and the cart mRNA levels in 11 feeding-related tissues was investigated. The Siberian sturgeon cart gene sequence was 1459 base pairs (bp), including a 3'-terminal untranslated region (3'-UTR) of 39 bp, a 5'-terminal untranslated region (5'-UTR) of 52 bp, and an open reading frame (ORF) of 348 bp encoding 115 amino acids. Siberian sturgeon cart gene has three exons and two introns including 341 bp intron 1 and 679 bp intron 2. The result of tissue distribution showed that cart was widely distributed in 11 tissues with the highest expression in the whole brain. The effects of periprandial (pre- and post-feeding), fasting, and re-feeding on cart mRNA abundance in the whole brain were assessed. Periprandial result showed the expression of cart mRNA in the whole brain significantly elevated after feeding for 3 h. However, fasting experiment showed that the level of cart significantly decreased after 1 day of fasting, but that significantly increased after 3-17 days of food deprivation and returned to the basic level after 3 days of re-feeding in the fishes which were fasted for 15 days. In conclusion, this study suggests that CART has the bidirectional effects on appetite, which acts as a satiety factor in short-term feeding regulation but as a starvation factor in long-term appetite regulation in Siberian sturgeon.