Leptin expression affects metabolic rate in zebrafish embryos (D. rerio)

Abstract

We used antisense morpholino oligonucleotide technology to knockdown leptin-(A) gene expression in developing zebrafish embryos and measured its effects on metabolic rate and cardiovascular function. Using two indicators of metabolic rate, oxygen consumption was significantly lower in leptin morphants early in development [<48 hours post-fertilization (hpf)], while acid production was significantly lower in morphants later in development (>48 hpf). Oxygen utilization rates in <48 hpf embryos and acid production in 72 hpf embryos could be rescued to that of wildtype embryos by recombinant leptin coinjected with antisense morpholino. Leptin is established to influence metabolic rate in mammals, and these data suggest leptin signaling also influences metabolic rate in fishes.

Signal transduction mechanism for glucagon-induced leptin gene expression in goldfish liver

“…In leptin receptor knockout medaka, largely deposits of visceral fat were observed 49. In leptin -A knockdown zebrafish embryos, the metabolic rate and oxygen consumption are significantly lower than in un-treated embryos 50. In leptin receptor knockout zebrafish, it has been shown that leptin is not required for adipostasis, food intake, or reproduction, but retains a role in the regulation of glucose homeostasis 51.…”

The Neuroendocrine Regulation of Food Intake in Fish: A Review of Current Knowledge

“…For example, in zebrafish, knocking down lepA decreases metabolic rate (Dalman et al, 2013) and in golden pompano, Trachinotus blochii (Perciforme), lepA gene polymorphisms are associated with different body weights, heights and lengths (Wu et al, 2016). Whereas in mammals, leptin acts as an adipostat and its plasma levels are proportional to the amount of body fat, there is little evidence for such a role in fish.…”

Comparative endocrinology of leptin: Assessing function in a phylogenetic context

“…Although the tissue distribution pattern of A and B are discrete (suggesting functional differences, (Angotzi et al, 2013; Gorissen et al, 2009), a great majority of fish studies exclusively focus on leptin A (Dalman et al, 2013; Frøiland et al, 2010; Huising et al, 2006; Liu et al, 2012). To date, functional study of leptin B has been limited to expression studies (responds to food restriction- Gorissen et al, 2009; increases during early development- Angotzi et al, 2013), and all manipulations using species-specific recombinant leptins have used leptin A (Dalman et al, 2013; Liu et al, 2012; Lu et al, 2012; Murashita et al, 2011, 2008). …”

“…Dalman et al, 2013; Mariano et al, 2013 in fishes; Lõhmus et al, 2004 in birds; French et al, 2011 in lizards; Crespi et al, 2012; Hicks-Courant, M.L. and Crespi, E.J., 2006 in amphibians), but recent studies emphasize the role leptin plays in energetic tradeoffs between the immune system and other physiological systems (see Demas, 2004).…”