Neuropeptide Y in Tiger Puffer (Takifugu rubripes): Distribution, Cloning, Characterization, and mRNA Expression Responses to Prandial Condition

Abstract

Neuropeptide tyrosine (NPY) is a potent orexigenic neuropeptide implicated in feeding regulation in rodents. However, the involvement of NPY in feeding behavior has not well been studied in fish. Therefore, we investigated the role of NPY in food intake using a tiger puffer (Takifugu rubripes) model. We observed the distribution of NPY-like immunoreactivity in the brain. Neuronal cell bodies containing NPY were located in the telencephalon, hypothalamus, mesencephalon, and medulla oblongata, and their nerve fibers were also found throughout the brain. We cloned two cDNAs, encoding NPYa and NPYb orthologs, respectively, from the brain, and also confirmed two genes encoding these NPYs in the Takifugu genome database. We examined the distribution of these transcripts in the brain using real-time PCR. Levels of NPYa mRNA in the telencephalon, mesencephalon and hypothalamus were much higher than in the medulla oblongata and cerebellum, whereas levels of NPYb mRNA in the medulla oblongata were higher than in other regions. We also examined prandial effects on the expression level of these transcripts in the telencephalon and hypothalamus. NPYa mRNA levels in the hypothalamus, but not in the telencephalon, obtained from fish fasted for one week were higher than those in fish that had been fed normally. The level was decreased at 2 h after feeding. Levels of NPYb mRNA were not affected by prandial conditions. These results suggest that NPY is present throughout the brain, and that NPYa, but not NPYb, in the hypothalamus is involved in the feeding regulation in the tiger puffer.

Characterization of neuropeptide Y in snakeskin gourami and the change in its expression due to feeding status and melanocortin 4 receptor expression

“…Both RT-PCR and in situ hybridization analyses demonstrated that TpNPY was expressed in the metencephalon, which is consistent with previous studies of the cerebellum of carp [30]. However, NPY mRNA was not detected in the cerebellum of tiger puffer [18] or Atlantic cod [21]. Here, we show that TpNPY is expressed in the pituitary gland, which is in agreement with previous reports in other fish species [9,15,32].…”

“…Although the prepro-TpNPY peptide exhibits a variable degree of similarity with the NPY peptides of other species, a maximal similarity was observed in mature peptide regions among teleosts. Moreover, the mature TpNPY sequence is completely identical to the NPY sequence of other fish, such as black porgy, mandarin fish, Nile tilapia, sea bass [5], Chinese perch [27] and tiger puffer [18]. The mature TpNPY peptide exhibited conserved aa residues, including Pro 2 , Pro 5 , Pro 8 , Tyr 20 and Tyr 27 , which are known to be crucial for the maintenance of the peptide conformation of the NPY family [6].…”

“…A daily rhythm and prandial variation in NPY expression were demonstrated in the rat, goldfish and tiger puffer [18,36,55]. The effects of fasting on NPY expression were demonstrated in a number of fish; however, the effects varied based on the food deprivation period, season, distinct brain region and species [18,29,32]. Furthermore, while food deprivation up-regulated NPY expression, a subsequent refeeding caused a decrease in NPY expression in goldfish [33].…”

“…It has been reported to be a key neuropeptide in the control of food intake and energy homeostasis, as well as in a variety of other physiological processes [10,49]. A daily rhythm and prandial variation in NPY expression were demonstrated in the rat, goldfish and tiger puffer [18,36,55]. The effects of fasting on NPY expression were demonstrated in a number of fish; however, the effects varied based on the food deprivation period, season, distinct brain region and species [18,29,32].…”

“…Recently, NPY has been characterized in a number of fish, including the goldfish, sea bass, catfish, Japanese flounder, orange spotted grouper, rainbow trout, Atlantic cod, Chinese perch winter flounder, salmon, and tiger puffer [1][2]5,9,18,21,23,26,27,29,32]. Among vertebrates, the fish family exhibits a significant amount of species diversity compared to other families.…”