Cloning and distribution of neuropeptide S and its receptor in the pig

Neuropeptide S (NPS) precursor gene is present in most vertebrates. However, the genes of NPS and its receptor (NPSR), and their functions in the pig are currently not well understood. In order to clarify their physiological functions, it is essential to characterize in detail the distribution of NPS and NPSR. In this report, the cDNAs of NPS and NPSR were cloned and sequenced. Homology and phylogenetic analysis of NPS gene sequences were performed. The expression of NPS and NPSR mRNA in the pig was systemically investigated using semiquantitative reverse transcription polymerase chain reaction (RT-PCR), while the distribution of NPS was determined by immunohistochemistry. Our results demonstrated that the gene and predicted amino acid sequences of both NPS and NPSR were highly conserved. Phylogenetic analysis showed that NPS coding sequences from related species display high degrees of homology. NPS and NPSR mRNAs were widely expressed in various tissues of the pig. NPS mRNA was highly expressed in CNS, while NPSR mRNA was widely expressed in many tissues, with high expression in the hypophysis, endocrine tissues and glands. NPS protein also exhibited the different distribution in various organs. In the pig brain, NPS immunoreactive cells were mainly found in the diencephalon, pons and hypophysis, while immunoreactive fibres were widely distributed in the hypothalamus and olfactory bulb. In the peripheral organs, NPS immunoreactive cells were observed in the respiratory tract, alimentary tract, endocrine organs, genitourinary tract, lymphatic organs, muscle tissue, skin and skin appendages. By showing gene sequences and distribution of NPS and NPSR, these results suggest that NPS and NPSR in the pig might play important role in modulating a variety of physiological functions as in human and other animals. This research provided molecular and morphological data for further study of physiological function of NPS-NPSR system.