Molecular cloning and functional characterization of growth hormone-releasing hormone in Mastacembelus armatus

Growth hormone-releasing hormone (GHRH) is a neuropeptide that controls growth hormone (GH) synthesis and release. In this study, the full-length cDNA of Mastacembelus armatus ghrh was obtained by rapid amplification of cDNA ends method. Sequence analysis showed that the cloned sequence is 1090 bp in length, containing an open reading frame (ORF) of 429 bp that encodes a precursor protein of 142 amino acids. Sequence alignment revealed that the 27-amino acid mature peptide of Ghrh in M. armatus is conserved. Real-time PCR showed that ghrh is highly expressed in the brain, with very low or no expression in other tissues. During embryonic and larval development, ghrh expression was low in embryos but increased gradually in the stages of larval development. The biological function of Ghrh peptide was further investigated in vivo. Ghrh injection could significantly upregulate the mRNA expression of growth hormone (gh) and insulin-like growth factor-1/2 (igf-1/2) in M. armatus. Our data indicate that Ghrh is able to activate the GH-IGFs axis in M. armatus.