Study On The Pituitary Action Of Corticotropin Releasing Hormone/Urotensin-1(CRH1a/UTS1) And Their Receptors In Grass Carp

Corticotropin-releasing hormone and urotensin-1(CRH1a/UTS1)is a member of the corticotropin-releasing hormone family,which exists and is widely distributed in many vertebrates.Their effect in mammals mainly focus on stress,reproduction,growth,etc.But their functions in fish pituitary are relatively less studied.Based on this,this thesis takes grass carp pituitary as the research target to explain the function and mechanism of CRH1a/UTS1 in grass carp pituitary.The main findings are as follows:Firstly,the sequences of CRH1a/UTS1 and its receptors were obtained,based on which sequence alignment analysis,tissue expression analysis and receptor ligand verification were performed.The sequences of CRH1a/UTS1 and its receptors were cloned.Through sequence analysis,it was found that the CRH1 a mature peptide sequence was highly similar between grass carp and zebrafish,with seven amino acid differences;UTS1 mature peptide sequence was found in grass carp and zebrafish.There is only one amino acid difference.Tissue expression analysis showed that CRH1a&UTS1 and their receptors CRHR1&CRHR2 were mainly present in the hypothalamus,pituitary,cerebellum and other tissues in grass carp brain,and mainly in gonads and kidneys in peripheral tissues.Finally,we found that CRH1a/UTS1 can activate both receptors through receptor ligand verification,among which CRH1 a has a higher activation power to CRHR1,while UTS1 has a higher activation power to CRHR2.Secondly,the mechanism of CRH1a/UTS1 regulating the synthesis and secretion of somatolactin α(SLα)and somatolactin β(SLβ)in the pituitary of grass carp was clarified.First,using transcriptome screening,it was found that both CRH1 a and UTS1 could induce the m RNA expression of SL gene in grass carp pituitary cells.Further studies found that CRH1 a and UTS1 not only induced the m RNA expression of SLα and SLβ in grass carp pituitary cells in a time-and dose-dependent manner,but also significantly induced the secretion of SLα and SLβ in pituitary cells.Finally,using a series of signaling pathway inhibitors to co-treat grass carp pituitary cells with CRH1 a or UTS1,it was found that CRH1 a and UTS1 induce pituitary SLα and SLβ mainly through three pathways of c AMP/PKA,PLC/IP3/P-KC and Ca2+/Ca M/Ca MK-II synthesis and secretion.