THE GOLDFISH VASOACTIVE INTESTINAL POLYPEPTIDE RECEPTOR - FUNCTIONAL-STUDIES AND TISSUE DISTRIBUTION

Vasoactive intestinal polypeptide (VIP)(1) is a neuropeptide that has numerous physiological actions and is widely distibuted in the body of most vertebrate species yet studied. A full-length VIP receptor cDNA was obtained by screening a goldfish brain and pituitary cDNA library. Functional expression of this receptor in mammalian COS-7 cells showe d that it is coupled to cAMP production in a VIP (Atlantic cod, Gadus morhua) concentration-dependent manner; the EC50 of the VIP receptor i n response to cod VIP stimulation was determined to be at 1.0 nM. At 1 00 nM of peptide, the relative potency of various peptides in stimulat ing cAMP in the transfected cells was cod VIP>human VIP>human PACAP-38 >human PACAP-27>human secretin>dogfish glucagon>carp GHRH. The recepto r was able to bind specifically to VIP and PACAP as indicated by compe titive displacement assays. By reverse-transcriptase polymerase chain reaction, the transcripts of this receptor were detected in goldfish b rain, pituitary gland, gall bladder, kidney, gill, small and large int estine, heart, muscle and spleen. The expression pattern of goldfish V IP receptor is similar to that of mammals and thus further evidence of the conservation of VIP function in vertebrates. Characterization of the VIP1 receptor from goldfish is the first step in understanding 2 o f the most important neuropeptides, VIP and PACAP, and their interacti on with multiple receptor system in lower vertebrates.