IDENTIFICATION AND SEQUENCE-ANALYSIS OF ARGININE-VASOPRESSIN MESSENGER-RNA IN NORMAL AND BRATTLEBORO RAT AORTIC TISSUE

Arginine vasopressin (AVP), a hormone of the hypothalamic-pituitary ad s, was also localized in peripheral tissues. To explore AVP precursor gene expression at the vascular level. we have investigated gene trans cripts by reverse transcription-polymerase chain reaction (RT-PCR) and sequencing in aortic tissue of normal rat and in the particular genet ic condition of the homozygous (di/di) Brattleboro rat strain sufferin g from diabetes insipidus. In these rats, a gene deletion induces an u nprocessed AVP precursor in the hypothalamus with undetectable immunor eactive AVP, in contrast to the detection of immunoreactive material a t the Vascular level. In normal rats, using primers complementary to e xon 1 and 3 of the AVP neurophysin precursor gene, RT-PCR and sequenci ng revealed transcripts of the expected size from aorta, mesenteric ar tery and hypothalamus with normal, authentic sequences. Removal of aor tic endothelium severely reduced the amounts of transcripts, suggestin g their main endothelial origin. In Brattleboro rats, transcripts of s imilar size were obtained from aorta and hypothalamus and sequencing r evealed the homozygous deletion (Delta G316) in both tissues, identica l to that found in genomic DNA (Delta G1864). While sequence data from normal rats provide the first direct evidence for the presence of AVP precursor transcripts in rat aortic tissue, identification of the del eted sequence of transcripts in Brattleboro rat aorta suggests that ti ssue-specific mechanisms are operating for the expression of vasopress in neurophysin precursor in peripheral vascular tissue compared with t he hypothalamus.