RNAS ENCODED BY A 3.5-KB BOVINE VASOPRESSIN GENE CONSTRUCT ARE TARGETED TO THE NEUROHYPOPHYSIS OF TRANSGENIC MICE

Recent studies have established that the RNA coding for the neuropepti de arginine-vasopressin (AVP) is expressed in the neurohypophyseal com partment of the hypothalamo-neurohypophyseal system. In order to deter mine the molecular mechanisms that direct this novel expression patter n we have now investigated whether an AVP transgene is similarly regul ated. Using a reverse transcriptase-polymerase chain reaction (RT-PCR) approach that permits simultaneous analysis of both endogenous and tr ansgene RNA levels, we have demonstrated that RNA derived from a 3.5-k b bovine vasopressin transgene is expressed in the neurohypophysis of transgenic mice, and is up-regulated by a physiological stimulus (salt -loading) in a similar manner to mouse AVP RNA. Sequences conserved be tween this region of the murine and bovine AVP genes are therefore suf ficient to mediate neurohypophyseal expression. These lines of transge nic mice will serve as a model for the delineation of sequences that t arget expression beyond the neuronal perikaryon.