CHARACTERIZATION OF IMMUNOREACTIVE AVP IN THE OVINE HYPOTHALAMOPITUITARY AXIS

The aims of these studies were to determine the precise molecular natu re of immunoreactive (IR-) vasopressin (AVP) in the ovine hypothalamo- pituitary axis and to examine a possible role for glucocorticoids in r egulating both AVP processing and levels in this axis. The IR-AVP in e xtracts of paraventricular nucleus, median eminence, portal blood, and anterior and neurointermediate pituitary elutes as a single peak on t wo distinct HPLC solvent systems, suggesting that AVP is processed ide ntically in these tissues. Identical profiles were also found in extra cts from pituitaries and sheep subjected to chronic (10 days) glucocor ticoid treatment, or hypothalamo-pituitary disconnection. The latter f indings confirm that in sheep, like the rat, AVP is synthesized and pr ocessed in the anterior pituitary and is not sequestered from extrapit uitary sources.