Effect of AVT antisense oligodeoxynucleotides on AVT release induced by hypertonic stimulation in chicks

In birds, arginine vasotocin (AVT) and mesotocin (MT) are the neurohypophyseal hormones. AVT is known to be an avian antidiuretic hormone and is released from the neurohypophysis by dehydration or hyperosmotic stimulation. The purpose of this study was to determine whether the mechanism of AVT synthesis is related to the mechanism of hormone release from the neurohypophysis. Four-day-old chicks received an AVT antisense oligodeoxynucleotide (ODN) injection into the cerebral ventricle (icv). Following antisense administration, the chicks received hypertonic saline stimulation. Plasma levels of AVT and MT were measured by radioimmunoassays. In control birds, a hypertonic saline injection resulted in the increase of plasma AVT level. The administration of a high dose (50 μg) of antisense ODN inhibited the increase of plasma AVT level induced by the hypertonic saline stimulation. Plasma levels of MT did not change with the administration of hypertonic saline or antisense ODN. These results suggest that the mechanisms that regulate the secretion of AVT from the neurohypophysis may be coupled to the mechanisms that regulate the synthesis of AVT.