抄録
Neurohypophysial hormone activities of the median eminence and the pars nervosa of the bullfrog and turtle were detected by several pharmacological methods. The activities of the frog and turtle median eminence were about 2 and 10 percent of those of the pars nervosa of the respective animals. The oxytocic activities of the median eminence and the pars nervosa of both species were reduced by more than 95 percent by the treatment with sodium thioglycollate. By means of high voltage paper electrophoresis, two principles, arginine vasotocin and oxytocin or an oxytocin-like principle, were well separated using extracts of the median eminence as well as the pars nervosa of both species. Both pharmacological and electrophoretic methods demonstrated that the ratios of vasotocin to oxytocin (or an oxytocin-like peptide) were higher in the median eminence than in the pars nervosa. The predominant presence of arginine vasotocin in the composition of the hormones in the median eminence was also observed in the duck extract similarly electrophoresed.
Neurohypophysial hormone activities in the turtle pars nervosa decreased 1hr. after intraperitoneal injection of 10 percent NaCl and showed a slight recovery in the activities 4hrs. after the injection. The activities also decreased in the pars nervosa of the turtles which were not allowed access to water for 14 days. However, no such activity change was discernible in the median eminence by these treatments. In the pars nervosa of the turtle sacrificed 4 hrs. after salt injection or after 14 days of dehydration, a decrease in vasopressor activity was more remarkable than a decrease in oxytocic activity and it was suggested that selective release of arginine vasotocin occured in the turtle pars nervosa.
