Effects of Thiols on Oxytocin and Vasopressin Receptors

Abstract

IT was shown by van Dyke et al.¹ that thioglycollate inactivates oxytocin and vasopressin presumably by reducing the S–S bond in these polypeptides. This effect has been widely used to detect the presence of posterior pituitary hormones in tissue extracts by incubating them with thioglycollate and testing whether their pharmacological activity is afterwards abolished. We have confirmed that thioglycollate inactivates oxytocin and vasopressin, but find that this is a slow process and that the lack of activity of S–S polypeptides in the presence of thioglycollate is largely due to a pharmacological antagonism at the receptor level. Another thiol, α-thioglycerol, also exhibits this antagonism, although its ability to destroy S–S polypeptides is negligible.