THE HYPOTHALAMO‐NEUROHYPOPHYSIAL SYSTEM OF NATIVE AUSTRALIAN DESERT RODENTS. THE VASOPRESSIN AND OXYTOCIN CONTENTS OF HYPOTHALAMUS AND POSTERIOR PITUITARY OF NOTOMYS ALEXIS AND PSEUDOMYS AUSTRALIS COMPARED WITH THOSE OF THE LABORATORY RAT AND MOUSE IN DIFFERENT STATES OF WATER BALANCE

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Abstract
Summary: The neurohypophysial hormones vasopressin (the antiduiretic hormone) and oxytocin have been quantified in xerophilic and mesophilic rodents under normal and dehydrated conditions in order to study the relative contribution of these hormones to survival under drought conditions. The ability to cope adequately with water deprivation or saline ingestion was found to be closely related to the magnitude (relative to body size) of pre‐existing hormone stores in the neural lobe and to the subsequent ability to enhance hypothalamic biosynthesis of vasopressin and oxytocin sufficiently in maintain those stores at near‐normal levels despite a continuing high level of demand for vasopressin and, apparently, also oxytocin.The possible role(s) of the release of oxytocin in these conditions is discussed.Attempts have been made to explain differences observed between laboratorybred Notomys and those taken from the wild in their relative abilities to withstand water deprivation, the former seeming to be more dependent upon acutely accelerated hormone biosynthesis than on previous adaptation via renal medullary ‘work‐load’ hypertrophy.