Effects of a dry diet on the antidiuretic hormone content of the neurohypophysis in spiny mice as compared to the albino rat and mouse

Abstract

Changes in ADH content of the neurohypophysis of two xeric rodent species ( Acomys cahirinus and Acomys russatus) and two mesic laboratory albino species ( Rattus norvegicus and Mus musculus) were investigated by means of bioassay. When kept on a dry diet, the ADH content of the rat hypophysis decreased continuously, sinking lowest at 17 days of water deprivation, by which time all the rats succumbed. On the other hand, in both species of Acomys and in the albino mouse on a similar regime, initial depletion of ADH was followed by repletion of the hormone store. This recovery was more evident when ADH content was expressed in relation to body weight. As normal specimens of all four species did not show any striking inter-specific variation in neurohypophysial ADH content, it appears that the resistant species are characterized by an adaptive mechanism of replenishing hormone content when challenged.