The incorporation of 35S-labelled cysteine in the hypothalamic-hypophyseal neurosecretory system of the dehydrated rat

Summary The effect of dehydration upon incorporation of ³⁵S-labelled 1-cysteine in the hypothalamic-hypophyseal neurosecretory system of the rat was studied by autoradiography. Grain counts were made of the supraoptic and paraventricular nuclei, median eminence and neurohypophysis. The results were statistically treated. The effect of dehydration was observed, at first, as an increase of incorporation in all the sites examined. Six hours after administration, the disappearance of the isotope from the nuclei was accelerated, and after 24 hours also that from the distal parts of the neurosecretory system. The results are interpreted, in the first place, in terms of activation of the neurosecretory system caused by dehydration.This work was supported by a grant from the Sigrid Jusélius Foundation, Helsinki.