Ultrastructural aspects of the inhibition of neurosecretion by puromycin

Summary The supraoptic nuclei and the infundibular process of the neurohypophysis were studied under the electron microscope in rats fed on dried food for 1 to 3 days and in similarly dehydrated animals but injected subarachnoidally with puromycin 4 to 24 hours prior to fixation. With 4 to 8 hours of puromycin the intracisternal filamentous material found in the control is greatly diminished. After 24 hours this inhibitory effect disappears in the perikaryon but the neurotubular material of the neuronal processes within the supraoptic nucleus and the neurosecretion in the infundibular process are greatly reduced. These results are discussed taking into consideration the inhibition of protein synthesis caused by puromycin and the neurosecretory cycle which characterizes the supraoptic neurons.Supported by grants from the Consejo Nacional de Investigaciones Cientificas y Técnicas and by the Air Force Office of Scientific Research (963–65).