[Reaction of the Gomori-positive hypothalamo-hypophyseal neurosecretory system of the rat to a single dose of thyroliberin].

A decrease in the functional neurosecretory cell activity of the rat hypothalamic supraoptical and paraventricular nuclei was seen 30 minutes after a single intramuscular thyroliberin injection (8 micrograms). The size of the neurosecretory cell nucleoli significantly diminished in both centers, while a large amount of intranuclear nucleoli-like bodies appeared in the paraventricular nucleus. The neurosecretory substance content in the posterior hypophysis significantly decreased, indicating an active neurohormone excretion. A possibility of negative feedback between the body thyroliberin level and the state of the Gomori-positive hypothalamic neurosecretory centers is discussed.