Neurosecretion of the hypothalamo-hypophyseal system after intragastric administration of zinc oxide.

Considering the importance of Zn for normal metabolic processes as well as its neurotoxic properties when ingested in undue amounts we have undertaken a study on the effect of ZnO intoxication on the neurosecretory function of the hypothalamus and hypophysis. The investigations were performed on rats that have been treated intragastrically with ten daily (100 mg) doses of ZnO. The intoxicated rats revealed elevated contents of neurosecretion in the neurosecretory nuclei of the hypothalamus along with decline amounts of neurosecretion in the nervous parts of the hypophysis. The contents of PAS-positive substances was increased all over the neurosecretory hypothalamo-hypophyseal system. The concurrent enlargement of the nuclear and cytoplasmatic areas of the secreting cells speaks in favour of the conclusion that the observed histochemical and morphometric alterations reflect both an increased neurosecretory activity of the hypothalamus and in enhanced release of antidiuretic hormone.