Abstract
Histochemical investigations were made upon activities of succinic dehydro-genase, lactic dehydrogenase, nicotinamide adenine dinucleotide diaphorase, cytochrome oxidase and glucose-6-phosphate dehydrogenase, and contents of copper and of nucleic acids in the diencephalon of rats in reference to aging.
1) In the diencephalon of senescent rats, a slight decrease of activity of glucose-6-phosphate dehydrogenase and a slight increase in the activities of both succinic dehydrogenase and cytochrome oxidase in the supraoptic and paraventricular nuclei were found.
2) A deposition of copper was increased with aging in the stratum periventriculare hypothalami, fimbria hippocampi and habenular nucleus.
3) A decrease of cytoplasmic RNA content of the diencephalon and an increase of RNA in the supraoptic nucleus as well as paraventricular nucleus were found with advancing age.
