Cholinesterase and Acid phosphatase in the Rabbit's Retinae Fo11owing Severance of the Optic nerve

Group totalling 55 young rabbits (both sexes), whose right optic nerves had been severed intraorbitally, were fed for 1 week, 2 weeks, 4 weeks and 8 weeks respectively. The retina of the left eye was used as a control and that of the right eye for the experiment. The histochemical changes of cholinesterase, acid phosphatase and ribonucleic acid in the reitna after to severance of the optic nerve were observed for 8 weeks after section. In the retina of the young rabbit, whose visual connection to the central nervous system was blocked, there was a decreasing specific cholinesterase activity beginning at the 4th week after the section of it. By the 8th week, the enzyme activity in the perikaryon of the ganglion cell and the inner plexiform layer was considerably decreased. Acid phosphatase activity in the young rabbit's retina peaked at the 2nd week, but decreaseed below normal after the 4th week. This rapid decline of acid phosphatase activity was characteristic in the experimental retinae and was in contrast to the rather slow alteration of enzymatic activity in neurons undergoing wallerian degeneration. Pyroninophilic granules contained in neural cytoplasm of the retina were affected by the surgical blocking of the visual connection with the central nervous system. By the 4th week the granules had partially disappeared from the perikaryon of the ganglion cell and from the inner nuclear layer. Consequently, as the result of histochemical studies, firstly it is postulated that the gradual decline of specific cholinesterase activity in the rabbit's retina was closely related to the intraorbital blocking of the optic nerve, and secondly, that the typical degeneration of the ganglion cell in the ganglion cell layer (which was associated with a partial disappearance of the ganglion cell) was related to the changes in the acid phosphatase activity and alteration of the pyroninophilic granules in the retina following optic nerve transection.

An Autoradiographic Study on Metabolism of Serotonin in Cerebral Nerve Cells Using 5-Hydroxytryptophan-C

In order to demonstrate autoradiographically the sites of serotonin metabolism in the brain, DL 5-HTP and DL 5-HTP-C14 were intraperitoneally administered to healthy adult mice. In order to distinguish histochemically serotonin-like substances which have staining characteristics similar to the enterochromaffin cells of the gastrointestinal tract, serotonin-releaser reserpine was administered intravenously to healthy adult rabbits. A stripping film technique for autoradiography, a ferric ferricyanide reduction test by Schmorl, and a Gomori-Burtner methenamine silver staining method for argentaffin cells were used in this study. In the brain tissues of mice treated with 5-HTP, it was observed that the cytoplasm of the nerve cells, of the cerebral cortex had blue positive staining substances by the ferric ferricyanide technique. In similar tissue sites in mice treated with 5-HTP-C14, a number of blackened-par-ticles reduced by beta rays were easily found. especially in the cytoplasm of nerve cells and neuroglia cells. It is suggested that the serotonin precursor, DL 5-hydrox-ytryptophan is metabolized the cerebral tissue, and serotonin is synthesized also in the nerve cells and the neuroglia cells.