Influence of changes in composition of the cerebrospinal fluid on the secretory activity of the subcommissural organ in Rana esculenta. A quantitative histochemical and autoradiographic study by means of scanning cytophotometry.

The effects of injection into the brain ventricle of noradrenaline dissolved in amphibian Ringer's solution, and of amphibian Ringer's solution alone on the secretory activity of the subcommissural organ (SCO) of Rana esculenta were studied. The parameters used were: the amount and mean concentration of secretory material within the SCO stained by aldehyde fuchsin (AF), the amount and mean concentration of radioactive material within the SCO labelled by 35S-cysteine, and the growth rate of the Reissner's or liquor fibre (LF). A significant influence on the amount of secretory material in the SCO was found to be exerted by the injection of amphibian Ringer's solution alone. This influence can be explained as an inhibition of the release of secretory material by the SCO. Injection of noradrenaline dissolved in amphibian Ringer's solution appeared to have a smaller inhibitory effect. Noradrenaline may be presumed to have only slightly stimulated the secretory activity of the SCO.