Radioautographic localization of radioactivity in rat brain after intraventricular or intracarotid injection of ³H-L-prolyl-L-leucyl glycinamide

Tritiated L-prolyl-L-leucyl-glycinamide was injected into the carotid artery or lateral ventricle of rats and the radioactivity localized by radioautography. After intracarotid administration, the radioactivity labeled the meninges, ependymal cells bordering the ventricles, and cells of the choroid plexus, as well as the median eminence and subfornical organ and thus may have reached the cerebrospinal fluid. After intraventricular injection, specific localization of radioactivity was found in cells of the nucleus lateralis septi, nucleus medialis septi, putamen, globus pallidus, indusium griseum, hippocampus, corpus callosum, and meninges. The results after intracarotid injection suggest that L-prolyl-L-leucyl-glycinamide may cross the blood brain barrier and the results after intraventricular injection suggest sites of localization which might be correlated with the previously reported effects of the tripeptide on the brain.