Uptake of 3H-leucine in the brain of the female rat and its change after castration.

Tritiated leucine was intraperitoneally injected into normal and castrated female rats, and the uptake in the brain was autoradiographically studied 2hr after the injection. Radioactivity was estimated by counting the number of reduced grains in various areas of the brain. In normal animals, the highest uptake of radioisotope was found in the cell bodies of neurons in the supraoptic nucleus. A less but still marked uptake was noted in the cell bodies of neurons in the paraventricular and accessory nuclei.The cell bodies of neurons in the medial habenular nuclei showed a relatively high uptake. The results suggest that the nuclear regions are active in protein synthesis. The cell bodies in the ventromedial and arcuate nuclei, the hippocampal formation and the cortex showed a relatively low uptake. In castrated animals, the uptake was enhanced in the cell bodies of neurons in the ventromedial and arcuate nuclei, whereas it was reduced in the supraoptic, paraventricular, accessory and medial habenular nuclei.