Twenty-two albino rats were divided into three groups for chronic brain electrode implantation. The effects of subsequent stimulation and ablation of the subcommissural organ (SCO), the bilateral lateral hypothalamic nuclei (LH), and the dorsal longitudinal fasciculus (FLD) on volume of water intake, and on concentration of urinary excretion were observed over twenty-two hour periods of free access to water both before and after treatments.
It was observed that neither stimulation nor lesion of the SCO resulted in disruption of water intake or of urinary volume and concentration. Similar stimulation of LH potentiated drinking, while similar lesions produced a hypodipsia that necessitated tube feeding. Lesions of LH produced, in addition, marked elevation of urine volume, but no change in urine concentration. Sectioning of the FLD was followed by effects similar to those following lesions of the LH nuclei.