Many studies have been reported on the role of hypothalamus as the regulating center of the water and electrolyte balance, also there have been many experimental assertions on direct connections of nerve fibers between hypothalamus and thalamus.
Korean domestic white male rabbits, weighting 1.8 kg. were used as experimental animals, were gavaged with 2% sodium chloride solution, 100 ml 3 times hourly for hydration before experiment.
The site of stimulation in thalamus and hypothalamus were divided 32 areas as illustrated in Fig. 2-1, 4-1, 8-1, and 10-1, so that each site was located 2 mm apart one another in 3 dimensions.
When the urine volume through the indwelling catherter exceeded 4 ml per 5 minutes after hydration, 0.05 ml of 2% sodium chloride solution was injected bilaterally to above 32 areas by the aids of stereotaxic apparatus, and so far urine volume was reduced in those areas, distilled water was injected to see the effects of hypotonic stimulation in the same way as mentioned above.
The following results were observed.
Ⅰ〕Rapid and marked reduction of urine volume by 2% sodiu, chloride solution injection and also significant increase of its volume by distilled water injection were observed in the following 6 areas.
1) area C in Fig. 2-2,; lower part of fornix in medial preoptic area.
2) area G in Fig. 4-2,; lower area of dorsal part of lateral geniculate body.
3) area J in Fig. 4-2,; habenulo-interpeduncular tract.
4) area N in Fig. 4-2,; a little ourside of paraventricular nucleus.
5) area Q in Fig. 8-2,; dosal part of lateral geniculate body.
6) area ζin Fig. 10-2,; lower part of medial geniculate body.
Ⅱ〕No remarkable change of urine volume was observed by the injection of 2% sodiu, chloride solution and distilled water in the rest of 26 areas.
I conclude therefore, from above experimental studies that the areas C,G,J,N,Q, and ζhave some osmoreceptic function directly or indirectly and it is possible, fiber connections exist between the supraoptic and paraventicular nucleus in hypothalamus where ADH is produced.
|