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KMID : 0377619620030050471
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Korean Jungang Medical Journal
1962 Volume.3 No. 5 p.471 ~ p.508
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Influence of the Central Nervous System on changes in Urinary Volume, Osmolality and Chloride Content
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Abstract
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Since the experiment by Verney in 1947, it has been known that there is a close relation between hypothalamus and water metabilism. It was then estabolished the an antidiuretic hormone is produced in the hypothalamus and that there exists an osmoreceptor. However the mechanism of conduction of afferent impluse from the limbic system to the hypothalamus has remained largely obscure.
In a previous experiment, the auther observed the effects of osmotic stimulations applied into the amygdala, septal region and hypothalamus that have afferent connections with the hypothalamus. It was then postulated that this pathway may, nerve fibre or otherwise had not been clarified.
In the present experiment, the auther stimulated various subcortical areas( Anterior and posterior hypothalamus, septal region amygdala, hippocampus and inhibitory area of reticular formation) following denervation of kidneys and transection of midbrain as well as spinal cord. The auther then observed changes in urine amount, urine psmolality and urinary chloride content to see the effect of these procedures.
Experiment;
Male rabbits weighing 2kg were used. In order to maintain the animals in positive water balance during the experiment, an intravenous infusion of 5% G/W at the rate of 30grrs./min. were Kept on throughout experiments. Osmotic stimuli were applied b injecting 0.1 c.c. of 3% NaCl solution, isotonic saline or water using sterotaxic apparatus. Urine volume was measured every 5 minutes by was of and indwelling catheter, and stimuli was not applied until volume reached 6.0 ml./5 min. por more. Urine osmolality was measured with Fiske osmoneter, and urine chloride content by schales and schales method. Using ether anesthesia, spinal cord transection was done at the level of 5 th cervical spine, and the midbrain transection at it´s frontal border. Renal denervation was done under ether anesthesia, and the experiment was performed at 48 hours following these procedure.
Result;
1. As a perliminary experiment, 01.c.c. each of 3% NaCl was injected into the putamen, cerevellum and cerebral cortex where there is no known afferent connection to the gypothalamus. There were no appreciable changes in urine amount, urine psmolalit or urine chloride content.
2. When the dame stimuli were applied to ingibitory area on 4 rabbits, there were profound changes in the results. In 3 of them, there were prompt and marked decreases in urine amount and rises in psmolality (antidiurietic response.) Urine chloride content paralleled that of urine amount. In the remaining animal, there was paradixical rise in urine volume with little change in osmolality. In separate experiment 0.1 c.c. each of distilled water was injected into this inhibitory area in 2 rabbits. There were slight increase in urine volume and little change in psmolality.
In one animal 0.1 c.c. of normal saline was injected resulting in little change.
3. When 3% NaCl was injected various subcortical areas at 48 hours following renal denervation, all animals showed prompt and marked decrease in urine amount as well as increase in its osmolity In one of 4 rabbits tested at the ingibitory area, there was no remarkable changes in urinary amount and its osmolality.
4. When same procemdure was carried out following the transection of spinal cord, all of them showed prompt and remarked antidiuretic response in one of 4 animals tested at the inhibitory area, there is no responses.
5. Following transection of the midbrain injections were carried out at various subcortical areas some were in fornt and some were in behind the transection.
When subcortical areas erer injected at posterior of the transecction there was only sligh change, while stimulation in subcortical areas of front of the transection caused slow but definite antidiuretic changes.
6.When both renal denervation and transection of the midbrain were carried out prior to the rxperiment, results were very similar to that of the experiment in paragraph 5.
From these experiments it became apparent that osmotic stimulation to either midbrain or inhibitory area of reticular formation caused antidiuretic activity, through the afferent connections to the hypothalamus from these areas It is also apparent from this study that the antidiuretic activity is not mediated neither the spinal cord nor the renal nerve. The limbic system, such as septal region, amygdala and hippcampus, is condidered to be a higher neural regulatory area which regulates the function of the hypothalamus i the same mechanism.
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