The objective of this study is to investigate effects of various areas of the central nervous system on bile secretion and mechanism of action of insulin on acceleration in bile flow.
The Korean male rabbits weighing 1. 8 kg. were subjected for the study following sixteen hours fasting.
The following results are obtained.
1) A normal bile flow rate was established by collecting bile through both hepatic ducts at intervals of ten minutes in three rabbits. The rate of bile flow during the first 10 minutes was 1.2 cc, 1.0 cc and 0. 9 cc, respectively. Thereafter, the bile flow gradually diminished in all.
2) Insulin was administered in doses of 0.5 u.,1.0 u., 1.5 u., 2.0 u., 3.0 u. and 4.0 u. intravenously to six rabbits. There was no change in the rate of bile flow when the dose of insulin was less than 1.5 u. A marked increase in the rate of the bile flow did occur by the dose greater than 2.0 u.
3) Insulin, 0.5 u., was injected into the caudate nucleus bilaterally utilizing steretaxic coordinates described by Choi. This caused an increase of bile flow by 68.5% 130 minutes after the injection compared to mean bile flow rate of pre-treatment in all five rabbits studied. The increase was significant at p<0. 05 compared to control group.
4) The mid-lateral hypothalamus was studied in the same manner which resulted in 50.1% increase in bile flow 100 minutes after the injection compared to pre-treatment in all five rabbits studied. This increase was significant at p5) The mammillary body was studied in the same manner. There was 78. 5% increase inbile flow 120 minutes after the injection compared to pre-treatment in all five rabbits studied. This increase was significant at p<0.05 compared to control group.
6) No change in the rate of bile flow was observed following the injection of insulin into hippocampus, preoptic area, amygdala, putamen, globus pallidus, anterior hypothalamus, mid-medial hypothalamus, posterior hypothalamus, midbrain and salivarius nucleus.
7) Neither distilled water nor 3% NaCl solution administered into the caudate nucleus, mid-lateral hypothalamus and mammillary body where isulin did change the rate of bile flow as well as anterior hypothalamus, mid-medial hypothalamus and posterior hypothalamus areas resulted in change of bile flow.
From the above results, it is evident that the caudate nucleus, mid-lateral hypothalamus and mammillary body act as the central regulatory areas in bile secretion. The mechanism of action of insulin in acceleration of bile secretion, unlike Fitz and Baldwin´s theory of vagal stimulation resulting hypoglycemia produced by insulin, is seemed to be direct action of insulin on the central nervous system, i.e., caudate nucleus, mid-lateral hypothalamus and mammillary body, involved in the `"-gulation of bile flow.
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