Intraperitoneal administration of ascorbic acid delays the turnover of 3H-labelled cortisol in the plasma of an ODS rat, but not in the Wistar rat. Evidence in support of the cardinal role of vitamin C in the progression of glucocorticoid synthesis
Kodama, M.; Inoue, F.; Kodama, T.; Kodama, M.
In Vivo 10(1): 97-102
1996
ISSN/ISBN: 0258-851X PMID: 8726814 Document Number: 461382
The purpose of this investigation was to reproduce in rats the enhancing effect of vitamin C on adrenal glucocorticoid production, a phenomenon that has been repeatedly observed in our human experiments. Here, we tried to assess the impact of vitamin C pretreatment on the turnover of erogenous 3H-labelled cortisol tracer in rats. 500 mg ascorbic acid in 15 ml isotonic liquid per rat was administered intraperitoneally into rats of the experimental group, and 15 ml physiological saline per rat was similarly introduced into rats of the control group. At various times after the loading of either vitamin C or saline, 3H-labelled cortisol, 20 mu-c/0.5 ml saline/rat, was injected subcutaneously into rats of both the experimental and control groups. Thirty minutes later, all rats were sacrificed by exsanguination, and the radioactivity content was measured in the lipophilic fractions as well as in the purified corticosteroid compounds of blood, adrenal, testis and liver samples. To test the specificity of vitamin C action, experimental results from scurvy-prone ODS rats were compared with those of scurvy-resistant Wistar rats. Results obtained are as follows: a) the practice of vitamin C loading markedly delayed the turnover of 3H-cortisol in both the plasma lipophilic fraction and the plasma cortisol fraction, a finding which indicates that the above vitamin C pretreatment enhanced the release of endogenous glucocorticoid in such as to delay the turnover of the tracer cortisol in plasma. b) The above "dilution" effect of endogenous glucocorticoid surge was very distinct in both the lipophilic fraction and the cortisol fraction of ODS rats, and was less distinct (lipophilic fraction) or insignificant (cortisol fraction) in Wistar rats, a finding to indicate that the observed effect of vitamin C was of physiological significance. c) The responses of the adrenal glands, testes and liver to vitamin C pretreatment were generally more distinct in ODS rats than in Wistar rats, but varied from one organ to another. The significance of the functional linkage between vitamin C and adrenal glucocorticoid, which has been confirmed both in both the humans and rats in our laboratory, was discussed in the light of the historical development of vitamino-endocrinology.