- Email: [email protected]
18-Oxocortisol: Effect of dexamethasone, ACTH and sodium restriction
Vol. 32, Printedin Great Britain
J. sreroid Biochem.
No. 3,
pp. 409-412, 1989
OC22-4731/89 $3.00 + 0.00
PergamonPress plc
1%OXOCORTISOL: EFFECT OF DEXAMETHASONE, ACTH AND SODIUM RESTRICTION CELSO E. GOMEZ-SANCHEZ,$ PHILIP G. ZAGER,* MARK F. FOECKJNG,0. BRYAN HOLLAND? and ARUNABHA GANGULY Departments of Internal Medicine, The University of South Florida College of Medicine, James A. Haley V.A. Hospital, Tampa, Florida, *The University of New Mexico, Albuquerque, New Mexico and tThe University of Texas Medical Branch, Galveston, Texas, U.S.A. (Received 9 May 1988) Summary-The urinary excretion of ll-oxocortisol in 37 normal subjects consuming a normal sodium diet was 1.2 k 0.9(SD) pg/24 h. Dexamethasone administration to 5 normal individuals suppressed the excretion of 18-oxocortisol from 1.16 + 0.5 fig/24 h to 0.6 + 0.2 rg/24 h. While they still received dexamethasone, ACTH administration raised the 18-oxo-cortisol excretion to 3.82 + 1.2 pg/24 h. Seven normal subjects were placed on a sodium restricted diet, and the urinary excretion of 18-oxocortisol rose from 1.5 + 1.21 pg/24 h to 8.54 f 5.08 fig/24 h and aldosterone from 6.6 + 2.0 pgg/24 h to 39.7 k 14.6 yg/24 h. Two of the seven individuals showed minimal increases in the excretion of 18-oxocortisol, but in ail cases aldosterone increased with sodium restriction. The urinary excretion of 18-oxocortisol correlated significantly with the excretion of aldosterone, 18-hydroxycortisol, cortisol, and 19nordeoxycorticosterone. These studies indicate that 18-oxocortisol secretion is under ACTH regulation, but since sodium restriction also increases the excretion of 18-oxocortisol, the renin-angiotensin system must also participate in its regulation. However, some individuals do not increase their excretion of 18-oxocortisol with sodium restriction, although aldosterone excretion increases as expected, suggesting that additional factors participate in the regulation of 18-oxocortisol production.
INTRODUCTION In the course of studies trying to explain the frequent discrepancy between the severity of hypertension and metabolic abnormalities ascribed to aldosterone secretion in patients with primary aldosteronism due to aldosterone-producing adenoma (APA), Chu and Ulick [l] isolated an abundant urinary steroid identified as 18-hydroxycortisol. Incubations of bullfrog interrenal organ, a model of adrenal zona glomerulosa, with cortisol resulted in the isolation of 18-hydroxycortisol and 18-oxocortisol [2]. Patients with APA and glucocorticoid suppressible aldosteronism (GSA) have been recently shown to excrete excessive amounts of these two new steroids [l-5]. The pathway that cortisol follows leading to the synthesis of these 18 hydroxylated steroids is believed to be through the cytochrome P-450corticosteroid methyl oxidase (P-450-CMO), which in the case of the usual substrate, corticosterone, leads to 18-hydroxycorticosterone and aldosterone. Cortisol is a suboptimal substrate [2]. The biological activity of l&hydroxycortisol is negligible [6] but 18-oxocortisol was 1% of the mineralocorticoid activity of aldosterone and 3% of the glucocorticoid activity of cortisol [7,8].
Regulation of the secretion of 18-oxocortisol has not been reported. The regulation of 18-hydroxycortisol has been studied [9-111. Production of 18-hydroxycortisol occurs in the zona glomerulosa and fasciculata [12]. The present report describes the effects of sodium restriction, dexamethasone suppression and ACTH stimulation on the urinary excretion of 18-oxocortisol. The correlation of urinary l&oxocortisol with the urinary excretion of cortisol, 19nordeoxycortL aldosterone- 18-oxoglucuronide, costerone and 18-hydroxycortisol is described.
EXPERIMENTAL Steroid measurement procedures
Urinary aldosterone 18-oxoglucuronide [ 131, cortisol [ 141, 18-oxocortisol [3], 1I-hydroxycortisol [l l] and 19-nor-deoxycorticosterone [ 151 were measured by radioimmunoassay. Experimental protocols
Thirty-seven normal subjects (9 men and 28 women with a mean age of 43.8 yr and a range of 22-69 yr) collected a 24 h urine while consuming a normal sodium diet. Sodium restriction
SAddress for correspondence: Celso E. Gomez-Sanchez, James A. Haley V.A. Hospital, 13000 Bruce B. Downs Blvd (1 II-M), Tampa, FL 33612, U.S.A.
Seven normal individuals were admitted to the Clinical Research Center and were given an isocaloric 409
410
C~LSO
E.
GOMEZ-SANCHEZ
120 mmol sodium, 70 mmol potassium diet for 2 days followed by 6 days on an isocaloric diet containing 10 mmol sodium 70 mmol potassium. Continuous 24 h urine collections were started. The samples corresponding to the second day of the 120mmol sodium and the sixth day of the 10 mmol sodium diets were used for the measurements.
et
0 a
al. 00
Normal
HO Low
Nd
dlet
Na’ diet
20
C w
f
Effect of dexamethasone and ACTH Five normal subjects underwent a protocol which consisted of a 1 day baseline period after which they received dexamethasone 1 mg, followed by 0.5 mg every 6 h for 2 days. During the second day of dexamethasone the subjects also received an infusion of cosyntropin 0.25 mg over 6 h. Daily 24 h urine samples were collected. Statistical analysis The data was analyzed using Statview 512 (BrainPower Inc.) software using a Macintosh SE computer (Apple Computer Inc.). Student’s t-test for paired data and regression analysis were used. RESULTS
excretion of 18-oxocortisol, The urinary l&hydroxycortisol, cortisol, aldosterone, and 19-nordeoxycorticosterone in the 37 normal subjects are shown in Table 1. The administration of dexamethasone to 5 normal subjects decreased the excretion of 18-oxocortisol from to 0.6 f 0.2 pg/24 h 1.16 f 0.05 pg/24 h (P < 0.01). Administration of ACTH raised the 18-oxocortisol excretion (while still receiving dexamethasone) to 3.82 + 1.2 pg/24 h (Fig. 1). Dietary sodium restriction for 6 days in 7 normal subjects resulted in a significant increase in from to ll-oxocortisol 1.5 f 1.21 pg/24 h 8.54 + 5.08 pg/24 h (Fig. 2) and aldosterone from
Patient
number
Fig. 2. Urinary excretion of I8-oxocortisol and aldosterone18-oxo-glucuronide in normal subjects consuming a normal and a low sodium diet.
6.6 + 2.0 fig/24 h to 39.7 f 14.6 pg/24 h. Two of the seven individuals showed minimal increases in the excretion of 18-oxocortisol, but in all cases aldosterone increased with sodium restriction. 18-Oxocortisol excretion during the normal and low sodium diet experiments showed a significant correlation with the excretion of llhydroxycortisol P < 0.001) [Fig. 31, aldosterone (r = 0.909, (r = 0.902, P < 0.001) [Fig. 41, cortisol (r = 0.512, P < 0.02) [Fig. 51 and 19nordeoxycorticosterone (r = 0.698, P < 0.001) [Fig. 61.
2
4
6
8
18-OXOCORTISOL
10
12
14
16
(pgl24hr)
Table I. Urinary excretion of steroids in 37 normal individuals
I .2 + 0.9 pg/24 h
I I-Oxocortisol
63 k 36 /q/24 h IO f 10 pg/24 h 6.1 + 2.7 ,ug/24 h 313 t 268 w/24 h
IS-Hydroxycortisol Cortisol Aldosterone 19-Nordeoxycorticosterone
Fig. 3. Correlation of the excretion of 18-hydroxycortisol to ll-oxocortisol. The open circles are measurements of samples obtained from subjects consuming a low sodium diet.
18-OXOCORTISOL
Basal
DOX
ACTH
Fig. 1. Urinary excretion of ll-oxocortisol before and after receiving dexamethasone and ACTH.
(pg/24hr)
Fig. 4. The urinary excretion of aldosterone-ll-oxoglucuronide is plotted against ll-oxocortisol. The open circles are measurements of samples obtained from subjects consuming a low sodium diet.
Urinary 18-oxocortisol excretion 601
r;0.,12 p.0.02
. ;
50
c1 3
40
D
.
--=-
KY., 0
2
( 4
6
8
10
18.OXOCORTISOL
12
14
16
(pg/24hr)
Fig. 5. The urinary excretion of cortisol is plotted against 18-oxocortisol. The open circles represent measurements from subjects consuming a low sodium diet.
DISCUSSION
Adrenal cells originate in the subcapsular region (zona glomerulosa) and migrate centripetally to form the zona fasciculata and reticularis [16, 171. Cells from the zona glomerulosa synthesize corticosterone, 18-hydroxycorticosterone and aldosterone, steroids which lack the 17-hydroxy group. The cytochrome P-450-corticosterone-methyl-oxidase undergoes involution and the 17-hydroxylase is induced as the cells migrate centripetally to become the zona fasciculata [18,19]. In the interphase between the zona and fasciculata there are morglomerulosa phologically distinct cells that share characteristics of the two areas and have been called intermediate or transitional cells [20,21]. It is likely that they are the same cells where the P-450-CM0 and 17-hydroxylase enzymes coexist, leading to the formation of the hybrid steroids 18-hydroxycortisol and 18-0x0cortisol in the transitional zone [22]. 18-Hydroxycortisol in the zona glomerulosa is an intermediate in the biosynthesis of 18-oxocortisol, but in the zona fasciculata can be formed by an alternative pathway involving an initial 18-hydroxylation of 1l-deoxycortisol to 18-hydroxy-1 I-deoxycortisol followed by 1lb-hydroxylation to 18-hydroxycortisol [12]. An increase in the excretion of 18-hydroxycortisol [l 1] and 18-oxocortisol with ACTH and suppression with dexamethasone suggests that both steroids are regulated by ACTH. Sodium restriction was also associated with an increase in the excretion of both steroids, although 18-hydroxycortisol did not in-
r.0.698
p
IS-OXOCORTISOL
(pg124hr)
Fig. 6. Urinary excretion of 19nordeoxycorticosterone is plotted against 18-oxocortisol. The open circles represent measurements from subjects consuming a low sodium diet.
411
crease in 2 out of 8 subjects previously studied [l 11. Aldosterone excretion increased significantly in all subjects and l&oxocortisol increased significantly in 5 out of the 7 subjects. In one of the subjects in whom l&oxocortisol did not increase, l&hydroxycortisol increased significantly. These studies suggest that sodium restriction, probably through activation of the renin-angiotensin system, was responsible for stimulating the secretion of l&hydroxycortisol and 18-oxocortisol. Corrie et al. [lo] have also shown an increase in the excretion of 18-hydroxycortisol with sodium restriction in dexamethasone suppressed individuals, but were unable to show stimulation of plasma 18-hydroxycortisol by angiotensin II administration, suggesting that a factor different from the renin-angiotensin system participates in its regulation. The biological activity of 18-hydroxycortisol is negligible [6] but ll-oxocortisol has 1% the mineralocorticoid activity of aldosterone and 3% the glucocorticoid activity of cortisol [7,8] and can induce hypertension when injected chronically into rats [23] and sheep (unpublished). The possibility exists that excess production of 18-oxocortisol might be playing a role in the pathogenesis of hypertension in glucocorticoid suppressible aldosteronism and in some patients with primary aldosteronism due to an adrenal adenoma. At the very least, these steroids might serve as markers for the differential diagnosis of the various types of primary aldosteronism. This study demonstrates that l&oxocortisol and 18-hydroxycortisol are excreted in normal individuals and that their regulation seems to be under ACTH and probably the renin-angiotensin system, although other unknown factors might also be playing a role. Acknowledgements-The expert technical help of Melinda Lake, Thomas Ries and Robert J. Upcavage and editorial assistance of Dr Elise Gomez-Sanchez are greatly appreciated. These studies were supported by research funds from the VA and NIH grants HL 27255, HL 27737, HL26856 and the General Clinical Research Centers Program of the Division of Research Resources RR-73 (UTMB) and RR997 (NM). The aldosterone antiserum was kindly provided by the NIAMDD.
REFERENCES
Chu M. D. and Ulick S.: Isolation and identification of 18-hydroxycortisol from the urine of patients with primary aldosteronism. J. hoi. Chem. 258 (1982) 2218-2224. Ulick S., Chu M. D. and Land M.: Biosynthesis of ll-oxocortisol by aldosterone producing adrenal tissue. J. biol. Chem. 258 (1983) 5498-5502. Gomez-Sanchez C. E., Montgomery M., Ganguly A., Holland 0. B., Gomez-Sanchez E. P., Grim C. E. and Weinberger M. H.: Elevated urinary excretion of in glucocorticoid-suppressible al1I-oxocortisol dosteronism. J. c/in. Endocr. Met& 59 (1984) 1022-1024. Ulick S. and Chu M. D.: Hypersecretion of a new corticosteroid, ll-hydroxycortisol in two types of adrenocortical hypertension. C/in. Exp. Hyper. A4 (1982) 1771-1777.
412
CELSO E. GOMEZ-SANCHEZetal.
5. Connell J. M. C., Kenyon C. J., Corrie J. E. T., Fraser R., Watt R. and Lever A. F.: Dexamethasonesuppressible hyperaldosteronism; adrenal transition cell hyperplasia? Hypertension 8 (1986) 669-676. 6. Gomez-Sanchez E. P., Gomez-Sanchez C. E., Smith J. S., Ferris M. W. and Foecking M. F.: Receptor binding and biological activity of iI-hydroxycortfsol. Endocrinoloav 115 (1984) 462-466. 7. Ulick S., L&d M. -and Chu M. D.: 18-Oxocortisol, a naturally occurring mineralocorticoid agonist. Endocrinology 113 (1983) 2320-2322. 8. Gomez-Sanchez C. E., Gomez-Sanchez E. P., Smith J. S., Ferris M. W. and Foecking M. F.: Receptor binding and biological activity of 18-oxocortisol. Endocrinology 116 (1985) 6-10. 9. Corrie J. E. T., Edwards C. R. W. and Budd P. S.: A radioimmunoassay for I I-hydroxycortisol in plasma and urine. Cfin. Chew. 31 (1985) 849-852. 10. Corrie J. E. T.. Edwards C. R. W.. Jones D. B.. Padfield P. L. and Budd P. S.: Factors affecting the secretion of 18-hydroxycortisol, a novel steroid of relevance to Conn’s syndrome. Clin. Endocr. 23 (1985) 579-586. 11 Gomez-Sanchez C. E., Upcavage R. J., Zager P., Foecking M. F., Holland 0. B. and Ganguly A.: Urinary 18-hydroxycortisol and its relationship to the excretion of other adrenal steroids. J. clin. Endocr. Metab. 65 (1987) 31CL314.
12. Gomez-Sanchez C. E., Foecking M. F., Shackleton C. H. L., Chavarri M. R. and Gomez-Sanchez E. P.: 18-Hydroxy-II-deoxycortisol: A new steroid isolated from incubations of the adrenal with 1I-deoxycortisol. J. steroid Biochem 26 (1987) 105-l 11. 13. Gomez-Sanchez C. E. and Holland 0. B.: Urinary tetrahydroaldosterone and aldosterone 18-oxoglucuronide excretion in white and black normal subjects and hypertensive patients. J. clin. Endocr. Merab. 52 (1981) 214-219.
14. Schoneshofer M., Fenner A., Attinok G. and Dulce B. H.: Specific and practicable assessment of urinary free cortisol by combination of automatic high pressure liquid chromatography and radioimmunoassay. C/in. Chim. Acta 106 (1980) 63-73. 15. Gomez-Sanchez C. E., Holland 0. B. and Upcavage R.: Urinary free 19-nordeoxycorticosterone and deoxycorticosterone in human hypertension. J. clin. Endocr. Metab. 60 (1985) 234-238. 16. Bertholet J. Y.: Proliferative activity and cell migration
in the adrenal cortex of fetal and neonatal rats: an autoradiographic study. J. Endocr. 87 (1980) l-9. 17. Zajicek G., Ariel I. and Arber N.: The streaming adrenal cortex: direct evidence of centripetal migration of adrenocytes by estimation of cell turnover rate. J. Endocr. 111 (1986) 477-482. 18. Crivello J. F., Hornsby P. J. and Gill G. N.: Suppression of cultured bovine adrenocortical zona glomerulosa cell aldosterone synthesis by steroids and its prevention by antioxidants. Endocrinology 113 (1983) 235-242. 19. Crivello J. F. and Gil G. N.: Induction
of cultured bovine adrenocortical zona glomerulosa cell 17-hydroxylase activity by ACTH. Molec. Ceil Endocr.
30, (1983) 97-107. 20. Cater D. B. and Lever J. D.: The zona intermedia of the
adrenal cortex. A correlation of possible functional significance with development, morphology and histochemistry. J. Anat. 88 (1954) 437-454. 21. Greep R. 0. and Deane H. W.: The cytology and cytochemistry of the adrenal cortex. Ann. N.Y. Acad. Sci. 50 (1949) 596-615. 22. Gomez-Sanchez C. E.:
18-Hydroxycortisol and 18-oxocortisol, steroids from the transitional zone. Endoer. Res. 10 (1984) 609-615. 23. Hall C. E. and Gomez-Sanchez C. E.: Hypertensive potency of ll-oxocortisol in the rat. Hyperfension 8 (1986) 317-322.
J. sreroid Biochem.
No. 3,
pp. 409-412, 1989
OC22-4731/89 $3.00 + 0.00
PergamonPress plc
1%OXOCORTISOL: EFFECT OF DEXAMETHASONE, ACTH AND SODIUM RESTRICTION CELSO E. GOMEZ-SANCHEZ,$ PHILIP G. ZAGER,* MARK F. FOECKJNG,0. BRYAN HOLLAND? and ARUNABHA GANGULY Departments of Internal Medicine, The University of South Florida College of Medicine, James A. Haley V.A. Hospital, Tampa, Florida, *The University of New Mexico, Albuquerque, New Mexico and tThe University of Texas Medical Branch, Galveston, Texas, U.S.A. (Received 9 May 1988) Summary-The urinary excretion of ll-oxocortisol in 37 normal subjects consuming a normal sodium diet was 1.2 k 0.9(SD) pg/24 h. Dexamethasone administration to 5 normal individuals suppressed the excretion of 18-oxocortisol from 1.16 + 0.5 fig/24 h to 0.6 + 0.2 rg/24 h. While they still received dexamethasone, ACTH administration raised the 18-oxo-cortisol excretion to 3.82 + 1.2 pg/24 h. Seven normal subjects were placed on a sodium restricted diet, and the urinary excretion of 18-oxocortisol rose from 1.5 + 1.21 pg/24 h to 8.54 f 5.08 fig/24 h and aldosterone from 6.6 + 2.0 pgg/24 h to 39.7 k 14.6 yg/24 h. Two of the seven individuals showed minimal increases in the excretion of 18-oxocortisol, but in ail cases aldosterone increased with sodium restriction. The urinary excretion of 18-oxocortisol correlated significantly with the excretion of aldosterone, 18-hydroxycortisol, cortisol, and 19nordeoxycorticosterone. These studies indicate that 18-oxocortisol secretion is under ACTH regulation, but since sodium restriction also increases the excretion of 18-oxocortisol, the renin-angiotensin system must also participate in its regulation. However, some individuals do not increase their excretion of 18-oxocortisol with sodium restriction, although aldosterone excretion increases as expected, suggesting that additional factors participate in the regulation of 18-oxocortisol production.
INTRODUCTION In the course of studies trying to explain the frequent discrepancy between the severity of hypertension and metabolic abnormalities ascribed to aldosterone secretion in patients with primary aldosteronism due to aldosterone-producing adenoma (APA), Chu and Ulick [l] isolated an abundant urinary steroid identified as 18-hydroxycortisol. Incubations of bullfrog interrenal organ, a model of adrenal zona glomerulosa, with cortisol resulted in the isolation of 18-hydroxycortisol and 18-oxocortisol [2]. Patients with APA and glucocorticoid suppressible aldosteronism (GSA) have been recently shown to excrete excessive amounts of these two new steroids [l-5]. The pathway that cortisol follows leading to the synthesis of these 18 hydroxylated steroids is believed to be through the cytochrome P-450corticosteroid methyl oxidase (P-450-CMO), which in the case of the usual substrate, corticosterone, leads to 18-hydroxycorticosterone and aldosterone. Cortisol is a suboptimal substrate [2]. The biological activity of l&hydroxycortisol is negligible [6] but 18-oxocortisol was 1% of the mineralocorticoid activity of aldosterone and 3% of the glucocorticoid activity of cortisol [7,8].
Regulation of the secretion of 18-oxocortisol has not been reported. The regulation of 18-hydroxycortisol has been studied [9-111. Production of 18-hydroxycortisol occurs in the zona glomerulosa and fasciculata [12]. The present report describes the effects of sodium restriction, dexamethasone suppression and ACTH stimulation on the urinary excretion of 18-oxocortisol. The correlation of urinary l&oxocortisol with the urinary excretion of cortisol, 19nordeoxycortL aldosterone- 18-oxoglucuronide, costerone and 18-hydroxycortisol is described.
EXPERIMENTAL Steroid measurement procedures
Urinary aldosterone 18-oxoglucuronide [ 131, cortisol [ 141, 18-oxocortisol [3], 1I-hydroxycortisol [l l] and 19-nor-deoxycorticosterone [ 151 were measured by radioimmunoassay. Experimental protocols
Thirty-seven normal subjects (9 men and 28 women with a mean age of 43.8 yr and a range of 22-69 yr) collected a 24 h urine while consuming a normal sodium diet. Sodium restriction
SAddress for correspondence: Celso E. Gomez-Sanchez, James A. Haley V.A. Hospital, 13000 Bruce B. Downs Blvd (1 II-M), Tampa, FL 33612, U.S.A.
Seven normal individuals were admitted to the Clinical Research Center and were given an isocaloric 409
410
C~LSO
E.
GOMEZ-SANCHEZ
120 mmol sodium, 70 mmol potassium diet for 2 days followed by 6 days on an isocaloric diet containing 10 mmol sodium 70 mmol potassium. Continuous 24 h urine collections were started. The samples corresponding to the second day of the 120mmol sodium and the sixth day of the 10 mmol sodium diets were used for the measurements.
et
0 a
al. 00
Normal
HO Low
Nd
dlet
Na’ diet
20
C w
f
Effect of dexamethasone and ACTH Five normal subjects underwent a protocol which consisted of a 1 day baseline period after which they received dexamethasone 1 mg, followed by 0.5 mg every 6 h for 2 days. During the second day of dexamethasone the subjects also received an infusion of cosyntropin 0.25 mg over 6 h. Daily 24 h urine samples were collected. Statistical analysis The data was analyzed using Statview 512 (BrainPower Inc.) software using a Macintosh SE computer (Apple Computer Inc.). Student’s t-test for paired data and regression analysis were used. RESULTS
excretion of 18-oxocortisol, The urinary l&hydroxycortisol, cortisol, aldosterone, and 19-nordeoxycorticosterone in the 37 normal subjects are shown in Table 1. The administration of dexamethasone to 5 normal subjects decreased the excretion of 18-oxocortisol from to 0.6 f 0.2 pg/24 h 1.16 f 0.05 pg/24 h (P < 0.01). Administration of ACTH raised the 18-oxocortisol excretion (while still receiving dexamethasone) to 3.82 + 1.2 pg/24 h (Fig. 1). Dietary sodium restriction for 6 days in 7 normal subjects resulted in a significant increase in from to ll-oxocortisol 1.5 f 1.21 pg/24 h 8.54 + 5.08 pg/24 h (Fig. 2) and aldosterone from
Patient
number
Fig. 2. Urinary excretion of I8-oxocortisol and aldosterone18-oxo-glucuronide in normal subjects consuming a normal and a low sodium diet.
6.6 + 2.0 fig/24 h to 39.7 f 14.6 pg/24 h. Two of the seven individuals showed minimal increases in the excretion of 18-oxocortisol, but in all cases aldosterone increased with sodium restriction. 18-Oxocortisol excretion during the normal and low sodium diet experiments showed a significant correlation with the excretion of llhydroxycortisol P < 0.001) [Fig. 31, aldosterone (r = 0.909, (r = 0.902, P < 0.001) [Fig. 41, cortisol (r = 0.512, P < 0.02) [Fig. 51 and 19nordeoxycorticosterone (r = 0.698, P < 0.001) [Fig. 61.
2
4
6
8
18-OXOCORTISOL
10
12
14
16
(pgl24hr)
Table I. Urinary excretion of steroids in 37 normal individuals
I .2 + 0.9 pg/24 h
I I-Oxocortisol
63 k 36 /q/24 h IO f 10 pg/24 h 6.1 + 2.7 ,ug/24 h 313 t 268 w/24 h
IS-Hydroxycortisol Cortisol Aldosterone 19-Nordeoxycorticosterone
Fig. 3. Correlation of the excretion of 18-hydroxycortisol to ll-oxocortisol. The open circles are measurements of samples obtained from subjects consuming a low sodium diet.
18-OXOCORTISOL
Basal
DOX
ACTH
Fig. 1. Urinary excretion of ll-oxocortisol before and after receiving dexamethasone and ACTH.
(pg/24hr)
Fig. 4. The urinary excretion of aldosterone-ll-oxoglucuronide is plotted against ll-oxocortisol. The open circles are measurements of samples obtained from subjects consuming a low sodium diet.
Urinary 18-oxocortisol excretion 601
r;0.,12 p.0.02
. ;
50
c1 3
40
D
.
--=-
KY., 0
2
( 4
6
8
10
18.OXOCORTISOL
12
14
16
(pg/24hr)
Fig. 5. The urinary excretion of cortisol is plotted against 18-oxocortisol. The open circles represent measurements from subjects consuming a low sodium diet.
DISCUSSION
Adrenal cells originate in the subcapsular region (zona glomerulosa) and migrate centripetally to form the zona fasciculata and reticularis [16, 171. Cells from the zona glomerulosa synthesize corticosterone, 18-hydroxycorticosterone and aldosterone, steroids which lack the 17-hydroxy group. The cytochrome P-450-corticosterone-methyl-oxidase undergoes involution and the 17-hydroxylase is induced as the cells migrate centripetally to become the zona fasciculata [18,19]. In the interphase between the zona and fasciculata there are morglomerulosa phologically distinct cells that share characteristics of the two areas and have been called intermediate or transitional cells [20,21]. It is likely that they are the same cells where the P-450-CM0 and 17-hydroxylase enzymes coexist, leading to the formation of the hybrid steroids 18-hydroxycortisol and 18-0x0cortisol in the transitional zone [22]. 18-Hydroxycortisol in the zona glomerulosa is an intermediate in the biosynthesis of 18-oxocortisol, but in the zona fasciculata can be formed by an alternative pathway involving an initial 18-hydroxylation of 1l-deoxycortisol to 18-hydroxy-1 I-deoxycortisol followed by 1lb-hydroxylation to 18-hydroxycortisol [12]. An increase in the excretion of 18-hydroxycortisol [l 1] and 18-oxocortisol with ACTH and suppression with dexamethasone suggests that both steroids are regulated by ACTH. Sodium restriction was also associated with an increase in the excretion of both steroids, although 18-hydroxycortisol did not in-
r.0.698
p
IS-OXOCORTISOL
(pg124hr)
Fig. 6. Urinary excretion of 19nordeoxycorticosterone is plotted against 18-oxocortisol. The open circles represent measurements from subjects consuming a low sodium diet.
411
crease in 2 out of 8 subjects previously studied [l 11. Aldosterone excretion increased significantly in all subjects and l&oxocortisol increased significantly in 5 out of the 7 subjects. In one of the subjects in whom l&oxocortisol did not increase, l&hydroxycortisol increased significantly. These studies suggest that sodium restriction, probably through activation of the renin-angiotensin system, was responsible for stimulating the secretion of l&hydroxycortisol and 18-oxocortisol. Corrie et al. [lo] have also shown an increase in the excretion of 18-hydroxycortisol with sodium restriction in dexamethasone suppressed individuals, but were unable to show stimulation of plasma 18-hydroxycortisol by angiotensin II administration, suggesting that a factor different from the renin-angiotensin system participates in its regulation. The biological activity of 18-hydroxycortisol is negligible [6] but ll-oxocortisol has 1% the mineralocorticoid activity of aldosterone and 3% the glucocorticoid activity of cortisol [7,8] and can induce hypertension when injected chronically into rats [23] and sheep (unpublished). The possibility exists that excess production of 18-oxocortisol might be playing a role in the pathogenesis of hypertension in glucocorticoid suppressible aldosteronism and in some patients with primary aldosteronism due to an adrenal adenoma. At the very least, these steroids might serve as markers for the differential diagnosis of the various types of primary aldosteronism. This study demonstrates that l&oxocortisol and 18-hydroxycortisol are excreted in normal individuals and that their regulation seems to be under ACTH and probably the renin-angiotensin system, although other unknown factors might also be playing a role. Acknowledgements-The expert technical help of Melinda Lake, Thomas Ries and Robert J. Upcavage and editorial assistance of Dr Elise Gomez-Sanchez are greatly appreciated. These studies were supported by research funds from the VA and NIH grants HL 27255, HL 27737, HL26856 and the General Clinical Research Centers Program of the Division of Research Resources RR-73 (UTMB) and RR997 (NM). The aldosterone antiserum was kindly provided by the NIAMDD.
REFERENCES
Chu M. D. and Ulick S.: Isolation and identification of 18-hydroxycortisol from the urine of patients with primary aldosteronism. J. hoi. Chem. 258 (1982) 2218-2224. Ulick S., Chu M. D. and Land M.: Biosynthesis of ll-oxocortisol by aldosterone producing adrenal tissue. J. biol. Chem. 258 (1983) 5498-5502. Gomez-Sanchez C. E., Montgomery M., Ganguly A., Holland 0. B., Gomez-Sanchez E. P., Grim C. E. and Weinberger M. H.: Elevated urinary excretion of in glucocorticoid-suppressible al1I-oxocortisol dosteronism. J. c/in. Endocr. Met& 59 (1984) 1022-1024. Ulick S. and Chu M. D.: Hypersecretion of a new corticosteroid, ll-hydroxycortisol in two types of adrenocortical hypertension. C/in. Exp. Hyper. A4 (1982) 1771-1777.
412
CELSO E. GOMEZ-SANCHEZetal.
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