Five healthy adult men were given metoclopramide (10 and 20 mg) iv, and in repeated tests almost always developed transient restlessness lasting from 10-30 min. The effects of L-dopa and dexamethasone on metoclopramide-induced increases in cortisol concentration were determined. These response values were compared with those of a control. After an injection of 10 mg metoclopramide, the cortisol level increased significantly only at 40 min; the ACTH level did not change. The cortisol rise was suppressed by dexamethasone pretreatment. Pretreatment with 0.5 g L-dopa resulted in a decrease in the PRL level from -20 min to 20 min, and the increase in cortisol seen at 40 min was cancelled. The ACTH level did not change. After injecting 20 mg metoclopramide, the ACTH level increased significantly from 20 min to 60 min and the cortisol level showed a significant increase from 20 min to 120 min. Pretreatment with dexamethasone resulted in a decrease in these hormones. The L-dopa pretreatment did not reduce even the rise in the PRL level which resulted from the administration of 20 mg metoclopramide. These findings suggest that the ACTH and cortisol response to metoclopramide is a stress-mediated effect. Plasma cortisol responses to 20 mg metoclopramide and insulin-induced hypoglycemia were studied and compared in seven volunteers and found to be similar.

Abstract. In normal New Zealand white rabbits, immunization with rabbit lung ACE (angiotensin converting enzyme) induced atherosclerotic retinal changes, and glomerular changes similar to those seen in diabetic nephropathy. Also, in genetically diabetogenic rats, immunization with the rabbit lung ACE induced diabetic nephropathy and retinopathy.

A single dose metyrapone test (MTP test) was carried out on 6 normal men by administering 1.0 g of metyrapone at 08.00\p=n-\09.00h with and without dexamethasone (DXM-MTP test) pre-treatment. Plasma 11\ x=r eq-\ deoxycortisol, pregnenolone, ACTH and cortisol were measured before administration of the drug, and at hourly intervals for 6 h. In the MTP test, 11-deoxycortisol increased significantly at 1 h with a peak at 5 h, whereas significant increases in pregnenolone and ACTH were not seen until 3 h. There was a definite decrease in the cortisol level at 1 h with the lowest level measured at 2 h. Thus, a time discrepancy between plasma 11-deoxycortisol and ACTH concentrations was observed. The increase in 11-deoxycortisol after metyrapone should be divided into two phases: the increase in phase II (after 3 h) is due to the pituitary ACTH reserve, and that in phase I (the first 2 h) is due to some mechanism other than the pituitary ACTH reserve. The increased amount of 11-deoxycortisol in phase II (218.1 nmol) occupied 60.5% of the total increased amount in phases I and II(360.6 nmol). The cortisol/(cortisol +11\x=req-\ deoxycortisol) ratio reached its lowest point 3 h after metyrapone treatment. This might be due to the initiation of an additional surge in 11-deoxycortisol by the ACTH reserve at 3 h.Metyrapone inhibits adrenal llß-hydroxylation, and prevents the conversion of 11-deoxycortisol to cortisol. The decreased cortisol level induces the release of ACTH, and ACTH stimulates produc¬ tion of adrenal cortical steroids. Recently, single dose metyrapone tests with specific measurement of peripheral 11-deoxycortisol have been widely utilized for clinical evaluation of the pituitary ACTH reserve (Spark 1971; Mahajan et al. 1972; Spiger et al. 1975; Lee & Schiller 1975; Sakamoto etal. 1976).However, in our unpublished studies, the re¬ sponse of 11-deoxycortisol to single dose metyra¬ pone was not consistent with the expected response of ACTH or pregnenolone (the first steroid formed from cholesterol) at different time inter¬ vals. Consequently, an accurate evaluation of the pituitary ACTH reserve was not obtained by the method widely used in other investigations (Spark 1971;Mahajan et al. 1972;Spiger et al. 1975;Lee & Schiller 1975;Sakamoto et al. 1976). We specu¬ late that the early increase of 11-deoxycortisol, caused by some unknown mechanism, precedes its later rise due to the pituitary ACTH reserve.To confirm our hypothesis, we examined the effects of a single dose metyrapone (MTP test), and a MTP test with dexamethasone pre-treatment (DXM-MTP test) on plasma 11-deoxycortisol, pregnenolone, ACTH and cortisol in normal healthy men. Materials and MethodsSix healthy men (21-25 years old), who had not taken any drugs or medication, were studied. During the test period, bed rest was prescribed for the subjects and they were not exposed to any undue stress.The MTP test was performed by administering 1.0 g of metyrapone orally at 08.00-09.00 h and by measuring 1 To whom requests for reprints should be sent.

In a random sample of 200 patients with type 2 diabetes mellitus, immunoreactivities to ACE (angiotensin converting enzyme) were measured by ELISA. Immunoreactivities were positive for 129 (64.5%) patients, and were positive in 30 (83.3%) out of 36 patients in the early stage of clinical diabetic nephropathy. Serum ACE activity in rabbits immunized with ACE decreased to 50% of the control level after 7 months (78.0 +/- 3.8 IU/L/37 degrees C, basal, 42.0 +/- 5.0 at 7 months and 33.3 +/- 3.5 IU/L/37 degrees C at 8 months, respectively). When rabbit serum containing antiACE antibodies was mixed, after heat-treatment at 56 degrees C for 30 min, with normal human serum, the ACE activity was reduced in a concentration-dependent manner. These results suggested that anti-ACE autoantibody may be present in patients with type 2 diabetes mellitus. However, the absence of data on the epitope for the antibody does not allow any conclusion except that the immunoreactivities to ACE are higher in type 2 diabetic patients than in non-diabetic individuals.

A radioimmunoassay for human plasma corticosterone has been developed. Antiserum against corticosterone was produced in rabbits immunized with corticosterone-21-hemisuccinate conjugated to bovine serum albumin. The antiserum cross-reacted with progesterone, DOC and dehydrocorticosterone more than 20%. After the extraction with ether, and the separation by Sephadex LH-20 microcolumn chromatography, recovery was 51.2 +/- 12.1% in 50 assays. The mean coefficient of variation between assays was 7.7% and within assays was 8.6%. Human plasma corticosterone is measured readily by assaying aliquots of an ether extract of 0.05 to 0.1 ml of plasma after microcolumn chromatography. The mean plasma corticosterone concentration at 9 a.m. was 7.1 +/- 3.2 ng/ml in 45 normal subjects. Plasma corticosterone increased 5.2 times as much as basal values after ACTH injection, whereas radioimmunoassayed cortisol increased 2.4 times. On the other hand, plasma corticosterone decreased to 22.6% of basal values at four hours after 1 mg dexamethasone, whereas radioimmunoassayed cortisol decreased to 12.3% of basal values.

A radioimmunoassay for human plasma corticosterone has been developed. Plasma corticosterone increased 4.83 times as much as basal value at 60 min after an im injection of 0.25 mg synthetic beta1-24 ACTH (Cortrosyn) in normal subjects, whereas plasma cortisol increased 2.12 times as much at 60 min. And basal corticosterone/cortisol ratio of 0.053 +/- 0.017 increased to 0.116 +/- 0.022 (P less than 0.001) after ACTH. This might be mainly due to a larger increment of corticosterone than that of cortisol after ACTH. Corticosterone decreased to 36.7% of basal value at 4 h after 1 mg dexamethasone administration in normal subjects, whereas cortisol decreased to 13.9% of basal value at 4 h. The basal corticosterone/cortisol ratio of 0.059 +/- 0.020 increased to 0.137 +/- 0.055 (0.001 less than P less than 0.01) after dexamethasone administration. This may have been mainly due to a more effective suppression of cortisol than that of corticosterone after dexamethasone.

We have demonstrated that metoclopramide stimulates cortisol secretion at least in part by a stress-mediated effect in normal men. To examine further the effect of the drug on the hypothalamo-pituitary adrenal system, we studied the cortisol response to 20 mg metoclopramide in patients with acromegaly, prolactinomas, and functional hyperprolactinemia and compared the results with the responses to insulin-induced hypoglycemia. In some patients, the effects of metoclopramide on CRH-induced ACTH and cortisol increase were studied to determine whether a change in dopaminergic (catecholaminergic) activity altered CRH stimulation of pituitary-adrenal function. No cortisol response to 20 mg metoclopramide occurred in 13 tests on 8 of 9 patients with prolactinoma or acromegaly with hyperprolactinemia, whereas both acromegalic patients without hyperprolactinemia had a response. All of the patients had a normal cortisol response to insulin-induced hypoglycemia. Pretreatment with metoclopramide enhanced the CRH-induced cortisol increase from 30-120 min after CRH in normal men, but only at 15 and 30 min in 5 agromegalic patients. The results suggest that metoclopramide acts in the hypothalamus to release ACTH through a dopamine antagonist-mediated (catecholaminergic) mechanism, and that metoclopramide may act additively with CRH to stimulate ACTH secretion in normal men. The absence of a metoclopramide-induced cortisol response in patients with acromegaly or prolactinomas and the absence of a normal cortisol response to metoclopramide-CRH in acromegalic patients could be due to endogenous catecholamine deficiency in these patients.

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