It was reported that ME and CA are costored and co-released from chromaffin vesicles in the adrenal medulla. The aim of this study is to investigate the relationship between ACTH and ME and CA (free and conjugated). We studied 8 healthy children (aged 6-13 yr) by performing a ACTH i.v. test (0.25 mg). Basal blood samples at 30' and 60' after ACTH injection were obtained. In 4 cases blood samples were obtained also at 5', 10' and 15' after the i.v. injection. Plasma ME and cortisol (F) were measured by RIA, Free and conjugated plasma CA were determined by a radioenzimatic method. ACTH rose F (p < 0.01 basal vs 30' and 60') without significant changes in plasma adrenaline and noradrenaline. However, a significant decrease in conjugated dopamine (DA) was observed (0': 1522 ± 314; 30': 1115 ± 203; 60': 1129 ± 278 pg/ml; p < 0.01 basal vs 30' and 60'). A decrement in conjugated DA was also seen 10' after ACTH stimulus 0': 1154 ± 267 vs 10': 992 ± 100 pg/ml; p < 0.01). Plasma ME rose significantly from basal values (0': 0.29±0.06 vs 30': 0.44±0.04 pmol/ml; p < 0.05). Our data show that ACTH acutely decreases total plasma DA levels by reducing its conjugated fraction and increases plasma ME leveles. These results suggest that the adrenal may not be the only source of ME secretion.
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Negueruela, M., Figuerola, M., Contreras, L. et al. 8 EFFECT OF ACTH ON PLASMA MET ENKEPHALIN (ME) AND FREE AND CONJUGATED CATECHOLAMINES (CA). Pediatr Res 36, 673 (1994). https://doi.org/10.1203/00006450-199411000-00032