Norio Sakuragawa

Human amniotic epithelial cells express makers of glial and neural stem cells. These cells also synthesize and release acetylcholine and catecholamines. This study of amniotic fluid demonstrated that acetylcholine and catecholamines can be readily identified in the fluid. Norepinephrine was the major catecholamine present, although dopamine and DOPAC could also be detected. The physiologic role of these amniotic fluid neurotransmitters in fetal-placental interactions and nervous system development is currently under investigation. (J ChiLd NeuroL 1999;14:265-266).

In this study, we investigated the presence, possible synthesis, and release of catecholamines (CA) by monkey amniotic epithelial cells (MAEC) using different methods. Immunocytochemical techniques demonstrated the presence of tyrosine hydroxylase (TH), aromatic L‐amino acid decarboxylase (AADC), dopamine‐β‐hydroxylase (DBH), and dopamine (DA) immunoreactivities, suggesting the capability of these cells to synthesize CA. Further evidence from high performance liquid chromatography (HPLC) studies indicated the presence of norepinephrine (NE), DA, and its metabolite 3,4‐dihydroxyphenylacetic acid (DOPAC) in the cell extracts of cultured MAEC. Incubation of MAEC for various time intervals in medium supplemented with L‐tyrosine and tetrahydrobiopterin significantly increased the production of CA, thus confirming active synthesis of CA by MAEC and that increasing the incubation time increases this synthesis. In contrast, pharmacological inhibition of TH by α‐methyl‐p‐tyrosine significantly reduced CA production, further confirming CA synthesis by MAEC. Catecholamines were also detected in the cell incubation media, suggesting the ability of MAEC to spontaneously secrete CA. Moreover, depolarization with high concentration of K⁺ increased the amount of CA released into the incubation media. Additionally, the detection of DOPAC, a primary metabolite of DA, in MAEC strongly indicates that these cells contain DA metabolizing enzymes. These results demonstrate the presence of CA in MAEC and that these cells can synthesize and release CA. Further extensive studies are needed to fully explore MAEC so that it may serve as a model to study the aspects of catecholaminergic activity in primate cells and may be a possible candidate for allotransplantation therapy of monkey model of Parkinson's disease. J. Neurosci. Res. 53:107–113, 1998.