TY - JOUR
T1 - Glucocorticoid effects on phenylethanolamine N-methyltransferase (PNMT) in explants of embryonic rat medulla oblongata
AU - Bohn, Martha C.
AU - Dreyfus, Cheryl F.
AU - Friedman, Wilma J.
AU - Markey, Keith A.
N1 - Funding Information:
The authorsw ouldlike to thank MsD. aryaSadri, Ms. Monica McTigue, and Ms. MarleneG ullies for expertt echnicaal ssistanceD,r . Ira B. Black for helpful discussionasn dc ommentosn the manuscripDt,r . S. Stony Simons for providingd examethason2e1-mesylateD, r. Robert Sapolskyf or help in performing radioimmunoassaoyfs c orticosteronlee vels in the media andM s. Diane Godden for secretarial help. We are also gratefutl o Schering-PloughIn,c . for theirg enerougsi ft of the raat drenalrse quiredfo r purificationof PNMT. This work was supportedb y National Institutes of Health Grants NS18420, NS20832,a nd NS20788,a TeacherS cientistA ward to C.F.D. from the Andrew W. Mellon Foundation and Research Career Development Awards NS00713a ndNS00910 tMo .C.B.
PY - 1987/12/15
Y1 - 1987/12/15
N2 - Although glucocorticoid hormones have important roles in the development of neurotransmitter systems in cells derived from the neural crest, it is not known whether they have parallel effects on neuronal development in the brain. To address this tissue, we have established an in vitro system of fetal medulla oblongata (MO) to follow development of the epinephrine-synthesizing enzyme, phenylethanolamine N-methyltransferase (PNMT). Embryonic MO was explanted from E13 or E18 embryos and maintained for up to 3 weeks. Successful culture of adrenergic neurons was possible only in explants taken from young embryos, since E18 explants failed to develop. In E13 explants, immunoreactivity to both PNMT and tyrosine hydroxylase, the rate limiting enzyme in catecholamine synthesis, was observed. PNMT catalytic activity which was barely detectable at the time of explanation increased markedly during the first week in vitro. To study the effects of glucocorticoids on PNMT development in central neurons, MO explants were grown in glucocorticoid deficient medium in which rat serum from adrenalectomized rats was substituted for human placental serum. Addition of natural glucocorticoids, cortisol or corticosterone, or the mineralcorticoid, deoxycorticosterone, during the third culture week had no effect on PNMT activity. Dexamethasone (DEX), a synthetic glucocorticoid, also had no effect on PNMT during the first or second weeks in culture. However, addition of DEX during the third culture week resulted in a doubling of PNMT activity. However, attempts to block the DEX effect during the third week or to block the increase in PNMT activity during the first week in control cultures with the glucocorticoid receptor antagonist, dexamethasone 21-mesylate, were unsuccessful. These results suggest that PNMT in central neurons does not require glucocorticoids for ontogeny during the embryonic period. This is in contrast to PNMT in adrenal medulla which requires glucocorticoids for normal development during both the embryonic and postnatal periods. More generally, these studies suggest that development of the same neurotransmitter phenotype in brain and periphery may be differentially regulated.
AB - Although glucocorticoid hormones have important roles in the development of neurotransmitter systems in cells derived from the neural crest, it is not known whether they have parallel effects on neuronal development in the brain. To address this tissue, we have established an in vitro system of fetal medulla oblongata (MO) to follow development of the epinephrine-synthesizing enzyme, phenylethanolamine N-methyltransferase (PNMT). Embryonic MO was explanted from E13 or E18 embryos and maintained for up to 3 weeks. Successful culture of adrenergic neurons was possible only in explants taken from young embryos, since E18 explants failed to develop. In E13 explants, immunoreactivity to both PNMT and tyrosine hydroxylase, the rate limiting enzyme in catecholamine synthesis, was observed. PNMT catalytic activity which was barely detectable at the time of explanation increased markedly during the first week in vitro. To study the effects of glucocorticoids on PNMT development in central neurons, MO explants were grown in glucocorticoid deficient medium in which rat serum from adrenalectomized rats was substituted for human placental serum. Addition of natural glucocorticoids, cortisol or corticosterone, or the mineralcorticoid, deoxycorticosterone, during the third culture week had no effect on PNMT activity. Dexamethasone (DEX), a synthetic glucocorticoid, also had no effect on PNMT during the first or second weeks in culture. However, addition of DEX during the third culture week resulted in a doubling of PNMT activity. However, attempts to block the DEX effect during the third week or to block the increase in PNMT activity during the first week in control cultures with the glucocorticoid receptor antagonist, dexamethasone 21-mesylate, were unsuccessful. These results suggest that PNMT in central neurons does not require glucocorticoids for ontogeny during the embryonic period. This is in contrast to PNMT in adrenal medulla which requires glucocorticoids for normal development during both the embryonic and postnatal periods. More generally, these studies suggest that development of the same neurotransmitter phenotype in brain and periphery may be differentially regulated.
KW - Catecholamine
KW - Glucocorticoid
KW - Neuronal cell culture
KW - Neuronal differentiation
KW - Neurotransmitter development
KW - Phenylethanolamine N-methyltransferase
KW - Tyrosine hydroxylase
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U2 - 10.1016/0165-3806(87)90247-1
DO - 10.1016/0165-3806(87)90247-1
M3 - Article
C2 - 3440206
AN - SCOPUS:0023490592
SN - 0165-3806
VL - 37
SP - 257
EP - 266
JO - Developmental Brain Research
JF - Developmental Brain Research
IS - 1-2
ER -