TY - JOUR
T1 - Pharmacological Studies on the Regulation of N‐Acetyltransferase Activity and Melatonin Content of the Pineal Gland of the Syrian Hamster
AU - Steinlechner, Stephan
AU - King, Thomas S.
AU - Champney, Thomas H.
AU - Richardson, Bruce A.
AU - Reiter, Russel J.
PY - 1985/4
Y1 - 1985/4
N2 - Thus far, all attempts to stimulate melatonin synthesis by β-adrenergic receptor agonists in the Syrian hamster pineal gland have failed. Neither a wide range of dosages of isoproterenol (0.5 mg/kg to 24 mg/kg), nor prolonged treatment with norepinephrine, the natural neurotransmitter, increased N-acetyltransferase (NAT) activity or melatonin production. In the present study, the administration of isoproterenol at night was likewise ineffective in advancing or enhancing the normal nightly melatonin peak. Also, we did not find a delayed effect 7 or 8 h after the administration of the drug. Furthermore, we tested the idea of coneurotransmitters such as octopamine or dopamine being possibly necessary for stimulation, but could not find any effect of these substances on melatonin synthesis. In addition, a parasympatholytic agent, atropine, did not increase the responsiveness to sympathomimetic agents. Administration of a phosphodiesterase inhibitor was also ineffective in stimulating NAT activity. On the other hand, isoproterenol did retard the drop in NAT and melatonin after lights-on at night, indicating that β-receptors are involved in maintaining elevated melatonin levels.
AB - Thus far, all attempts to stimulate melatonin synthesis by β-adrenergic receptor agonists in the Syrian hamster pineal gland have failed. Neither a wide range of dosages of isoproterenol (0.5 mg/kg to 24 mg/kg), nor prolonged treatment with norepinephrine, the natural neurotransmitter, increased N-acetyltransferase (NAT) activity or melatonin production. In the present study, the administration of isoproterenol at night was likewise ineffective in advancing or enhancing the normal nightly melatonin peak. Also, we did not find a delayed effect 7 or 8 h after the administration of the drug. Furthermore, we tested the idea of coneurotransmitters such as octopamine or dopamine being possibly necessary for stimulation, but could not find any effect of these substances on melatonin synthesis. In addition, a parasympatholytic agent, atropine, did not increase the responsiveness to sympathomimetic agents. Administration of a phosphodiesterase inhibitor was also ineffective in stimulating NAT activity. On the other hand, isoproterenol did retard the drop in NAT and melatonin after lights-on at night, indicating that β-receptors are involved in maintaining elevated melatonin levels.
KW - N‐acetyltransferase activity
KW - catecholamines
KW - isoproterenol
KW - melatonin
KW - norepinephrine
KW - pineal gland
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U2 - 10.1111/j.1600-079X.1985.tb00632.x
DO - 10.1111/j.1600-079X.1985.tb00632.x
M3 - Article
C2 - 3007727
AN - SCOPUS:0021799673
VL - 2
SP - 109
EP - 119
JO - Journal of Pineal Research
JF - Journal of Pineal Research
SN - 0742-3098
IS - 2
ER -