Effects of cycloheximide and aminophylline on 5-methoxytryptophol and melatonin contents in the chick pineal gland.
The chick pineal gland rhythmically synthesizes two 5-methoxyindoles, melatonin and 5-methoxytryptophol. These rhythms are circadian in nature and have opposite phases. The aim of this study was to determine the effects of cycloheximide, a protein synthesis inhibitor, and aminophylline, an inhibitor of phosphodiesterase, on 5-methoxytryptophol content in the chick pineal gland and to compare this with the drugs' action on pineal melatonin production. Inhibition of melatonin biosynthesis by cycloheximide (1 mg/kg, i.p. ), revealed by a marked reduction in the nighttime activity of serotonin N-acetyltransferase (AA-NAT; a key regulatory enzyme in melatonin synthesis) and melatonin concentrations, was accompanied by a significant increase in 5-methoxytryptophol content. In contrast, administration of aminophylline (100 mg/kg, i.p.) to light-exposed chicks significantly increased pineal AA-NAT activity and melatonin levels and decreased 5-methoxytryptophol concentrations. It is concluded that in the chick the production of pineal 5-methoxytryptophol and melatonin is inversely correlated.
Zawilska
J B
JB
Department of Biogenic Amines, Polish Academy of Sciences, Lodz 1, 90-950, Poland.
Rosiak
J
J
Vivien-Roels
B
B
Skene
D J
DJ
Pévet
P
P
Nowak
J Z
JZ
D000121:Acetylserotonin O-Methyltransferase / Q000378:metabolism; D000628:Aminophylline / Q000494:pharmacology*; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000378:metabolism; D002645:Chickens / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology*; D003624:Darkness; D007211:Indoles / Q000378:metabolism*; D008027:Light; D008297:Male; D008550:Melatonin / Q000378:metabolism*; D010870:Pineal Gland / Q000187:drug effects* / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*
D007211:Indoles; D011500:Protein Synthesis Inhibitors; D000628:Aminophylline; C002465:methoxytryptophol; D003513:Cycloheximide; D000242:Cyclic AMP; D000121:Acetylserotonin O-Methyltransferase; D001191:Arylamine N-Acetyltransferase; D008550:Melatonin