Insulin modulates norepinephrine-mediated melatonin synthesis in cultured rat pineal gland

Insulin (10(-8)M) potentiates norepinephrine-mediated melatonin synthesis in ex vivo incubated pineal glands.

• Norepinephrine synthesis of melatonin peaks during the dark phase in mammals.
• Insulin enhances the activity of tryptophan hydroxylase, which is involved in melatonin production.
• In synchronized ex vivo incubated pineal glands, insulin increases melatonin synthesis and activity of the enzyme arylalkylamine-N-acetyltransferase.
• Insulin does not influence the activity of hydroxyindole-O-methyltransferase or the gene expression of key enzymes related to melatonin synthesis.

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