mRNA transcription determines the lag period for the induction of pineal melatonin synthesis in the Syrian hamster pineal gland

✍ Scribed by Aldo Gonzalez-Brito; Maureen E. Troiani; Armando Menendez-Pelaez; Maria J. Delgado; Russel J. Reiter

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 422 KB
• Volume: 44
• Category: Article
• ISSN: 0730-2312
• DOI: 10.1002/jcb.240440105

✦ Synopsis

The nocturnal pattern of Syrian hamster pineal melatonin synthesis is characterized by a 6-8 h lag period, followed by a late-night, short-duration peak in both N-acetyltransferase (NAT) activity and melatonin content. Administration of cycloheximide (20 mgkg body weight) given either at the time of lights out or 4 h into the dark phase to Syrian hamsters blocked the nocturnal increase in both pineal NAT activity and melatonin content. Actinomycin D (5 mgkg body weight) prevented the nocturnal increase in both constituents only when it was administered at darkness onset, being significantly less effective when injected after 4 h of dark exposure. Reinduction of melatonin production by isoproterenol (2 m@g body weight) administration to acutely light-exposed animals during late darkness was prevented by cycloheximide, but not by actinomycin D administration. The results suggest that whereas Syrian hamster pineal melatonin production requires protein synthesis both early and late in the dark phase, the transcription of a putative NAT-related mRNA, which occurs only during the early night, seems to determine the lag period in melatonin synthesis and pineal responsiveness to p-adrenergic receptor agonist stimulation.