Norepinephrine activates NF-κB transcription factor in cultured rat pineal gland

• Published in: Life sciences (1973) 2014-01, Vol.94 (2), p.122-129
• Main Authors: Villela, Darine, de Sá Lima, Larissa, Peres, Rafael, Peliciari-Garcia, Rodrigo Antonio, do Amaral, Fernanda Gaspar, Cipolla-Neto, José, Scavone, Cristóforo, Afeche, Solange Castro
• Format: Article
• Language: English
• Subjects: AANAT activity; Aanat transcription; Animals; Arylalkylamine N-Acetyltransferase - biosynthesis; Arylalkylamine N-Acetyltransferase - metabolism; Arylalkylamine N-Acetyltransferase - physiology; Cyclic AMP Response Element-Binding Protein - biosynthesis; Cyclic AMP Response Element-Binding Protein - physiology; Electrophoretic Mobility Shift Assay; Enzyme Activation - drug effects; Flow Cytometry; Male; Melatonin; Melatonin - biosynthesis; Melatonin - physiology; NF-kappa B - antagonists & inhibitors; NF-kappa B - biosynthesis; NF-kappa B - physiology; NF-κB; Norepinephrine; Norepinephrine - pharmacology; Organ Culture Techniques; Pineal gland; Pineal Gland - drug effects; Pineal Gland - metabolism; Pineal Gland - physiology; Pyrrolidines - pharmacology; Rats; Rats, Wistar; Real-Time Polymerase Chain Reaction; Sodium Salicylate - pharmacology; Thiocarbamates - pharmacology
• ISSN: 0024-3205; 1879-0631
• DOI: 10.1016/j.lfs.2013.11.004

The circadian rhythm in mammalian pineal melatonin secretion is modulated by norepinephrine (NE) released at night. NE interaction with β1-adrenoceptors activates PKA that phosphorylates the transcription factor CREB, leading to the transcription and translation of the arylalkylamine-N-acetyltransferase (AANAT) enzyme. Several studies have reported the interplay between CREB and the nuclear factor-κB (NF-κB) and a circadian rhythm for this transcription factor was recently described in the rat pineal gland. In this work we studied a direct effect of NE on NF-κB activation and the role played by this factor on melatonin synthesis and Aanat transcription and activity. Cultured rat pineal glands were incubated in the presence of two different NF-κB inhibitors, pyrrolidine-dithiocarbamate or sodium salicylate, and stimulated with NE. Melatonin content was quantified by HPLC with electrochemical detection. AANAT activity was measured by a radiometric assay and the expression of Aanat mRNA was analyzed by real-time PCR. Gel shift assay was performed to study the NF-κB activation in cultured rat pineal glands stimulated by NE. Our results showed that the p50/p50 homodimer of NF-κB is activated by NE and that it has a role in melatonin synthesis, acting on Aanat transcription and activity. Here we present evidence that NF-κB is an important transcription factor that acts, directly or indirectly, on Aanat transcription and activity leading to a modulation of melatonin synthesis. NE plays a role in the translocation of NF-κB p50/p50 homodimer to the nucleus of pinealocytes, thus probably influencing the nocturnal pineal melatonin synthesis.