Gene expression of the key enzymes of melatonin synthesis in extrapineal tissues of the rat

Citation
J. Stefulj et al., Gene expression of the key enzymes of melatonin synthesis in extrapineal tissues of the rat, J PINEAL R, 30(4), 2001, pp. 243-247
Citations number
22
Categorie Soggetti
Physiology
Journal title
JOURNAL OF PINEAL RESEARCH
ISSN journal
07423098 → ACNP
Volume
30
Issue
4
Year of publication
2001
Pages
243 - 247
Database
ISI
SICI code
0742-3098(200105)30:4<243:GEOTKE>2.0.ZU;2-5
Abstract
Besides the pineal gland, melatonin is reported to be produced in a number of extrapineal sites, where it could act as an intracellular mediator or pa racrine signal in addition to its endocrine effects. In view of the suggest ed immunoregulatory role of melatonin, we compared lymphoid organs and seve ral other tissues of the rat for their potential to synthesize melatonin. U sing the reverse transcription-polymerase chain reaction (RT-PCR) method. w e determined the tissue-specific expression of mRNAs encoding two key enzym es of the melatonin biosynthesis: serotonin-N-acetyltransferase (NAT) and h ydroxyindole-O-methyltransferase (HIOMT). The minimal number of PCR cycles required to obtain a positive signal served as a measure for the abundance of a given mRNA. NAT and HIOMT mRNAs were detected in all tested tissues at high numbers of PCR cycles (40 and 45, respectively). At 35 cycles, only g ut, testis, spinal cord, raphe nuclei, stomach fundus and striatum yielded positive signals for both enzymes. In conclusion, the presence of NAT and H IOMT mRNAs in a wide range of tissues corroborates and extends the notion o f extrapineal melatonin synthesis. Comparatively low levels of the HIOMT me ssages in lymphoid organs, however, indicate a limited significance of mela tonin synthesis within the immune system.