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Gene expression of the key enzymes of melatonin synthesis in extrapineal tissues of the rat
Author(s) -
Stefulj Jasminka,
Hörtner Michael,
Ghosh Meenakshi,
Schauenstein Konrad,
Rinner Ingo,
Wölfler Albert,
Semmler Johann,
Liebmann Peter M.
Publication year - 2001
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1034/j.1600-079x.2001.300408.x
Subject(s) - melatonin , pineal gland , biology , paracrine signalling , messenger rna , medicine , microbiology and biotechnology , endocrinology , gene , biochemistry , receptor
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 paracrine signal in addition to its endocrine effects. In view of the suggested immunoregulatory role of melatonin, we compared lymphoid organs and several other tissues of the rat for their potential to synthesize melatonin. Using the reverse transcription‐polymerase chain reaction (RT‐PCR) method, we determined the tissue‐specific expression of mRNAs encoding two key enzymes of the melatonin biosynthesis: serotonin‐N‐acetyltransferase (NAT) and hydroxyindole‐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 gut, testis, spinal cord, raphe nuclei, stomach fundus and striatum yielded positive signals for both enzymes. In conclusion, the presence of NAT and HIOMT mRNAs in a wide range of tissues corroborates and extends the notion of extrapineal melatonin synthesis. Comparatively low levels of the HIOMT messages in lymphoid organs, however, indicate a limited significance of melatonin synthesis within the immune system.