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Comparison of circadian expression of tryptophan hydroxylase isoform mRNAs in the rat pineal gland using real‐time PCR
Author(s) -
Sugden David
Publication year - 2003
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2003.01959.x
Subject(s) - tph2 , tryptophan hydroxylase , pineal gland , pinealocyte , medicine , endocrinology , serotonergic , biology , serotonin , gene isoform , circadian rhythm , melatonin , messenger rna , endocrine gland , tryptophan , gene expression , hormone , gene , biochemistry , amino acid , receptor
A second gene encoding a functional tryptophan hydroxylase activity has recently been described ( TPH2 ), which is expressed abundantly in brainstem, the primary site of serotonergic neurons in the CNS. As serotonin (5‐HT) has an important role as a precursor of the nocturnal synthesis of the pineal gland hormone, melatonin, it was of interest to determine the relative expression of TPH1 and 2 mRNA in the rat pineal during the light:dark (L:D) cycle using sensitive real‐time RT‐PCR assays which were developed for each TPH isoform. TPH1 mRNA expression was 10 5 ‐fold more abundant in rat pineal than TPH2, and showed a significant ∼4‐fold nocturnal increase in expression which may contribute to the previously described nocturnal increase in pineal tryptophan hydroxylase activity. TPH2 expression within the gland showed no significant variation with time of day and was very low (∼300 copies/gland) indicating expression in the small proportion of ‘non‐pinealocyte’ cells in the gland.