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Serotonin content and melatonin production in the pineal gland of the male Djungarian hamster ( Phodopus sungorus )
Author(s) -
Lerchl Alexander,
Schlatt Stefan
Publication year - 1992
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 - 10.1111/j.1600-079x.1992.tb00039.x
Subject(s) - melatonin , endocrinology , medicine , serotonin , pineal gland , hamster , phodopus , biology , receptor
Diurnal variations in serum melatonin levels and pineal concentrations of serotonin (5‐HT), N ‐acetylserotonin (NAS), 5‐hydroxyindole acetic acid (5‐HIAA), and melatonin were estimated in adult male Djungarian hamsters kept under long‐day (LD 16:8) or short‐day (LD 8:16) photoperiods. The nocturnal increase in melatonin production was accompanied by a marked drop in pineal serotonin concentrations. Serotonin levels, however, decreased approximately 4 hr before pineal melatonin increased. Correlations of the mean values for pineal serotonin and pineal melatonin indicated significant correlations at both LD 16:8 (r = ‐0.92, P < 0.001) and LD 8:16 (r = ‐0.85, P < 0.001). The mean levels of pineal serotonin and serum melatonin were correlated as well (LD 16:8, r = ‐0.91, P < 0.001; LD 8:16, r = ‐0.81, P < 0.01). The levels of pineal serotonin declined at approximately the same time as serum melatonin levels increased. These data suggest that the drop in pineal serotonin is primarily a consequence of melatonin production (as reflected by increasing serum concentrations). Consequently, pineal concentrations of melatonin may not be the best estimate of actual melatonin production, but a measure of how much melatonin is accumulated within the pineal due to high synthesis rates while the release of the hormone from the gland is limited.