The presence of histamine and tele-methylhistamine in the pineal gland of chick
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The levels of histamine (HA) and tele-methylhistamine (t-MeHA) in the pineal gland of chick were measured by RIA and two time points, i.e. at the end of the light (L) phase and in the middle of the dark (D) phase of 12h :12h L:D cycle.The chick pineal gland showed high HA levels.The t-MeHA content of chick pineal gland was about 20-times lower than HA levelAn aminoacid precursor of HA, L-histidine given to chicks during L or D significantly increased both HA and t-MeHA content of pineal gland.The L-histidine-evoked elevations in HA level were 2-4 times higher than changes in t-MeHA content.Enzymatic study showed the presence of chick pineal gland of a moderate activity of L-histidine decarboxylase, and well expressed activity of HA-methyltransferase, HA synthetizing and inactivating enzyme, respectively, which suggest that both HA and t-MeHA may be produced within the gland.It is suggested that the metabolic dynamics of the pineal HA may be higher during lighthours than darkhours of the daily light:dark illumination cycle.
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