On the occurrence of 5-methoxytryptamine in brain.

A quantitative gas chromatography-mass spectrometry method has been used to determine 5-methoxytryptamine (5-MT) in the CNS and pineal gland of various species. The mean +/- S.D. levels of 5-MT in sheep, pig and cow pineal glands was 545 +/- 180, 228 +/- 119 and 117 +/- 48 pmol/g, respectively. The postmortem levels of 5-MT in the pig pineal gland was stable for 2 h after death but decreased by more than 90% 24 h after death. In the CNS, 5-MT was found only in the sheep hypothalamus (28 +/- 4 pmol/g). Analysis of the rat pineal gland and CNS failed to detect any 5-MT at the limit of sensitivity of the method which is at variance with previously reported results.