5-Methoxytryptophol injections in the Syrian hamster: plasma and pineal concentrations.

Plasma and pineal 5-methoxytryptophol (ML) levels were determined by radioimmunoassay (RIA) following subcutaneous (s.c.) injection of ML (1, 25 and 100 micrograms) to hamsters, Mesocricetus auratus. A dose-dependent increase in plasma ML occurred, with the duration of the supra-physiological levels being related to the dose. However, only the 100 micrograms dose significantly increased pineal ML levels above control values. Plasma profiles after 1 or 25 micrograms ML fitted a one-compartment model with half-lives of 18.6 and 25.2 min, respectively. Following 100 micrograms ML a biphasic decay curve was evident, the half-lives of the 2 phases being 6.6 min and 2.95 h.