“…As with the bovine enzyme (Morton, 1986), trout HIOMT was capable of methylating all the hydroxyindoles commonly found in the pineal gland (Table 1) which raises the possibility that methoxyindoles other than melatonin may be physiologically active particularly as these substances have been suggested to be bioactive (Mullen et al, 1979;Pevet, 1983;Reiter and Vaughan, 1977). Of particular interest was the observation that hydroxytryptophol had a similar affinity to the melatonin precursor, N-acetylserotonin, for trout HIOMT and it is possible, therefore, that methoxytryptophol may be physiologically important in the trout as a mediator of pineal activity.…”