Abstract
The effect of parachlorophenylalanine (PCPA), the inhibitor of tryptophan hydroxylase which is the catalyzer for tryptophan to 5-hydroxytryptophan (5 HTP), on the duration of animal hypnosis induced by inversion has been investigated to test the possibility of the involvement of 5-hydroxytryptamine (5 HT) in animal hypnosis.
The duration of animal hypnosis in rabbits was diminished gradually for 9 days and the diminished duration of animal hypnosis lasted for about 3 weeks by treatment of 300 mg/kg of PCPA.
Animal hypnosis could be divided into two periods by reference of frequency analysed subcortical EEG during inversion. One is the period of reduced θ and α activities and the other is of the additional augementation of δ activity. PCPA mainly reduced the second period and influenced on the first period slightly.
When 40 mg/kg 5 HTP, a precussor of 5 HT, was applied intraperitoneally 21 days after PCPA treatment, the reduced duration of animal hypnosis which exhibited first period of EEG alone increased to control value causing second period of EEG change.
These dataes indicated the involvement of 5 HT in the maintenance of the second period of animal hypnosis by inversion.
