Influence of FLA-63 on pentobarbitone sleep in chicks and rats

The influence of FLA-63 on pentobarbitone-induced sleep was studied in young chicks and adult rats. FLA-63 produced a time-dependent biphasic effect on the gross behaviour of chicks and rats; an initial sedation followed by behavioural excitation. The behavioural effects of FLA-63 were associated with an initial EEG synchronization prior to an increased activity of the EMG of the neck muscle and desynchronization of the EEG of the hyperstriatum, optic tectum and pontine reticular formation of the chick. Similarly, in rats, the EEG of the frontal cortex, optic lobe and pontine reticular formation was desynchronized while the EMG activity of the neck muscle was enhanced by FLA-63. FLA-63 delayed the onset and shortened the duration of pentobarbitone sleep. Pentobarbitone-induced EEG synchronization and decreased EMG activity in chicks was antagonized by FLA-63. Dopamine-induced antagonism of pentobarbitone sleep was potentiated by FLA-63 in chicks. Levodopa antagonized pentobarbitone-induced sleep in rats and this effect was potentiated by FLA-63. FLA-63 potentiated levodopa-induced desynchronization of the EEG of the frontal cortex, optic lobe and pontine reticular formation of the rat. Haloperidol antagonized the effect of FLA-63 on pentobarbitone-induced sleep in both rats and chicks. Noradrenaline induced behavioural sleep in young chicks dose-dependently; this effect was antagonized by phentolamine. In the rat, phentolamine shortened pentobarbitone sleeping time but did not significantly influence the effects of FLA-63 on pentobarbitone sleep. Those results suggest that an increased dopamine neurotransmission may be associated with the mechanism of wakefulness in chicks and rats.