Effects of chronic administration of D-amphetamine on PGO wave activity in the cat

The effects of depletion of serotonin by the chronic administration of amphetamine (twice daily, 7.5 mg/kg per injection on days 1-6; 15 mg/kg per injection on the remaining days, i.p.) for 10-14 days on ponto-geniculo-occipital (PGO) waves was examined in cats. While the regimen of pretreatment with amphetamine produced comparable decreases in the content of central serotonin (i.e. 40-70%) to those observed in other studies (i.e. with reserpine, p-chlorophenylalanine, methiothepin) of ponto-geniculo-occipital wave activity, no ponto-geniculo-occipital waves of the rapid-eye-movement sleep type were observed during waking after chronic treatment with amphetamine. These results are discussed within the context of the "serotonin gating" hypothesis of the generation of ponto-geniculo-occipital waves, an hypothesis which states that ponto-geniculo-occipital waves emerge into waking when a critical level of the depletion of serotonin is reached, thus opening the "gate" for ponto-geniculo-occipital waves to enter waking states. The present authors suggest that a gradual depletion of serotonin, such as occurs following the chronic administration of amphetamine, will not elicit ponto-geniculo-occipital waves into waking, whereas a rapid depletion of serotonin, such as occurs following treatment with reserpine, results in the emergence of ponto-geniculo-occipital waves into walking.