Effect of reserpine and p-chlorophenylalanine on the electrocorticogram of unrestrained rats during short and long recording sessions

The effect of reserpine and p-chlorophenylalanine (PCPA) on the integrated voltage of the electrocorticogram (ECoG) of unrestrained rats was examined during 15 min and 2½ hr recording sessions. As previously reported, reserpine caused an increase in the ECoG voltage during 15 min sessions. This effect was slightly enhanced by PCPA pretreatment. PCPA treatment alone produced an increase in the ECoG voltage and an increase in synchronized activity similar to that induced by reserpine. Thus, it appears that the ECoG effect of reserpine during 15 min recording sessions does not depend upon increased “free” 5-HT. During 2½ hr sessions, PCPA produced a decrease in voltage with decreased slow-wave activity. A consistent increase in ECoG voltage was observed 4 hr after reserpine injection using the long recording time. By 24 hr, the voltage had returned to the control levels and was lower than the control at 48 hr and later. α-Methyltyrosine restored the decreased voltage to the control levels. PCPA pretreatment antagonized the reserpine-induced increase in ECoG voltage and instead of a return to the control at 24 hr after reserpine, a marked decrease in voltage was seen in the PCPA-pretreated animals at this time period. These results are discussed in terms of reciprocally acting “catecholaminergic” and “serotoninergic” systems.