[Regulatory effect of ventral tegmental area on sleep-wakefulness in rats]

Experiments were performed on 31 male SD rats. The results were as follows: (1) The time of waking was increased during the second and third hours after microinjection of 3.3 and 6.6 nmol bromocriptine into bilateral VTA (P < 0.01), but the 1.33 nmol group was without significant effect. (2) The time of waking was decreased during the second and third hours after microinjection of 2 and 4 nmol SCH23390 into VTA (P < 0.01 and P < 0.05 respectively), while 3.4 nmol sulpiride group was without effect. (3) One week after administration of kainic acid (0.3 microgram), the rats presented less time of waking in the day (P < 0.05), while sleep-wakefulness cycle at night showed no change. The results suggest that bromocriptine could increase wakefulness by activating VTA DA neurons via D1 receptor and that the DA neurons might exert a tonic effect for maintaining the wakefulness at the daytime.