DA depletion impaired the inhibitory effects of nociceptive responses induced by HFS. A. Nociceptive discharges were recorded in the PFC of the side ipsilateral to 6-OHDA injection. Pre: Nociceptive responses were normally evoked by mechanical stimulation delivered to the rat tail. At 60 min after HFS delivery to the BLA, there were no apparent effects on nociceptive responses. DA depletion completely blocked LLS of nociceptive responses induced by HFS. B. The duration of nociceptive responses tended to increase in this group, but the difference from the pre-HFS control value did not reach statistical significance. Error bars represent S.E. n = 8 The control figure is same as figure 2 B. *p < 0.05, **p < 0.001, versus the pre-HFS control value.