The functional role of ascending nociceptive control in defensive behavior

Ascending nociceptive control is a novel spino-striato-rostral ventral medulla pain modulation pathway that mediates heterosegmental pain-induced analgesia, i.e., noxious stimulus-induced antinociception. In this study, we used the dorsal immobility response in rats as a model of the defensive responses. We demonstrated that the activation of ascending nociceptive control by peripheral noxious stimulation and spinal AMPA and mGluR1 receptor blockade significantly potentiated the duration of the dorsal immobility response in rats via an opioid-dependent mechanism in the nucleus accumbens. These results demonstrated the functional role of ascending nociceptive control in the modulation of defensive responses and spinal glutamatergic receptors in the dorsal immobility response. The immobility response is an antipredator behavior that reflects the underlying state of fear, and ascending nociceptive control may modulate fear.

► The ascending nociceptive control (ANC) pathway mediates pain-induced analgesia.
► We show the functional role of ANC in the modulation of defensive responses.
► ANC activation potentiated the duration of the dorsal immobility in rats.
► This effect was mediated by an opioid-dependent mechanism in the nucleus accumbens.
► The immobility response reflects the state of fear and ANC may modulate fear.