Conditioned Place Aversion induced by electrical stimulation of the Lateral Parabrachial Area is blocked by selective mu-opioid antagonists

Abstract

The Parabrachial Complex of the brainstem, which processes visceral and sensory information, has been associated with several “motivated behaviors”. The external lateral subnucleus (LPBe), located at the most lateral end of this area, seems to be part of different brain circuits involved in processes of both reinforcing and aversive nature. This structure has indeed been associated with the emotional, autonomic and visceral processing of negative events, and is considered as a relay for the nociceptive spino-trigeminal-parabrachial-hypothalamic system. Previous studies using electrophysiological techniques such as intracerebral electrical stimulation, carried out by our team, have shown that activation of this area can induce consistent preferences or aversions towards gustatory and spatial stimuli with which it is associated, with a preference for the latter. Since the identification of μ and κ opioid receptors in this region, some authors have suggested that μ receptors might be involved in positive reinforcement processes, whereas κ receptors might be related to the processing of aversive information Preliminary results from our current research, in which animals received an injection of CTOP (a μ-receptor-specific antagonist), have shown that this drug can block aversion to spatial cues associated with electrical stimulation of the LPBe in the negative subgroup of male and female rats. These results will be discussed in relation to the role of the parabrachial area in the processing of stimuli with positive and negative valence. (Psychobiology Research Group, CTS-430; Supported by funds from Plan Propio UGR-FEDER [C-SEJ-348-UGR23]).