Selective mu antagonist CTOP blocked spatial preferences induced by electrical stimulation of the Parabrachial Complex in female rats

Abstract

Controversy persists in current research about the involvement of dopaminergic and non-dopaminergic circuits in the brain reward system and their differential role in the processing of some of its specific components. In this regard, some of our previous studies have identified a small brain structure in the first central levels of the visceral-vagal information relay, the external lateral parabrachial subnucleus (LPBe), whose activation induces preference for associated gustatory and spatial stimuli. In the same line, other researchers recently found that the vagal-brain axis is involved in processing rewarding signals from the gastrointestinal tract.

Mu and kappa opioid receptors are present in this parabrachial region, and the aim of the present study is to elucidate the differential involvement of these receptors by using ctop [D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2], a selective mu receptor antagonist, to pre-treat a group of female rats subjected to electrical stimulation of the LPBe. Preliminary results demonstrate that electrical stimulation of the LPBe induces preferences for associated stimuli in a concurrent Conditioned Place Preference [cCPP] procedure, and that these preferences are completely blocked after the administration of the selective mu receptor antagonist ctop. Given the role of the vagal-cerebral axis in modulating reward, these results will be discussed in relation to its involvement in the modulation of the hedonic/affective component and its usefulness for the treatment of affective disorders. (Supported by funds from Plan Propio UGR-FEDER [C-SEJ-348-UGR23]).