Pain and emotion are strongly regulated by neurons in the central nucleus of the amygdala (CeA), a major output of the limbic system; yet, the neuronal signalling pathways underlying this modulation are incompletely understood. Here, we characterized a subpopulation of CeA neurons that express the CaMKIIα gene (CeACAM neurons) and project to the lateral parabrachial nucleus (LPBN), a brainstem region known for its critical role in distributing nociceptive and other aversive signals throughout the brain. In male Sprague-Dawley rats, we show that CeACAM-LPBN neurons are GABAergic and mostly express somatostatin. In anaesthetised rats, optogenetic stimulation of CeACAM-LPBN projections inhibited responses of LPBN neurons evoked by electrical activation of Aδ- and C-fibre primary afferents; this inhibition could be blocked by intra-LPBN application of the GABAA receptor antagonist bicuculline. CeACAM-LPBN stimulation also dampened LPBN responses to noxious mechanical, thermal, and chemical stimuli. In behaving...