BACKGROUND: The lateral parabrachial nucleus (LPBn) serves a critical hub for processing and transmitting pain signals. It has two main efferent pathways, the LPBn-CeA and LPBn-BNST, which are crucial for pain regulation and the management of negative emotions METHODS: In our study, we investigated the projections from the LPBn by performing stereotaxic injections of AAV2/2Retro-hSyn-EGFP (abbreviated as EGFP) into the bed nucleus of the stria terminalis (BNST) and AAV2/2Retro-hSyn-tdTomato (abbreviated as tdTomato) into the central amygdala (CeA) in mice. The animals subsequently underwent spared nerve injury (SNI) surgery on the contralateral side to the AAV injections. To examine the expression of calcitonin gene-related peptide (CGRP) and c-Fos, we conducted immunofluorescent histochemistry. RESULTS: Our results indicated that approximately 26 % of the LPBn neurons retrogradely labeled with either EGFP or tdTomato were dual-labeled with both markers. Moreover, a significant majority (85.49 %) of these double-labeled neurons were CGRP positive (CGRP CONCLUSION: These findings suggest that a subset of CGRP