Expectations of enhanced pain and injury, or nocebo, can arise from environmental cues such as surroundings, even cues from social partners. We previously showed that systemic antagonism of cholecystokinin receptors blocks enhanced pain in mice provoked by observing a social partner expressing overt pain. The purpose of this study was to determine the function of cholecystokinin receptors in pain enhancement triggered by social cues from the environment. Based on our finding of increased neural activation (immunohistochemistry for c-Fos) in the lateral periaqueductal grey (PAG), we cannulated mice (C57BL/6, same sex cagemate pairs of both sexes, 8-9 weeks old) above the lateral PAG bilaterally. We waited 1 week for recovery, and then applied bilateral drug microinfusions to the lateral PAG to test the effects on behavior. We found that application of proglumide, a cholecystokinin antagonist, to the lateral PAG diminishes enhanced pain when observing a cagemate in pain. Additionally, we found that application of cholecystokinin to the lateral PAG enhances paw flicking and licking responses on the hot plate. This data indicates that cholecystokinin receptors in the lateral PAG are involved in descending facilitation of the nocebo response when mice observe cagemates in pain. Our findings build a more neuroanatomically precise understanding of the role of cholecystokinin in pain facilitation due to social context and the neural mechanisms underlying environmental and social-communicative enhancement of pain. Funding: Natural Sciences and Engineering Research Council of Canada, Canadian Foundation for Innovation, and Ontario Ministry of Innovation. Canadian Foundation for Innovation 36548, NSERC RGPIN-2016-06284, Ontario Ministry of Innovation ER16-12-060.