# Cholecystokinin input from the anterior cingulate cortex to the lateral periaqueductal gray mediates nocebo pain behavior in mice

- **DOI:** [10.1038/s41467-026-73266-y](https://doi.org/10.1038/s41467-026-73266-y)
- **Rating:** Strong (4.0 out of 5)
- **Verdict:** A strong circuit-neuroscience advance linking ACC-to-lPAG CCK signaling to nocebo-like pain, constrained by preclinical construct validity.
- **Framework version:** v5.0
- **Pipeline version:** v0.4
- **Evaluation date:** 2026-06-25
- **Evaluation page:** https://www.nabu.science/paper/10.1038%2Fs41467-026-73266-y

## Strengths

- **Convergent circuit evidence across paradigms** Figures 1-4 link systemic CCK receptor blockade, PAG activation, local lPAG manipulation, ACC-to-lPAG tracing, and pathway-specific optogenetics into a coherent circuit argument. The use of both contextual conditioning and social observation strengthens the claim that the pathway is not tied to a single assay format.
  - Dimension: methodological rigour
  - Location: Results pp. 4-9; Figures 1-4
- **Specific localization within the PAG** The study narrows the relevant site from broad PAG activation to the intermediate lPAG, where proglumide blocks hypersensitivity and CCK-8S induces pain behavior. RNAscope evidence for Fos and Cckbr co-expression further supports the receptor-level localization.
  - Dimension: contribution
  - Location: Results pp. 5-7; Figure 3
- **Reverse translational framing is substantive** The Discussion connects the mouse circuit findings to human proglumide evidence, PAG fMRI findings, and clinical nocebo concerns in pain care. This gives the preclinical mechanism a clearer translational trajectory than a purely discovery-oriented circuit study.
  - Dimension: application pathway
  - Location: Discussion pp. 10-13

## Limitations

- **Nocebo construct remains indirectly measured** The mouse paradigms show conditioned and socially enhanced pain hypersensitivity, but they do not directly measure expectation. Claims that the circuit mediates nocebo hyperalgesia specifically therefore remain stronger than the behavioral construct evidence alone.
  - Dimension: contribution
  - Location: Abstract; Main Text p. 3; Discussion pp. 9-13
- **Statistical audit trail is incomplete** The figure legends repeatedly state that full statistical details are in File S1, but those details are not in the supplied manuscript text. This limits independent verification of exact test outputs, multiplicity handling, and effect-size reporting.
  - Dimension: methodological rigour
  - Location: Figure legends pp. 21-23
- **Clinical transfer remains preliminary** The work is entirely in mice and the Discussion acknowledges that human nocebo effects are often larger in female subjects, whereas the mouse models did not show stark sex differences. Selective CCK-2 antagonist development is also presented as a future requirement rather than an available intervention.
  - Dimension: application pathway
  - Location: Discussion pp. 10-13

## Reliability checks

Caveats (4 of 4 checks).

- **Internal coherence:** Noted. The experimental sequence is internally coherent and supports a circuit-level claim, but the construct label of nocebo is stronger than the direct behavioral evidence because expectation is inferred rather than measured. Statistical details are repeatedly deferred to File S1, limiting verification from the supplied manuscript alone.
- **Research conduct:** Noted. Animal ethics approval, random allocation, and blinding are declared, but the supplied manuscript does not provide a protocol identifier or explicit data, code, preregistration, reporting-standard, or COI statements. These are transparency limitations rather than evidence of misconduct.
- **Reference integrity:** Clean. All 74 cited references resolved to real publications via PubMed, Crossref, or OpenAlex.
  - References not verified automatically are resolved manually within 24 hours.

## Post-publication record

- **Status:** Clean
- **Summary:** No retraction or expression of concern found in Crossref (includes Retraction Watch).
- **Last checked:** 2026-10-17