Neuropeptide S (NPS) neurons: Parabrachial identity and novel distributions

Neuropeptide S (NPS) increases wakefulness. A small number of neurons in the brainstem express Nps. These neurons are located in or near the parabrachial nucleus (PB), but we know very little about their ontogeny, connectivity, and function. To identify Nps‐expressing neurons within the molecular framework of the PB region, we used in situ hybridization, immunofluorescence, and Cre‐reporter labeling in mice. The primary concentration of Nps‐expressing neurons borders the lateral lemniscus at far‐rostral levels of the lateral PB. Caudal to this main cluster, Nps‐expressing neurons scatter through the PB and form a secondary concentration medial to the locus coeruleus (LC). Most Nps‐expressing neurons in the PB region are Atoh1‐derived, Foxp2‐expressing, and mutually exclusive with neurons expressing Calca or Lmx1b. Among Foxp2‐expressing PB neurons, those expressing Nps are distinct from intermingled subsets expressing Cck or Pdyn. Examining Nps Cre‐reporter expression throughout the brain identified novel populations of neurons in the nucleus incertus, anterior hypothalamus, and lateral habenula. This information will help focus experimental questions about the connectivity and function of NPS neurons.