Highlights Development of inhalation-based anaesthesia for early postnatal (P0−2) mice. 3D-printed mould allows anaesthetic maintenance for neonatal surgery. Improved mouse welfare through reliable neonatal inhalation anaesthesia. Rapid procedure for brain transduction of mouse litter in under 2 h.

Highlights• Development of inhalation-based anaesthesia for early postnatal (P0-2) mice• 3D-printed mould allows anaesthetic maintenance for neonatal surgery • Improved mouse welfare through reliable neonatal inhalation anaesthesia• Rapid procedure for brain transduction of mouse litter in under 2 hours Abstract Investigating brain function requires tools and techniques to visualise, modify and manipulate neuronal tissue. One powerful and popular method is intracerebral injection of customised viruses, allowing expression of exogenous transgenes. This technique is a standard procedure for adult mice, and is used by laboratories worldwide. Use of neonatal animals in scientific research allows investigation of developing tissues, and enables longterm study of cell populations. However, procedures on neonatal mice are more challenging, due to the lack of reliable methods and apparatus for anaesthesia of these animals. Here, we report an inhalation-based protocol for anaesthesia of neonatal (P0-2) mice, and present a custom 3D-printed apparatus for maintenance of anaesthesia during surgical procedures.This approach significantly enhances animal welfare and facilitates wider and simpler use of neonatal rodents in scientific research. Our optimised method of anaesthesia enables a rapid method of stereotactic injection in neonatal mice for transduction of brain tissue. We demonstrate this procedure for targeted labelling of specific brain regions, and in vivo modification of tissue prior to organotypic culture. This anaesthetic approach can be readily employed by any laboratory, and will enable safer use of neonatal rodents across a diverse spectrum of scientific disciplines.

The unfolded protein response (UPR) is a direct consequence of cellular endoplasmic reticulum (ER) stress and a key disease driving mechanism in IPF. The resolution of the UPR is directed by PPP1R15A (GADD34) and leads to the restoration of normal ribosomal activity. While the role of PPP1R15A has been explored in lung epithelial cells, the role of this UPR resolving factor has yet to be explored in lung mesenchymal cells. The objective of the current study was to determine the expression and role of PPP1R15A in IPF fibroblasts and in a bleomycin-induced lung fibrosis model. A survey of IPF lung tissue revealed that PPP1R15A expression was markedly reduced. Targeting PPP1R15A in primary fibroblasts modulated TGF-b-induced fibroblast to myofibroblast differentiation and exacerbated pulmonary fibrosis in bleomycin-challenged mice. Interestingly, the loss of PPP1R15A appeared to promote lung fibroblast senescence. Taken together, our findings demonstrate the major role of PPP1R15A in the regulation of lung mesenchymal cells, and regulation of PPP1R15A may represent a novel therapeutic strategy in IPF.