A single dose of radiation elicits comparable effects to fractionated radiation in a mouse model of acute salivary gland injury after head and neck cancer radiotherapy.

The salivary glands are often damaged during head and neck cancer radiotherapy. This results in chronic dry mouth, which adversely affects quality of life, for which there is no long-term cure. Mouse models of salivary gland injury are routinely used in regenerative research. However, there is no clear consensus on the radiation regime required to cause injury. Here, we analysed three regimes of gamma irradiation of the submandibular salivary gland. Transcriptional analysis, immunofluorescence and flow cytometry was used to profile DNA damage, gland architecture and immune cell changes 3 days after single doses of 10 or 15 Gy or 3 doses of 5 Gy. Irrespective of the regime, radiation induced comparable DNA damage, cell cycle arrest, loss of glandular architecture, increased pro-inflammatory cytokines and a reduction in tissue-resident macrophages, when compared to non-irradiated submandibular gland. Given these data, coupled with the fact that repeated anaesthetic can negatively affect animal welfare and interfere with saliva secretion, we conclude that a single dose of 10 Gy irradiation is the most refined method of inducing acute salivary gland injury in a mouse model.