Phospho-ERK labelling of the paraventricular hypothalamic nucleus (PVN) (A) and the anterior part of the paraventricular thalamic nucleus (PVA) (B). Positive cell numbers and positive staining intensity were analysed by unpaired t-test, showing that blue light induced a significant decrease in ERK activation in the PVN compared with white light (*P<0.05, **P<0.01). The indicated number inside the column shows the number of mice calculated in each group.