2.8.2 Signal intensity of MOP immunoreactivity in the spinal
cord
For measurements of MOP immunoreactivity, the spinal cord was divided
along the dorsoventral axis and the signal intensity of each section was
measured using ImageJ (version 1.52v, NIH). Superficial and deep lamina
sections of Oprm1 cKO and WT mice (3 per group) were quantified
by using a global background threshold and compared by their total
integrated density (area×mean gray value).