Figure 1. Generation and characterization of mice lacking GluA1 or GluA2 in Nav1.8-expressing neurons (nociceptors) of the DRG.

(A) Immunohistochemistry with anti-GluA1, anti-Cre, and anti-GluA2/3 antibodies on sections of the DRG, spinal dorsal horn, and forebrain (anterior cingulate cortex is shown) of control mice (GluA1^fl/fl mice), nociceptor-specific GluA1 knockout mice (SNS-GluA1^–/– mice), and mice globally lacking GluA1 (GluA1^–/– mice). (B) Immunohistochemistry with an antibody recognizing GluA2 and GluA3 (anti-GluA2/3) and anti-GluA1 and anti-Cre antibodies on sections of the DRG, spinal dorsal horn, and forebrain of control mice (GluA2^fl/fl mice), nociceptor-specific GluA2 knockout mice (SNS-GluA2^–/– mice), and mice globally lacking GluA2 (GluA2^–/– mice). (A and B) Scale bars: 50 μm (DRG images); 100 μm (spinal cord and brain images). (C and D) Quantitative size frequency analysis of DRG neurons immunoreactive against anti-GluA1 or anti-GluA2/GluA3 confirms that small-diameter neurons lose and large-diameter neurons maintain expression of the respective genetically targeted subunits in (C) SNS-GluA1^–/– mice and (D) SNS-GluA2^–/– mice. (C) In contrast, anti-GluA2/GluA3 immunoreactivity is maintained in SNS-GluA1^–/– mice, and (D) anti-GluA1 is maintained in SNS-GluA2^–/– mice. (E) Dual immunofluorescence quantitative analysis of anti-GluA1 and anti-GluA2 with markers of peptidergic nociceptors (CGRP) and nonpeptidergic nociceptors (IB₄) confirms a near complete loss of GluA1 in nociceptors of SNS-GluA1^–/– mice and loss of anti-GluA2 in SNS-GluA2^–/– mice. In C–E, y axes represent immunopositive cells represented as a percentage of all cells counted in corresponding DRG sections. *P < 0.05 as compared to corresponding flox control mice. (F) Western blot analyses confirm DRG-specific deletion of GluA1 or GluA2 in SNS-GluA1^–/– and SNS-GluA2^–/– mice, respectively. Units for numbers in F are kDa. α-Tubulin represents a loading control.