Fig. 4. Calcitonin gene–related peptide (CGRP) levels in dorsal root ganglia as measured by radioimmunoassay were significantly ( P < 0.05, t test, as indicated by the asterisk ) lower 6 weeks after unilateral infection with the KACGRP vector compared with the control dorsal root ganglia contralateral to the viral infection. Data are presented as mean ± SEM. KACGRP = antisense CGRP viral vector.