Effects of KOR deletion on weight gain and sensory function. (a, d) Weight gain in knockout mice did not differ from littermate controls. (n=9–14) (b, e). Startle responding in knockout mice did not statistically differ from controls. Hearing thresholds for all genotypes was 86 dB. (n=8–10) (c, f). Vision was not affected in either KOR-mutant line. (n=7–9) #P<0.05 compared with no stimulation (no stim) condition. Each genotype was analyzed individually. **P<0.01, ***P<0.001, ****P<0.0001 compared with 50%.