It does not appear that 5-HT2A and 5-HT3 receptors are upregulated after nerve injury (Hu et al., 2016; Okamoto et al., 2002; Peters et al., 2010) but enhanced spinal gain may still arise from a combination of plasticity in descending pathways and spinal circuits (such as increased 5-HTR coupling to downstream mediators). The gene discussed is HTR2A; the disease is injury.