GRIA4 and postherpetic neuralgia: Moreover, we observed an increase in keratinocyte GluA4 expression in skin biopsies from patients afflicted with atopic dermatitis (AD), while a decrease in GluA4 was observed in postherpetic neuralgia (PHN).25,30,31,35 Furthermore, a decrease of GluA4 expression occurred in organotypic cultures of human keratinocytes treated with algogenic agents.