Recent observations suggest that glutamate is important in sensory transduc
tion in the periphery, contributing to peripheral sensitization of nocicept
ors and the hyperalgesia that accompanies inflammation. This study examined
the presence of ionotropic glutamate receptors N-methyl-D-aspartate (NMDA)
, alpha-amino-3-hydroxy-5-methylisoxazolone-4-propionic acid (AMPA) and kai
nate (KA) in normal human hairy skin (n = 6) using immunohistochemistry at
the electron microscopic level. Analysis of labeled axons at the dermal-epi
dermal junction demonstrated that 26.9 +/- 2, 19.5 +/- 3 and 18.5 +/- 1% of
the axons analyzed were labeled for subunits of the NMDA, AMPA or KA recep
tors, respectively. An occasional Schwann cell process was labeled for eith
er NMDA or KA receptors. The findings support the hypothesis that glutamate
and its ionotropic receptors may play a role in the periphery in sensory p
rocessing in humans. (C) 2000 Elsevier Science Ireland Ltd. All rights rese
rved.