Effect of vasoactive substances on membrane potentials in retinal microvascular pericytes

Abstract

Intrathecal administration of prostaglandin E2 (PGE2) produces mechanical hyperalgesia, thermal hyperalgesia, and touch-evoked allodynia in rats. Experiments were conducted to examine the effects of intrathecal administration of relatively selective PGE2 receptor (EP receptor) agonists to establish which spinal EP receptors mediate these behavioral effects of spinally administered PGE2. Administration of either sulprostone (EP3 receptor agonist) or PGE1 alcohol (EP4 receptor agonist) produced marked mechanical and thermal hyperalgesia and touch-evoked allodynia. Neither 17-phenyl trinor PGE2 (EP1 receptor agonist) nor butaprost (EP2 receptor agonist) produced any significant changes in behavioral response thresholds to mechanical or thermal stimuli. However, 17-phenyl trinor PGE2 (EP1 receptor agonist) did produce marked touch-evoked allodynia. These data suggest that in rats activation of spinal EP3 and EP4 receptors by PGE2 is important for development of both mechanical and thermal hyperalgesia as well as for touch-evoked allodynia. PGE2-induced allodynia also appears to involve activation of spinal EP1 receptors.