Responses of spinal neurons to iontophoretically applied prostaglandin E1 in the frog

Prostaglandin E1 (PGE1) has been tested by microiontophoresis on interneurons and motoneurons in the isolated spinal cord of the frog. PGE1 action was almost exclusively excitatory, regardless of the cell type and the test condition used. In general, the excitatory response had rapid onset and termination, and was susceptible to tachyphylaxis. Responsive interneurons were scattered throughout the tissue, and the incidence of responses showed no obvious relation to the mono- vs. polysynaptic connection of cells to primary afferents and descending fibers of the lateral funiculus. PGE1-sensitive interneurons were encountered more often in preparations from summer than from winter animals. These findings, coupled with the demonstration of prostaglandin biosynthesis and catabolism in the tissue, suggest that PGE1 plays a role in the normal function of spinal neurons. The intimate mechanism of PGE1 action remains to be elucidated.