RT Journal Article
SR Electronic
T1 Pharmacodynamic Effects of a <span class="sc">d</span>-Amino Acid Oxidase Inhibitor Indicate a Spinal Site of Action in Rat Models of Neuropathic Pain
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 502
OP 511
DO 10.1124/jpet.113.204016
VO 345
IS 3
A1 Hopkins, Seth C.
A1 Zhao, Fei-Yue
A1 Bowen, Carrie A.
A1 Fang, Xin
A1 Wei, Haifeng
A1 Heffernan, Michele L. R.
A1 Spear, Kerry L.
A1 Spanswick, David C.
A1 Varney, Mark A.
A1 Large, Thomas H.
YR 2013
UL http://jpet.aspetjournals.org/content/345/3/502.abstract
AB Inhibition of d-amino acid oxidase (DAAO) activity is a potential target for the treatment of chronic pain. Here we characterized the effects of systemic administration of the DAAO inhibitor 4H-furo[3,2-b]pyrrole-5-carboxylic acid (SUN) in rat models of neuropathic and inflammatory pain. Oral administration of SUN dose dependently attenuated tactile allodynia induced by ligation of the L5 spinal nerve (SNL) and similarly reversed thermal hyperalgesia produced by chronic constriction injury. In addition, SUN was efficacious against complete Freund’s adjuvant-induced thermal hyperalgesia. In these models, maximal reversal of pain-related behaviors corresponded with maximum rates of increase in brain and plasma d-serine concentrations, indicative of full inhibition of DAAO activity. To investigate the possible site(s) of action, we recorded spontaneous nerve activity and mechanically evoked responses of central spinal cord dorsal horn neurons and compared these with spontaneous activity of peripheral dorsal root filaments in anesthetized SNL model animals. Oral SUN reduced spontaneous activity in both central and peripheral recordings at doses and pretreatment times that corresponded to reduced mechanical allodynia in behavioral experiments. After intravenous administration of SUN, the onset of action for this central effect was rapid (maximal effects within 30 minutes), but was abolished by severing afferent inputs to the dorsal horn. Overall, these results indicate that inhibition of DAAO in peripheral afferent spinal circuits reduced spontaneous neuronal activity to attenuate pain-related behaviors in rat models of neuropathic and inflammatory pain.