Amniotic-fluid ingestion enhances central δ-opioid-induced hypoalgesia in rats in the cold-water tail-flick assay in a repeated-measures design.

Amniotic-fluid ingestion enhances central δ-opioid-induced hypoalgesia in rats in the cold-water tail-flick assay in a repeated-measures design. Brain Res. 2018 Jun 11;: Authors: Thompson AC, Feeney C, Kristal MB Abstract Placental Opioid Enhancing Factor (POEF) is found in amniotic fluid (AF) and placenta. When ingested, it enhances opioid-mediated pain relief. Our laboratory has shown that ingestion of AF specifically enhances the hypoalgesia associated with δ-opioid receptor activation in the brain. The specific biochemical compound in AF responsible for the enhancement of δ-opioid activity is of great interest as an analgesic adjunct for pain but is unknown at this time. Research efforts to isolate and characterize this biochemical compound are hampered by the lack of an algesiometric assay that allows repeated measurement of pain threshold and repeated exposure to δ-opioid receptor activation. The cold water tail-flick assay (CWTF) may be a sensitive and reliable pain threshold test of (a) all species of opioids that is (b) not subject to repeated-testing effects. Therefore the CWTF test is potentially ideal for the study of δ opioid systems in a repeated measures design. Here, we confirm these attributes of the CWTF test, and determined that (a) there are no repeated-exposure effects associated with the CWTF assay; (b) there are no repeated-exposure effects associated with repeated central injections of DPDPE ([D-Pen2,D-Pe...
Source: Brain Research - Category: Neurology Authors: Tags: Brain Res Source Type: research