Antinociception delta receptor-mediated

Delta receptors nevertheless mediate some delta agonist induced analgesia, as suggested by reduced DPDPE and deltorphin activity in the DOR mutant after ITH applications [52], or enhanced antinociceptive activity in MOR mutants subjected to CFA inflammation [65]. Delta receptors also depress respiratory neurons in slice preparations [66] and mediate SNC80-evoked convulsions [67]. 

Delta Opioid Receptor-Mediated Antinociception/Analgesia... 

SPINAL DELTA OPIOID RECEPTOR-MEDIATED ANTINOCICEPTION... 

INVOLVEMENT OF G PROTEINS AND ION CHANNELS IN SPINAL DELTA OPIOID RECEPTOR-MEDIATED ANTINOCICEPTION... 

Figure 2 Schematic model of the intracellular signaling mechanisms including phosphatidylinositol-specific phospholipase C (PI-PLC) isoforms, inositol-1,4,5-triphosphate (IP3) receptor, and protein kinase C (PKC) in the expression of delta opioid receptor agonist-induced spinal antinociception. In addition, PKC is considered to play a substantial role in an intracellular negative feedback action on the spinal delta opioid receptor-mediated antinociceptive pathway.

An ITH injection of [D-Ala2]deltorphin II produces an acute antinociceptive tolerance [128], Concomitant pretreatment with lower doses of the PKC inhibitor calphostin C markedly prevents the development of acute tolerance to the ITH-administered [D-Ala2]deltorphin II-induced antinociception. On the other hand, the PKA inhibitor KT5720, has no effect on the development of acute tolerance to [D-Ala2]deltorphin II antinociception [128], It is therefore likely that PKC, but not PKA, plays an important role in the process of homologous desensitization of the spinal delta opioid receptor-mediated antinociception. 

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