| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 2006448 | Peptides | 2011 | 7 Pages |
Periaqueductal gray (PAG) plays a very important role in pain modulation through endogenous opiate peptides including leucine-enkephalin (L-Ek), methionine-enkephalin (M-Ek), β-endorphin (β-Ep) and dynorphin A1–13 (DynA1–13). Our pervious study has demonstrated that intra-PAG injection of oxytocin (OXT) increases the pain threshold, and local administration of OXT receptor antagonist decreases the pain threshold, in which the antinociceptive role of OXT can be reversed by pre-PAG administration of OXT receptor antagonist. The experiment was designed to investigate the effect of OXT on endogenous opiate peptides in the rat PAG during the pain process. The results showed that (1) the concentrations of OXT, L-Ek, M-Ek and β-Ep, not DynA1–13 in the PAG perfusion liquid were increased after the pain stimulation; (2) the concentrations of L-Ek, M-Ek and β-Ep, not DynA1–13 in the PAG perfusion liquid were decreased by the OXT receptor antagonist; (3) the increased pain threshold induced by the OXT was attenuated by naloxone, an opiate receptor antagonist; and (4) the concentrations of L-Ek, M-Ek and β-Ep, not DynA1–13 in the PAG perfusion liquid were increased by exogenous OXT administration. The data suggested that OXT in the PAG could influence the L-Ek, M-Ek and β-Ep rather than DynA1–13 to participate in pain modulation, i.e. OXT in the PAG participate in pain modulation by influencing the L-Ek, M-Ek and β-Ep rather than DynA1–13.
► The concentrations of oxytocin (OXT), leucine-enkephalin (L-Ek), methionine-enkephalin (M-Ek) and β-endorphin (β-Ep), not dynorphin A1–13 (DynA1–13) in the PAG perfusion liquid were increased after the pain stimulation. ► The concentrations of L-Ek, M-Ek and β-Ep, not DynA1–13 in the PAG perfusion liquid were decreased by the OXT receptor antagonist. ► The increased pain threshold induced by the OXT was attenuated by naloxone. ► The concentrations of L-Ek, M-Ek and β-Ep, not DynA1–13 in the PAG perfusion liquid were increased by exogenous OXT administration. ► OXT in the PAG participate in pain modulation by influencing the L-Ek, M-Ek and β-Ep rather than DynA1–13.
