ENHANCED EXPRESSION OF THE PERIPHERAL BENZODIAZEPINE RECEPTOR (PBR) AND ITS ENDOGENOUS LIGAND OCTADECANEUROPEPTIDE (ODN) IN THE REGENERATING ADULT-RAT SCIATIC-NERVE

In this study we have investigated the expression of the peripheral be nzodiazepine receptor (PER) and its endogenous ligand octadecaneuropep tide (ODN) in the sciatic nerve of the adult rat by immunohistochemist ry. We have also determined the effect of nerve freezing lesion or chr onic denervation on PER and ODN expression. In the sciatic nerve of co ntrol rats PBR- and ODN-immunoreactivities (IR) were associated to Sch wann cells. Ten days after nerve injury, PBR- and ODN-IR increased sig nificantly in the distal stump. PBR-IR was associated to Schwann cells and macrophages, whereas ODN-IR was only detected in Schwann cells. I mmunoreactivities returned to normal levels when axons were allowed to regenerate for 2 months after nerve freezing-injury. Under chronic de nervation conditions, PBR- and ODN-IR remained elevated in the distal stump, at least for this period of time. These results suggest that PE R and ODN are regulated by signals from regenerating axons and that PE R and its endogenous ligand may play a role in peripheral nerve regene ration. Copyright (C) 1996 Elsevier Science Ireland Ltd.