Effects of antisense oligodeoxynucleotides against opioid receptors on thereceptor mRNA contents

It was demonstrated in the previous study that the microinjection of antise nse oligodeoxynucleotide (AS ODN) against mu -opioid receptor (MOR) into pe riaqueductal gray (PAG) of rat brain selectively decreased the MOR mRNA con tent in PAG, and the decrease in MOR mRNA content was enhanced by pretreatm ent of the PAG with MOR AS ODN. In the present investigation, effects of th e pretreatment of PAG with AS ODN against kappa- or delta -opioid receptor (KOR or DOR) on the decrease in the MOR mRNA content induced by MOR AS ODN were examined. Both KOR and DOR AS ODNs significantly decreased the target mRNA contents, while they did not significantly change MOR mRNA content. Th e decrease in MOR mRNA content induced by MOR AS ODN, however, was signific antly enhanced by the pretreatment of PAG with either KOR or DOR AS ODNs. R esults show that the AS ODN has both the specific target mRNA decreasing ac tion and the nonspecific enhancing action on the AS-induced decrease in the mRNA content. (C) 2001 Elsevier Science Inc. All rights reserved.