Masanobu Yoshikawa1, Kouichi Yokogami2, Ken Kitamura1,
Tomomi Kobayashi1, Masayuki Kanai1, Takao Taniguchi1,
Kazuhito Akahori1, Masaru Nakabayashi1, Kayoko Iwao1,
Masao Hyodo2 and Tetsuo Oka1
1Department of Pharmacology, School of Medicine, Tokai University,
Isehara 259 - 1193, Japan
2Department of Biological Science and Technology, Tokai University
School of High-Technology for Human Welfare,
Numazu 410 - 0395, Japan
Abstract: The effect of phosphorothioated antisense oligodeoxynucleotide
(AS ODN) against the ƒÊ-opioid receptor (MOR) on MOR mRNA level in the periaqueductal
gray (PAG) of rat brain was investigated. The MOR mRNA levels at 3, 6, 12,
24, 48 and 72 h after MOR AS ODN microinjection into the PAG were determined
by reverse transcriptase-polymerase chain reaction. The MOR mRNA level was
significantly decreased only at 12 h after the injection of 10 ƒÊg MOR AS
ODN. When 10 ƒÊg MOR AS ODN was given three times at the interval of 48
h, MOR mRNA levels were significantly decreased at 6, 12 and 24 h after
the last injection of the AS ODN. However, MOR mRNA levels were not significantly
changed by three injections at 48-h interval of MOR sense ODN or AS ODNs
against ƒÂ- and ƒÈ-opioid receptors, although the two latter AS ODNs significantly
reduced the respective targeted mRNA levels. In conclusion, the present
results show that the selective decrease in MOR mRNA is at least one reason
why the reported diminished effects of MOR agonists are produced in animals
pretreated with MOR AS ODN, although they could be produced through several
mechanisms in which MOR mRNA level does not change.
Keywords: Antisense oligodeoxynucleotide, ƒÊ-Opioid receptor, mRNA level,
RT-PCR (reverse transcription-polymerase chain reaction)