[mRNA expression of muscarinic receptors in spinal cord and brainstem in morphine dependent rats].
OBJECTIVE
To observe mRNA expression of muscarinic acetylcholine receptors in spinal cord and brainstem in morphine dependent or withdrawal rats.


METHODS
The mRNA expression level of m1, m2, m3, m4 and m5 were determined by RT-PCR, the beta-actin mRNA expression was used as internal control.


RESULTS
The mRNA level of m1, m2, m3, m4 and m5 in spinal cord and m1 and m2 in brainstem were increased significantly during morphine dependence, and the levels of m1, m2, m3 and m4 in spinal cord and m1 in brainstem were decreased 1 h after the injection of naloxone (4 mg.kg-1, i.p.) in morphine dependent rats. Either scopolamine (0.5 mg.kg-1) or pirenzepine (10 mg.kg-1) was shown to significantly decrease the morphine withdrawal symptoms in rats. The levels of m1, m2, m3 and m5 in spinal cord were increased by pretreatment with pirenzepine and the levels of m2, m3 and m4 in spinal cord were increased by pretreatment with scopolamine.


CONCLUSIONS
The adaptive expression of muscarinic receptors at spinal and supraspinal levels play important role in mediating morphine dependence and withdrawal in rats.
Zhou
Wen-hua
WH
Ningbo Institute of Microcirculation and Henbane, Ningbo Addiction Research and Treatment Center, Ningbo 315010, China.
Liu
Hui-fen
HF
Gu
Jun
J
Xie
Xiao-hu
XH
Tang
Shuai-en
SE
Yang
Guo-dong
GD
Wu
Qi-xia
QX
D000818:Animals; D001933:Brain Stem / Q000187:drug effects* / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D008297:Male; D009020:Morphine / Q000633:toxicity*; D009021:Morphine Dependence / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D011976:Receptors, Muscarinic / Q000096:biosynthesis* / Q000145:classification / Q000235:genetics; D013116:Spinal Cord / Q000187:drug effects* / Q000378:metabolism; D013375:Substance Withdrawal Syndrome / Q000378:metabolism
D012333:RNA, Messenger; D011976:Receptors, Muscarinic; D009020:Morphine