M2 muscarinic receptor of spinal cord mediated increase of nNOS expression in locus coeruleus during morphine withdrawal.
Abstract
AIM: To investigate the effects of different muscarinic receptor (M) subtypes in
the spinal cord on the scores of naloxone-precipitated morphine-withdrawal
symptoms and the changes of nNOS expression in locus coeruleus (LC).
METHODS: nNOS immunohistochemistry, intrathecal injection (it), and antisense
oligonucleotides (AS-ONs) techniques were used.
RESULTS: Intrathecal injection of M2-antisense oligonucleotides (M2-AS) decreased
the scores of morphine withdrawal symptoms. M1-AS attenuated morphine-withdrawal
symptoms, but the effect was less than that of M2-AS. The expression of nNOS
positive neurons in the LC increased in morphine-dependent rats and increased to
a greater extent during morphine withdrawal. Intrathecal injection of M2-AS
inhibited the increase of nNOS expression in LC during morphine-withdrawal, but
there was no effect in case of M1-AS.
CONCLUSION: M2 muscarinic receptor of spinal cord mediated the increase of nNOS
expression in LC during morphine withdrawal.
Keywords:
the spinal cord on the scores of naloxone-precipitated morphine-withdrawal
symptoms and the changes of nNOS expression in locus coeruleus (LC).
METHODS: nNOS immunohistochemistry, intrathecal injection (it), and antisense
oligonucleotides (AS-ONs) techniques were used.
RESULTS: Intrathecal injection of M2-antisense oligonucleotides (M2-AS) decreased
the scores of morphine withdrawal symptoms. M1-AS attenuated morphine-withdrawal
symptoms, but the effect was less than that of M2-AS. The expression of nNOS
positive neurons in the LC increased in morphine-dependent rats and increased to
a greater extent during morphine withdrawal. Intrathecal injection of M2-AS
inhibited the increase of nNOS expression in LC during morphine-withdrawal, but
there was no effect in case of M1-AS.
CONCLUSION: M2 muscarinic receptor of spinal cord mediated the increase of nNOS
expression in LC during morphine withdrawal.