Volume 17, Number 20,
Issue of October 15, 1997
pp. 8018-8023
Copyright ©1997 Society for Neuroscience
Different Mechanisms Mediate Development and Expression of
Tolerance and Dependence for Peripheral µ-Opioid Antinociception
in Rat
Received June 6, 1997; revised August 1, 1997; accepted August 1, 1997.
Kochuvelikakam O. Aley and
Jon D. Levine
Department of Anatomy, Medicine, and Oral Surgery and Division of
Neuroscience, University of California, San Francisco, California
94143
The µ-opioid
[D-Ala2,N-Me-Phe4,Gly-ol5]-enkephalin
(DAMGO) exerts a peripheral antinociceptive effect against
prostaglandin E2 (PGE2)-induced
mechanical hyperalgesia in the hindpaw of the rat. Tolerance and
dependence develop to this effect. We have shown previously that
tolerance and dependence can be dissociated and are mediated by
different second messenger systems. In the present study, we evaluated
whether the same or different second messenger systems mediate the
development of this peripheral opioid tolerance or
dependence compared with the expression of the loss of
antinociceptive effect or rebound opioid antagonist hyperalgesia (i.e.,
expression of tolerance and dependence). DAMGO-induced tolerance was
prevented by pretreatment with the nitric oxide synthase inhibitor
NG-methyl-L-arginine
(NMLA) but not by the protein kinase C (PKC) inhibitor chelerythrine,
the adenylyl cyclase inhibitor 2
,5
-dideoxyadenosine (ddA), or the
calcium chelators 3,4,5-trimethoxybenzoic acid 8-(diethylamino)-octyl ester (TMB-8) and
2-[(2-bis-[carboxymethyl]amino-5-methylphenoxy)-methyl]-6-methoxy-8-bis[carboxymethyl]aminoquinoline (Quin-2). Once established, however, expression of DAMGO
tolerance was acutely reversed by TMB-8 or Quin-2 but not by
chelerythrine or NMLA. In contrast, naloxone-precipitated hyperalgesia
in DAMGO-tolerant paws, a measure of dependence, was blocked by
pretreatment with chelerythrine but not by NMLA, ddA, TMB-8, or Quin-2.
Naloxone-precipitated hyperalgesia in DAMGO-tolerant paws was acutely
reversed by chelerythrine, ddA, TMB-8, or Quin-2 but not by NMLA. Taken
together, these results provide the first evidence that different
mechanisms mediate the development and expression of both tolerance and
dependence to the peripheral antinociceptive effect of DAMGO. However,
although the development of tolerance and dependence are entirely
separable, the expression of tolerance and dependence shares common
calcium-dependent mechanisms.
Key words:
protein kinase A;
protein kinase C;
nitric oxide;
adenylyl cyclase;
calcium;
opioids;
nociception;
prostaglandin
E2