Physiology and Pharmacology
Physiol Pharmacol
Medical Sciences
http://ppj.phypha.ir
32
journal32
24765236
24765244
10.61186/phypha
(previous ISSN: 17350581)
en
jalali
1390
5
1
gregorian
2011
8
1
15
2
online
1
fulltext
en
Microinjection of orexin-A into the locus coeruleus area induces morphine withdrawal-like behaviors in morphine dependent rats
Nervous system (others)
Others
Experimental research article
Experimental research article
Introduction: It has been shown that orexin peptides have a role in opioid withdrawal behaviors. Orexin-expressing
neurons that are present in the hypothalamic nuclei send dense projections to the Locus Coeruleus (LC). Withdrawal
syndrome is temporally associated with hyperactivity of LC neurons. However, LC neurons do not show withdrawalinduced
hyperactivity in the brain slices from morphine-dependent rats. Thus, it has been suggested that the increase in
LC neuronal activity seen in vivo is mediated by extrinsic factors. Therefore, this study was carried out to find whether
LC microinjection of orexin-A can induce withdrawal behaviors.
Methods: Adult male Wistar rats weighing 250-300 grams were rendered morphine dependent by subcutaneous
injection of morphine sulfate (10 mg/kg) at an interval of 12 h for 9 days. On day 10, intra-LC microinjection of orexin-
A (100 μM, 200 nl) was performed two hours after morphine administration. Thereafter, somatic signs of withdrawal
were evaluated in a Plexiglas chamber (30 cm diameter, 50 cm height) during a period of 25 min.
Results: Orexin-A induced several signs of morphine withdrawal including chewing, scratching, rearing, teeth
chattering, wet-dog shake and paw tremor. Acute LC microinjection of an orexin type 1 receptor antagonist, SB-
334867-A, prior to orexin-A prevents the expression of these signs.
Conclusion: It may be concluded that orexin, via orexin type 1 receptor at LC acts as an extrinsic factor in the
expression of morphine withdrawal syndrome.
Orexin-A, SB-334867, Morphine withdrawal, Locus coeruleus
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http://ppj.phypha.ir/browse.php?a_code=A-10-493-1&slc_lang=en&sid=1
Hossein
Azizi
azizihf@yahoo.com
320031947532846009122
320031947532846009122
No
Tarbiat Modares University
Saeed
Semnanian
ssemnan@modares.ac.ir
320031947532846009123
320031947532846009123
Yes
Tarbiat Modares University
Seyed Javad
Mirnajafizadeh
mirnajaf@modares.ac.ir
320031947532846009124
320031947532846009124
No
Tarbiat Modares University