Physiology and Pharmacology
Physiol Pharmacol
Medical Sciences
http://ppj.phypha.ir
32
journal32
24765236
24765244
10.61186/phypha
(previous ISSN: 17350581)
en
jalali
1385
1
1
gregorian
2006
4
1
10
1
online
1
fulltext
en
Intrathecal administration of epinephrine inhibits and reverses analgesic tolerance to analgesic effect of morphine in rats
Pain and addiction
Neurophysiology/Pharmacology
Experimental research article
Experimental research article
Introduction: Several researches have reported that stress is able to inhibit the development of morphine
tolerance via activating of Hypothalamic-Pituitary-Adrenal (HPA) axis. In the present study we tried to examine
the effect of epinephrine, the product of adrenal medulla, on the development of morphine tolerance.
Methods: Analgesic tolerance was induced by intrathecal (i.t.) injection of morphine 15 μg/kg, twice a day
for 5 days. To study the effect of epinephrine on morphine tolerance, epinephrine (2, 5, 10 or 20 μg/kg, i.t.) was
administrated 20 minutes before morphine injection. Analgesia was assessed using tail flick test.
Results: In animals that received combined treatments of morphine and epinephrine in doses 2, 5, 10 or 20 μg/
kg for 5 days, at 6th day, morphine produced a more potent analgesia comparing with animals that received saline
and morphine during days 1-5. Following tolerance induction during first 5 days, co-administration of epinephrine
and morphine during days 6 – 10 reduced the initial tolerance as it induced potent analgesia on day 11th.
Conclusion: Our results showed that i.t. administration of epinephrine is able to inhibit and reverse the
analgesic tolerance to morphine. It also suggests the possible role of adrenal medulla and epinephrine in mediating
the inhibitory effect of stress and HPA activation of the development of analgesic tolerance to morphine.
Tolerance, Morphine, Opioids, Epinephrine.
57
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http://ppj.phypha.ir/browse.php?a_code=A-10-3-2&slc_lang=en&sid=1
Leila
Satarian
320031947532846002885
320031947532846002885
No
Mohammad
Javan
320031947532846002886
320031947532846002886
Yes
Yagoob
Fathollahi
320031947532846002887
320031947532846002887
No