The potentiation of analgesic activity of paracetamol plus morphine involves the serotonergic system in rat brain.
Inflamm Res
; 48(3): 120-7, 1999 Mar.
Article
in En
| MEDLINE
| ID: mdl-10219653
ABSTRACT
OBJECTIVE AND DESIGN:
We investigated the antinociceptive effect of subactive doses of paracetamol and morphine, given in combination. MATERIAL AND TREATMENT Male Wistar rats were injected with paracetamol (50 or 100 mg/kg i.p.) and morphine (2, 3 or 5 mg/kg s.c.) 10 min later and subjected to algesimetric tests 20 min thereafter.METHODS:
Pain threshold was evaluated in the hot-plate and formalin tests. 5-HT2 receptor binding capacity and 5-HT and 5-HIAA levels were measured in cortical and pontine areas of the brain by means of radioligand binding technique and by HPLC, respectively. Statistical analysis was done using Student-Neuman-Keul's test and 2 x 2 factorial analysis.RESULTS:
Only when given in combination, paracetamol (100 mg/kg) and morphine (2 and 3 mg/kg) were able to evoke an antinociceptive effect in both tests associated with an increase in 5-HT levels and a decrease in 5-HT2 receptors in the cortex. These effects were prevented by i.p. pretreatment with naloxone (1 mg/kg i.p.).CONCLUSIONS:
Subactive doses of paracetamol and morphine exert an analgesic effect when given in combination in the rat and indicate an involvement of both serotonergic and opiatergic systems.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Brain
/
Serotonin
/
Analgesics, Non-Narcotic
/
Analgesics, Opioid
/
Acetaminophen
/
Morphine
Limits:
Animals
Language:
En
Journal:
Inflamm Res
Journal subject:
ALERGIA E IMUNOLOGIA
/
PATOLOGIA
Year:
1999
Document type:
Article
Affiliation country:
Italia