ISSN:
1420-908X
Keywords:
Key words: Paracetamol — Morphine — Antinociception — 5-Hydroxytryptamine (5-HT) — 5-HT2 receptors — Brain
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
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 × 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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s000110050434
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