Association of terpinolene and diclofenac presents antinociceptive and anti-inflammatory synergistic effects in a model of chronic inflammation.
ACTA ACUST UNITED AC 2017;
49:S0100-879X2016000700602. [PMID:
27332775 PMCID:
PMC4918787 DOI:
10.1590/1414-431x20165103]
[Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 03/10/2016] [Indexed: 12/16/2022]
Abstract
Pharmacological treatment of inflammatory pain is usually done by administration of
non-steroidal anti-inflammatory drugs (NSAIDs). These drugs present high efficacy,
although side effects are common, especially gastrointestinal lesions. One of the
pharmacological strategies to minimize such effects is the combination of drugs and
natural products with synergistic analgesic effect. The monoterpene terpinolene (TPL)
is a chemical constituent of essential oils present in many plant species, which have
pharmacological activities, such as analgesic and anti-inflammatory. The association
of ineffective doses of TPL and diclofenac (DCF) (3.125 and 1.25 mg/kg
po, respectively) presented antinociceptive and anti-inflammatory
effects in the acute (0, 1, 2, 3, 4, 5 and 6 h, after treatment) and chronic (10
days) inflammatory hyperalgesia induced by Freund's complete adjuvant (CFA) in the
right hind paw of female Wistar rats (170-230 g, n=6-8). The mechanical hyperalgesia
was assessed by the Randall Selitto paw pressure test, which determines the paw
withdrawal thresholds. The development of edema was quantified by measuring the
volume of the hind paw by plethismography. The TPL/DCF association reduced
neutrophils, macrophages and lymphocytes in the histological analysis of the paw,
following a standard staining protocol with hematoxylin and eosin and the counts were
performed with the aid of optical microscopy after chronic oral administration of
these drugs. Moreover, the TPL/DCF association did not induce macroscopic gastric
lesions. A possible mechanism of action of the analgesic effect is the involvement of
5-HT2A serotonin receptors, because ketanserin completely reversed the
antinociceptive effect of the TPL/DCF association. These results suggest that the
TPL/DCF association had a synergistic anti-inflammatory and analgesic effect without
causing apparent gastric injury, and that the serotonergic system may be involved in
the antinociceptive effect of this association.
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