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Effects of removal of dietary polyunsaturated fatty acids on plasma extravasation and mechanical allodynia in a trigeminal neuropathic pain model.

Martin YB, Avendaño C - Mol Pain (2009)

Bottom Line: When compared with basal levels (in naive and/or sham cases), the net effect of CCI-IoN on ipsilateral extravasation was a reduction in the MD group, but an increase in the RD group, effectively neutralizing the original intergroup differences.In summary, PUFA intake reduces CAP-induced neurogenic plasma extravasation in the trigeminal territory, and their removal significantly alters the mechanical allodynia and the plasma extravasation that result from a unilateral CCI-IoN.It is likely that this "protective" effect of dietary lipids is temporary.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anatomy, Histology & Neuroscience, Autonoma University of Madrid, Medical School, Madrid, Spain. yasmina.martin@uam.es

ABSTRACT

Background: Neuropathic pain (NP) is partially mediated by neuroinflammatory mechanisms, and also modulates local neurogenic inflammation. Dietary lipids, in particular the total amount and relative proportions of polyunsaturated fatty acids (PUFAs) of the omega-3 and omega-6 families, have been reported to modify the threshold for thermal and mechanical allodynia in the partial sciatic nerve ligation model of NP in rats. The effects of dietary lipids on other popular NP models, such as the chronic constriction injury (CCI), have not yet been examined. It is also unknown whether dietary PUFAs exert any effect on the capsaicin (CAP)-induced neurogenic inflammation under control or NP conditions. In this study we investigated these interrelated phenomena in the trigeminal territory, which has been much less explored, and for which not all data derived from limb nerves can be directly applied.

Results: We studied the effects of a CCI of the infraorbital nerve (IoN) on the development of mechanical allodynia and CAP-induced plasma extravasation in rats fed either a regular diet (RD), or a modified diet (MD) with much lower total content and omega-3:omega-6 ratio of PUFAs. In rats kept on MD, mechanical allodynia following CCI-IoN was more pronounced and developed earlier. Extravasation was substantially increased in naive rats fed MD, and displayed differential diet-depending changes one and four weeks after CCI-IoN. When compared with basal levels (in naive and/or sham cases), the net effect of CCI-IoN on ipsilateral extravasation was a reduction in the MD group, but an increase in the RD group, effectively neutralizing the original intergroup differences.

Conclusion: In summary, PUFA intake reduces CAP-induced neurogenic plasma extravasation in the trigeminal territory, and their removal significantly alters the mechanical allodynia and the plasma extravasation that result from a unilateral CCI-IoN. It is likely that this "protective" effect of dietary lipids is temporary. Also, the presence of contralateral effects of CCI-IoN precludes using the contralateral side as control.

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CAP-induced plasma extravasation is larger in naive rats fed MD. Extravasation nearly doubled on both sides of the snout in animals maintained on MD (n = 14) compared to those on RD (n = 14; ** p < 0.01). Data represent means ± SD of normalized EB absorbance values (see Methods).
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Figure 2: CAP-induced plasma extravasation is larger in naive rats fed MD. Extravasation nearly doubled on both sides of the snout in animals maintained on MD (n = 14) compared to those on RD (n = 14; ** p < 0.01). Data represent means ± SD of normalized EB absorbance values (see Methods).

Mentions: CAP-induced plasma extravasation in unoperated animals kept on MD (n = 14) was almost twice as large as that in the RD group (n = 14; Fig. 2). Pooling both sides for each group, extravasation values were 12.38 ± 5.13 for RD, and 21.57 ± 9.46 for MD. This 72% difference was very significant even when each side was compared separately (p = 0.012 for the left sides, p < 0.001 for the right). Similar values were obtained when comparisons between diet groups were made for the sham-operated animals (9.8 ± 4.4 for RD, n = 9; 24.9 ± 11.7 for MD, n = 9; p = 0.002).


Effects of removal of dietary polyunsaturated fatty acids on plasma extravasation and mechanical allodynia in a trigeminal neuropathic pain model.

Martin YB, Avendaño C - Mol Pain (2009)

CAP-induced plasma extravasation is larger in naive rats fed MD. Extravasation nearly doubled on both sides of the snout in animals maintained on MD (n = 14) compared to those on RD (n = 14; ** p < 0.01). Data represent means ± SD of normalized EB absorbance values (see Methods).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2651866&req=5

Figure 2: CAP-induced plasma extravasation is larger in naive rats fed MD. Extravasation nearly doubled on both sides of the snout in animals maintained on MD (n = 14) compared to those on RD (n = 14; ** p < 0.01). Data represent means ± SD of normalized EB absorbance values (see Methods).
Mentions: CAP-induced plasma extravasation in unoperated animals kept on MD (n = 14) was almost twice as large as that in the RD group (n = 14; Fig. 2). Pooling both sides for each group, extravasation values were 12.38 ± 5.13 for RD, and 21.57 ± 9.46 for MD. This 72% difference was very significant even when each side was compared separately (p = 0.012 for the left sides, p < 0.001 for the right). Similar values were obtained when comparisons between diet groups were made for the sham-operated animals (9.8 ± 4.4 for RD, n = 9; 24.9 ± 11.7 for MD, n = 9; p = 0.002).

Bottom Line: When compared with basal levels (in naive and/or sham cases), the net effect of CCI-IoN on ipsilateral extravasation was a reduction in the MD group, but an increase in the RD group, effectively neutralizing the original intergroup differences.In summary, PUFA intake reduces CAP-induced neurogenic plasma extravasation in the trigeminal territory, and their removal significantly alters the mechanical allodynia and the plasma extravasation that result from a unilateral CCI-IoN.It is likely that this "protective" effect of dietary lipids is temporary.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Anatomy, Histology & Neuroscience, Autonoma University of Madrid, Medical School, Madrid, Spain. yasmina.martin@uam.es

ABSTRACT

Background: Neuropathic pain (NP) is partially mediated by neuroinflammatory mechanisms, and also modulates local neurogenic inflammation. Dietary lipids, in particular the total amount and relative proportions of polyunsaturated fatty acids (PUFAs) of the omega-3 and omega-6 families, have been reported to modify the threshold for thermal and mechanical allodynia in the partial sciatic nerve ligation model of NP in rats. The effects of dietary lipids on other popular NP models, such as the chronic constriction injury (CCI), have not yet been examined. It is also unknown whether dietary PUFAs exert any effect on the capsaicin (CAP)-induced neurogenic inflammation under control or NP conditions. In this study we investigated these interrelated phenomena in the trigeminal territory, which has been much less explored, and for which not all data derived from limb nerves can be directly applied.

Results: We studied the effects of a CCI of the infraorbital nerve (IoN) on the development of mechanical allodynia and CAP-induced plasma extravasation in rats fed either a regular diet (RD), or a modified diet (MD) with much lower total content and omega-3:omega-6 ratio of PUFAs. In rats kept on MD, mechanical allodynia following CCI-IoN was more pronounced and developed earlier. Extravasation was substantially increased in naive rats fed MD, and displayed differential diet-depending changes one and four weeks after CCI-IoN. When compared with basal levels (in naive and/or sham cases), the net effect of CCI-IoN on ipsilateral extravasation was a reduction in the MD group, but an increase in the RD group, effectively neutralizing the original intergroup differences.

Conclusion: In summary, PUFA intake reduces CAP-induced neurogenic plasma extravasation in the trigeminal territory, and their removal significantly alters the mechanical allodynia and the plasma extravasation that result from a unilateral CCI-IoN. It is likely that this "protective" effect of dietary lipids is temporary. Also, the presence of contralateral effects of CCI-IoN precludes using the contralateral side as control.

Show MeSH
Related in: MedlinePlus