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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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Extravasation differences between groups on the constricted side. When compared with results in naive animals fed the same diet, the changes in CAP-induced extravasation generated by the CCI had opposite directions, depending on the diet. In animals fed RD, the values of plasma extravasation increased significantly (p = 0.043) after surgery. This increase was most marked at 8 dps (* p = 0.017), and more moderate at 26 dps (showing statistical tendency, p = 0.052). In contrast, in animals fed MD the extravasation decreased with respect to naive animals, and this decrease showed statistical tendency at 26 dps (p = 0.056). No significant differences were found in lesioned rats on the side of the CCI between RD and MD groups at any of the postsurgical times tested. Data represent means ± SD; number of cases as in Fig. 4.
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Figure 5: Extravasation differences between groups on the constricted side. When compared with results in naive animals fed the same diet, the changes in CAP-induced extravasation generated by the CCI had opposite directions, depending on the diet. In animals fed RD, the values of plasma extravasation increased significantly (p = 0.043) after surgery. This increase was most marked at 8 dps (* p = 0.017), and more moderate at 26 dps (showing statistical tendency, p = 0.052). In contrast, in animals fed MD the extravasation decreased with respect to naive animals, and this decrease showed statistical tendency at 26 dps (p = 0.056). No significant differences were found in lesioned rats on the side of the CCI between RD and MD groups at any of the postsurgical times tested. Data represent means ± SD; number of cases as in Fig. 4.

Mentions: In the RD group, CAP-induced plasma extravasation increased significantly after surgery with respect to both naive (Kruskal-Wallis, p = 0.043) and sham-operated groups (ANOVA, p < 0.001). Compared to the naive animals (Fig. 5), this increase reached a significant 68% at 8 days after surgery (* p = 0.017), but displayed a more moderate 35% at 26 dps (showing statistical tendency, p = 0.052). In contrast, in animals fed MD the extravasation decreased with respect to naive animals. This decrease was a non-significant 26% at 8 dps, but reached 34% at 26 dps (p = 0.056). Compared to the sham-operated rats, the extravasation increases observed in the RD group became highly significant at 8 (p < 0.002) and 26 dps (p < 0.001), whereas the moderate decreases detected in the MD group remained below the significance level.


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)

Extravasation differences between groups on the constricted side. When compared with results in naive animals fed the same diet, the changes in CAP-induced extravasation generated by the CCI had opposite directions, depending on the diet. In animals fed RD, the values of plasma extravasation increased significantly (p = 0.043) after surgery. This increase was most marked at 8 dps (* p = 0.017), and more moderate at 26 dps (showing statistical tendency, p = 0.052). In contrast, in animals fed MD the extravasation decreased with respect to naive animals, and this decrease showed statistical tendency at 26 dps (p = 0.056). No significant differences were found in lesioned rats on the side of the CCI between RD and MD groups at any of the postsurgical times tested. Data represent means ± SD; number of cases as in Fig. 4.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Extravasation differences between groups on the constricted side. When compared with results in naive animals fed the same diet, the changes in CAP-induced extravasation generated by the CCI had opposite directions, depending on the diet. In animals fed RD, the values of plasma extravasation increased significantly (p = 0.043) after surgery. This increase was most marked at 8 dps (* p = 0.017), and more moderate at 26 dps (showing statistical tendency, p = 0.052). In contrast, in animals fed MD the extravasation decreased with respect to naive animals, and this decrease showed statistical tendency at 26 dps (p = 0.056). No significant differences were found in lesioned rats on the side of the CCI between RD and MD groups at any of the postsurgical times tested. Data represent means ± SD; number of cases as in Fig. 4.
Mentions: In the RD group, CAP-induced plasma extravasation increased significantly after surgery with respect to both naive (Kruskal-Wallis, p = 0.043) and sham-operated groups (ANOVA, p < 0.001). Compared to the naive animals (Fig. 5), this increase reached a significant 68% at 8 days after surgery (* p = 0.017), but displayed a more moderate 35% at 26 dps (showing statistical tendency, p = 0.052). In contrast, in animals fed MD the extravasation decreased with respect to naive animals. This decrease was a non-significant 26% at 8 dps, but reached 34% at 26 dps (p = 0.056). Compared to the sham-operated rats, the extravasation increases observed in the RD group became highly significant at 8 (p < 0.002) and 26 dps (p < 0.001), whereas the moderate decreases detected in the MD group remained below the significance level.

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