Central Neuropathic Pain Development Modulation Using Coffee Extract Major Polyphenolic Compounds in Spinal-Cord-Injured Female Mice

Abstract

It was recently shown that coffee polyphenolic extract exerts preventive effects on central neuropathic pain development, but it is unknown whether its beneficial effects are associated with only one of its major polyphenolic compounds or if the whole extract is needed to exert such effects. The main objective of this study was to determine whether the separate administration of major polyphenols from coffee extract exerts preventive effects on the development of central neuropathic pain in mice compared with the effects of the whole coffee extract. Thus, spinal-cord-injured female ICR-CD1 mice were daily treated with either coffee extract or its major polyphenolic compounds during the first week, and reflexive and nonreflexive pain responses were evaluated within the acute phase of spinal cord injury. In addition, the injury-induced gliosis and dorsal horn sprouting were evaluated with immunohistochemistry. The results showed that the coffee extract prevented spinal cord injury-induced neuropathic pain, whereas its major polyphenolic compounds resulted in reflexive pain response attenuation. Both preventive and attenuation effects were associated with gliosis and afferent fiber sprouting modulation. Overall, the results suggested that coffee extract effects may be associated with potential synergistic mechanisms exerted by its major polyphenolic compounds and not by the sole effect of only one of them.

Keywords: 4-O-caffeoylquinic acid; chlorogenic acid; coffee extract; gliosis; neochlorogenic acid; neuropathic pain; polyphenols; spinal cord injury.

Figure 1

Effects of major coffee extract polyphenolic compounds on reflexive pain responses and locomotor activity: (a) thermal hyperalgesia; (b) mechanical allodynia; (c) BMS scores. Data are illustrated as mean ± SEM. a–c: not sharing a letter means significant differences, p < 0.05. Administration week (W0 to W1) is indicated with a thicker line.

Figure 2

Effects of major coffee extract polyphenolic compounds on depression-like behavior fourteen days post-injury. Data are illustrated as mean ± SEM. a,b: not sharing a letter means significant differences in %immobility time, p < 0.05; intra-groups significant differences: *** p < 0.0001, ** p < 0.001, * p < 0.05 %immobility vs. %mobility.

Figure 3

Spinal cord astroglia after polyphenolic treatments fourteen days post-injury: (a) Representative GFAP images of dorsal horn for each group. Scale bars = 100 μm; (b) Percentage of GFAP immunoreactivity. Data are illustrated as median ± IQR, and the x indicate the mean. a–d: not sharing a letter means significant differences, p < 0.05.

Figure 4

Spinal cord microglia reactivity after polyphenolic treatments fourteen days post-injury: (a) Representative IBA1 images of dorsal horn for each group. Scale bars = 100 μm; (b) Percentage of reactive and non-reactive microglia cells. Data are illustrated as median ± IQR, and the x indicate the mean. a–e: not sharing a letter means significant differences, p < 0.05.

Figure 5

Sprouting of peptidergic afferent nerve fibers in the spinal cord after polyphenolic treatments fourteen days post-injury: (a) Representative CGRP images for each group. Scale bars = 100 μm. (b) Percentage of dorsal horn CGRP-immunoreactivity. Data are illustrated as median ± IQR, and the x indicate the mean. a–e: not sharing a letter means significant differences, p < 0.05.

Figure 6

Sprouting of non-peptidergic afferent nerve fibers in the spinal cord after polyphenolic treatments fourteen days post-injury. (a) Representative IB4 images for each group. Scale bars = 100 μm. (b) Percentage of dorsal horn IB4 immunoreactivity. Data are illustrated as median ± IQR, and the x indicate the mean. a–f: not sharing a letter means significant differences, p < 0.05.

Figure 7

(a) Time−course weight. Data are illustrated as mean ± SEM. Administration week (W0 to W1) is highlighted with a thicker line. No differences between groups are shown over time. Serum biomarkers quantification of (b,c) hepatotoxicity and (d) nephrotoxicity of each experimental group fourteen days post-injury. Data are illustrated as median ± IQR, and the x indicate the mean. No differences between groups are shown in any of the parameters.