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Antiallodynic effects of alpha lipoic acid in an optimized RR-EAE mouse model of MS-neuropathic pain are accompanied by attenuation of upregulated BDNF-TrkB-ERK signaling in the dorsal horn of the spinal cord.

Khan N, Gordon R, Woodruff TM, Smith MT - Pharmacol Res Perspect (2015)

Bottom Line: In an experimental autoimmune encephalomyelitis (EAE)-mouse model of MS, chronic alpha lipoic acid (ALA) treatment reduced clinical disease severity, but MS-neuropathic pain was not assessed.The antiallodynic effect of ALA (10 mg kg(-1) day(-1)) was associated with a marked reduction in the aforementioned spinal dorsal horn markers to match their respective levels in the vehicle-treated sham-mice.Our findings suggest that ALA at 10 mg kg(-1) day(-1) produced its antiallodynic effects in RR-EAE mice by reducing augmented CD3(+) T-cell infiltration and BDNF-TrkB-ERK signaling in the spinal dorsal horn.

View Article: PubMed Central - PubMed

Affiliation: Center for Integrated Preclinical Drug Development, University of Queensland St Lucia Campus, Brisbane, Queensland, 4072, Australia ; School of Pharmacy, University of Queensland, Pharmacy Australia Center of Excellence Woolloongabba, Brisbane, Queensland, 4102, Australia.

ABSTRACT
Neuropathic pain may affect patients with multiple sclerosis (MS) even in early disease. In an experimental autoimmune encephalomyelitis (EAE)-mouse model of MS, chronic alpha lipoic acid (ALA) treatment reduced clinical disease severity, but MS-neuropathic pain was not assessed. Hence, we investigated the pain-relieving efficacy and mode of action of ALA using our optimized relapsing-remitting (RR)-EAE mouse model of MS-associated neuropathic pain. C57BL/6 mice were immunized with MOG35-55 and adjuvants (Quil A and pertussis toxin) to induce RR-EAE; sham-mice received adjuvants only. RR-EAE mice received subcutaneous ALA (3 or 10 mg kg(-1) day(-1)) or vehicle for 21 days (15-35 d.p.i.; [days postimmunization]); sham-mice received vehicle. Hindpaw hypersensitivity was assessed blinded using von Frey filaments. Following euthanasia (day 35 d.p.i.), lumbar spinal cords were removed for immunohistochemical and molecular biological assessments. Fully developed mechanical allodynia in the bilateral hindpaws of vehicle-treated RR-EAE mice was accompanied by marked CD3(+) T-cell infiltration, microglia activation, and increased brain-derived neurotrophic factor (BDNF)-tyrosine kinase B (TrkB) signaling in the dorsal horn of the lumbar spinal cord. Consequently, phospho-ERK, a marker of central sensitization in neuropathic pain, was upregulated in the spinal dorsal horn. Importantly, hindpaw hypersensitivity was completely attenuated in RR-EAE mice administered ALA at 10 mg kg(-1) day(-1) but not 3 mg kg(-1) day(-1). The antiallodynic effect of ALA (10 mg kg(-1) day(-1)) was associated with a marked reduction in the aforementioned spinal dorsal horn markers to match their respective levels in the vehicle-treated sham-mice. Our findings suggest that ALA at 10 mg kg(-1) day(-1) produced its antiallodynic effects in RR-EAE mice by reducing augmented CD3(+) T-cell infiltration and BDNF-TrkB-ERK signaling in the spinal dorsal horn.

No MeSH data available.


Related in: MedlinePlus

Immunohistochemical analysis of the extent of CD3+ T-cell infiltration into the dorsal horn of lumbar (L4-L6) spinal cord sections from RR-EAE mice administered ALA at 10 mg kg−1 day−1 or vehicle, for 3-weeks (15–35 d.p.i.) relative to sham-mice administered vehicle by the same dosing schedule. CD3+ T-cell immunofluorescence (IF) in lumbar spinal dorsal horn was ∼4.7-fold higher (F(3,44) = 26.44; P < 0.05) for vehicle-treated RR-EAE mice c.f. that for vehicle-treated sham-mice. By contrast, CD3+ T-cell IF in lumbar spinal dorsal horn of RR-EAE mice administered ALA at 10 mg kg−1 day−1 for 21 consecutive days did not differ significantly (F(3,44) = 26.44; P > 0.05) from the corresponding data for vehicle-treated sham-mice. After cessation of ALA-treatment (10 mg kg−1 day−1) at 35 d.p.i. in RR-EAE mice, CD3+ T-cell IF in lumbar spinal dorsal horn at day 55  d.p.i. was again increased by ∼2.5-fold (F(3,44) = 26.44; P < 0.05) *P < 0.05 ((one-way ANOVA followed by Tukey’s multiple comparison test) to match the corresponding levels for vehicle-treated RR-EAE mice). Scale bars are 50 μm. EAE, experimental autoimmune encephalomyelitis, Veh, vehicle; ALA, alpha lipoic acid.
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fig02: Immunohistochemical analysis of the extent of CD3+ T-cell infiltration into the dorsal horn of lumbar (L4-L6) spinal cord sections from RR-EAE mice administered ALA at 10 mg kg−1 day−1 or vehicle, for 3-weeks (15–35 d.p.i.) relative to sham-mice administered vehicle by the same dosing schedule. CD3+ T-cell immunofluorescence (IF) in lumbar spinal dorsal horn was ∼4.7-fold higher (F(3,44) = 26.44; P < 0.05) for vehicle-treated RR-EAE mice c.f. that for vehicle-treated sham-mice. By contrast, CD3+ T-cell IF in lumbar spinal dorsal horn of RR-EAE mice administered ALA at 10 mg kg−1 day−1 for 21 consecutive days did not differ significantly (F(3,44) = 26.44; P > 0.05) from the corresponding data for vehicle-treated sham-mice. After cessation of ALA-treatment (10 mg kg−1 day−1) at 35 d.p.i. in RR-EAE mice, CD3+ T-cell IF in lumbar spinal dorsal horn at day 55  d.p.i. was again increased by ∼2.5-fold (F(3,44) = 26.44; P < 0.05) *P < 0.05 ((one-way ANOVA followed by Tukey’s multiple comparison test) to match the corresponding levels for vehicle-treated RR-EAE mice). Scale bars are 50 μm. EAE, experimental autoimmune encephalomyelitis, Veh, vehicle; ALA, alpha lipoic acid.

Mentions: As the role of reactive T-cells in MS-associated neuropathic pain is unknown (Khan and Smith 2014), we examined CD3+ T-cell IF in the lumbar spinal dorsal horn of RR-EAE mice. Specifically, CD3+ T-cell IF was ∼4.7-fold higher (F(3,44) = 26.44; P < 0.05) in vehicle-treated RR-EAE mice exhibiting neuropathic pain behavior at 35 d.p.i. c.f. the respective levels in vehicle-treated sham-mice. For RR-EAE mice administered ALA at 10 mg kg−1 day−1 for 21-days, CD3+ T-cell IF in the lumbar spinal dorsal horn did not differ significantly (P > 0.05) from that for vehicle-treated sham-mice. However, by 3 weeks after cessation of ALA treatment at 10 mg kg−1 day−1 in Cohort-2 RR-EAE mice at 55 d.p.i., CD3+ T-cell IF in the spinal dorsal horn was again increased to ∼2.5-fold higher (F(3,44) = 26.44; P < 0.05) than in vehicle-treated sham-mice (Fig.2).


Antiallodynic effects of alpha lipoic acid in an optimized RR-EAE mouse model of MS-neuropathic pain are accompanied by attenuation of upregulated BDNF-TrkB-ERK signaling in the dorsal horn of the spinal cord.

Khan N, Gordon R, Woodruff TM, Smith MT - Pharmacol Res Perspect (2015)

Immunohistochemical analysis of the extent of CD3+ T-cell infiltration into the dorsal horn of lumbar (L4-L6) spinal cord sections from RR-EAE mice administered ALA at 10 mg kg−1 day−1 or vehicle, for 3-weeks (15–35 d.p.i.) relative to sham-mice administered vehicle by the same dosing schedule. CD3+ T-cell immunofluorescence (IF) in lumbar spinal dorsal horn was ∼4.7-fold higher (F(3,44) = 26.44; P < 0.05) for vehicle-treated RR-EAE mice c.f. that for vehicle-treated sham-mice. By contrast, CD3+ T-cell IF in lumbar spinal dorsal horn of RR-EAE mice administered ALA at 10 mg kg−1 day−1 for 21 consecutive days did not differ significantly (F(3,44) = 26.44; P > 0.05) from the corresponding data for vehicle-treated sham-mice. After cessation of ALA-treatment (10 mg kg−1 day−1) at 35 d.p.i. in RR-EAE mice, CD3+ T-cell IF in lumbar spinal dorsal horn at day 55  d.p.i. was again increased by ∼2.5-fold (F(3,44) = 26.44; P < 0.05) *P < 0.05 ((one-way ANOVA followed by Tukey’s multiple comparison test) to match the corresponding levels for vehicle-treated RR-EAE mice). Scale bars are 50 μm. EAE, experimental autoimmune encephalomyelitis, Veh, vehicle; ALA, alpha lipoic acid.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
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getmorefigures.php?uid=PMC4492753&req=5

fig02: Immunohistochemical analysis of the extent of CD3+ T-cell infiltration into the dorsal horn of lumbar (L4-L6) spinal cord sections from RR-EAE mice administered ALA at 10 mg kg−1 day−1 or vehicle, for 3-weeks (15–35 d.p.i.) relative to sham-mice administered vehicle by the same dosing schedule. CD3+ T-cell immunofluorescence (IF) in lumbar spinal dorsal horn was ∼4.7-fold higher (F(3,44) = 26.44; P < 0.05) for vehicle-treated RR-EAE mice c.f. that for vehicle-treated sham-mice. By contrast, CD3+ T-cell IF in lumbar spinal dorsal horn of RR-EAE mice administered ALA at 10 mg kg−1 day−1 for 21 consecutive days did not differ significantly (F(3,44) = 26.44; P > 0.05) from the corresponding data for vehicle-treated sham-mice. After cessation of ALA-treatment (10 mg kg−1 day−1) at 35 d.p.i. in RR-EAE mice, CD3+ T-cell IF in lumbar spinal dorsal horn at day 55  d.p.i. was again increased by ∼2.5-fold (F(3,44) = 26.44; P < 0.05) *P < 0.05 ((one-way ANOVA followed by Tukey’s multiple comparison test) to match the corresponding levels for vehicle-treated RR-EAE mice). Scale bars are 50 μm. EAE, experimental autoimmune encephalomyelitis, Veh, vehicle; ALA, alpha lipoic acid.
Mentions: As the role of reactive T-cells in MS-associated neuropathic pain is unknown (Khan and Smith 2014), we examined CD3+ T-cell IF in the lumbar spinal dorsal horn of RR-EAE mice. Specifically, CD3+ T-cell IF was ∼4.7-fold higher (F(3,44) = 26.44; P < 0.05) in vehicle-treated RR-EAE mice exhibiting neuropathic pain behavior at 35 d.p.i. c.f. the respective levels in vehicle-treated sham-mice. For RR-EAE mice administered ALA at 10 mg kg−1 day−1 for 21-days, CD3+ T-cell IF in the lumbar spinal dorsal horn did not differ significantly (P > 0.05) from that for vehicle-treated sham-mice. However, by 3 weeks after cessation of ALA treatment at 10 mg kg−1 day−1 in Cohort-2 RR-EAE mice at 55 d.p.i., CD3+ T-cell IF in the spinal dorsal horn was again increased to ∼2.5-fold higher (F(3,44) = 26.44; P < 0.05) than in vehicle-treated sham-mice (Fig.2).

Bottom Line: In an experimental autoimmune encephalomyelitis (EAE)-mouse model of MS, chronic alpha lipoic acid (ALA) treatment reduced clinical disease severity, but MS-neuropathic pain was not assessed.The antiallodynic effect of ALA (10 mg kg(-1) day(-1)) was associated with a marked reduction in the aforementioned spinal dorsal horn markers to match their respective levels in the vehicle-treated sham-mice.Our findings suggest that ALA at 10 mg kg(-1) day(-1) produced its antiallodynic effects in RR-EAE mice by reducing augmented CD3(+) T-cell infiltration and BDNF-TrkB-ERK signaling in the spinal dorsal horn.

View Article: PubMed Central - PubMed

Affiliation: Center for Integrated Preclinical Drug Development, University of Queensland St Lucia Campus, Brisbane, Queensland, 4072, Australia ; School of Pharmacy, University of Queensland, Pharmacy Australia Center of Excellence Woolloongabba, Brisbane, Queensland, 4102, Australia.

ABSTRACT
Neuropathic pain may affect patients with multiple sclerosis (MS) even in early disease. In an experimental autoimmune encephalomyelitis (EAE)-mouse model of MS, chronic alpha lipoic acid (ALA) treatment reduced clinical disease severity, but MS-neuropathic pain was not assessed. Hence, we investigated the pain-relieving efficacy and mode of action of ALA using our optimized relapsing-remitting (RR)-EAE mouse model of MS-associated neuropathic pain. C57BL/6 mice were immunized with MOG35-55 and adjuvants (Quil A and pertussis toxin) to induce RR-EAE; sham-mice received adjuvants only. RR-EAE mice received subcutaneous ALA (3 or 10 mg kg(-1) day(-1)) or vehicle for 21 days (15-35 d.p.i.; [days postimmunization]); sham-mice received vehicle. Hindpaw hypersensitivity was assessed blinded using von Frey filaments. Following euthanasia (day 35 d.p.i.), lumbar spinal cords were removed for immunohistochemical and molecular biological assessments. Fully developed mechanical allodynia in the bilateral hindpaws of vehicle-treated RR-EAE mice was accompanied by marked CD3(+) T-cell infiltration, microglia activation, and increased brain-derived neurotrophic factor (BDNF)-tyrosine kinase B (TrkB) signaling in the dorsal horn of the lumbar spinal cord. Consequently, phospho-ERK, a marker of central sensitization in neuropathic pain, was upregulated in the spinal dorsal horn. Importantly, hindpaw hypersensitivity was completely attenuated in RR-EAE mice administered ALA at 10 mg kg(-1) day(-1) but not 3 mg kg(-1) day(-1). The antiallodynic effect of ALA (10 mg kg(-1) day(-1)) was associated with a marked reduction in the aforementioned spinal dorsal horn markers to match their respective levels in the vehicle-treated sham-mice. Our findings suggest that ALA at 10 mg kg(-1) day(-1) produced its antiallodynic effects in RR-EAE mice by reducing augmented CD3(+) T-cell infiltration and BDNF-TrkB-ERK signaling in the spinal dorsal horn.

No MeSH data available.


Related in: MedlinePlus