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Recruitment of dorsal midbrain catecholaminergic pathways in the recovery from nerve injury evoked disabilities.

Mor D, Kang JW, Wyllie P, Thirunavukarasu V, Houlton H, Austin PJ, Keay KA - Mol Pain (2015)

Bottom Line: The PAG encompasses subgroups of the A10 dopaminergic and A6 noradrenergic cell groups; the origins of significant ascending projections to hypothalamic and forebrain regions, which regulate sleep, complex behaviours and endocrine function.Evidence for increased tyrosine hydroxylase transcription and translation in the constitutive A10/A6 cells was found in the midbrain of rats that showed an initial 2-3 day post-CCI, behavioural and endocrine change, which recovered by days 5-6 post-CCI.The data suggests a role for dopaminergic and noradrenergic outputs, and catecholaminergic inputs of the vPAG in the expression of one of the profiles of behavioural and endocrine change triggered by nerve injury.

View Article: PubMed Central - PubMed

Affiliation: School of Medical Sciences, Discipline of Biomedical Sciences, The University of Sydney, C42, Cumberland Campus, Lidcombe, NSW, 2141, Australia. david.mor@sydney.edu.au.

ABSTRACT

Background: The periaqueductal gray region (PAG) is one of several brain areas identified to be vulnerable to structural and functional change following peripheral nerve injury. Sciatic nerve constriction injury (CCI) triggers neuropathic pain and three distinct profiles of changes in complex behaviours, which include altered social and sleep-wake behaviours as well as changes in endocrine function. The PAG encompasses subgroups of the A10 dopaminergic and A6 noradrenergic cell groups; the origins of significant ascending projections to hypothalamic and forebrain regions, which regulate sleep, complex behaviours and endocrine function. We used RT-PCR, western blots and immunohistochemistry for tyrosine hydroxylase to determine whether (1) tyrosine hydroxylase increased in the A10/A6 cells and/or; (2) de novo synthesis of tyrosine hydroxylase, in a 'TH-naïve' population of ventral PAG neurons characterized rats with distinct patterns of behavioural and endocrine change co-morbid with CCI evoked-pain.

Results: Evidence for increased tyrosine hydroxylase transcription and translation in the constitutive A10/A6 cells was found in the midbrain of rats that showed an initial 2-3 day post-CCI, behavioural and endocrine change, which recovered by days 5-6 post-CCI. Furthermore these rats showed significant increases in the density of TH-IR fibres in the vPAG.

Conclusions: Our data provide evidence for: (1) potential increases in dopamine and noradrenaline synthesis in vPAG cells; and (2) increased catecholaminergic drive on vPAG neurons in rats in which transient changes in social behavior are seen following CCI. The data suggests a role for dopaminergic and noradrenergic outputs, and catecholaminergic inputs of the vPAG in the expression of one of the profiles of behavioural and endocrine change triggered by nerve injury.

No MeSH data available.


Related in: MedlinePlus

TH mRNA and protein expression in rats with distinct patterns of injury-triggered disability. Box and whisker plots showing: a relative TH mRNA expression and; b relative TH protein expression as determined by real-time RT-PCR and western blotting, respectively. Data are shown for behavioural controls (white); sham controls (green); Pain alone (yellow); Pain and Disability (blue); and Pain and Transient Disability (pink). Significance with respect to behavioural controls and sham surgery controls are shown **p < 0.01 (one-way ANOVA, post hoc Bonferroni test). c Examples of two different western blots showing fluorescence for TH protein (60 KDa) and beta-actin (43 KDa). In each example gel specific examples of a protein sample from each control and experimental group, are indicated by a different coloured arrow: behavioural controls (white); sham controls (green); Pain alone (yellow); Pain and Disability (blue); and Pain and Transient Disability (pink). (We have shown entire gels in this figure, Pain alone rats in lanese, f, g, h, I, k; Pain and Disability rats in lanesa, b, j; Pain and Transient Disability rats in lanesc, d, l; sham control rats in lanesm, n, o; and behavioural controls in lanesp, q).
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Fig2: TH mRNA and protein expression in rats with distinct patterns of injury-triggered disability. Box and whisker plots showing: a relative TH mRNA expression and; b relative TH protein expression as determined by real-time RT-PCR and western blotting, respectively. Data are shown for behavioural controls (white); sham controls (green); Pain alone (yellow); Pain and Disability (blue); and Pain and Transient Disability (pink). Significance with respect to behavioural controls and sham surgery controls are shown **p < 0.01 (one-way ANOVA, post hoc Bonferroni test). c Examples of two different western blots showing fluorescence for TH protein (60 KDa) and beta-actin (43 KDa). In each example gel specific examples of a protein sample from each control and experimental group, are indicated by a different coloured arrow: behavioural controls (white); sham controls (green); Pain alone (yellow); Pain and Disability (blue); and Pain and Transient Disability (pink). (We have shown entire gels in this figure, Pain alone rats in lanese, f, g, h, I, k; Pain and Disability rats in lanesa, b, j; Pain and Transient Disability rats in lanesc, d, l; sham control rats in lanesm, n, o; and behavioural controls in lanesp, q).

Mentions: Quantitative real time RT-PCR was used to determine relative TH mRNA expression and western blotting was used to determine relative TH protein expression levels in the midbrains of CCI and control rats; these results are presented in Fig. 2. Rats with Pain and Transient Disability had increased levels of TH mRNA compared to each of the control groups (F4,32 = 4.95, p < 0.01) (Fig. 2a). The Western blots identified TH and beta-actin with single bands of ~60 kDa and ~43 kDa, respectively (Fig. 2c). TH protein levels were calculated with respect to the housekeeping protein beta-actin; then the relative expression of TH in CCI and sham injured rats was expressed relative to behavioural controls (Fig. 2c). Pain and Transient Disability rats showed a significant increase in TH protein expression compared to both behavioural and sham controls (F4,31 = 5.9, p < 0.01), and compared to Pain alone rats (F4,31 = 5.9, p < 0.05) (Fig. 2b).Fig. 2


Recruitment of dorsal midbrain catecholaminergic pathways in the recovery from nerve injury evoked disabilities.

Mor D, Kang JW, Wyllie P, Thirunavukarasu V, Houlton H, Austin PJ, Keay KA - Mol Pain (2015)

TH mRNA and protein expression in rats with distinct patterns of injury-triggered disability. Box and whisker plots showing: a relative TH mRNA expression and; b relative TH protein expression as determined by real-time RT-PCR and western blotting, respectively. Data are shown for behavioural controls (white); sham controls (green); Pain alone (yellow); Pain and Disability (blue); and Pain and Transient Disability (pink). Significance with respect to behavioural controls and sham surgery controls are shown **p < 0.01 (one-way ANOVA, post hoc Bonferroni test). c Examples of two different western blots showing fluorescence for TH protein (60 KDa) and beta-actin (43 KDa). In each example gel specific examples of a protein sample from each control and experimental group, are indicated by a different coloured arrow: behavioural controls (white); sham controls (green); Pain alone (yellow); Pain and Disability (blue); and Pain and Transient Disability (pink). (We have shown entire gels in this figure, Pain alone rats in lanese, f, g, h, I, k; Pain and Disability rats in lanesa, b, j; Pain and Transient Disability rats in lanesc, d, l; sham control rats in lanesm, n, o; and behavioural controls in lanesp, q).
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getmorefigures.php?uid=PMC4538917&req=5

Fig2: TH mRNA and protein expression in rats with distinct patterns of injury-triggered disability. Box and whisker plots showing: a relative TH mRNA expression and; b relative TH protein expression as determined by real-time RT-PCR and western blotting, respectively. Data are shown for behavioural controls (white); sham controls (green); Pain alone (yellow); Pain and Disability (blue); and Pain and Transient Disability (pink). Significance with respect to behavioural controls and sham surgery controls are shown **p < 0.01 (one-way ANOVA, post hoc Bonferroni test). c Examples of two different western blots showing fluorescence for TH protein (60 KDa) and beta-actin (43 KDa). In each example gel specific examples of a protein sample from each control and experimental group, are indicated by a different coloured arrow: behavioural controls (white); sham controls (green); Pain alone (yellow); Pain and Disability (blue); and Pain and Transient Disability (pink). (We have shown entire gels in this figure, Pain alone rats in lanese, f, g, h, I, k; Pain and Disability rats in lanesa, b, j; Pain and Transient Disability rats in lanesc, d, l; sham control rats in lanesm, n, o; and behavioural controls in lanesp, q).
Mentions: Quantitative real time RT-PCR was used to determine relative TH mRNA expression and western blotting was used to determine relative TH protein expression levels in the midbrains of CCI and control rats; these results are presented in Fig. 2. Rats with Pain and Transient Disability had increased levels of TH mRNA compared to each of the control groups (F4,32 = 4.95, p < 0.01) (Fig. 2a). The Western blots identified TH and beta-actin with single bands of ~60 kDa and ~43 kDa, respectively (Fig. 2c). TH protein levels were calculated with respect to the housekeeping protein beta-actin; then the relative expression of TH in CCI and sham injured rats was expressed relative to behavioural controls (Fig. 2c). Pain and Transient Disability rats showed a significant increase in TH protein expression compared to both behavioural and sham controls (F4,31 = 5.9, p < 0.01), and compared to Pain alone rats (F4,31 = 5.9, p < 0.05) (Fig. 2b).Fig. 2

Bottom Line: The PAG encompasses subgroups of the A10 dopaminergic and A6 noradrenergic cell groups; the origins of significant ascending projections to hypothalamic and forebrain regions, which regulate sleep, complex behaviours and endocrine function.Evidence for increased tyrosine hydroxylase transcription and translation in the constitutive A10/A6 cells was found in the midbrain of rats that showed an initial 2-3 day post-CCI, behavioural and endocrine change, which recovered by days 5-6 post-CCI.The data suggests a role for dopaminergic and noradrenergic outputs, and catecholaminergic inputs of the vPAG in the expression of one of the profiles of behavioural and endocrine change triggered by nerve injury.

View Article: PubMed Central - PubMed

Affiliation: School of Medical Sciences, Discipline of Biomedical Sciences, The University of Sydney, C42, Cumberland Campus, Lidcombe, NSW, 2141, Australia. david.mor@sydney.edu.au.

ABSTRACT

Background: The periaqueductal gray region (PAG) is one of several brain areas identified to be vulnerable to structural and functional change following peripheral nerve injury. Sciatic nerve constriction injury (CCI) triggers neuropathic pain and three distinct profiles of changes in complex behaviours, which include altered social and sleep-wake behaviours as well as changes in endocrine function. The PAG encompasses subgroups of the A10 dopaminergic and A6 noradrenergic cell groups; the origins of significant ascending projections to hypothalamic and forebrain regions, which regulate sleep, complex behaviours and endocrine function. We used RT-PCR, western blots and immunohistochemistry for tyrosine hydroxylase to determine whether (1) tyrosine hydroxylase increased in the A10/A6 cells and/or; (2) de novo synthesis of tyrosine hydroxylase, in a 'TH-naïve' population of ventral PAG neurons characterized rats with distinct patterns of behavioural and endocrine change co-morbid with CCI evoked-pain.

Results: Evidence for increased tyrosine hydroxylase transcription and translation in the constitutive A10/A6 cells was found in the midbrain of rats that showed an initial 2-3 day post-CCI, behavioural and endocrine change, which recovered by days 5-6 post-CCI. Furthermore these rats showed significant increases in the density of TH-IR fibres in the vPAG.

Conclusions: Our data provide evidence for: (1) potential increases in dopamine and noradrenaline synthesis in vPAG cells; and (2) increased catecholaminergic drive on vPAG neurons in rats in which transient changes in social behavior are seen following CCI. The data suggests a role for dopaminergic and noradrenergic outputs, and catecholaminergic inputs of the vPAG in the expression of one of the profiles of behavioural and endocrine change triggered by nerve injury.

No MeSH data available.


Related in: MedlinePlus