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result(s) for
"MacQuillan, Anthony"
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Glucagon-like peptide 1 receptor (GLP-1R) expression by nerve fibres in inflammatory bowel disease and functional effects in cultured neurons
2018
Glucagon like-peptide 1 receptor (GLP-1R) agonists diminish appetite and may contribute to the weight loss in inflammatory bowel disease (IBD).
The aim of this study was to determine, for the first time, the expression of GLP-1R by colon nerve fibres in patients with IBD, and functional effects of its agonists in cultured rat and human sensory neurons.
GLP-1R and other nerve markers were studied by immunohistochemistry in colon biopsies from patients with IBD (n = 16) and controls (n = 8), human dorsal root ganglia (DRG) tissue, and in GLP-1R transfected HEK293 cells. The morphological effects of incretin hormones oxyntomodulin, exendin-4 and glucagon were studied on neurite extension in cultured DRG neurons, and their functional effects on capsaicin and ATP signalling, using calcium imaging.
Significantly increased numbers of colonic mucosal nerve fibres were observed in IBD biopsies expressing GLP-1R (p = 0.0013), the pan-neuronal marker PGP9.5 (p = 0.0008), and sensory neuropeptide CGRP (p = 0.0014). An increase of GLP-1R positive nerve fibres in IBD colon was confirmed with a different antibody to GLP-1R (p = 0.016). GLP-1R immunostaining was intensely positive in small and medium-sized neurons in human DRG, and in human and rat DRG cultured neurons. Co-localization of GLP-1R expression with neuronal markers in colon and DRG confirmed the neural expression of GLP-1R, and antibody specificity was confirmed in HEK293 cells transfected with the GLP-1R. Treatment with oxyntomodulin, exendin-4 and GLP-1 increased neurite length in cultured neurons compared with controls, but did not stimulate calcium influx directly, or affect capsaicin responses. However, exendin-4 significantly enhanced ATP responses in human DRG neurons.
Our results show that increased GLP-1R innervation in IBD bowel could mediate enhanced visceral afferent signalling, and provide a peripheral target for therapeutic intervention. The differential effect of GLP-1R agonists on capsaicin and ATP responses in neurons suggest they may not affect pain mechanisms mediated by the capsaicin receptor TRPV1, but may enhance the effects of purinergic agonists.
Journal Article
Mechanisms Underlying Clinical Efficacy of Angiotensin II Type 2 Receptor (AT2R) Antagonist EMA401 in Neuropathic Pain: Clinical Tissue and in Vitro Studies
by
MacQuillan, Anthony
,
Sinisi, Marco
,
Yiangou, Yiangos
in
Analgesics
,
Angiotensin AT2 receptors
,
Angiotensin II
2015
Background
The clinical efficacy of the Angiotensin II (AngII) receptor AT2R antagonist EMA401, a novel peripherallyrestricted analgesic, was reported recently in post-herpetic neuralgia. While previous studies have shown that AT2R is expressed by nociceptors in human DRG (hDRG), and that EMA401 inhibits capsaicin responses in cultured hDRG neurons, the expression and levels of its endogenous ligands AngII and AngIII in clinical neuropathic pain tissues, and their signalling pathways, require investigation. We have immunostained AngII, AT2R and the capsaicin receptor TRPV1 in control post-mortem and avulsion injured hDRG, control and injured human nerves, and in cultured hDRG neurons. AngII, AngIII, and Ang-(1-7) levels were quantified by ELISA. The in vitro effects of AngII, AT2R agonist C21, and Nerve growth factor (NGF) were measured on neurite lengths; AngII, NGF and EMA401 effects on expression of p38 and p42/44 MAPK were measured using quantitative immunofluorescence, and on capsaicin responses using calcium imaging.
Results
AngII immunostaining was observed in approximately 75% of small/medium diameter neurons in control (n = 5) and avulsion injured (n = 8) hDRG, but not large neurons i.e. similar to TRPV1. AngII was co-localised with AT2R and TRPV1 in hDRG and in vitro. AngII staining by image analysis showed no significant difference between control (n = 12) and injured (n = 13) human nerves. AngII levels by ELISA were also similar in control human nerves (4.09 ± 0.36 pmol/g, n = 31), injured nerves (3.99 ± 0.79 pmol/g, n = 7), and painful neuromas (3.43 ± 0.73 pmol/g, n = 12); AngIII and Ang-(1-7) levels were undetectable (<0.03 and 0.05 pmol/g respectively). Neurite lengths were significantly increased in the presence of NGF, AngII and C21 in cultured DRG neurons. AngII and, as expected, NGF significantly increased signal intensity of p38 and p42/44 MAPK, which was reversed by EMA401. AngII mediated sensitization of capsaicin responses was not observed in the presence of MAP kinase inhibitor PD98059, and the kinase inhibitor staurosporine.
Conclusion
The major AT2R ligand in human peripheral nerves is AngII, and its levels are maintained in injured nerves. EMA401 may act on paracrine/autocrine mechanisms at peripheral nerve terminals, or intracrine mechanisms, to reduce neuropathic pain signalling in AngII/NGF/TRPV1-convergent pathways.
Journal Article
Glucagon-like peptide 1 receptor
by
MacQuillan, Anthony
,
Akbar, Ayesha
,
Sinisi, Marco
in
Cell receptors
,
Development and progression
,
Genetic aspects
2018
Glucagon like-peptide 1 receptor (GLP-1R) agonists diminish appetite and may contribute to the weight loss in inflammatory bowel disease (IBD). The aim of this study was to determine, for the first time, the expression of GLP-1R by colon nerve fibres in patients with IBD, and functional effects of its agonists in cultured rat and human sensory neurons. GLP-1R and other nerve markers were studied by immunohistochemistry in colon biopsies from patients with IBD (n = 16) and controls (n = 8), human dorsal root ganglia (DRG) tissue, and in GLP-1R transfected HEK293 cells. The morphological effects of incretin hormones oxyntomodulin, exendin-4 and glucagon were studied on neurite extension in cultured DRG neurons, and their functional effects on capsaicin and ATP signalling, using calcium imaging. Significantly increased numbers of colonic mucosal nerve fibres were observed in IBD biopsies expressing GLP-1R (p = 0.0013), the pan-neuronal marker PGP9.5 (p = 0.0008), and sensory neuropeptide CGRP (p = 0.0014). An increase of GLP-1R positive nerve fibres in IBD colon was confirmed with a different antibody to GLP-1R (p = 0.016). GLP-1R immunostaining was intensely positive in small and medium-sized neurons in human DRG, and in human and rat DRG cultured neurons. Co-localization of GLP-1R expression with neuronal markers in colon and DRG confirmed the neural expression of GLP-1R, and antibody specificity was confirmed in HEK293 cells transfected with the GLP-1R. Treatment with oxyntomodulin, exendin-4 and GLP-1 increased neurite length in cultured neurons compared with controls, but did not stimulate calcium influx directly, or affect capsaicin responses. However, exendin-4 significantly enhanced ATP responses in human DRG neurons. Our results show that increased GLP-1R innervation in IBD bowel could mediate enhanced visceral afferent signalling, and provide a peripheral target for therapeutic intervention. The differential effect of GLP-1R agonists on capsaicin and ATP responses in neurons suggest they may not affect pain mechanisms mediated by the capsaicin receptor TRPV1, but may enhance the effects of purinergic agonists.
Journal Article
The variance of nerve axon to muscle fibre ratio and its effect on outcome in functional muscle transfer
by
MacQuillan, Anthony
in
Surgery
2006
The results of functional muscle transfer for the treatment of facial palsy are varied. Surgical technique in such cases remains constant with only the selected ramus of the buccal branch of the facial nerve changing. Differing sized branches of the facial nerve in the rabbit were used to reinnervate a constant sized muscle transfer to see if this might explain the spectrum of clinical results seen and additionally provide some insight into the phenomenon of \"late onset tightening\" seen in some cases. Peripheral limb reconstruction using functional muscle transfer following injury or tumour resection has been widely reported in the literature. The results of such procedures often fail to deliver the physiological strength that might be hoped for in relation to the size of the transferred muscle. Differing sized pure motor nerves were used to reinnervate a constant sized muscle transfer to see if functional results could be improved in an experimental model analogous to peripheral limb reconstruction. The rectus femoris muscle in the New Zealand White rabbit was used as a standardised muscle transfer for investigation into how the reinnervating axonal load affects outcome, defined in terms of physiological force developed by the muscle post-operatively, looking at both the central and peripheral nervous systems. Corroboratory investigations were also undertaken to determine the reinnervating characteristics of the nerves studied and those of reinnervated muscle.
Dissertation
Our History: Probus Club founded on friendship values
2017
On March 4, 1999 the Rotary Club of Yass District 9710 hosted a foundation meeting for Probus Club of Yass. Welcoming guests were Rotarian Chris Norwood; Chairman of the District Probus Committee, Kim Turner; Yass Rotary President and joint convenors Jack Kemp and Alfred McCarthy; Yass Rotary. A resolution to form Probus Club of Yass was duly passed by the meeting and a standard Probus Club constitution and by-laws duly adopted by the meeting, as was a ...
Newspaper Article
Our History: Probus Club founded on friendship values
2017
On March 4, 1999 the Rotary Club of Yass District 9710 hosted a foundation meeting for Probus Club of Yass. Welcoming guests were Rotarian Chris Norwood; Chairman of the District Probus Committee, Kim Turner; Yass Rotary President and joint convenors Jack Kemp and Alfred McCarthy; Yass Rotary. A resolution to form Probus Club of Yass was duly passed by the meeting and a standard Probus Club constitution and by-laws duly adopted by the meeting, as was a ...
Newspaper Article
Our History: Probus Club founded on friendship values
2017
On March 4, 1999 the Rotary Club of Yass District 9710 hosted a foundation meeting for Probus Club of Yass. Welcoming guests were Rotarian Chris Norwood; Chairman of the District Probus Committee, Kim Turner; Yass Rotary President and joint convenors Jack Kemp and Alfred McCarthy; Yass Rotary. A resolution to form Probus Club of Yass was duly passed by the meeting and a standard Probus Club constitution and by-laws duly adopted by the meeting, as was a ...
Newspaper Article