Select steroid hormone glucuronide metabolites can cause toll-like receptor 4 activation and enhanced pain.
Brain Behav Immun
; 44: 128-36, 2015 Feb.
Article
em En
| MEDLINE
| ID: mdl-25218902
ABSTRACT
We have recently shown that several classes of glucuronide metabolites, including the morphine metabolite morphine-3-glucuronide and the ethanol metabolite ethyl glucuronide, cause toll like receptor 4 (TLR4)-dependent signaling in vitro and enhanced pain in vivo. Steroid hormones, including estrogens and corticosterone, are also metabolized through glucuronidation. Here we demonstrate that in silico docking predicts that corticosterone, corticosterone-21-glucuronide, estradiol, estradiol-3-glucuronide and estradiol-17-glucuronide all dock with the MD-2 component of the TLR4 receptor complex. In addition to each docking with MD-2, the docking of each was altered by pre-docking with (+)-naloxone, a TLR4 signaling inhibitor. As agonist versus antagonist activity cannot be determined from these in silico interactions, an in vitro study was undertaken to clarify which of these compounds can act in an agonist fashion. Studies using a cell line transfected with TLR4, necessary co-signaling molecules, and a reporter gene revealed that only estradiol-3-glucuronide and estradiol-17-glucuronide increased reporter gene product, indicative of TLR4 agonism. Finally, in in vivo studies, each of the 5 drugs was injected intrathecally at equimolar doses. In keeping with the in vitro results, only estradiol-3-glucuronide and estradiol-17-glucuronide caused enhanced pain. For both compounds, pain enhancement was blocked by the TLR4 antagonist lipopolysaccharide from Rhodobacter sphaeroides, evidence for the involvement in TLR4 in the resultant pain enhancement. These findings have implications for several chronic pain conditions, including migraine and temporomandibular joint disorder, in which pain episodes are more likely in cycling females when estradiol is decreasing and estradiol metabolites are at their highest.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Dor
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Hormônios Esteroides Gonadais
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Glucuronídeos
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Receptor 4 Toll-Like
Tipo de estudo:
Etiology_studies
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Prognostic_studies
Limite:
Animals
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Humans
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Male
Idioma:
En
Revista:
Brain Behav Immun
Assunto da revista:
ALERGIA E IMUNOLOGIA
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CEREBRO
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PSICOFISIOLOGIA
Ano de publicação:
2015
Tipo de documento:
Article