Enteric Dysfunctions in Experimental Parkinson's Disease: Alterations of Excitatory Cholinergic Neurotransmission Regulating Colonic Motility in Rats.
J Pharmacol Exp Ther
; 356(2): 434-44, 2016 Feb.
Article
en En
| MEDLINE
| ID: mdl-26582732
ABSTRACT
Parkinson's disease is frequently associated with gastrointestinal symptoms, mostly represented by constipation and defecatory dysfunctions. This study examined the impact of central dopaminergic denervation, induced by injection of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle, on distal colonic excitatory cholinergic neuromotor activity in rats. Animals were euthanized 4 and 8 weeks after 6-OHDA injection. In vivo colonic transit was evaluated by radiologic assay. Electrically induced and carbachol-induced cholinergic contractions were recorded in vitro from longitudinal and circular muscle colonic preparations, whereas acetylcholine levels were assayed in the incubation media. Choline acetyltransferase (ChAT), HuC/D (pan-neuronal marker), muscarinic M2 and M3 receptors were assessed by immunohistochemistry or western blot assay. As compared with control rats, at week 4, 6-OHDA-treated animals displayed the following changes decreased in vivo colonic transit rate, impaired electrically evoked neurogenic cholinergic contractions, enhanced carbachol-induced contractions, decreased basal and electrically stimulated acetylcholine release from colonic tissues, decreased ChAT immunopositivity in the neuromuscular layer, unchanged density of HuC/D immunoreactive myenteric neurons, and increased expression of colonic muscarinic M2 and M3 receptors. The majority of such alterations were also detected at week 8 post 6-OHDA injection. These findings indicate that central nigrostriatal dopaminergic denervation is associated with an impaired excitatory neurotransmission characterized by a loss of myenteric neuronal ChAT positivity and decrease in acetylcholine release, resulting in a dysregulated smooth muscle motor activity, which likely contributes to the concomitant decrease in colonic transit rate.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Acetilcolina
/
Colon
/
Sistema Nervioso Entérico
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Trastornos Parkinsonianos
/
Motilidad Gastrointestinal
Tipo de estudio:
Diagnostic_studies
Límite:
Animals
Idioma:
En
Revista:
J Pharmacol Exp Ther
Año:
2016
Tipo del documento:
Article