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The role of the vagal pathway and gastric dopamine in the gastroparesis of rats after a 6‐hydroxydopamine microinjection in the substantia nigra
Author(s) -
Zheng L.F.,
Song J.,
Fan R.F.,
Chen C.L.,
Ren Q.Z.,
Zhang X.L.,
Feng X.Y.,
Zhang Y.,
Li L.S.,
Zhu J.X.
Publication year - 2014
Publication title -
acta physiologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.591
H-Index - 116
eISSN - 1748-1716
pISSN - 1748-1708
DOI - 10.1111/apha.12229
Subject(s) - substantia nigra , gastroparesis , gastric emptying , medicine , dopaminergic , endocrinology , dopamine , dopamine receptor , microinjection , pimozide , stomach , haloperidol
Abstract Aim Gastroparesis is a common non‐motor system symptom of Parkinson's disease ( PD ). However, the mechanism responsible for the gastric motor abnormality is not clear. We previously reported on the impaired gastric motility in 6‐hydroxydopamine (6‐ OHDA ) rats, which were treated with a bilateral microinjection of 6‐ OHDA in the substantia nigra ( SN ). We hypothesize that the enhanced dopamine system and reduced acetylcholine (Ach) in gastric tissues might contribute to the delayed gastric emptying observed in PD . Methods A strain gauge force transducer, digital X ‐ray imaging system, W estern blot, immunofluorescence and Radio Immunoassay were used in this study. Results Dopaminergic neurones in the SN were greatly reduced following the bilateral microinjection of 6‐ OHDA . 6‐ OHDA rats exhibited impaired gastric motility and delayed gastric emptying, accompanied by increased dopamine content and the overexpression of D 2 receptors in the stomach. The administration of the D 2 receptor antagonist domperidone relieved gastric dysmotility in 6‐ OHDA rats, but the D 1 receptor antagonist SCH 23390 failed to do so. Subdiaphragmatic vagotomy prevented the increase in the gastric dopamine content and D 2 receptor expression and improved gastric dysmotility in 6‐ OHDA rats. Conclusion Dopaminergic deficiency in the SN results in impaired gastric motility, possibly as a result of the enhanced activity of dopamine system and reduced Ach in gastric tissue. The vagus nerve plays an important role in peripheral gastric motility disorder.