Parkinson's disease (PD) is a neurodegenerative disease with
a progressive loss of mesencephalic dopaminergic neurons of the
substantia nigra (SN). To further evaluate its pathophysiology,
accurate animal models are needed. The current study aims to
verify the impact of a 6-hydroxydopamine (6-OHDA) bilateral
microinjection into the SN on gastrointestinal symptoms in rats
and confirm that the 6-OHDA rat model is an appropriate tool to
investigate the mechanisms of Parkinsonian GI disorders.
Immunohistochemistry, digital X-ray imaging, short-circuit
current, FITC-dextran permeability and ultra-performance liquid
chromatography tandem mass spectrometry were used in this
study. The results indicated that the dopaminergic neurons in SN
and fibres in the striatum were markedly reduced in 6-OHDA
rats. The 6-OHDA rats manifested reductions in occupancy in
a rotarod test and increases in daily food debris but no difference
in body mass or daily consumption. Compared with control rats,
faecal pellets and their contents were significantly decreased,
whereas gastric emptying and intestinal transport were delayed
in 6-OHDA rats. The increased in vivo FITC-dextran permeability
and decreased intestinal transepithelial resistance in the model
suggest attenuated barrier function in the digestive tract in the
PD model. Moreover, inflammatory factors in the plasma showed
that pro-inflammatory factors IL-1β and IL-8 were significantly
increased in 6-OHDA rats. Collectively, these findings indicate
that the model is an interesting experimental tool to investigate
the mechanisms involved in the progression of gastrointestinal
dysfunction in PD.