[Gastrointestinal dysfunction has important implications for plasma L-dopa concentrations in Parkinson's disease]

Neuregulin 1 improved gastric motility and reduced gastric inflammation by activating the α7nAChR through the cholinergic anti-inflammatory pathway in diabetic rats

Diabetic gastroparesis (DGP), a prevalent complication of diabetes, is characterized by delayed gastric emptying and inflammation. The dorsal motor nucleus of the vagus (DMV) plays a crucial role in modulating gastric function via the vagus nerve. Neuregulin 1 (NRG1), which is present in the DMV and influences the autonomic nervous system, has an unclear role in DGP. This study aimed to investigate the expression of NRG1 in the DMV of Zucker diabetic fatty (ZDF) rats and to evaluate the impact of centrally administered NRG1 on gastric motility and inflammation, as well as the underlying mechanisms. Our findings revealed a decrease in NRG1 and choline acetyltransferase (ChAT) expression in the DMV of ZDF rats, corresponding to weakened gastric motility. Microinjection of AAV-NRG1 (overexpressed NRG1 by means of an adeno-associated viral vector delivery of NRG1) into the DMV enhanced gastric motility and increased vagal nerve discharge frequency. Moreover, AAV-NRG1 upregulated acetylcholine (Ach) and α7 nicotinic acetylcholine receptor (α7nAChR) expression in the gastric body, mitigating gastric inflammation. The beneficial effects of AAV-NRG1 were partially reversed by vagotomy or α7nAChR antagonism. These findings provide novel evidence that NRG1 in the DMV can stimulate Ach release and activate α7nAChRs, thereby reducing inflammation and restoring gastric motility via the vagus nerve. This implicates the NRG1 as a potential therapeutic target for DGP.

Correlation Between Lacunae and the Wearing-off Phenomenon in Parkinson's Disease

PURPOSE

Lacunae are imaging biomarkers of cerebral small vessel disease (CSVD) and are correlated with the degree of gait instability in Parkinson's disease (PD). The wearing-off phenomenon (WO) occurs more frequently in PD patients as disease progresses. The present study aimed to investigate the overall impact of the quantity and location of lacunae on the WO in PD.

PATIENTS AND METHODS

This retrospective, single-center study included 315 consecutive eligible patients with PD from Beijing Tiantan Hospital from May 2016 to August 2018. We collected data on demographics and clinical features, assessed lacunae and examined the presence of the WO. The association between lacunae and the WO was assessed using a binary logistic regression model.

RESULTS

The number of lacunae was significantly associated with the WO in patients with PD according to a model adjusted for age at onset, disease duration, Hoehn-Yahr (H-Y) staging, Movement Disorder Society-Unified Parkinson's Disease Rating Scale part III (MDS-UPDRS III) total score and levodopa equivalent daily dosage (LEED) (P=0.037, OR 1.156, 95% CI 1.009, 1.325) and to a model further adjusted for other CSVD imaging biomarkers (P=0.046, OR 1.172, 95% CI 1.003, 1.369). Following additional adjustment for other potential confounders, the association remained significant (P=0.043, OR 1.195, 95% CI 1.005, 1.421). Lacunae in subcortical areas (P=0.004, OR 0.498, 95% CI 0.308, 0.803) and basal ganglia (P=0.046, OR 1.616, 95% CI 1.009, 2.587), especially in the caudate nuclei (P=0.023, OR 1.104, 95% CI 0.185, 0.881), were significantly associated with the WO in PD patients.

CONCLUSION

Our finding highlights the significant association between lacune and the WO, and lacunae may be an independent contributor to the WO in PD patients. Promoting neurovascular health may prevent the progression of the WO in PD patients.

Bioavailability of dietary polyphenols: Factors contributing to their clinical application in CNS diseases

The anatomical location of the central nervous system (CNS) renders it immunologically and pharmacologically privileged due to the blood brain barrier (BBB). Although this limits the transport of unfavorable molecules to the CNS, the ensuing privilege could be disadvantageous for therapeutic compounds. Hence, the greatest challenge in the pharmacotherapy of CNS diseases is to ensure efficient brain targeting and drug delivery. Research evidences indicate that dietary polyphenols have neuroprotective potential against CNS diseases. However, their selective permeability across BBB, poor absorption, rapid metabolism and systemic elimination limit their bioavailability and therapeutic efficacy. Consequently, the beneficial effects of these orally administered agents in the CNS still remain a subject of debate. This has also limited its clinical application either as independent or adjunctive therapy. Improving the in vivo bioavailability by novel methods could improve the therapeutic feasibility of polyphenols and assist in evolving novel drugs and their derivatives with improved efficacy in vivo. Here we review the mechanistic and pharmacological issues related to the bioavailability of polyphenols with therapeutic implications for CNS diseases. We surmise that improving the bioavailability of polyphenols entails efficient in vivo transport across BBB, biochemical stability, improved half-life and persistent neuroprotection in the CNS.

Expression of dopamine D2 receptor in the gastrointestinal mucosa of rats with slow transit constipation

AIM: To investigate the expression of dopamine D2 receptor (Drd2) in the gastrointestinal mucosa of rats with slow transit constipation (STC) to explore the possible pathogenesis of STC.

METHODS: Twenty-four healthy Wistar rats were randomly into two groups: an experiment group and a control group. Rats of the experiment group were daily administered diphenoxylate (8 mg/kg) for 90 d to induce STC, while the control rats were fed normal saline. The number and weight of fecal granules and the body weight of rats were recorded every 5 d. After successful induction of STC, the rats were killed to take tissues of the gastric antrum, small intestine, and colon. Real-time polymerase chain reaction (RT-PCR) was used to detect the expression of Drd2 in the above tissues.

RESULTS: The daily number and mean weight of fecal granules and the time to discharge of the first black granule differed significantly between the two groups, suggesting that STC was successfully induced. Drd2 was specifically amplified by RT-PCR. Compared with the control group, the expression of Drd2 in the stomach and small intestine was not significantly different in the experiment group (P > 0.05 for both). However, the expression of Drd2 in colon tissues of STC rats was significantly higher than that in control rats (1.93 ± 0.78, P < 0.05).

CONCLUSION: The expression of Drd2 in the stomach and small intestine does not change significantly in STC rats, but Drd2 expression is up-regulated in colon tissues of STC rats, which may contribute to the pathogenesis of STC.