Neuropeptide-S prevents 6-OHDA-induced gastric dysmotility in rats.

This study aims to explore the effect of chronic central neuropeptide-S (NPS) treatment on gastrointestinal dysmotility and the changes of cholinergic neurons in the dorsal motor nucleus of the vagus (DMV) of a Parkinson's disease (PD) rat model. The PD model was induced through a unilateral medial forebrain bundle (MFB) administration of the 6-hydroxydopamine (6-OHDA). Locomotor activity (LMA), solid gastric emptying (GE), and gastrointestinal transit (GIT) were measured 7 days after the surgery. NPS was daily administered (1 nmol, icv, 7 days). In substantia nigra (SN), dorsal motor nucleus of the vagus (DMV), and gastric whole-mount samples, changes in tyrosine hydroxylase (TH), choline acetyltransferase (ChAT), neuronal nitric oxide synthase (nNOS), glial fibrillary acidic protein (GFAP), NPS receptor (NPSR), and alpha-synuclein (Ser129) were examined by immunohistochemistry. Cuprolinic blue staining was used to evaluate the number of neuronal cells in myenteric ganglia. The GIT rate, the total number of myenteric neurons, and the expressions of ChAT, nNOS, TH, and GFAP in the myenteric plexus were not changed in rats that received the 6-OHDA. Chronic NPS treatment reversed 6-OHDA-induced impairment of the motor performance, and GE, while preventing the loss of dopaminergic and cholinergic neurons in SN and DMV, respectively. NPS attenuated 6-OHDA-induced α-syn (Ser129) pathology both in SN and DMV. Additionally, expression of NPSR protein was detected in gastro-projecting cells in DMV. Taken together, centrally applied NPS seems to prevent 6-OHDA-induced gastric dysmotility through a neuroprotective action on central vagal circuitry.