Objective: Abnormal gastric acid secretion and gastric dyskinesia are common gastroenterological ailments. Our study aims to investigate the effect of orexin-A in the paraventricular nucleus (PVN) gastric motility and gastric acid secretion.
Methods: The source of orexin-A neuronal projections to the PVN were explored by retrograde tracing and fluorescence immunohistochemistry experiments. Neuronal discharge recordings of single cells were taken within the PVN. Gastric motility was recorded using a force transducer implanted into the stomach, and gastric acid secretion measured through a pyloric catheter.
Results: Orexin-A-positive neuronal projections from LHA to PVN were found. Administration of orexin-A to PVN activated the firing of 63.2% NPY-excited/GD-excitatory (GD-E) neurons but suppressed the firing of 55.9% NPY-inhibited/GD-inhibitory (GD-I) neurons, promoted gastric motility and gastric acid secretion in a dose-dependent manner. Responses produced by orexin-A could be partially blocked by Y1 receptor antagonist GR-231118; Electrical stimulation to the the hypothalamic lateral area (LHA) altered NPY-sensitive/GD neuronal activity in the PVN, stimulated gastric motility and gastric acid secretion. Additionally, these effects induced by LHA electrical stimulation were blocked by administration of the OX1R antagonist SB-334867 to the PVN.
Conclusion: Orexin-A from LHA neurons act on the PVN to enhance gastric motility and gastric acid secretion, with Y1 receptor signaling playing a critical role.
Keywords: Arcuate nucleus; Gastric acid secretion; Gastric motility; Orexin-A; Paraventricular nucleus; Y(1) receptor.
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