Central nesfatin‐1 influences the excitability of ghrelin‐responsive gastric distension neurons in the arcuate nucleus and reduces gastric motility in rats

Abstract

Although the novel satiety peptide nesfatin-1 has been shown to regulate gastric motility, the underlying mechanisms have yet to be elucidated. The study aimed to explore the effects of nesfatin-1 on ghrelin-responsive gastric distension (GD) neurons in the arcuate nucleus (Arc), and potential regulation mechanisms of gastric motility by the paraventricular nucleus (PVN). Single-unit discharges in the Arc were recorded extracellularly, and gastric motility in conscious rats was monitored during the administration of nesfatin-1 to the Arc or electrical stimulation of the PVN. Retrograde tracing and fluo-immunohistochemistry staining were used to determine NUCB2/nesfatin-1 neuronal projections. Nesfatin-1 inhibited most of the ghrelin-responsive GD-excitatory neurons, but excited ghrelin-responsive GD-inhibitory neurons in the Arc. Gastric motility was significantly reduced by nesfatin-1 administration to the Arc in a dose-dependent manner. The firing activity in the Arc and changes to gastric motility were partly reduced by SHU9119, an antagonist of melanocortin 3/4 receptors. Electrical stimulation of PVN excited most of the ghrelin-responsive GD neurons in the Arc and promoted gastric motility. Nonetheless, pretreatment with an anti-NUCB2/nesfatin-1 antibody in the Arc further increased the firing rate of most of the ghrelin-responsive GD-excitatory neurons and decreased the ghrelin-responsive GD-inhibitory neurons following electrical stimulation of the PVN. Gastric motility was enhanced by pretreatment with an anti-NUCB2/nesfatin-1 antibody in the Arc following PVN stimulation. Furthermore, NUCB2/nesfatin-1/fluorogold double-labeled neurons were detected in the PVN. These results suggest that nesfatin-1 could serve as an inhibitory factor in the Arc to regulate gastric motility via the melanocortin pathway. The PVN could be involved in the regulation of the Arc in gastric activity.

The Inhibitory Effects of Nesfatin-1 in Ventromedial Hypothalamus on Gastric Function and Its Regulation by Nucleus Accumbens

“…Forty rats were prepared for GD following the protocol mentioned above, and the electrophysiological recording procedure was based on the previously described method (Li et al, 2013). The anesthetized rats were bound on a stereotaxic frame, and craniotomy was performed around the coordinates: −2.5 mm posterior to Bregma and 0.8 mm lateral.…”

“…Further, the receptor for nesfatin-1 is yet unknown, making a mechanistic understanding of nesfatin-1 signaling in the central nervous system difficult to ascertain. To begin to answer these questions, we have injected nesfatin-1 in PVN and ARC (Li et al, 2013; Guo et al, 2015), and found that nesfatin-1 signaling in these areas has an inhibitory role in gastric motility. Moreover, these effects were caused by nesfatinergic projections from lateral hypothalamic area (LHA) to PVN or from PVN to ARC.…”

Extrinsic Orexin-A in Lateral Hypothalamic Area Regulates Gastric Motility in Rats

“…Briefly, the abdominal cavity was exposed and contractile force transducers were sutured onto the serosa of the gastric antrum, 0.5 cm caudal to the pyloric ring, to measure circular muscle motility [14] . The lead wires of the force transducers were tunneled subcutaneously and exteriorised at the nape of the neck, protruding 2-3 cm through a small incision between the scapulae [14] . Following this, the abdomen was closed with suture and the animals were allowed to recover for 4 days before administrating chemicals.…”

“…Verification of the correct position of administration site was performed by injection of Pontamine sky blue (2μL) at the end of the recording of gastric motility [14] . After perfusion and fixation of the brain, 50 μm frozen coronal sections were cut through the regions of the LHA, stained with Neutral Red and observed under a light microscope [14] .…”

“…After perfusion and fixation of the brain, 50 μm frozen coronal sections were cut through the regions of the LHA, stained with Neutral Red and observed under a light microscope [14] . Samples with incorrect locations were eliminated from the analysis.…”