Study On The Constitute Of Nesfatin-1Neuronal Pathway From The Hypothalamic Paraventicular Nucleus To The Arcuate Nucleus And Its Modulation On Gastric Motility In Rats

Objective:Although the novel satiety peptide nesfatin-1has been revealed to regulate gut motor function, the underlying mechanisms have yet to be elucidated. The study aimed①to explore the effects of nesfatin-1in Arcuate nucleus (ARC) on ghrelin responsive gastric distension (GD) neurons and the regulation by the hypothalamic paraventricular nucleus (PVN); to illustrate the formation between the PVN and ARC nesfatin-1pathway;②to observe the effect of nesfatin-1in the ARC on the gastric motility and the potential egulation mechanisms.Methods:①The extracellular discharges of single unit neuron, nuclei microinjection and nuclei electrical stimulation were used to observe the effects of nesfatin-1and electrical stimulation of the PVN on the ghrelin responsive GD neurons in the Arc.②Gastric motility recording in vivo and nuclei electrical stimulation were used to monitor the effects of nesfatin-1and electrical stimulation of the PVN on the amplitude of constriction and frequency of gastric motility in conscious rats.③Retrograde tracing and fluorescent-immunohistochemistry were used to determine NUCB2/nesfatin-1neuronal projections.Results:①Of246recorded neurons in Arc,164neurons were GD responsive neurons. Administration of ghrelin to the Arc could excite62GD-E neurons, while inhibit47GD-Ⅰ neurons. Additionally, injection of nesfatin-1could inhibit39ghrelin responsive GD-E neurons with the firing rate significantly decreased (P<0.01), increased (P<0.01). However, pretreatment with SHU9119could partly absorb the responses of ghrelin responsive GD neurons induced by nesfatin-1(P<0.05).②Out of62ghrelin-responsive GD-E neurons in the Arc,21(21/62,33.9%) were excited by electrical stimulation of the PVN.14(14/62,22.6%) were inhibited and27(27/62,43.5%) had no response.13out of47(13/47,27.7%) ghrelin-responsive GD-I neurons were also excited by electrical stimulation of the PVN, while12(12/47,25.5%) were inhibited and22(22/47,46.8%) had no change. However, pretreatment with anti-NUCB2/nesfatin-1antibody in the Arc could further increase the firing rate of most of the ghrelin-responsive GD-E neurons (16/21,76.2%;3.84±0.03Hz vs.4.21±0.03Hz, P<0.001) but decrease the rate in ghrelin-responsive GD-I neurons (10/13,76.9%;3.71Hz±0.02Hz vs.3.39±0.02Hz, P<0.001) induced by electrical stimulation of the PVN.③We observed in vivo that after5min of administration of nesfatin-1, the amplitude (P<0.05-0.01) and frequency (P<0.05-0.01) of the gastric motility could be significantly reduced in a dose dependent manner. However, injection of mixture of nesfatin-1and SHU9119could weaken the responses induced by nesfatin-1(P<0.05).④Electrical stimulation of PVN increased the amplitude and frequency with a latency of approximately3min after electrical stimulation of the PVN and reached the peak at approximately13min. The promotional effect induced by electrical stimulation of the PVN was further enhanced by administration of anti-NUCB2/nesfatin-1antibody in the Arc (P<0.01-0.001).⑤NUCB2/nesfatin-1/fluorogold-double labeled neurons were detected in the PVN.Conclusions:Nesfatin-1could serve as an inhibitory factor in Arc to regulate gastric motility via melanocortin pathway and influence the firing activity of ghrelin responsive GD neurons.