| ObjectiveNesfatin-1,a novel hormone of the gut-brain peptide,distributed widely in central nerve system and peripheral organs,such as gastrointestinal tract,and was proved to inhibit food intake and gastric motility.The ventromedial hypothalamus(VMH),named as the“satiety center",is believed to be closely related to the regulation of feeding,and the nucleus accumbens(NAc)palys a role in modulating feeding and "wanting" to eat food.VMH and VAc contains nesfatin-1 expressing cells.Until now,it is unknown the modulating effect of nesfatin-1 in the VMH and NAc on food intake and gastric functions of acid secretion,motility and emptying.Here the VMH and NAc will be focused on:?to observe the effect of gastric distention on the activity of nesfatin-limmuno-positive neurons in the VMH;to study the constitution of nesfatin-1 neural pathway from the NAc to the VMH;? to explore the effects of nesfatin-1 on the firing rate of gastric distension(GD)responsive neurons in the VMH;to observe the regulation of the NAc on the GD-responsive neurons in the VMH;to illustrate the constitution of nesfatin-1 functional pathway from the NAc to the VMH;?to explore the regulation of nesfatin-1 in the VMH on food intake,gastric acid secretion,gastric motility and gastric emptying;to study the effect of nesfatin-1 pathway from the NAc to the VMH on the functions of VMH for supplementing and completing the central regulating mechanisms of feeding and gastric function.Methods1.The expressions of nesfatin-1 and the activity of nesfatin-1 neurons in VMH were detected by fluo-immunohistochemistry staining techniques.The constitution of nesfatin-1 neuronal pathway from the NAc to the VMH was observed by retrograde tracer deposits of Fluoro-Gold and fluo-immunohistochemistry staining.2.Microinjection on the surface of neurons,electrical stimulation in the nuclei and extracellular discharge recording method were employed to observe the effects of nesfatin-1,melanocortin 3/4 receptors antagonist SHU9119 and electrical stimulation of the NAc on the firing rate of GD neurons in the VMH.3.Nuclei microinjection,electrical stimulation,auto-feeding recording,gastric acid titrating method,gastric motility recording and gastric emptying of phenol red method were employed to observe the effects of nesfatin-1 administration into the VMH and electrical stimulation in the NAc on food intake,gastric acid titrating,gastric motility and gastric emptying in the conscious rats.Results1.Nesfatin-1 was expressed in the VMH of rats,and gastric distention increased the c-Fos expression of the nesfaitn-1 immuno-positive neurons in the VMH and stimulated cellular activity.2.Fluoro-Gold,injected in the VMH,was found to retrograde to the NAc and colocalize with nesfatin-1 in the NAc neurons.It suggested that the NAc has neural fiber projections to the VMH and there wer projections from nesfatin-1 immuno-positive neurons in the NAc to the VMH.3.64 gastric distention responsive neurons were recorded in the VMH.Out of them 35 neurons(54.70%)were identified as GD-excitatory(GD-E)and 29(45.30%)were GD-inhibited(GD-1),indicating that the VMH could receive the afferent signals from the stomach.4.After administration of nesfatin-1 in the VMH,24.14%GD-I neurons were excited with firing frequency increased from 2.45 ± 0.37 Hz to 3.82 + 0.56 Hz(p<0.05),and 22.86%GD-I neurons were inhibited with firing frequency decreased from 2.77± 0.39 Hz to 1.67 ± 0.37 Hz(p<0.05).The effects of nesfatin-1 on the GD-responsive neurons were blocked by pretreatment with melanocortin 3/4 receptors antagonist SHU9119(p<0.01).5.After electrical stimulating the NAc,59.26%GD-I neurons were excited by nesfatin-1 in the VMH with firing frequency increased from 3.73 ± 0.97 Hz to 5.53 ±0.97 Hz(p<0.05),which was blocked by pretreatment of nesfatin-1 antibody into the VMH.53.06%GD-E neurons were excited with firing frequency increased from 2.74 ± 0.71 Hz to 5.08 ± 1.15 Hz(p<0.05).Pretreatment with nesfatin-1 antibody in the VMH improved the effects of electrical stimulation in the NAc on the GD-E neurons,and the firing frequency increased to 6.81 ± 1.13 Hz(p<0.05).Nesfatin-1 antibody or NS administration singly to the VMH had no significant effect on the GD neurons(p>0.05).6.Microinjection of VMH with low dosage of nesfatin-1 decreased the 2-h cumulative food intake,and high dosage decreased the 4-6 hours cumulation,the gastric acid secretion induced by 2-DG.About 4 munites after nesfatin-1 injecion,the gastric motility began to decrease and touched the bottom at 15 min by 35.2 ± 8.9%(p<0.05).The gastric emptying was inhibited by ensfatin-1 to 50.15 ±15.6%(p<0.05).The inhibiting effects induced by injection of VMH with nesfatin-1 were significantly diminished by pretreatment with SHU9119(p>0.05).7.The NAc electrical stimulation with 20?A had no effect on the food intake,but the 50 ?A stimulation inhibited the cumulative food intake at 2-6 h(p<0.05).After the NAc electrical stimulation with 50 ?A,the gastric acid secretion induced by 2-DG was reduced from 9.16 ± 1.53 to 5.52 ± 0.88 ?Eq/15min(p<0.05)?the MI%of gastric motility and the rate of gastric emptying respectively decreased to 72.25 ±9.82%and 68.36 ± 8.79%of the values of control group(p<0.05).The inhibiting effects were significantly weakened by pretreatment with nesfatin-1 antibody in the VMH.Nesfatin-1 antibody or NS administration singly to the VMH had no effect on gastric acid secretion,gastric motility and gastric emptying(p>0.05).Conclusions1.There were nesfatin-1 immuno-positive neurons in the hypothalamic VMH,and gastric distention modified activity of some nesfatin-1 neurons.2.Nesfatin-1 immuno-positive neurons in the NAc projected neural fibers to the VMH,which is believed to be a nesfatin-1 neural pathway from NAc to VMH.3.The VMH received the afferent signals from the stomach,and palyed a role in the regulation of food intake and the gastric functions,such as gastric acid secretion,gastric motility and gastric emptying.4.Nesfatin-1 regulated food intake,gastric acid secretion,gastric motility and gastric emptying via NAc-VMH pathway in rats,which suggested the nesfatin-1 functional pathway lay between NAc and VMH. |
PDF Full Text Request