Time course study of growth hormone releasing peptide-6-induced c-fos expression in neurons of feeding-related nuclei of hypothalamus / 生理学报

The present study was aimed to explore the effects of intraperitoneal injection of growth hormone releasing peptide-6 (GHRP-6), a ghrelin receptor agonist, on food intake and neuronal activity of feeding-related nuclei in the hypothalamus of NMRI mice. Accumulated amount of food intake was measured, and total number of c-fos immunoreactive neurons in arcuate nucleus (ARC), paraventricular nucleus (PVN) and supraoptic nucleus (SON) was counted by immunohistochemistry at 1, 3 and 6 h after the GHRP-6 injection. The results showed that GHRP-6 significantly increased the amount of food intake with a peak at 3 h after the GHRP-6 injection. Meanwhile, GHRP-6 could promote c-fos expression in the ARC and PVN independent of food intake, and the total number of c-fos immunoreactive neurons was peaked at 1 h after injection and then decreased gradually. These results suggest that GHRP-6 may increase food intake in time-dependent manner, which is associated with up-regulations of c-fos protein expression in the ARC and PVN.

Role of miR-663 in acute renal graft rejection: an in vitro study / 南方医科大学学报

<p><b>OBJECTIVE</b>To compare the serum miR-663 levels in renal transplant patients with and without acute rejection (AR) and explore the role of miR-663 acute renal graft rejection.</p><p><b>METHODS</b>Real time-PCR was used to determine serum miR-663 levels in renal transplant recipients with and without AR. MTT assay and Annexin V-FITC assay were employed to examine the viability and apoptosis of human renal glomerular endothelial cells (HRGEC) treated with a miR-663 mimic or a miR-663 inhibitor, and ELISA was performed to detect the expression of inflammation-related cytokines including IL-6, IFN-γ, CCL-2 and TNF-α in the cells. Transwell assay was used to examine the effect of miR-663 mimic and miR-663 inhibitor on the chemotactic capability of macrophages.</p><p><b>RESULTS</b>Serum miR-663 level was significantly higher in renal transplant recipients with AR than in those without AR. The miR-663 mimic significantly inhibited the viability of HRGECs and increase the cell apoptosis rate, while miR-663 inhibitor suppressed the cell apoptosis. The miR-663 mimic increased the expression levels of inflammation-related cytokines and enhanced the chemotactic capability of macrophages.</p><p><b>CONCLUSION</b>miR-663 might play important roles in acute renal graft rejection and may become a therapeutic target for treating AR.</p>

Ghrelin acts on rat dorsal vagal complex to stimulate feeding via arcuate neuropeptide Y/agouti-related peptide neurons activation / 生理学报

Ghrelin, an endogenous ligand for the growth hormone secretagogue (GHS) receptor, stimulates feeding and increases body weight. The primary action site of ghrelin has been reported to be the neuropeptide Y (NPY)/agouti-related peptide (AgRP) neurons in the hypothalamic arcuate nucleus (ARC). In addition to the hypothalamus, the caudal brainstem also appears to be an important mediator for the orexigenic activity of ghrelin. However, it is not clear whether ghrelin applied directly to the caudal brainstem activates forebrain structures. The aim of this study was to determine whether recruitment of forebrain structures was required for hyperphagic responses stimulated by ghrelin delivery within the caudal brainstem. In our experiment, all rats were surgically implanted with indwelling cannulas in the dorsal vagal complex (DVC), and ghrelin (20 pmol in 0.5 μL) was delivered to the DVC. After the injection, the orexigenic response to ghrelin was recorded by Feeding and Activity Analyser, and NPY/AgRP mRNA expressions in rat hypothalamus were detected by real-time PCR. In addition, the NPY immunoreactive neurons in the ARC were assayed by immunohistochemistry. The results showed that ghrelin significantly increased cumulative food intake at 1, 2 and 3 h after ghrelin injection, maximal response occurring at 2 h after injection. NPY/AgRP mRNA levels in ARC treated with ghrelin increased significantly compared with those in control group (injected with saline). The highest levels of NPY and AgRP mRNA were detected at 2 h after injection. The total number and mean optical density of NPY-positive neurons increased in ghrelin treated rats compared with those in control group. Consistently, ghrelin's effect was most pronounced at 2 h after injection. Taken together, we conclude that the activation of NPY/AgRP neurons in the ARC is involved in the mediation of the hyperphagic response to brainstem ghrelin administration in neurologically intact rats.

Expression of growth hormone secretagogue receptor type 1a in visceral vagal and spinal afferent pathways / 生理学报

In this study, the expressions of growth hormone secretagogue receptor type 1a (GHS-R1a) in the rat dorsal root ganglion (DRG) and nodose ganglion (NG) were investigated by using immunohistochemistry and in situ hybridization. The results clearly showed the presence of GHS-R1a mRNA and GHS-R1a-positive neurons in the rat DRG and NG. GHS-R1a was also co-localized with calcitonin gene-related peptide (CGRP) in some DRG and NG neurons, indicating the existence of subpopulations of the visceral afferents. The extrinsic primary afferent visceroceptive DRG and NG neurons from the stomach were identified by retrograde tracing fluorogold and stained for GHS-R1a and CGRP. Some neurons both positive for CGRP and GHS-Rla were labled by fluorogold. Our results not only demonstrate the expression of GHS-R1a in the vagal afferents but also provide the first and direct morphological evidence for its presence in the spinal visceral afferents, and gherin might have a modulatory role in the visceral afferent signaling.

Expression of motilin in the hypothalamus and the effect of central erythromycin on gastric motility in diabetic rats / 神经科学通报·英文版

<p><b>OBJECTIVE</b>To investigate the expression of motilin-immunoreactive neurons in the hypothalamus and the effect of central administration of erythromycin (EM) on the regulation of gastric motility in diabetic rats.</p><p><b>METHODS</b>The motilin immunoreactive neurons in the hypothalamus and the hippocampus were detected by immunohistochemistry with rabbit anti-motilin polyclonal antibody. To measure the gastric motility, force transducers were surgically affixed to the gastric serosa. A microinjection syringe was connected via a plastic tube to an injection cannula, which was connected with a stainless steel guide cannula. The syringe was inserted into the right lateral cerebral ventricle for microinjecting the chemicals.</p><p><b>RESULTS</b>Diabetic mellitus was successfully induced in cohorts of rats. Motilin-immunoreactive neurons significantly increased in the paraventricular (PVN) and supraoptic nuclei (SON) of the hypothalamus in the diabetic rats. Intracerebroventricular (i.c.v.) administration of EM, a motilin receptor agonist, stimulated the gastric motility of diabetic rats. EM (91.56 nmol, i.c.v.) dose-dependently increased the amplitude by (174.82 +/- 48.62)% (P<0.05), and increased the frequency by (70.43 +/- 27.11)% (P < 0.05) in 5 min. The stimulatory effect lasted more than 15 min to the end of the measurement, and can be blocked partially by the prior treatment of motilin receptor antagonist GM-109.</p><p><b>CONCLUSION</b>Motilin-immunoreactive neurons are increased in the PVN and SON of the hypothalamus in diabetic rats. Centrally administered EM may regulate gastric motility by binding to the central motilin receptors, and central motilin might be involved in regulation of gastric motility in diabetic rats.</p>

Effect of motilin receptor agonist-erythromycin on the glucose responsive neurons in hypothalamus of rats / 中国应用生理学杂志

<p><b>AIM</b>In order to explore the mechanism of central motilin-induced feeding behavior, the effects of erythromycin, a motilin receptor agonist, on glucose responsive neurons in hypothalamus were observed.</p><p><b>METHODS</b>Extracellular recordings were made from single neurons in region of lateral hypothalamic area (LHA) and ventromedial hypothalamic nucleus (VMH) in anesthetized rats. On the basis of their responsiveness to intracarotid injection of 0.58 mol/L glucose solution 0.2 ml, glucose-sensitive neurons (GSNs) in LHA and glucoreceptor neurons (GRNs) in VMH were recognized. Effects of intracerebroventricularly (i. c. v.) administration of 4 microg erythromycin on neural activities of glucose responsive neurons and non-glucose responsive neurons were examined. The mixture of EM and GM-109 1 microl were used to GSNs and GRNs which were sensitive to i. c. v. administration of EM.</p><p><b>RESULTS</b>In LHA, EM increased activity of GSNs significantly (P < 0.05 vs non-glucose-sensitive neurons group). Whereas in VMH, EM significantly decreased the activities of GRNs (P < 0.01 vs non-glucoreceptor neurons group). The mixture of EM and GM-109 had no effect on GSNs and GRNs.</p><p><b>CONCLUSION</b>EM, a motilin receptor agonist, can stimulate GSNs in LHA and suppress GRNs in VMH and this may contribute to central motilin's effect on feeding behavior.</p>

The effect of motilin in PVN of hypothalamus on the gastric motility / 中国应用生理学杂志

<p><b>AIM</b>To investigate the role of motilin in paraventricular nucleus (PVN) of hypothalamus on the regulation of gastric motility and the mechanism.</p><p><b>METHODS</b>Immunohistochemistry and microinjection of motilin into PVN were used to observe motilin neural cells in PVN, the neural path between PVN and dorsal vagal complex (DVC) and the changes of gastric motility in conscious rats.</p><p><b>RESULTS</b>(1) There were motilin immunoreactive-cells in PVN and a significant increase was found in groups of fasting and HCL-perfusion into duodenum. (2) HRP-positive cells were found in PVN after microinjection HRP into dorsal nucleus of vagal nerve. It proved that there was neural relationship between PVN and DVC. (3) The amplitude and frequency of gastric motility increased significantly by microinjection motilin into PVN in conscious rats. The effects produced by motilin could be abolished by vagotomy.</p><p><b>CONCLUSION</b>All these results presented imply that motilin in PVN may increase gastric motility through PVN-DVC-Vagal nerve axis.</p>

Administration of motilin into the lateral hypothalamus increases gastric antrum motility and activates the dorsal vagal complex in rats / 生理学报

The effects of administration of motilin into the lateral hypothalamic area (LHA) on gastric antrum motility in conscious rats and on gastric distention (GD) sensitive neurons in dorsal vagal complex (DVC) in anesthetized rats were studied. Microinjection of motilin (0.37 nmol/0.5 microl) into the LHA increased the gastric antrum motility index by 76.29 +/- 4.09% (P<0.01). In 60 GD sensitive neurons, firing rate increased in 39 neurons (65%) and decreased in 21 neurons (35%), which were classified as GD-excitatory and GD-inhibitory neurons, respectively. Firing rate by 7.17 +/- 7.89% within 1.5 min in 15 of 24 GD-excitatory neurons, and firing rate increased by 44.35 +/- 7.89% in 12 of 14 GD-inhibitory neurons after motilin microinjection into the LHA. The results suggest that exogenous motilin in LHA plays a role in the regulation of gastric antrum motility possibly via the vagal pathway from LHA-DVC to the stomach.