A Method of Nodose Ganglia Injection in Sprague-Dawley Rat

Calik, Michael W.; Radulovački, Miodrag; Carley, David W.

doi:10.3791/52233

Cited by 9 publications

(6 citation statements)

References 23 publications

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“…To overcome these obstacles, we used the bilateral delivery of an shRNA-expressing viral vector into the NG to accomplish an inducible molecular manipulation of VAN function in adult rats. To our knowledge, NG injection has so far been limited to nonsurvival administration of compounds for electrophysiological recordings (24) and, more recently, to the unilateral delivery of viral tracers and optogeneticsrelated tools (25). Here, we demonstrate that bilateral NG injection of a viral-mediated shRNA yields a specific and long-lasting reduction of GLP-1R expression in the VANs.…”

Section: Discussionmentioning

confidence: 80%

Knockdown of GLP-1 Receptors in Vagal Afferents Affects Normal Food Intake and Glycemia

et al. 2015

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Nutrient stimulation of enteroendocrine L cells induces the release of the incretin and satiating peptide glucagonlike peptide 1 (GLP-1). The vagus nerve innervates visceral organs and may contribute to the mediation of gut-derived GLP-1's effects on food intake, energy homeostasis, and glycemic control. To test the hypothesis that vagal afferent neuron (VAN) GLP-1 receptors (GLP-1Rs) are necessary for these effects of endogenous GLP-1, we established a novel bilateral nodose ganglia injection technique to deliver a lentiviral vector and to knock down VAN GLP-1Rs in male Sprague Dawley rats. We found that a full expression of VAN GLP-1Rs is not necessary for the maintenance of longterm energy balance in normal eating conditions. VAN GLP-1R knockdown (kd) did, however, increase meal size and accelerated gastric emptying. Moreover, postmeal glycemia was elevated and insulin release was blunted in GLP-1R kd rats, suggesting that VAN GLP-1Rs are physiological contributors to the neuroincretin effect after a meal. Collectively, our results highlight a crucial role for the VANs in mediating the effects of endogenous GLP-1 on food intake and glycemia and may promote the further development of GLP-1-based therapies.Glucagon-like peptide 1 (GLP-1) is an incretin and satiating hormone that has provided new tools for the pharmacotherapy of obesity and diabetes (1,2). Yet, despite the clinical effectiveness of GLP-1-based drugs in ameliorating the symptoms of type 2 diabetes, the role of endogenous GLP-1 in the control of energy intake and glucose homeostasis is not fully understood. Vagal afferent neurons (VANs) express GLP-1 receptors (GLP-1Rs) (3,4) and terminate in the lamina propria of the intestinal mucosa as well as in the wall of the hepatic portal vein (HPV) (5). VANs may therefore relay the gut GLP-1-derived signals to the brain and, hence, mediate satiating and glucoregulatory responses. Previous studies using lesioning approaches have implicated the vagus nerve in the effects of peripherally administered GLP-1 on food intake and glycemia (reviewed in 6,7). In more recent studies, sudiaphragmatic vagal deafferentation (SDA) in rats clearly attenuated the acute eating-inhibitory effect of intraperitoneally (IP) infused GLP-1 (8) and exendin-4 (Ex-4), a GLP-1R agonist (9). Moreover, unlike Sham-operated rats, SDA rats failed to show a GLP-1R-mediated incretin response (10). Based on these findings, it is reasonable to hypothesize that endogenous gut-derived GLP-1 could activate GLP-1Rs on VANs in a paracrine-like fashion to reduce food intake, limit gastric emptying, and trigger a neural component of the incretin effect. Disruption of this endogenous GLP-1 signaling mechanism in the VANs due to genetic or environmental factors may contribute to the pathophysiology of obesity and diabetes. Hence, we examined the physiological role of in the control of food intake and regulation of glucose homeostasis by generating a specific knockdown (kd) of VAN GLP-1R expression in rats. Our approach is based on the delivery of a...

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Section: Discussionmentioning

confidence: 80%

Knockdown of GLP-1 Receptors in Vagal Afferents Affects Normal Food Intake and Glycemia

et al. 2015

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“…The current was completely blocked by BIBP3226 (300 nM), a Y 1 R selective antagonist and PTX 100 nM, the blocker for G-protein coupled receptor, respectively (Figure 7D-7G ). Even though AP discharge was not changed in the presence of Pro34, Y 1 R activation-mediated reduction in current density of I Ca may still change the neurotransmission in NTS due perhaps to the similar membrane structure between soma and its pre-synapse [ 21 ]. Similar results were also observed by Y 2 R activation in separate set of A-type BRNs under the same experimental condition (Data not shown).…”

Section: Resultsmentioning

confidence: 99%

Neuropeptide Y-mediated sex- and afferent-specific neurotransmissions contribute to sexual dimorphism of baroreflex afferent function

Liu

et al. 2016

Oncotarget

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BackgroundMolecular and cellular mechanisms of neuropeptide-Y (NPY)-mediated gender-difference in blood pressure (BP) regulation are largely unknown.MethodsBaroreceptor sensitivity (BRS) was evaluated by measuring the response of BP to phenylephrine/nitroprusside. Serum NPY concentration was determined using ELISA. The mRNA and protein expression of NPY receptors were assessed in tissue and single-cell by RT-PCR, immunoblot, and immunohistochemistry. NPY was injected into the nodose while arterial pressure was monitored. Electrophysiological recordings were performed on nodose neurons from rats by patch-clamp technique.ResultsThe BRS was higher in female than male and ovariectomized rats, while serum NPY concentration was similar among groups. The sex-difference was detected in Y1R, not Y2R protein expression, however, both were upregulated upon ovariectomy and canceled by estrogen replacement. Immunostaining confirmed Y1R and Y2R expression in myelinated and unmyelinated afferents. Single-cell PCR demonstrated that Y1R expression/distribution was identical between A- and C-types, whereas, expressed level of Y2R was ∼15 and ∼7 folds higher in Ah- and C-types than A-types despite similar distribution. Activation of Y1R in nodose elevated BP, while activation of Y2R did the opposite. Activation of Y1R did not alter action potential duration (APD) of A-types, but activation of Y2R- and Y1R/Y2R in Ah- and C-types frequency-dependently prolonged APD. N-type ICa was reduced in A-, Ah- and C-types when either Y1R, Y2R, or both were activated. The sex-difference in Y1R expression was also observed in NTS.ConclusionsSex- and afferent-specific expression of Neuropeptide-Y receptors in baroreflex afferent pathway may contribute to sexual-dimorphic neurocontrol of BP regulation.

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“…Another approach could involve the delivery of viral vectors to unlock a new spectrum of vagal-specific genetic manipulations. The nodose ganglion contains the cell bodies of all vagal afferent neurons and hence is a well-suited delivery site[108]. Whether viral vector delivery could potentially be efficient at manipulating gene expression in vagal afferent neurons, and which type of viral vectors are suitable for these neurons, has not been investigated yet.…”

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confidence: 99%