Un metodo di nodose Ganglia iniezione in Sprague-Dawley Rat
Summary
Afferent vagal signaling transmits important information to central nervous system from receptors located in organs of the abdomen and thorax. The nodose ganglia of vagus nerves contain many types of receptors that modulate vagal activity. This protocol describes a method of local injections of neurochemicals into the nodose ganglia.
Abstract
Afferent signaling via the vagus nerve transmits important general visceral information to the central nervous system from many diverse receptors located in the organs of the abdomen and thorax. The vagus nerve communicates information from stimuli such as heart rate, blood pressure, bronchopulmonary irritation, and gastrointestinal distension to the nucleus of solitary tract of the medulla. The cell bodies of the vagus nerve are located in the nodose and petrosal ganglia, of which the majority are located in the former. The nodose ganglia contain a wealth of receptors for amino acids, monoamines, neuropeptides, and other neurochemicals that can modify afferent vagus nerve activity. Modifying vagal afferents through systemic peripheral drug treatments targeted at the receptors on nodose ganglia has the potential of treating diseases such as sleep apnea, gastroesophageal reflux disease, or chronic cough. The protocol here describes a method of injection neurochemicals directly into the nodose ganglion. Injecting neurochemicals directly into the nodose ganglia allows study of effects solely on cell bodies that modulate afferent nerve activity, and prevents the complication of involving the central nervous system as seen in systemic neurochemical treatment. Using readily available and inexpensive equipment, intranodose ganglia injections are easily done in anesthetized Sprague-Dawley rats.
Introduction
Afferent signaling via the vagus nerve (cranial nerve X) transmits important general visceral information to the central nervous system (CNS) from baro-, chemo-, hepatic osmo-, cardiac, pulmonary, and gastric receptors located in the organs of the abdomen and thorax. The vagus nerve communicates information from stimuli such as heart rate, blood pressure, bronchopulmonary irritation, and gastrointestinal distension to the nucleus of solitary tract (NTS) of the medulla. The cell bodies of the pseudounipolar neurons of the vagus nerve are located in the nodose and petrosal ganglia, of which the majority is found in the former. Nodose ganglion cells contain a wealth of receptors for amino acids, monoamines, neuropeptides, and other neurochemicals that when activated, can modify afferent vagus nerve activity.1 Numerous innervations of the afferent vagus nerves coupled with the diversity of receptors located on the nodose ganglia illustrate the biological importance of this cranial nerve, and systemic drugs that do not cross into the CNS targeted at receptors on nodose ganglia can be used to treat various diseases, such as sleep apnea, gastroesophageal reflux disease, or chronic cough.2-4
The ease of access to the nodose ganglia lends itself to experimental manipulation by midline longitudinal incision made at the neck. The vagus nerve emerges from the posterior lacerated foramen at the base of the skull, and immediately displays a swelling of the nerve that is the nodose ganglion. The nodose ganglion is easily recognizable due to two nerve branches that arise from it: anteriorly the pharyngeal branch; and posteriorly superior laryngeal branch.5 Previous experimental manipulations of the nodose ganglia involved electrophysiological recordings,6 injections of immunohistochemical or immunofluorescent compounds for nerve tracings,7-10 superfusion or injections of neuroexcitotoxins,11-13 injections of adeno-associated virus to knockdown receptors,14,15 and injections of receptor-specific neurochemicals to change the activity of the vagus nerve.16,17
Systemic injections of neurochemicals are problematic in that systemic treatment affects both peripheral and central nervous systems. Thus, systemic treatment does not isolate the effect of neurochemicals on afferent vagal nerve activity. This protocol describes a method using readily available equipment of intranodose injections in the Sprague-Dawley rat that modulates vagus nerve activity without affecting the central nervous system. Stimulation of serotonin type 3 (5-HT3) receptors on nodose ganglia by intravenous (IV) infusion of serotonin (5-HT) induces the Bezold-Jarisch reflex, a vagal response trifecta of bradycardia, hypotension, and apnea, which can be abolished by supranodose vagatomy.11,17-19 Apnea is easily measured by placing a respiratory transducer around the abdomen of the rat.17,18 Cannabinoids decrease 5-HT-induced current in nodose ganglia cells,20 and intranodose ganglia injections of dronabinol attenuate 5-HT-induced apnea.
Protocol
Representative Results
Discussion
Le fasi critiche per l'iniezione di sostanze neurochimiche successo nella gangli nodosi sono: 1) identificare e pulizia del tessuto connettivo off gangli nodosi; 2) confermando l'integrità dei gangli nodosi prima dell'iniezione; 3) e utilizzando un ago piccolo per iniettare delicatamente in, ma non completamente attraverso la puntura, gangli nodoso.
Il nervo vago innerva molti organi del collo e dell'addome, e trasmette le informazioni importanti come la frequenza cardiaca, …
Declarações
The authors have nothing to disclose.
Acknowledgements
Questo studio è stato sostenuto dal National Institutes of Health (Grant 1UM1HL112856).
Materials
| Name of Material/ Equipment | Company | Catalog Number | Comments/Description |
| 5-HT HCl | MP Biomedicals | 215376591 | 12.5 µg/kg per 350 µl/kg |
| Dronabinol (Marinol) 10 mg Capsules (80 µg/µl) | AbbVie | NDC 0051-0023-21 | Dilute with sesame oil to 20 µg/µl |
| Sesame Oil | Sigma-Aldrich | S3547 | |
| Intramedic Polyethylene-50 | BD | 427411 | Ordered from VWR (Cat. # 63019-047) |
| Graefe Forceps | Roboz | RS-5138 | Two are needed |
| Johns Hopkins Bulldog Clamp | Roboz | RS-7441 | Three are needed |
| Piezoelectric Strain Gauge | Ambu | 813255-100 | |
| Data Acquisition USB Subsystems | DataWave Technologies | NA | |
| Sciworks Experimenter Software | NA | ||
| CyberAmp | Axon Instruments | NA | |
| Syringe, 500 µL, Model 1750 TLL | Hamilton Company | 81220 | |
| Syringe, 10 µL, Model 1801 RN | 7659-01 | ||
| Needle, 28 gauge, Small Hub RN | 7803-02 | Point Style 4, Angle 35, Length 0.5 in |
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