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A Method of Nodose Ganglia Injection in Sprague-Dawley Rat

Afferent signaling via the vagus nerve transmits important general visceral information to the central nervous system from many diverse receptors located ...

University of Illinois at Chicago

Physical inactivity in combination with a sedentary lifestyle is strongly associated with an increased risk of development of inflammatory-mediated diseases, including autoimmune disorders. Recent studies suggest that anti-inflammatory effects of physical exercise may be of therapeutic value in some affected individuals. In this study, we determined the effects of forced-exercise (treadmill running) on the development and progression of experimental autoimmune neuritis (EAN), an established animal model of Guillain-Barré syndrome. Adult male Lewis rats were subjected to sedentary (control) or forced-exercise (1.2 km per day, 5 days a week) for three weeks prior to induction of EAN. P2 (53-78)-immunized sedentary control rats developed a monophasic course of EAN beginning on post-injection day 12.33 ± 0.59 (n = 18) and reaching peak severity on day 15.83 ± 0.35 (n = 18). At near peak of disease, ankle- and sciatic notch-evoked compound muscle action potential (CMAP) amplitudes in sedentary control rats were reduced (~50%) while motor nerve conduction velocity (MNCV) was slowed (~30%) compared with pre-induction evoked responses. In marked contrast, rats undergoing forced-exercise exhibited a significantly less severe clinical course of EAN beginning on post-injection day 12.63 ± 0.53 (n = 16) and reaching peaking severity on day 14.69 ± 0.73 (n = 16). At near peak of disease, ankle- and sciatic-notch-evoked CMAP amplitudes in forced-exercised rats were preserved while EAN-associated slowing of MNCV was modestly attenuated by exercise. Three weeks of forced-exercise reduced by 46% total plasma corticosterone content while elevating the levels of corticosteroid binding globulin. We conclude from this study that forced-exercise administered prior to and during development of EAN affords a novel measure of protection against autoimmune-associated deficits in peripheral nerve evoked responses independent of steroid-induced immune suppression.

Forced-exercise attenuates experimental autoimmune neuritis.

Obstructive sleep apnea represents a significant public health concern. Afferent vagal activation is implicated in increased apnea susceptibility by reducing upper airway muscle tone via activation of serotonin receptors in the nodose ganglia. Previous investigations demonstrated that systemically administered cannabinoids can be used therapeutically to decrease the apnea/hypopnea index in rats and in humans. However, cannabinoids have effects on both the central and peripheral nervous systems, and the exact mechanism of decreased apnea/hypopnea index with cannabinoids is unknown. Here, we hypothesized that intranodose ganglion injections of a cannabinoid will attenuate 5-HT-induced reflex apnea and increase upper airway muscle tone. We show that dronabinol injected locally into the nodose ganglia suppresses 5-HT-induced reflex apnea, and increases phasic, but not tonic, activation of the genioglossus. These data support the view that dronabinol stabilizes respiratory pattern and augments upper airway muscles by acting at the nodose ganglia. These findings underscore a therapeutic potential of dronabinol for the treatment of obstructive sleep apnea.

Intranodose ganglion injections of dronabinol attenuate serotonin-induced apnea in Sprague-Dawley rat.

The prevalence of obstructive sleep apnea (OSA) in Americans is 9% and increasing. Increased afferent vagal activation may predispose to OSA by reducing upper airway muscle activation/patency and disrupting respiratory rhythmogenesis. Vagal afferent neurons are inhibited by cannabinoid type 1 (CB1) or cannabinoid type 2 (CB2) receptors in animal models of vagally-mediated behaviors. Injections of dronabinol, a non-selective CB1/CB2 receptor agonist, into the nodose ganglia reduced serotonin (5-HT)-induced reflex apneas. It is unknown what role CB1 and/or CB2 receptors play in reflex apnea. Here, to determine the independent and combined effects of activating CB1 and/or CB2 receptors on dronabinol's attenuating effect, rats were pre-treated with CB1 (AM251) and/or CB2 (AM630) receptor antagonists. Adult male Sprague-Dawley rats were anesthetized, instrumented with bilateral electrodes to monitor genioglossus electromyogram (EMGgg) and a piezoelectric strain gauge to monitor respiratory pattern. Following intraperitoneal treatment with AM251 and/or AM630, or with vehicle, serotonin was intravenously infused into a femoral vein to induce reflex apnea. After baseline recordings, the nodose ganglia were exposed and 5-HT-induced reflex apneas were again recorded to confirm that the nerves remained functionally intact. Dronabinol was injected into each nodose ganglion and 5-HT infusion was repeated. Prior to dronabinol injection, there were no significant differences in 5-HT-induced reflex apneas or phasic and tonic EMGgg before or after surgery in the CB1, CB2, combined CB1/CB2 antagonist, and vehicle groups. In the vehicle group, dronabinol injections reduced 5-HT-induced reflex apnea duration. In contrast, dronabinol injections into nodose ganglia of the CB1, CB2, and combined CB1/CB2 groups did not attenuate 5-HT-induced reflex apnea duration. However, the CB1 and CB2 antagonists had no effect on dronabinol's ability to increase phasic EMGgg. These findings underscore the therapeutic potential of dronabinol in the treatment of OSA and implicate participation of both cannabinoid receptors in dronabinol's apnea suppression effect.

Michael W. Calik

Center for Narcolepsy,
Sleep and Health Research,
Department of Biobehavioral Health Science,
Center for Narcolepsy, Sleep and Health Research

University of Illinois at Chicago

A Method of Nodose Ganglia Injection in Sprague-Dawley Rat

Michael W. Calik

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Center for Narcolepsy,Sleep and Health Research,Department of Biobehavioral Health Science,Center for Narcolepsy, Sleep and Health Research

University of Illinois at Chicago

A Method of Nodose Ganglia Injection in Sprague-Dawley Rat

Center for Narcolepsy,
Sleep and Health Research,
Department of Biobehavioral Health Science,
Center for Narcolepsy, Sleep and Health Research