Sacral nerve stimulation increases gastric accommodation in rats: a spinal afferent and vagal efferent pathway

Impaired gastric accommodation (GA) has been frequently reported in various gastrointestinal diseases. No standard treatment strategy is available for treating impaired GA. We explored the possible effect of sacral nerve stimulation (SNS) on GA and discovered a spinal afferent and vagal efferent mechanism in rats. Sprague-Dawley rats (450–500 g) with a chronically implanted gastric cannula and ECG electrodes were studied in a series of sessions to study: 1) the effects of SNS with different parameters on gastric tone, compliance, and accommodation using a barostat device; two sets of parameters were tested as follows: parameter 1) 5 Hz, 500 µs, 10 s on 90 s off; 90% motor threshold and parameter 2) same as parameter 1 but 25 Hz; 2) the involvement of spinal afferent pathway via detecting c-fos immunoreactive (IR) cells in the nucleus of the solitary tract (NTS) of the brain; 3) the involvement of vagal efferent activity via the spectral analysis of heart rate variability derived from the ECG; and 4) the nitrergic mechanism, Nω-nitro-l-arginine methyl ester (l-NAME), a nitric oxide synthase (NOS) inhibitor, was given before SNS at 5 Hz. Compared with sham-SNS: 1) SNS at 5 Hz inhibited gastric tone and increased gastric compliance and GA. No difference was noted between the stimulation frequencies of 5 and 25 Hz. 2) SNS increased the expression of c-fos in the NTS. 3) SNS increased cardiac vagal efferent activity and decreased the sympathovagal ratio. 4) l-NAME blocked the relaxation effect of SNS. In conclusion, SNS with certain parameters relaxes gastric fundus and improves gastric accommodation mediated via a spinal afferent and vagal efferent pathway. NEW & NOTEWORTHY Currently, there is no adequate medical therapy for impaired gastric accommodation, since medications that relax the fundus often impair antral peristalsis and thus further delay gastric emptying that is commonly seen in patients with functional dyspepsia or gastroparesis. The advantage of the potential sacral nerve stimulation therapy is that it improves gastric accommodation by enhancing vagal activity, and the enhanced vagal activity would lead to enhanced antral peristalsis rather than inhibiting it.

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Anti-inflammatory effects of sacral nerve stimulation: a novel spinal afferent and vagal efferent pathway

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00330.2019 ◽

2020 ◽

Vol 318 (4) ◽

pp. G624-G634 ◽

Cited By ~ 4

Author(s):

Lei Tu ◽

Payam Gharibani ◽

Nina Zhang ◽

Jieyun Yin ◽

Jiande DZ Chen

Keyword(s):

Brain Stem ◽

Nerve Stimulation ◽

Sacral Nerve Stimulation ◽

Vagal Activity ◽

Sacral Nerve ◽

Efferent Pathway ◽

Afferent Vagal ◽

Anti Inflammatory ◽

The Brain ◽

Inflammatory Effect

Sacral nerve stimulation (SNS) was reported to improve 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis in rats. The aim of this study was to investigate whether the SNS anti-inflammatory effect is mediated via the local sacral splanchnic nerve or the spinal afferent-vagal efferent-colon pathway. Under general anesthesia, rats were administrated with TNBS intrarectally, and bipolar SNS electrodes were implanted unilaterally at S3. The sacral and vagal nerves were severed at different locations for the assessment of the neural pathway. SNS for 10 days improved colonic inflammation only in groups with intact afferent sacral nerve and vagus efferent nerve. SNS markedly increased acetylcholine and anti-inflammatory cytokines (IL-10) and decreased myeloperoxidase and proinflammatory cytokines (IL-2, IL-17A, and TNF-α) in colon tissues. SNS increased the number of c-fos-positive cells in the brain stem and normalized vagal activity measured by spectral analysis of heart rate variability. SNS exerts an anti-inflammatory effect on TNBS-induced colitis by enhancing vagal activity mediated mainly via the spinal afferent-brain stem-vagal efferent-colon pathway. NEW & NOTEWORTHY Our findings support that there is a possible sacral afferent-vagal efferent pathway that can transmit sacral nerve stimulation to the colon tissue. Sacral nerve stimulation can be carried out by spinal cord afferent to the brain stem and then by the vagal nerve (efferent) to the target organ.

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Transcutaneous auricular vagal nerve stimulation improves functional dyspepsia by enhancing vagal efferent activity

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00426.2020 ◽

2021 ◽

Author(s):

Ying Zhu ◽

Feng xu ◽

Dewen Lu ◽

Peijing Rong ◽

Jiafei Cheng ◽

...

Keyword(s):

Functional Dyspepsia ◽

Nerve Stimulation ◽

Vagal Nerve ◽

Vagal Nerve Stimulation ◽

Slow Waves ◽

Dyspeptic Symptom ◽

Vagal Activity ◽

Gastric Accommodation ◽

Efferent Activity ◽

Gastric Slow Waves

Objectives: This study was designed to investigate whether transcutaneous auricular vagal nerve stimulation (taVNS) would be able to improve major pathophysiologies of functional dyspepsia (FD) in patients with FD. Methods: Acute: Thirty-six FD patients (21F) were studied in two sessions (taVNS and sham-ES). Physiological measurements, including gastric slow waves, gastric accommodation and autonomic functions, were assessed by the electrogastrogram (EGG), a nutrient drink test and the spectral analysis of heart rate variability derived from the electrocardiogram (ECG), respectively. Chronic: Thirty-six FD patients (25F) were randomized to receive 2-week taVNS or sham-ES. The dyspeptic symptom scales, anxiety and depression scores and the same physiological measurements were assessed at the beginning and the end of the 2-week treatment. Results: Acute: In comparison with sham-ES, acute taVNS improved gastric accommodation (p=0.008), increased the percentage of normal gastric slow waves (%NSW, fasting: p=0.010; fed: p=0.007) and vagal activity (fasting: p=0.056; fed: p=0.026). Chronic：In comparison with baseline, 2-week taVNS but not sham-ES reduced symptoms of dyspepsia (p=0.010), decreased the scores of anxiety (p=0.002) and depression (p<0.001), improved gastric accommodation (p<0.001) and the %NSW (fasting: p<0.05; fed: p<0.05) by enhancing vagal efferent activity (fasting: p=0.015; fed: p=0.048). Compared with the HC, the patients showed increased anxiety (p<0.001) and depression (p<0.001), and decreased gastric accommodation (p<0.001) and %NSW (p<0.001) as well as decreased vagal activity (fasting: p=0.047). Conclusions: The noninvasive taVNS has a therapeutic potential for treating non-severe FD by improving gastric accommodation and gastric pace-making activity via enhancing vagal activity.

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