Neuroenteric Stimulation for Gastroparesis

Safety and Feasibility of Per-Oral Pyloromyotomy as Augmentative Therapy after Prior Gastric Electrical Stimulation for Gastroparesis

BACKGROUND

For medically refractory diabetic or idiopathic gastroparesis, gastric electrical stimulation (GES) is an excellent option for symptom control; however, a small subset of patients may develop recurrent or persistent symptoms. Per-oral pyloromyotomy (POP, also described by some authors as gastric per-oral endoscopic myotomy or G-POEM) is an emerging therapy for medically refractory gastroparesis. This study investigated the safety and feasibility of POP after previous GES for recurrent or persistent gastroparesis.

STUDY DESIGN

We retrospectively identified all patients undergoing POP between January 2016 and December 2017, with GES in situ. Patient characteristics, gastroparesis etiology, and procedural data were collected. Symptoms were assessed with the Gastroparesis Cardinal Symptom Index (GCSI) both before and 30 to 90 days after POP. Standard pre- and post-procedure 4-hour gastric emptying tests were obtained when available.

RESULTS

There were 22 patients who met inclusion criteria (81.8% female, mean age 42.3 ± 12.4 years). Causes of gastroparesis were diabetes in 38.1%, and idiopathic in 61.9%. The average time since GES insertion was 3.45 years. Mean preoperative 4-hour gastric retention was 50.1%. Most POP procedures were performed in the operating room (90.9%), with mean operative time of 40 minutes and a 1.4-day length of stay. There were 4 readmissions within 30 days, but no POP-related complications. Overall, GCSI improved by an absolute reduction of 1.63 points (p = 0.002), with significant improvements in all sub-scores. Of 11 patients with post-procedural motility or emptying studies available, 7 were normal.

CONCLUSIONS

Per-oral pyloromyotomy appears to be safe and feasible for patients with recurrent gastroparesis symptoms after GES. Both symptoms and motility significantly improved in the short-term. These data replicate similar data suggesting laparoscopic pyloroplasty as an effective augmentative therapy after GES, but may provide a less invasive option for patients.

Sepiapterin alleviates impaired gastric nNOS function in spontaneous diabetic female rodents through NRF2 mRNA turnover and miRNA biogenesis pathway

An impaired nitrergic system and altered redox signaling contribute to gastric dysmotility in diabetics. Our earlier studies show that NF-E2-related factor 2 (NRF2) and phase II antioxidant enzymes play a vital role in gastric neuronal nitric oxide synthase (nNOS) function. This study aims to investigate whether supplementation of sepiapterin (SEP), a precursor for tetrahydrobiopterin (BH₄) (a cofactor of NOS) via the salvage pathway, restores altered nitrergic systems and redox balance in spontaneous diabetic (DB) female rats. Twelve-week spontaneous DB and age-matched, non-DB rats, with and without dietary SEP (daily 20 mg/kg body wt for 10 days) treatment, were used in this study. Gastric antrum muscular tissues were excised to investigate the effects of SEP in nitrergic relaxation and the nNOS-nitric oxide (NO)-NRF2 pathway(s). Dietary SEP supplementation significantly ( P < 0.05) reverted diabetes-induced changes in nNOS dimerization and function; nitric oxide (NO) downstream signaling molecules; HSP-90, a key regulator of nNOSα activity and dimerization; miRNA-28 that targets NRF2 messenger RNA (mRNA), and levels of microRNA (miRNA) biogenesis pathway components, such as DGCR8 (DiGeorge Syndrome Critical Region Gene 8) and TRBP (HIV1-1 transactivating response RNA-binding protein). These findings emphasize the importance of the BH₄ pathway in regulating gastric motility functions in DB animals by modulating nNOSα dimerization in association with changes in enteric NRF2 and NO downstream signaling. Our results also identify a new pathway, wherein SEP regulates NRF2 mRNA turnover by suppressing elevated miRNA-28, which could be related to alterations in miRNA biogenesis pathway components. NEW & NOTEWORTHY This study is the first to show a causal link between NF-E2-related factor 2 (NRF2) and neuronal nitric oxide synthase (nNOS) in gastric motility function. Our data demonstrate that critical regulators of the miRNA biosynthetic pathway are upregulated in the diabetic (DB) setting; these regulators were rescued by sepiapterin (SEP) treatment. Finally, we show that low dihydrofolate reductase expression may lead to impaired nNOS dimerization/function-reduced nitric oxide downstream signaling and elevate oxidative stress by suppressing the NRF2/phase II pathway through miRNA; SEP treatment restored all of the above in DB gastric muscular tissue. We suggest that tetrahydrobiopterin supplementation may be a useful therapy for patients with diabetes, as well as women with idiopathic gastroparesis.

Diabetes and the Stomach

OPINION STATEMENT

Longstanding diabetes mellitus (both type 1 and type 2) can impair gastric motor function and cause significant upper gastrointestinal symptoms which significantly degrade quality of life, cause nutritional deficits, and degrade healthcare resource use. The most commonly considered gut complication of diabetes, diabetic gastroparesis, is a syndrome of delayed gastric emptying in the absence of mechanical obstruction which leads to symptoms of nausea, vomiting, postprandial fullness, early satiation, bloating, and upper abdominal pain. Gastroparesis also can lead to loss of glycemic control. A diagnosis of gastroparesis is made by documenting delayed gastric emptying and excluding mechanical obstruction. Gastric emptying scintigraphy is the most commonly utilized test for the diagnosis of gastroparesis but novel tests of gastric function have recently been introduced including the gastric emptying breath test and wireless motility capsule. Management most often is aimed at controlling symptoms, which includes dietary modification, optimization of glycemic control, and medication therapy with prokinetics, antiemetics, and neuromodulatory agents. Endoscopic and/or surgical therapies may be considered for refractory cases of gastroparesis. Recent research has provided new insights into the pathophysiology of this disease and is characterizing potential benefits of novel therapeutic agents which show promise in the treatment of this condition. This article will review the pathophysiology, new insights into disease mechanism, and treatment options for diabetic gastroparesis.