Tetrahydrobiopterin deficiency induces gastroparesis in newborn mice

Area of Science:

• Gastroenterology
• Developmental Biology
• Physiology

Background:

• Pyloric stenosis is a common infant gastrointestinal disease with unknown etiology.
• Abnormal gastric muscle function and gastroparesis are suspected contributors but remain poorly understood.
• The tetrahydrobiopterin (BH4)-deficient hph-1 mouse model offers a platform to study disease mechanisms.

Purpose of the Study:

• To investigate the role of impaired gastric muscle contraction and relaxation in the hph-1 mouse model of pyloric stenosis.
• To evaluate age-dependent changes in gastric emptying and muscle function in BH4-deficient mice.
• To explore the involvement of neuronal nitric oxide synthase (nNOS) and oxidative stress.

Main Methods:

• In vitro studies of gastric fundus muscle contraction and relaxation in hph-1 and wild-type mice.
• Assessment of gastric emptying via stomach content/body weight ratio.
• Measurement of nNOS protein expression, enzyme activity, and superoxide generation.
• Pharmacological manipulation with BH4.

Main Results:

• Newborn hph-1 mice exhibited significantly increased stomach content/body weight ratio, indicating abnormal gastric emptying.
• Upregulated nNOS expression and evidence of enzyme uncoupling with increased superoxide generation were observed in newborn hph-1 mice.
• Carbachol-induced contraction and nNOS-dependent relaxation were significantly reduced in newborn hph-1 gastric muscle.
• BH4 preincubation enhanced contraction in newborn hph-1 gastric muscle, but not in wild-type.

Conclusions:

• Newborn hph-1 mice display gastroparesis-like changes, suggesting a link between BH4 deficiency and impaired gastric motility.
• These findings highlight the potential role of BH4 deficiency and associated gastroparesis in the pathogenesis of infantile pyloric stenosis.
• Further research is warranted to elucidate the precise mechanisms and therapeutic implications.