17β-Estradiol Suppresses Gastric Inflammatory and Apoptotic Stress Responses and Restores nNOS-Mediated Gastric Emptying in Streptozotocin (STZ)-Induced Diabetic Female Mice

Gastroparesis (Gp) is a severe complication of diabetes mellitus (DM) observed predominantly in women. It is characterized by abnormal gastric emptying (GE) without mechanical obstruction in the stomach. Nitric oxide (NO) is an inhibitory neurotransmitter produced by neuronal nitric oxide synthase (nNOS). It plays a critical role in gastrointestinal (GI) motility and stomach emptying. Here, we wanted to demonstrate the protective effects of supplemental 17 beta-estradiol (E-2) on NO-mediated gastric function. We showed E-2 supplementation to alleviate oxidative and inflammatory stress in streptozotocin (STZ)-induced diabetic female mice. Our findings suggest that daily administration of E-2 at therapeutic doses is beneficial for metabolic homeostasis. This restoration occurs via regulating and modulating the expression/function of glycogen synthase kinase-3 beta (GSK-3 beta), nuclear factor-erythroid 2 p45-related factor 2 (Nrf2), Phase II enzymes, MAPK- and nuclear factor kappa-light-chain-enhancer of activated B cells (NFkB)-mediated inflammatory cytokines (IL-1 beta, IL-6, TNF alpha, IGF-1), and gastric apoptotic regulators. We also showed E-2 supplementation to elevate GCH-1 protein levels in female diabetic mice. Since GCH-1 facilitates the production of tetrahydrobiopterin (BH4, cofactor for nNOS), an increase in GCH-1 protein levels in diabetic mice may improve their GE and nitrergic function. Our findings provide new insights into the impact of estrogen on gastric oxidative stress and intracellular inflammatory cascades in the context of Gp.

Automated summary

Gastroparesis is a severe complication observed in women with diabetes mellitus, characterized by abnormal gastric emptying without mechanical obstruction. Our study demonstrates the protective effects of supplemental 17 beta-estradiol on NO-mediated gastric function. The administration of E-2 alleviates oxidative and inflammatory stress and improves metabolic homeostasis in diabetic mice.