Brainstem microglial cell morphology in neonatal rats with necrotizing enterocolitis and the effects of prenatal heparin-binding epidermal growth factor-like growth factor.

Abstract:

Background: Necrotizing enterocolitis (NEC) is associated with increased neurodevelopmental impairment. Gut-brain interactions through the brainstem may be central to NEC-related microglia-driven neuroinflammation. Heparin-binding epidermal growth factor-like growth factor (HB-EGF) has intestinal protective properties and is a potential therapy for NEC. The aim of this study is to test the hypothesis that HB-EGF in pregnant rats reduces both NEC incidence and proinflammatory changes in the brainstem microglia of newborn rats.

Methods: We compared four experimental groups, HB-EGF⁺/NEC^-, HB-EGF^-/NEC^-, HB-EGF⁺/NEC⁺ and HB-EGF^-/NEC⁺, depending on whether HB-EGF was given prenatally, and whether the newborn rats underwent the NEC induction protocol. We stained brainstem microglia and performed fractal analyses to provide objective measures of morphological changes.

Results: NEC incidence was lower in the HB-EGF⁺/NEC⁺ group (n=64, p<0.005) than in the HB-EGF^-/NEC⁺ group. Brainstem microglia of breastfed rats had a larger cell area, perimeter, roughness, and less circularity compared with smaller, denser, compact cells in the NEC⁺ pups (p<0.0001, n=320 cells). HB-EGF⁺/NEC⁺ and HB-EGF^-/NEC⁺ pups had similar-appearing microglia.

Conclusions: Prenatal HB-EGF treatment reduces NEC incidence in neonatal rats. NEC-related proinflammatory changes are seen in microglial cells present in crucial centers controlling the gut-brain pathway. HB-EGF has a growth-promoting effect on healthy microglia in the offspring but does not avert microglial activation in the brainstem of newborn rats with NEC.