Amniotic fluid levels of glial fibrillary acidic protein in fetal rats with retinoic acid induced myelomeningocele: A potential marker for spinal cord injury

Objective The objective of this study was to determine whether amniotic fluid levels of glial acidic fibrillary protein (GFAP) would reflect myelomeningocele-related neurodegeneration in the rat model of retinoic acidinduced myelomeningocele, which is a model that is very similar to human myelomeningocele and develops the entire spectrum of disease severity including features of the Chiari II malformation. Study Design Time-dated (embryonic day 10) pregnant Sprague-Dawley rats were gavage fed 60 mg/kg/bodyweight retinoic acid that had been dissolved in olive oil or olive oil alone. Myelomeningocele, retinoic acidexposed no myelomeningocele, and control fetuses were harvested at specific time points throughout gestation. A standard set of pinching tests was performed to interrogate the sensorimotor reflex arc of hindpaws and tails. Amniotic fluidGFAP levels were analyzed by standard enzyme-linked immunosorbent assay techniques. Results Amniotic fluidGFAP levels were similar between groups at embryonic days 14, 16, and 18, respectively. Compared with control fetuses, amniotic fluid GFAP levels were significantly increased in myelomeningocele fetuses at embryonic days 20 and 22 (P < .001). Defect size (P < .001), presence of clubfoot deformity (P = .0004), and absence of sensorimotor function (P < .01) at embryonic day 22 correlated with amniotic fluidGFAP levels. Conclusion Amniotic fluidGFAP levels appear to correlate with spinal cord injury as gestation proceeds in fetal rats with myelomeningocele.