Systemic glycerol decreases neonatal rabbit brain and cerebellar growth independent of intraventricular hemorrhage

BACKGROUND: Cerebellar hypoplasia is common problem for preterm infants, and infants that suffer intraventricular hemorrhage (IVH). To evaluate the effects of IVH on cerebellar growth and development, we used a neonatal rabbit model of systemic glycerol to produce IVH. METHODS: New Zealand White rabbit kits were surgically delivered 2 d preterm, and treated with i.p. glycerol (3.25 to 6.5 g/kg). Controls were born at term. IVH was documented by ultrasound. Brain MRI volumes, cerebellar foliation, proliferation (Ki-67) and Purkinje cell density were done at two weeks of life. Tissue glycerol and glutathione concentrations were measured. RESULTS: Glycerol increased IVH, subarachnoid hemorrhages and mortality in a dose-dependent manner. Total cerebellar volumes, cerebellar foliation and cerebellar proliferation were decreased in a dose-dependent manner. Glycerol accumulated rapidly in blood, brain and liver and was associated with increased glutathione concentration. All of these results were independent of IVH status. CONCLUSIONS: Cerebellar hypoplasia was induced after glycerol administration in a dose-dependent manner. Given rapid tissue accumulation of glycerol, dose dependent decreased brain growth and lack of IVH effect on measured outcomes we question the validity of this model as glycerol toxicity cannot be ruled out. A more physiologic model of IVH is needed.