Intrauterine growth restriction alters the postnatal development of the rat cerebellum

Intrauterine growth restriction (IUGR) is a major cause of antenatal brain injury. We aimed to characterize cerebellar deficits following IUGR and to investigate the potential underlying cellular and molecular mechanisms. At embryonic day 18, pregnant rats underwent either sham surgery (controls; n = 23) or bilateral uterine vessel ligation to restrict blood flow to fetuses (IUGR; n = 20). Offspring were collected at postnatal day 2 (P2), P7, and P35. Body weights were reduced at P2, P7, and P35 in IUGR offspring (p < 0.05) compared with controls. At P7, the width of the external granule layer (EGL) was 30% greater in IUGR than control rats (p < 0.05); there was no difference in the width of the proliferative zone or in the density of Ki67-positive cells in the EGL. Bergmann glia were disorganized at P7 and P35 in IUGR pups, and by P35, there was a 10% decrease in Bergmann glial fiber density (p < 0.05) compared with controls. At P7, trophoblast antigen-2 (Trop2) mRNA and protein levels in the cerebellum were decreased by 88 and 40%, respectively, and astrotactin 1 mRNA levels were increased by 20% in the IUGR rats (p < 0.05) compared with controls; there was no difference in ASTN1 protein. The expressions of other factors known to regulate cerebellar development (astrotactin 2, brain-derived neurotrophic factor, erb-b2 receptor tyrosine kinase 4, neuregulin 1, sonic hedgehog and somatostatin) were not different between IUGR and control rats at P7 or P35. These data suggest that damage to the migratory scaffold (Bergmann glial fibers) and alterations in the genes that influence migration (Trop2 and Astn1) may underlie the deficits in postnatal cerebellar development following IUGR.