Ontogeny of brain-derived neurotrophic factor gene expression in the forebrain of prairie and montane voles.

Brain-derived neurotrophic factor (BDNF) plays an important role in normal brain development. In the present study, we examined the ontogenetic pattern of BDNF gene expression in both monogamous prairie voles (Microtus ochrogaster) and promiscuous montane voles (M. montanus); two closely related microtine rodents that differ in life strategy and social behavior. In both species, BDNF mRNA showed an early appearance and a transient expression in a regionally specific manner. In the dentate gyrus and CA3 region of the hippocampus, BDNF mRNA was found neonatally, increased gradually during development, and reached a peak at weaning, followed by a subsequent decline to the adult level. In the paraventricular nucleus of the hypothalamus, levels of BDNF mRNA persisted until weaning, followed by a significant increase to the adult levels at 3 months of age. BDNF mRNA also demonstrated a species-specific developmental pattern. In the cingulate cortex, BDNF mRNA labeling displayed a transient increase in the second and third postnatal weeks followed by a subsequent decrease to the adult level in prairie voles, but persisted throughout the course of development in montane voles. In general, montane voles achieved an adult pattern of BDNF mRNA expression earlier than did prairie voles. Together, these data indicate that BDNF may function differently in infant and adult brains, and that the two species of voles differ in the ontogenetic pattern of BDNF mRNA expression in a regional-specific manner, which may be associated with their different life strategy and brain and behavioral development.