Social Cell Biology

We are interested in how different cell types interact to coordinate the onset of plasticity in neurons, glia and blood vessels of the rat cerebral cortex after short term housing in a complex environment (EC) (work supported by Keck and Abshire funds from Whitman College). Our data offers new insight into the timecourse of angiogenesis induced by behavioral stimuli. While only 4 days of differential houses is sufficient to stimulate significant growth of dendritic branches (Wallace et al. 1992) and astrocytic processes (Jones et al.1996), blood vessel density is actually lower in EC cortex at this time point (as measured by relative density of processes positive for the endothethial cell specific surface antigen PECAM 1, Gumina, et al. 1996) (Wallace et al. provisionally accepted, Fig. 3). These new data suggest that active growth of dendrites outstrips the growth of blood vessels in the early stages of the brain's response to environmental complexity. By 30 days of differential housing, however, new capillary branches have been added (Black et al. 1987; Sirevaag et al. 1988) and the density of EC synapses per volume of neuropil has returned to values similar to that of individually caged (IC) controls. These data support the hypothesis that vascular growth is triggered by neuronal metabolic demand, and proceeds until the capillary network is expanded to match expanded synaptic territory. See Wallace, C.S., Withers, G.S., Farnand, A.*, Lobinger, B.T.*, McCleery, E.J.* (2011). Evidence that angiogenesis lags behind neuron and astrocyte growth in experience dependent plasticity. Developmental Psychobiology, 53(5):435-42. (* = undergraduate coauthor).

Fig. caption. Rat visual cortex stained to reveal A) a neuron impregnated with Golgi stain; B) astroglial processes (GFAP immunostaining); C) vasculature (PECAM-1 immunostaining). D) changes in cortical thickness (blue), density of glial processes (magenta) and density of blood vessels (yellow) after only 4 days in the complex environment, graphed as %difference from rats housed in individual cages. Images made from composites generated by tiling multiple frames, at 60X across a field (1.5 mm X 2.5 mm, 25 planes at 1 µm intervals in the Z axis). Scale bar=50µm Figure copyright, Dev. Psychobiol. Download

Immunofluorescent antibody staining, combined with optical sectioning can reveal the physical interactions between different cell types to test the new hypothesis that in cortical plasticity, as in retinal development, astrocytes are the critical link between neuronal growth and vascular plasticity.