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In vivo studies of the roof plate of the spinal cord and midline optic tectum in rodent and the developing subplate in the telencephalon of the chick showed that two glycosaminoglycans, keratin sulfate and chondroitin sulfate, possibly in the proteoglycan form (KS-PG, CS-PG, or KS/CS-PG), were present at times when axons approach closely but do not invade(More)
Certain types of glial structures, located at strategic positions along axon pathways, may provide the mechanical and/or chemical elements for the construction of barriers which can grossly direct the elongation of axons during development. The roof plate, a putative axon barrier, is located along the dorsal midline of the developing spinal cord and may be(More)
Growth cone turning is an important mechanism for changing the direction of neurite elongation during development of the nervous system. Our previous study indicated that actin filament bundles at the leading margin direct the distal microtubular cytoskeleton as growth cones turn to avoid substratum-bound chondroitin sulfate proteoglycan. Here, we(More)
Developing neurons express a motor protein called kinesin-5 (also called kif11 or Eg5) which acts as a 'brake' on the advance of the microtubule array during axonal growth. Pharmacological inhibition of kinesin-5 causes the developing axon to grow at a faster rate, retract less and grow past cues that would otherwise cause it to turn. Here we demonstrate(More)
The extracellular matrix through which growth cones navigate contains molecules, such as chondroitin sulfate proteoglycan, that can inhibit growth cone advance and induce branching and turning. Growth cone turning is accompanied by rearrangement of the cytoskeleton. To identify changes in the organization of actin filaments and microtubules that occur as(More)
In the developing retina, retinal ganglion cell (RGC) axons elongate toward the optic fissure, even though no obvious directional restrictions exist. Previous studies indicate that axon-matrix interactions are important for retinal ganglion cell axon elongation, but the factors that direct elongation are unknown. Chondroitin sulfate proteoglycan (CS-PG), a(More)
Proteoglycans (PGs) are complex macromolecules of the extracellular matrix (ECM) that have a wide variety of effects on developing and regenerating neurons in vivo and in vitro. One hypothesis regarding the mechanisms of PG regulation of neuronal behavior states that the conformation of PGs may be critical, and thus that ECM- or cell surface-bound PGs may(More)
Cocaine exposure results in aberrant outgrowth and decreased survival for locus coeruleus (LC), a noradrenergic population of neurons that putatively regulates attentional function; however, the underlying mechanisms for these events are not known. We previously showed that cocaine exposure in vitro activates pro-apoptotic Bax, caspase-9, and caspase-3 in(More)
Following spinal cord injury, a regenerating neurite encounters a glial scar enriched in chondroitin sulfate proteoglycans (CSPGs), which presents a major barrier. There are two points at which a neurite makes contact with glial scar CSPGs: initially, filopodia surrounding the growth cone extend and make contact with CSPGs, then the peripheral domain of the(More)
BACKGROUND Prenatal cocaine exposure produces attentional deficits which to persist through early childhood. Given the role of norepinephrine (NE) in attentional processes, we examined the forebrain NE systems from prenatal cocaine exposed rats. Cocaine was administered during pregnancy via the clinically relevant intravenous route of administration.(More)