Laminin and a basement membrane extract have different effects on axonal and dendritic outgrowth from embryonic rat sympathetic neurons in vitro.
We have characterized the effects of laminin and a basement membrane extract (BME) on the morphology of embryonic rat sympathetic neurons maintained in tissue culture in the absence of nonneuronal cells. Neurons were grown on polylysine-coated coverslips in the presence or absence of laminin or BME in serum-free medium. Axons were distinguished from dendrites using intracellular dye injections, immunocytochemistry, and [3H]uridine autoradiography. In short-term (less than or equal to 24 hr) culture, laminin had a potent neurite-promoting effect, causing increases in the number of processes, total neuritic length, and neuritic branching. In long-term (3-35 days) cultures chronically exposed to laminin, most (greater than 75%) neurons maintained supernumerary axons but failed to form dendrites. In contrast, most neurons (greater than 70%) grown in long-term culture on polylysine in the absence of laminin were unipolar, extending a single axon. BME caused sympathetic neurons to extend multiple (range, 1-15) dendrites. Morphometric measurements made after 1 month of exposure to BME indicated that the amount of dendritic growth that occurred in vitro was similar to that normally occurring during a comparable period in situ. BME did not cause changes in the number of axons per neuron or in the uptake of neurotransmitter. Preliminary characterization of the dendrite-promoting activity of BME suggests that it resides in extracellular matrix (ECM) molecules and not in low-molecular weight contaminants. These observations indicate that (1) axonal and dendritic growth may be differentially regulated by various constituents of the ECM, and (2) such process-specific interactions can significantly affect the morphological development of sympathetic neurons.
Lein
P J
PJ
Department of Pharmacology and Therapeutics, School of Medicine, State University of New York, Buffalo 14214.
Higgins
D
D
D000818:Animals; D001369:Axons / Q000648:ultrastructure*; D001485:Basement Membrane / Q000502:physiology*; D002454:Cell Differentiation / Q000187:drug effects; D046508:Culture Techniques; D003712:Dendrites / Q000648:ultrastructure*; D004305:Dose-Response Relationship, Drug; D005728:Ganglia, Sympathetic / Q000166:cytology* / Q000378:metabolism; D007797:Laminin / Q000494:pharmacology*; D009638:Norepinephrine / Q000378:metabolism; D011107:Polylysine / Q000494:pharmacology; D012313:RNA / Q000378:metabolism; D051381:Rats
D007797:Laminin; D011107:Polylysine; D012313:RNA; D009638:Norepinephrine