Neuronal Growth Factors

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)


Physiology and Biophysics


Survival, growth and development of neurons in culture are influenced by serum and neuronal target-tissue derived macromolecules.Gel filtration of sera at pH 3.6 yields a fraction which supports long term (months) survival of dissociated rat central neurons in monolayer culture more reliably than the traditionally used unfractionated sera. The cultures remain neuron-rich, because this fraction does not support the proliferation of glia and fibroblasts that occurs in whole sera. The active factor(s) in this fraction has an apparent molecular weight of 55,000 daltons and an isoelectric point of 5.6.This active serum fraction, present in a variety of mammalian sera, is sufficient to support the in vitro survival of neurons from rat spinal cord, brain stem, striatum, hippocampus, cerebellum, cortex, and retina. The fraction also supports the survival of rat skeletal muscle and fibroblasts, in culture. The fraction alone is not able to support the survival of dorsal root ganglia neurons in vitro; however, in combination with Nerve Growth Factor, the fraction does promote longer survival times and greater neuritic outgrowth than that found with Nerve Growth Factor alone.Macromolecules synthesized by neuronal target tissue influence certain aspects of neuronal development other than survival. Extracts prepared from muscle, and medium conditioned over cells in culture both contain components that influence protein and neurotransmitter synthesis in spinal cord neuronal cultures. Namely, these macromolecules induce an increase in the rate of protein and acetylcholine synthesis, increase choline acetyltransferase activity, and decrease the rate of (gamma)-aminobutyric acid synthesis. Although these macromolecules all elute at an apparent molecular weight of 35,000 upon gel filtration, their relative abundance in various sources suggests the presence of discrete factors.


Biology, Animal Physiology

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