Embryonic limb buds derived neurotrophins on the survival of neurons and the growth of axons in culture in vitro.

Bioactive proteins from SD rat limb buds were extracted and purified. Fractions of 22 ku, 34 ku and 95 ku were proved to have neurotrophic activity to neurons, and the combined activity of these three fractions was the highest. So they were combinedly added into the culture medium of sensor neurons in dorsal root ganglia and motor neurons of anterior spinal cord from 2-week-old embryonic rats, and PBS was added as control. Phase-contrast microscopic and electron microscopic observations, and true cholinesterase measurements were performed to evaluate the survival and changes in growth, function, and ultrastructure of these cultured neurons. In the experimental group, it was found that the AchE activity was higher (P < 0.01), ultrastructural changes in mitochondria, Gorgi's complex and other cell organs were milder than those in the control group. The results showed limb buds derived neurotrophins played an important role in maintaining the survival of the neurons and promoting the growth of axons. It was concluded that embryonic limb buds derived neurotrophins had high neurotrophic activities on neurons' survival and axon growth.