An Experimental Study On Relationship Between Activin A And Development Of Oligodendrocytes In Neonatal Rats

Objective To investigate the effect of exogenous activin A (ACT A) on the development of oligodendrocytes(OL) in neonatal rats. Methods 96 neonatal SD rats were divided into 4 groups according to postnatal days:3,7,14 and 21-day-old.Each group was divided randomly into experimental group and control group. The rats in experimental groups were given ACT A by intraperitoneal injection in the dose of 5ml/kg (0.025μg/ml)after birth, and the rats in control groups were given the isovolumic phosphate buffered solution (PBS)after birth. The specimens were collected at 2.5h after administration. The light microscope was used to observe the pathologic change and the electron microscope was used to observe the ultrastructural changes of brain tissue. The immunohistochemical method was used to detect the expression of ACT A in brain tissue. Results Under the light microscope, the OL s maturated and myelin sheath showed up gradually by the increase of postnatal days in brain white matter of control groups. The OL s of experimental groups were bigger and maturer than those of control groups of the same postnatal days, especially in groups of earlier postnatal days. The ultrastructural observation under the electron microscope shows the furthe confirmation to the results above. The result of immunochistochemistry shows, there's a negative correlation between the counts of positive ACT A cells and its postnatal in both experimental and control groups(experimental group r=-0.827, P<0.001; control group r=-0.7788, P<0.001). The counts of positive ACT A cells of experimental groups were less than those of control groups at the same postnatal days in P3,P7,P14 (19.08±1.509vs24.29±3.081, P<0.001; 14.89±3.826vs18.28±2.617, P<0.05; 12.83±1.938vs15.46±2.379, P<0.05), and no significant difference in P21 (6.702±3.778 vs9.82±7.165, P>0.05). Conclusion Exogenous ACT A can promote the maturity of the developing OLs and the formation of myelin sheath, especially in the early developmental stage. It suggests that exogenous ACT A have a promotive effect on the development and plerosis of nervous system in neonates, especially in prematures.