Objective: To study the ultrastructural changes in the cerebral cortex and cerebellar cortex of rats under simulated weightlessness and the possible mechanism.
Method: The tail-suspended rats model (-30 degrees head down tilt) was adopted to simulate weightlessness in the experiment. The rats were suspended for 7 d, 14 d, 21 d, and 28 d, and then were perfused through the hearts. The specimens were drawn from the rats' cerebral cortex and cerebellar cortex for electron microscopy.
Result: The results showed that under simulated weightlessness, the main changes in the neuron can be described as follows: swelling of mitochondria, endoplasmic reticulum and Golgi complex, even formation of big empty vesicles; reduction of number of synaptic vesicles in IV layer; increase corrugation of capillary lumen and thickening of basement membrane. Degranulation of rough endoplasmic reticulum in Purkinje's cells of the cerebellar cortex occurred obviously. On the 14th and the 21st day of suspension, the changes were most significant and tended to return to normal on the 28th day.
Conclusion: The experimental results demonstrated that simulated weightlessness led to ultrastructural changes in the cerebral cortex and cerebella cortex of rats. The ultrastructure changed with the course of simulated weightlessness and tended to return to normal. It showed an adaption to the simulated weightlessness.