do you expect neurons in your spinal cord to have regularly fluctuation levels of cyclin?

Since the levels of cyclins generally change in regards to movement through the cell cycle it would, at first, seem unlikely that this would happen. However, there have been some studies to indicate that changes in the levels of cyclins may not be strictly limited to progression through the cell cycle. Given that motor neurons have to support extremely long axons and respond to a large number of stressors (one of the areas where cyclins may also act), it seems possible that some of the cyclins may change their levels in the course of a motor neurons functional life.  As for interneurons and the others I would say that it is less likely, but I believe that it is currently unknown.