Effect of hydrocortisone on bioelectric activity and morphological pattern of spinal cord in frogs

The effect of 1 mg hydrocortisone (HC) administered 3 h before the experiment was studied the bioelectric activity of ventral roots of spinal cord, the size and morphology of motoric neurons and also the size of synaptic endings being measured under different frequency of electric stimulation in frogs. It was found that the effect of HC on the electric activity of spinal cord and morphology of its neural elements was dependent on the stimulation used. Under the resting conditins the administration of HC resulted in a small decrease of the size of neurons. Under a low frequency stimulation HC did not affect the electric activity of spinal cord, but prevented the swelling of neurons and of synaptic endings resulting from the stimulation. Under a high frequency stimulation themorphology of neurons was remarkably changed, a shrinkage of these and an appearance of "dark" cells being found. Also these changes were prevented by the administration of HC. It was concluded that in all experiments HC prevented the changes resulting from electrostimulation, its effect, however, being dependent on the parameters of the stimulation used.