Reactions of neural elements of neocortex to action of hypoxia at the early neonatal period in rats

Abstract

In this work we studied reactions of neural elements of various neocortex areas (sensomotor, visual, auditory) on action of acute normobaric hypoxia. The study is performed on the model of human premature pregnancy (action of normobaric hypoxia on rat pups at the 2nd postnatal day). There are revealed monotypical and monodirected structural reconstructions in all studied neocortex parts. The chosen parameters of hypoxic action initiate several direct reactions as early as at the next day: a decrease in sizes of cell bodies and in volume of the cytoplasm, as well as an enhancement, as compared with control, of the apoptotic cell death. By the end of the neonatal period (5 days), several ultrastructural alterations indicating deceleration of processes of differentiation of nerve cells are revealed: arrest of processes of complication of smooth and rough endoplasmic reticulum and of Golgi apparatus, a small number of single ribosomes and polysomes in the cytoplasm, a decrease of the number of growth cones of axons and dendrites in neuropil, delay and disturbance of myelination processes in nerve fibers. The detected morphofunctional reconstructions can serve the structural ground for development of neonatal encephalopathies.