Effect of hyperthermia on morphology and histochemistry of spinal cord in the rat.

Studies were performed on mature Wistar strain rats, subjected to 43 degrees C environmental temperature for 4 h at a relative air humidity of 60-70%. Spinal cords of rats sacrificed 1, 24, 48, 72 h and one week after hyperthermia served as a material for the studies. Routinely stained preparations (H+E, Nissl) and enzymatic activity of some phosphatases and esterases was estimated as well in sections subjected to Feulgen reaction karyo- and cytophotometric measurements were performed on cell nuclei of anterior horns neurocytes, anterior columns oligodendrocytes and on anterior funicle astrocytes of the spinal cord lumbar segment. The hyperthermia resulted in rat spinal cords in several morphological and histochemical alterations. Signs of diffuse spinal cord lesion of vascular origin were present with degenerative alterations of neurocytes, oligodendroglia proliferation and astroglia hyperplasia. In histoenzymatic studies changes in enzymatic activity of NsE, AChE, ChE, AcP, ATPase and TPPase were noted. They were dependent upon the time which elapsed after hyperthermia. Karyo- and cytophotometric measurements demonstrated cell nuclei oedema in neurocytes, oligodendrocytes and astrocytes associated with a decrease in the relative DNA level and changes in density and concentration of nuclear chromatin. The observed morphological, histoenzymatic and cytophotometric changes were of a reversible type and majority of them vanished within a week after hyperthermia.