Morphological changes in rat's brain choroid plexus after exposure to low doses of high energy oxygen ions, fast neutrons, and gamma radiation.

Ultrastructural and morphometrical changes in choroid plexus cells of the rat's brain in the delay period after irradiation with low doses of oxygen ions [= 300 MeV/nucleon], and fast neutrons [1.5 MeV], and gamma rays (Co60) were described. The applied irradiations provoked similar ultrastructural changes in choroid plexus cells; however, the obtained morphometrical data showed differing effects of these radiations, due to, probably, different mechanisms of their effect on the cells.

[Ultrastructural changes in neurons of the arcuate nucleus-median eminence complex in rats irradiated with carbon ions and gamma rays]. / Ul'trastrukturnye izmeneniia neironov kompleksa arkuatnoe iadrosredinnoe vozvyshenie u krys, obluchennykh ionami ugleroda i gamma-izlucheniem.

Ultrastructural changes in the arcuate nucleus and medial eminence area of rats were examined 5 weeks after their exposure to accelerated carbon ions with an energy of 300 MeV/nuclon and 60Co gamma-rays at a dose of 2.0 Gy. In carbon-irradiated animals the ultrastructural changes of arcuate nucleus neurons, their processes and synapses were more significant and diversified than in gamma-irradiated rats.

[Ultrastructural changes in the rat cerebellar cortex in the remote periods after exposure to accelerated carbon ions]. / U'ltrastrukturnye izmeneniia kory mozzhechka krys v otdalennye sroki posle vozdeistviia uskorennykh ionov ugleroda.

The cerebellar cortex of rats irradiated with carbon ion fluxes of 320 Mev/nuclon and 60Co gamma-radiation was examined by light and electron microscopy 1, 3 or 6 months after exposure. Carbon ions induced the greatest pathomorphological changes. A month after exposure the changes were diffuse and reversible while 3 and, especially, 6 months after irradiation they were focal disorders, a large portion of which being irreversible. 3 and 6 months after exposure some structures of the cerebellar cortex showed destructive while others exhibited reparative changes. Structural disorders in various nerve and glial cells were of different type. Disorders of the Purkinje cells were of the dark type and those of adjacent Bergmann glial cells of the light type. In the granular layer, neurons showed light type changes and adjacent oligodendrocytes, a densely packed karyo- and cytoplasm and a higher osmiophilia. It can be assumed that the above changes are to maintain disordered neuronal functions, including cell interactions. Study of time course variations in the neuronal and glial ultrastructure of the cerebellar cortex of irradiated animals shows an increase of destructive changes with time. This investigation has demonstrated that CNS cells may be damaged long after exposure even to small fluxes of heavy charged particles.

[Incidence of morphologic changes in cerebral cortex neurons of the rat exposed to accelerated carbon ions]. / Issledovanie chastoty morfologicheskikh izmenenii v neironakh kory golovnogo mozga krys pri vozdeistvii uskorennykh ionov ugleroda.

Structural lesions in neurons of the brain cortex of rats were investigated 1 and 3 months after their exposure to accelerated carbon ions with the energy 320 MeV/nuclon 10(4) particles/cm2 (LET = 120 MeVcm2/g) as well as to gamma-radiation in the dose 1.0 Gy. The irradiated animals showed morphofunctional, dystrophic and reparative lesions in neurons. The rats exposed to carbon ions developed more distinct changes that the animals exposed to gamma-radiation. It is postulated that similar fluxes of cosmic radiations will not produce a deleterious effect on the integrative functions of the central nervous system of cosmonauts.