RESUMO
Diurnal variations in the incorporation of labelled precursors of RNA and proteins into the spinal, stem, and cerebral cell populations of the rat nervous system were studied on surviving brain slices under standard conditions and during exercise by swimming. Cosinor analysis of the relative level of 3H-uridine incorporation into spinal ganglia L5, superior cervical ganglia, spinal cord L5, hypothalamic suprachiasmatic nuclei and cerebellar cortex revealed that the arrangement of the calculated acrophases of these organs in the dark period of a day. The acrophases of visual and somatosensory cortical cells were observed in the light period of a day. The calculated maximum values of the rate of 3H-leucine incorporation into nerve cell proteins (the internal acrophases ranged from 3 to 9 hours) were seen at certain intervals. Thus, the processes providing the function of a protein-synthesizing apparatus of nerve cells are characterized by a definite time organization and these processes vary significantly in their activity during a diurnal cycle. Depending on the time of a day when exercise was performed, there were differences in the changing activity of genetic and protein-synthesizing apparatuses during nerve cell reactions. This is associated with the different time of the onset of a reaction, passage of its some stages, with the rate of processes, and with the periods of normalization. The curves of a phasic response are discussed.