CHOLINE ACETYLTRANSFERASE ACTIVITY AND TOTAL PROTEIN CONTENT IN SELECTED OPTIC AREAS OF THE RAT AFTER COMPLETE LIGHT‐DEPRIVATION DURING CNS DEVELOPMENT1

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Abstract
Cholin acetyl-transferase (acetyl-CoA: choline O-acetyltransferase, I.U.B. 2.3.1.6) activity and total protein content in visual and extra-visual areas were compared in normal Long-Evans rats and in rats subjected to complete light-deprivation for 21 days from birth. The enzyme activity and the protein content in the superior colliculi, lateral geniculate bodies and visual cortex, as well as in the sensory-motor cortex, hy-pothalamus, brain stem and cerebellum, were measured in both mothers and progeny. By means of a radiochemical techique modified in this laboratory, a significant decline of ChAc activity was observed in the lateral geniculate bodies and superior colliculi, with no significant decline in the visual cortex of the experimental progeny. Total protein content, measured colorimetrically, was significantly decreased in the superior colliculi of the progeny. The biochemical data obtained from all other brain areas in the experimental animals (progeny and mothers) and controls demonstrated no marked differences. The enzymic alterations observed in the cholinergic system of progeny after complete light-deprivation during this critical period of CNS [central nervous system] development can be specially correlated with decreased functional maturation of the visual system. If it is accepted that ACh is a neuro-transmitter in some parts of the visual pathway, the data presented here suggest that complete light-deprivation from birth to 21 days of age in the rat has an effect on a biochemical system involved in synaptic transmission.