[Serotonin binding activity of light and heavy synaptosomes from different animal brain structures following light deprivation].

The extent of interaction between serotonin (ST) with light and heavy synaptosomes from different brain regions of normal and dark-reared rabbits was studied by the author's technique, using gel filtration. The activity of this interaction in the heavy synaptosomes of the visual cortex and the colliculi superiores of the control rabbits was the same and significantly higher than that in the motor cortex. The light synaptosomes of all the investigated regions were similar by the extent of this process activity. In dark-reared rabbits the activity of ST binding by heavy synaptosomes in the visual cortex and the colliculi superiores decreased by 74--81 per cent only. A fall in the ST binding by light synaptosomes in all the regions was the same (approximately 73 per cent as compared to the control). The results obtained are discussed in the light of a possible mediator or modulator role of ST in the visual system structures.