Distribution of adenosine A1 receptors in primary visual cortex of developing and adult monkeys

Adenosine is an endogenous neuromodulator, whose actions in the brain are mediated by several, highly specific receptor systems. This study examined the distribution of adenosine Al receptors in the primary visual cortex of developing and adult monkeys by way of radioligand-binding autoradiography. Receptor density was found to be highest in layers 2/3 and 5 of adult striate cortex and lowest in layer 4. A similar pattern was found in infant monkeys that were in the critical period of development. Furthermore, removal of visual stimulation appeared to have no effect on receptor density in any of the layers. These results show that levels of adenosine Al receptors are not affected within ocular dominance columns after removal of visual input and that the geniculorecipient layer is less likely to be influenced by endogenous adenosine than other layers during early development and in the adult.