Calcium calmodulin dependent kinase II in cat visual cortex and its development.

A monoclonal antibody against the alpha-subunit of calcium/calmodulin-dependent protein kinase II (CAM-K II) was used to visualize the kinase in developing kitten visual cortex. CAM-K II was first expressed in neurons of the deep cortical layers (V and VI) at postnatal day 1-4 and appeared in the remaining cortical layers within the first 2 weeks. The level of immunoreactivity declined in cells of layer V and upper layer VI at about 30-40 days of age. By postnatal day 90, the most densely labelled neurons were concentrated in cortical layers II, III, lower layer IV and in layer VI. This laminar pattern remained constant into adulthood. EM studies showed that the kinase was found in both pre- and postsynaptic locations. About twice as many immunopositive neurons were found in cortical layers II-IV and VI in young adult cats when geniculate input was removed by an unilateral thalamic lesion performed early in life. These results indicate that expression of CAM-K II is developmentally regulated in visual cortical neurons; the alteration of immunoreactivity after early LGN lesions suggests that the level of the kinase (or its alpha-subunit) is also regulated by cortical input.