Regulation of protein kinase C activity by sensory deprivation in the olfactory and visual systems

Environmental regulation of sensory function has provided an important model of plastic mechanisms mediating neural information processing. To define potential commonalities in information processing in different systems, we investigated molecular changes elicited by sensory deprivation in the developing rat olfactory and visual systems. Protein kinase C (PKC), an intracellular messenger implicated in synaptic plasticity and memory, was analyzed. Initial, developmental studies indicated that PKC activity in the soluble and particulate fractions of the olfactory bulb increased three- to fourfold from birth to 3 months of age. Unilateral olfactory deprivation prevented the developmental increase in both soluble and particulate PKC activities in the ipsilateral olfactory bulb and piriform cortex, the second-order relay. Phorbol ester binding localized PKC to intrinsic neuronal populations and their dendrites in the control and deprived bulbs. Moreover, PKC was similarly lower in the visual cortex of dark-reared rats than in light-reared controls. The changes in PKC were region specific, as activity was unchanged by either treatment in the parietal cortex, a control area that does not process primary olfactory or visual information. Our results suggest that the important intracellular messenger, PKC, is similarly regulated in entirely different sensory systems by different environmental stimuli. Consequently, different sensory systems may use common molecular mechanisms to process information.