Developmental expression of neuronal calmodulin mRNA species in the rat brain analyzed by in situ hybridization

The temporal and spatial distribution of calmodulin mRNAs which are preferentially expressed in neurons was determined during postnatal development of rat central nervous system. Expression of these mRNAs was strongly detected in the developing neocortex, hippocampus, and cerebellum. Differences in the pattern of expression of a 1.8 and 4.0 kb neuronal calmodulin mRNA species were identified in the developing cerebellum. Expression of the smaller mRNA appeared to correlate with proliferating and developing cerebellar granule neurons while the larger mRNA was present in the mature granule neuron population. A transient elevation in the neuronal calmodulin mRNA species was observed in the superior and inferior colliculus and in the thalamus at postnatal days 5 and 10.