MODULATION OF A NEURONAL CALMODULIN MESSENGER-RNA SPECIES IN THE RAT-BRAIN STEM BY RESERPINE

Reserpine evokes transsynaptic impulse activity by depleting catecholaminergic neurotransmitters in the rat brain. Previous studies suggest a relationship between catecholaminergic activity and calmodulin concentration. In this report we employ Northern blot analysis to examine the effect of a single subcutaneous injection of reserpine on levels of calmodulin mRNA species which are preferentially expressed in neurons of the rat brain. Regional differences in mRNA levels were also investigated by in situ hybridization and drug-induced changes were noted particularly in specific regions of the rat brain stem. The riboprobe used in the in situ hybridization study recognized a 4.0 kilobase neuronal calmodulin mRNA species (NGB1), which was derived from the rat CaM1 gene. A calmodulin radio-immunoassay was utilized to demonstrate a drug-induced increased in calmodulin protein levels in a region which included the brain stem.