NEURONAL EXPRESSION OF HIPPOCAMPAL CHOLINERGIC NEUROSTIMULATING PEPTIDE (HCNP)-PRECURSOR MESSENGER-RNA IN RAT-BRAIN

The expression of hippocampal cholinergic neuro-stimulating peptide (H CNP)-precursor mRNA in rat brain was examined by Northern blot and in situ hybridization analyses. Northern blot analysis using rat HCNP-pre cursor cDNA revealed a 1.1-kilobase (kb) transcript. A message of iden tical size was also detected with the antisense precursor riboprobe. I n situ hybridization disclosed that HCNP-precursor mRNA was expressed in many areas of the brain, including the basal forebrain cholinergic system, the olfactory system, and the cerebellum. Very high levels wer e seen in the pyramidal cells of the CA3 region and in the hilus of th e dentate gyrus of the hippocampal formation. High levels were also fo und in the septal area, piriform cortex, entorhinal cortex, thalamic n uclei, subthalamic nuclei, medial habenular nuclei, substantia nigra. Purkinje cells of the cerebellum, and choroid plexus, By contrast, gli al cells were not labeled by the antisense HCNP-precursor riboprobe. T he expression of HCNP-precursor mRNA by a variety of neurons suggests that HCNP and its precursor protein play significant roles in the stim ulation of cholinergic activity, as well as in other not yet defined f unctions. (C) 1996 Wiley-Liss, Inc.