Fig. 1. cPKC expression and cellular distribution in the spiral ganglion (SG). (A) mRNA levels of cPKCs in P5 rat brain and SG. Semi-quantitative RT-PCR was performed using primers specific for PKC, PKCßI, PKCßII, PKC and ß-actin genes. Densitometric analysis was performed and results are expressed as the ratio of cPKC gene/ß-actin in arbitrary units (au). (B) Immunoblotting for PKC, PKCßI, PKCßII and PKC from P5 rat SG or adult rat hippocampus total protein extracts. All four isoforms of cPKCs are recognised by their specific antibody at the expected molecular weight of 80 kDa in hippocampus protein extracts, whereas only PKC and PKCßI isoforms are present in SG extracts. Each western blot was repeated on at least three different occasions, and with protein extracts from distinct SG samples. (C) Representative confocal micrographs of P5 rat SG sections selected in the medial cochlear turn and double stained for ßIII tubulin (TUJ1, neuronal marker) and different cPKC isoforms detected with the antibodies used in western blot experiments. Anti-PKC antibody reveals a ubiquitous expression towards SG cells whereas anti-PKCßI antibody stains SGNs exclusively. No PKCßII or PKC were detected in SG sections. The experiments were performed in triplicate and repeated on at least three independent occasions, and observations were made in all cochlear turns, with similar results. Bar, 40 µm.