Expression Of Atrial Natriuretic Peptides In Primary Cultured Spiral Ganglion Neurons From Cochlea Of Rat

AIMThe purpose of this study to observe whether there was a expression of atrial natriuretic peptides(ANP)in primary cultured spiral ganglion neurons(SGN)from cochlea of rat, and to explain the significance of that.MethodsCultured and purified SGN were establish from postnatal day 3～5 Sprague-Dawley rats in vitro. The process of cellular growth and differentiation of SGN were observed by fluorescent inverted/phase contrast microscope. To identify the cultured SGN derived from neurons, the expression of neuron-specific nuclear protein(NeuN)in cultured cells was examined by immunocytochemistry. The expression of ANP in cultured SGN was also examined by immunocytochemistry and reverse-transcription polymerase chain reaction(RT-PCR).ResultsThe trypsin dissociated and cultured SGN of SD rats could survive well and had a normal phenotypic differentiation in vitro. The stable neuronal plasticity of SGN existed in the postnatal SD rats under the present experimental conditions. The neuron-specific nuclear protein(NeuN)was positive in cultured SGN, and ANP immunoreactive granules localized around the perinuclear cytoplasm of neurons. Co-expression of ANP and NeuN in SGN was confirmed by immunofluorescence staining, and the expression of ANP-mRNA was aslo detected by RT-PCR.ConclusionThe results suggested that primary cultured SGN which were derived from neurons could express and synthesize ANP, indicating that the ANP might play a role as a neurotransmitter or neuromodulator in neuromodulation of physiological activity and neurotransmission in SGN of the inner ear.