Objective: To investigate the expression of gamma-aminobutyric acid (GABA)A receptor alpha 2 subunit mRNA on rat cochlear spiral neurons and its' significance.
Methods: In the rat cochlear paraffin slides, the GABAA alpha 2 receptor in spiral ganglion neuron was detected with in situ hybridization. Digoxigenin-GABAA alpha 2 cDNA probe (549 base pair), anti-digoxigenin-AP(Fab fragments) and BM purple substrate(precipitating) were used.
Results: Positive signals(GABAA alpha 2 mRNA) were seen in all cochlear spiral neurons and their nerves. GABAA alpha 2 mRNA was not found in other structure such as bony spiral lamina. As a positive control, GABAA alpha 2 mRNA was seen in Purkinje cells, granule cells and their axons in rat's cerebellum. GABAA alpha 2 mRNA was not found in OMP cDNA probe (olfactory membrane estrogen receptor probe) negative control, non-probe negative control and non-anti-digoxingenin control in cochlear spiral neuron and cerebellum.
Conclusion: GABAA alpha 2 receptor has been found in type I spiral neurons and their nerves. It strongly indicates that GABA as a nerve transmitter plays an important role in inhibiting the excessive stimulation transmission of the inner hair cells.