INGEBI   02650
INSTITUTO DE INVESTIGACIONES EN INGENIERIA GENETICA Y BIOLOGIA MOLECULAR "DR. HECTOR N TORRES"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Shaping auditory pathways: Effect of a mutation in the nicotinic cholinergic receptor of hair cells on central auditory pathways
Autor/es:
TORBIDONI V.
Lugar:
Chicago, IL, United States
Reunión:
Simposio; IBRO Alumni Symposium during Society for Neuroscience 2009; 2009
Institución organizadora:
IBRO
Resumen:
&lt;!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:ES-AR; mso-fareast-language:ES-AR;} p.MsoHeader, li.MsoHeader, div.MsoHeader {mso-style-link:" Car Car2"; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; tab-stops:center 220.95pt right 441.9pt; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:ES-AR; mso-fareast-language:ES-AR;} span.CarCar2 {mso-style-name:" Car Car2"; mso-style-locked:yes; mso-style-link:Encabezado; mso-ansi-font-size:12.0pt; mso-bidi-font-size:12.0pt; mso-ansi-language:ES-AR; mso-fareast-language:ES-AR; mso-bidi-language:AR-SA;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:35.4pt; mso-footer-margin:35.4pt; mso-paper-source:0;} div.Section1 {page:Section1;} --&gt; Introduction: I have just started my Post doctoral work in a new laboratory, where we are studying the auditory system. There are two different types of hair cells in the Organ of Corti of the cochlea: inner hair cells (IHCs) that transform the sound information into electrical signals and outer hair cells (OHCs) known as the cochlear amplifier, because they increase the sound-evoked motions of the organ of Corti. Sound processing is modulated by efferent terminals, one of them synapsing with OHCs. These terminals release acetylcholine (ACh) that acting on heteromeric nicotinic receptor α9/α10 (nAChR) of the OHCs, inhibits amplification and thus reduces cochlear sensitivity. In the Dr.’s Elgoyhen laboratory, where I am working as a postdoc, a knock-in mouse with a mutation at 9 position of α9 subunit of the α9/α10 receptor (L9’T knock-in, Ki) has been generated. This change determined a gain in the receptor function (Taranda et al. 2009). Purpose: analyze if this cochlear modification in the nAChR could induce molecular changes at any of the different nuclei of the central auditory pathways. Material and Methods: Wild type (WT) and L9’T Ki mice of postnatal day 11 and 20 (P11 and P20), before and after onset of hearing respectively. We used immunohistochemistry of brainstem cryosections to analyze the Medial Nucleus of the Trapezoid Body (MNTB), an important nucleus  in sound processing and localization. We study Voltage-sensitive K channels (Kv1.1), particularly important in determining the discharge patterns of neurons. We measured the immunoreactivity to Kv1.1 along the medial-lateral axe dividing the MNTB it in three areas: lateral, intermediate and medial. Results: We found that the Kv1.1 immunoreactivity was present in all neurons along the medial lateral axe of the MNTB in both types of animals. There was a week correlation between the intensity of the immunoreactivity to Kv1.1 with the area along the medial-lateral axe in WT animals, being stronger in lateral areas than in medial. At P11, we observed a decrease in the Kv1.1 immunoreactivity in L9’T Ki animals (p<0,05) in all areas measured. After the onset of hearing these differences were still detected. Future: Test the differences in Kv1.1 between WT and L9’T Ki by other techniques (Western blot, RT-PCR). Analyze other molecules such us: NMDA, AMPA, GABA-R. Perform electrophysiology of the MNTB. Analyze other relay centers of the auditory pathway. Conclusions: Kv1.1 channels are concentrated in neurons of the MNTB. The modification of the activity the nAChR of OHC induced a reduction in the intensity of Kv1.1 immunoreactivity in the MNTB in P11 and P20.