Developmental regulation and adult maintenance of potassium channel proteins (Kv 1.1 and Kv 1.2) in the cochlear nucleus of the rat.
The development and maintenance of the adult expression and distribution of Kv 1.1 and Kv 1.2, two voltage-dependent potassium channel subunits, were investigated in the anteroventral cochlear nucleus (AVCN) of the rat. Both Kv 1.1 and Kv 1.2 were found in AVCN neuronal cell bodies at birth, as detected by in situ hybridization and immunocytochemistry. However, Kv 1.1 and Kv 1.2 were not seen in axons until the end of the third postnatal week. From postnatal day 21 through adulthood, labeling for both potassium channels was in axonal processes, whereas the number of cell bodies labeled for Kv 1.1 decreased and there were no cell bodies labeled for Kv 1.2. Therefore, these two potassium channel proteins are targeted to their final subcellular destinations in axons well after hearing onset. Once the adult distribution pattern of Kv 1.1 and Kv 1.2 is attained, its maintenance does not depend on signals from auditory nerve synapses. Eliminating auditory nerve input to the cochlear nucleus by means of bilateral cochleotomy did not change Kv 1.1 or Kv 1.2 expression or distribution, as seen by in situ hybridization, immunocytochemistry and Western blot. Thus, normal excitatory synaptic input in adult animals is not a requirement to regulate the expression and cellular and subcellular distribution of these potassium channel proteins.
Caminos
Elena
E
Facultad de Medicina and Centro Regional de Investigaciones Biomédicas (CRIB), Universidad de Castilla-La Mancha, 02006 Albacete, Spain.
Vale
Carmen
C
Lujan
Rafael
R
Martinez-Galan
Juan Ramon
JR
Juiz
José M
JM
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western / Q000379:methods; D064032:Calbindin 2; D002452:Cell Count / Q000379:methods; D017626:Cochlear Nucleus / Q000254:growth & development / Q000293:injuries / Q000378:metabolism* / Q000648:ultrastructure; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization / Q000379:methods; D051662:Kv1.1 Potassium Channel / Q000235:genetics / Q000378:metabolism*; D051663:Kv1.2 Potassium Channel / Q000378:metabolism*; D016253:Microscopy, Immunoelectron / Q000379:methods; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism / Q000648:ultrastructure; D016708:Synaptophysin / Q000378:metabolism
D064032:Calbindin 2; C489293:Kcna1 protein, rat; D051663:Kv1.2 Potassium Channel; C489787:MAP2 protein, rat; D008869:Microtubule-Associated Proteins; D064030:S100 Calcium Binding Protein G; D016708:Synaptophysin; D051662:Kv1.1 Potassium Channel