Article

Deafness associated changes in two-pore domain potassium channels in the rat inferior colliculus.

Kresge Hearing Research Institute, Department of Otolaryngology, Head and Neck, Surgery, University of Michigan, 1301 East Ann Street, Ann Arbor, MI 48109-0506, USA.
Neuroscience (impact factor: 3.38). 11/2007; 149(2):421-33. DOI:10.1016/j.neuroscience.2007.05.054 pp.421-33
Source: PubMed

ABSTRACT Two-pore potassium channels can influence neuronal excitability by regulating background leakage of potassium ions and resting membrane potential. The present study used quantitative real time PCR and in situ hybridization to determine if the decreased activity from deafness would induce changes in two-pore potassium channel subunit expression in the rat inferior colliculus (IC). Ten subunits were assessed with quantitative real-time PCR at 3 days, 3 weeks and 3 months following bilateral cochlear ablation. TASK-1, TASK-5 and THIK-2 showed significant decreases in expression at all three times assessed. TASK-5, relatively specific to auditory neurons, had the greatest decrease. TWIK-1 was significantly decreased at 3 weeks and 3 months following deafness and TREK-2 was only significantly decreased at 3 days. TASK-3, TWIK-2, THIK-1, TRAAK and TREK-1 did not show any significant changes in gene expression. In situ hybridization was used to examine TASK-1, TASK-5, TWIK-1 and THIK-2 in the central nucleus, dorsal cortex and lateral (external) cortex of the IC in normal hearing animals and at 3 weeks following deafening. All four subunits showed expression in neurons throughout IC subdivisions in normal hearing rats, with TASK-5 having the greatest overall number of labeled neurons. There was no co-localization of subunit expression with glial fibrillary acidic protein immunostaining, indicating no expression in glia. Three weeks following deafening there was a significant decrease in the number of neurons expressing TASK-1 and THIK-2 in the IC, while TASK-5 had significant decreases in the central nucleus and dorsal cortex and TWIK-1 in the lateral and dorsal cortices.

0 0
 · 
0 Bookmarks
 · 
22 Views
  • Article: Structure, chromosome localization, and tissue distribution of the mouse twik K+ channel gene.
    I Arrighi, F Lesage, J C Scimeca, G F Carle, J Barhanin
    [show abstract] [hide abstract]
    ABSTRACT: We have recently discovered a new class of potassium channels with two pore-forming domains and four membrane-spanning domains. When heterologously expressed, these channels produce time- and voltage-independent currents that classify them as background or leak channels. TWIK (for tandem of P domains in a weak inwardly rectifying K+ channel) was the first member of this family to be cloned. Here, we describe the genomic organization of TWIK in the mouse. The coding sequence as well as the untranslated sequences are contained in three exons. The twik gene (or KCNK1) has been mapped to chromosome 8, consistent with its localization to 1q42-43 in human. The twik gene is expressed in virtually all mouse tissues. It is most abundantly expressed in brain and moderately in other organs such as kidney. The level of expression is increased in brain and kidney from neonate to adult animals, but the TWIK message is also detected during embryogenesis, as early as day 7 post conception.
    FEBS Letters 04/1998; 425(2):310-6. · 3.54 Impact Factor
  • Article: Deafness associated changes in expression of two-pore domain potassium channels in the rat cochlear nucleus.
    Avril Genene Holt, Mikiya Asako, R Keith Duncan, Catherine A Lomax, Jose M Juiz, Richard A Altschuler
    [show abstract] [hide abstract]
    ABSTRACT: Two-pore domain potassium channels (K(2PD)+) play an important role in setting resting membrane potential by regulating background leakage of potassium ions, which in turn controls neuronal excitability. To determine whether these channels contribute to activity-dependent plasticity following deafness, we used quantitative real-time PCR to examine the expression of 10 K(2PD)+ subunits in the rat cochlear nucleus at 3 days, 3 weeks and 3 months after bilateral cochlear ablation. There was a large sustained decrease in the expression of TASK-5, a subunit that is predominantly expressed in auditory brain stem neurons, and in the TASK-1 subunit which is highly expressed in several types of cochlear nucleus neurons. TWIK-1 and THIK-2 also showed significant decreases in expression that were maintained across all time points. TWIK-2, TREK-1 and TREK-2 showed no significant change in expression at 3 days but showed large decreases at 3 weeks and 3 months following deafness. TRAAK and TASK-3 subunits showed significant decreases at 3 days and 3 weeks following deafness, but these differences were no longer significant at 3 months. Dramatic changes in expression of K(2PD)+ subunits suggest these channels may play a role in deafness-associated changes in the excitability of cochlear nucleus neurons.
    Hearing Research 216-217:146-53. · 2.70 Impact Factor
  • Article: Down-regulation of inhibition following unilateral deafening.
    J E Mossop, M J Wilson, D M Caspary, D R Moore
    [show abstract] [hide abstract]
    ABSTRACT: Physiological and neurochemical experiments described here suggest that unilateral deafening causes a reduction in inhibition in the adult gerbil inferior colliculus (IC) contralateral to the deafened ear. Multiple-unit recordings were made from single electrode penetrations in the IC prior to and directly after contralateral cochlear ablation. These recordings showed up to 60% increases in the proportion of sampled loci at which neural activity excited by ipsilateral stimulation was observed after the ablation. Novel excitatory responses were evident within minutes of the ablation. Western blotting for glutamic acid decarboxylase protein levels showed significant decreases in the IC contralateral to cochlear ablation, relative to those in the ipsilateral IC, at 24 h and 7 days survival after the ablation. Four hour or 1 year survival post-ablation did not produce significant contralateral/ipsilateral differences in relation to the control group. Taken together, these results suggest the presence of at least two, short-term mechanisms involved in the central response to cochlear removal, both of which appear to implicate a decreased inhibitory influence. One is a very rapid, stimulus-related, functional unmasking. The other is a more delayed reduction in the capacity of gamma-aminobutyric acid synthesis in the IC.
    Hearing Research 10/2000; 147(1-2):183-7. · 2.70 Impact Factor

Show more

Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

3 days
 
3 weeks
 
decreased activity
 
dorsal cortex
 
dorsal cortices
 
gene expression
 
glial fibrillary acidic protein immunostaining
 
greatest decrease
 
normal hearing rats
 
potassium ions
 
quantitative real time PCR
 
quantitative real-time PCR
 
rat inferior colliculus
 
regulating background leakage
 
resting membrane potential
 
significant changes
 
significant decrease
 
subunit expression
 
two-pore potassium channel subunit expression
 
Two-pore potassium channels
 

Y L Cui