Group i metabotropic glutamate receptors in spiral ganglion neurons contribute to excitatory neurotransmissions in the cochlea

Loss of GABAB Receptors in Cochlear Neurons: Threshold Elevation Suggests Modulation of Outer Hair Cell Function by Type II Afferent Fibers

“…Indirect pharmacological evidence for lack of AMPA-type receptors in OHCs is provided by the observation that cochlear perfusion of AMPA agonists evokes swelling of afferent dendrites in the IHC area (Pujol and Puel 1999), reminiscent of the excitotoxic effects seen after acoustic overexposure (Robertson 1983), whereas no histologic consequences of either manipulation are seen beneath the OHCs (Pujol and Lenoir 1986). There is limited in situ hybridization data suggesting that both type I and type II afferents express metabotropic glutamate receptors (e.g., mGluR1: Peng et al 2004); however, the main afferent transmitter at the OHC/type II synapse remains a matter of speculation.…”

Connexin29 Is Highly Expressed in Cochlear Schwann Cells, and It Is Required for the Normal Development and Function of the Auditory Nerve of Mice

“…Both techniques are widely used in both research and clinical practices to assess the hearing functions (Whitehead et al, 1996). Details of the ABR and noise exposure protocols can be found in our previous publication (Peng et al, 2004b). Briefly, mice were anesthetized with ketamine (80 mg/kg) and xylazine (10 mg/kg).…”

“…Sounds, consisting of either click or tone bursts of various frequencies (10 ms in duration and a rise-fall time of 0.5 ms), were generated by Tucker-Davis System II hardware and software (TuckerDavis Technologies, Alachua, FL). For testing noise sensitivities, wildtype and Cx29 Ϫ/Ϫ mice were exposed to white-band noise [110 dB sound pressure level (SPL)] for 1 h to create temporary threshold shifts (TTSs) (Peng et al, 2004b). The long-term effect of noise exposures on hearing sensitivity was monitored by measuring ABR thresholds for 4 weeks after noise exposures.…”

Immunocytochemical and pharmacological characterization of metabotropic glutamate receptors of the vestibular end organs in the frog

“…In contrast to Wndings for the frog SCC (Guth et al, 1998b), AIDA also diminished spontaneous activity and slightly aVected the AMPA-and NMDA-induced responses. The evidence directly implicating group I mGluR in cochlear excitatory neurotransmission was obtained by molecular biology, immunolabeling and patch clamp methods (Peng et al, 2004).…”