The role of inositol trisphosphate on ACh-induced outward currents in bullfrog saccular hair cells

1994 ◽  
Vol 644 (1) ◽  
pp. 90-100 ◽  
Author(s):  
Naohiro Yoshida ◽  
Takashi Shigemoto ◽  
Tokio Sugai ◽  
Harunori Ohmori
Keyword(s):  
Hair Cells ◽  
Inositol Trisphosphate ◽  
Outward Currents

scholarly journals 5-HT and GABA Modulate Intrinsic Excitability of Type I Interneurons in Hermissenda

2009 ◽  
Vol 102 (5) ◽  
pp. 2825-2833 ◽  
Author(s):  
Nan Ge Jin ◽  
Lian-Ming Tian ◽  
Terry Crow
Keyword(s):  
Hair Cells ◽  
Spike Activity ◽  
Potential Role ◽  
Neuronal Excitability ◽  
Intrinsic Excitability ◽  
Resting Membrane Potential ◽  
Type I ◽  
Outward Currents

The sensory neurons (photoreceptors) in the visual system of Hermissenda are one site of plasticity produced by Pavlovian conditioning. A second site of plasticity produced by conditioning is the type I interneurons in the cerebropleural ganglia. Both photoreceptors and statocyst hair cells of the graviceptive system form monosynaptic connections with identified type I interneurons. Two proposed neurotransmitters in the graviceptive system, serotonin (5-HT) and γ-aminobutyric acid (GABA), have been shown to modify synaptic strength and intrinsic neuronal excitability in identified photoreceptors. However, the potential role of 5-HT and GABA in plasticity of type I interneurons has not been investigated. Here we show that 5-HT increased the peak amplitude of light-evoked complex excitatory postsynaptic potentials (EPSPs), enhanced intrinsic excitability, and increased spike activity of identified type Ie(A) interneurons. In contrast, 5-HT decreased spike activity and intrinsic excitability of type Ie(B) interneurons. The classification of two categories of type Ie interneurons was also supported by the observation that 5-HT produced opposite effects on whole cell steady-state outward currents in type Ie interneurons. Serotonin produced a reduction in the amplitude of light-evoked complex inhibitory PSPs (IPSPs), increased spontaneous spike activity, decreased intrinsic excitability, and depolarized the resting membrane potential of identified type Ii interneurons. In contrast to the effects of 5-HT, GABA produced inhibition in both types of Ie interneurons and type Ii interneurons. These results show that 5-HT and GABA can modulate the intrinsic excitability of type I interneurons independent of the presynaptic effects of the same transmitters on excitability and synaptic efficacy of photoreceptors.

Magnesium and Hearing

2003 ◽  
Vol 14 (04) ◽  
pp. 202-212 ◽  
Author(s):  
Michael J. Cevette ◽  
Jürgen Vormann ◽  
Kay Franz
Keyword(s):  
Hair Cells ◽  
Auditory Nerve ◽  
Mg Deficiency ◽  
Noise Damage ◽  
Susceptibility To Noise ◽  
Major Progress ◽  
A Current ◽  
Putative Mechanism ◽  
Increased Susceptibility

The last several decades have revealed clinical and experimental data regarding the importance of magnesium (Mg) in hearing. Increased susceptibility to noise damage, ototoxicity, and auditory hyperexcitibility are linked to states of Mg deficiency. Evidence for these processes has come slowly and direct effects have remained elusive because plasma Mg levels do not always correlate with its deficiency. Despite the major progress in the understanding of cochlear mechanical and auditory nerve function, the neurochemical and pharmacologic role of Mg is not clear. The putative mechanism suggests that Mg deficiency may contribute to a metabolic cellular cascade of events. Mg deficiency leads to an increased permeability of the calcium channel in the hair cells with a consequent over influx of calcium, an increased release of glutamate via exocytosis, and over stimulation of NMDA receptors on the auditory nerve. This paper provides a current overview of relevant Mg metabolism and deficiency and its influence on hearing.

The role of plant villin in the organization of the actin cytoskeleton, cytoplasmic streaming and the architecture of the transvacuolar strand in root hair cells of Hydrocharis

Planta ◽  
2000 ◽  
Vol 210 (5) ◽  
pp. 836-843 ◽  
Author(s):  
Motoki Tominaga ◽  
Etsuo Yokota ◽  
Luis Vidali ◽  
Seiji Sonobe ◽  
Peter K. Hepler ◽  
...  
Keyword(s):  
Actin Cytoskeleton ◽  
Hair Cells ◽  
Root Hair ◽  
Cytoplasmic Streaming ◽  
Root Hair Cells

Phosphoinositide synthesis in desensitized rat pancreatic acinar cells

1995 ◽  
Vol 268 (6) ◽  
pp. G1043-G1050
Author(s):  
J. S. Lods ◽  
B. Rossignol ◽  
C. Dreux ◽  
J. Morisset
Keyword(s):  
Phorbol Ester ◽  
Inositol Trisphosphate ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Basal Rate ◽  
Phosphoinositide Turnover ◽  
Dose Dependent

To help understand the possible role of phosphoinositide turnover in the desensitization process, the availability of phosphatidylinositol 4,5-bisphosphate was investigated in normal and desensitized pancreatic acinar cells treated with carbamylcholine (Cch), caerulein (Cae), and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). In control acini, incorporation of [myo-3H]inositol into total phosphoinositides was maximal at 120 min, was Cch and Cae dose dependent, and was insensitive to TPA. Cch stimulation increased the proportion of [myo-3H]inositol incorporated into phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2], whereas Cae specifically channeled [myo-3H]inositol incorporation into phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate. In the desensitized cells, preexposure to Cch and Cae, but not to TPA, increased the subsequent basal rate of [myo-3H]inositol incorporation into total phosphoinositol (PI) by 66 and 50% above control values. There were no subsequent responses to increasing concentrations of Cch, Cae, and TPA during a second incubation. Desensitization of the pancreatic secretory responses to Cch, Cae, and TPA does not seem to result from a decrease either in total PI or in specific PtdIns(4,5)P2 synthesis, which is needed for inositol trisphosphate and diacylglycerol production.

scholarly journals Critical role of spectrin in hearing development and deafness

2019 ◽  
Vol 5 (4) ◽  
pp. eaav7803 ◽  
Author(s):  
Yan Liu ◽  
Jieyu Qi ◽  
Xin Chen ◽  
Mingliang Tang ◽  
Cenfeng Chu ◽  
...  
Keyword(s):  
Hair Cells ◽  
Knockout Mice ◽  
Crucial Role ◽  
Structural Organization ◽  
Critical Role ◽  
Super Resolution ◽  
Mechanical Vibrations ◽  
Hearing Ability ◽  
Profound Deafness

Inner ear hair cells (HCs) detect sound through the deflection of mechanosensory stereocilia. Stereocilia are inserted into the cuticular plate of HCs by parallel actin rootlets, where they convert sound-induced mechanical vibrations into electrical signals. The molecules that support these rootlets and enable them to withstand constant mechanical stresses underpin our ability to hear. However, the structures of these molecules have remained unknown. We hypothesized that αII- and βII-spectrin subunits fulfill this role, and investigated their structural organization in rodent HCs. Using super-resolution fluorescence imaging, we found that spectrin formed ring-like structures around the base of stereocilia rootlets. These spectrin rings were associated with the hearing ability of mice. Further, HC-specific, βII-spectrin knockout mice displayed profound deafness. Overall, our work has identified and characterized structures of spectrin that play a crucial role in mammalian hearing development.

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