The Postnatal Growth of Cochlear Nucleus Subdivisions and Neuronal Somata of the Anteroventral Cochlear Nucleus in the Mongolian Gerbil (Meriones unguiculatus)

1998 ◽  
Vol 3 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Otto Gleich ◽  
Celia Kadow ◽  
Jürgen Strutz
Keyword(s):  
Mongolian Gerbil ◽  
Cochlear Nucleus ◽  
Postnatal Growth ◽  
Meriones Unguiculatus ◽  
Neuronal Somata ◽  
Anteroventral Cochlear Nucleus

Microcysys in the Posteroventral Cochlear Nucleus of the Gerbil by Scanning Electron Microscopy

1997 ◽  
Vol 3 (S2) ◽  
pp. 257-258
Author(s):  
S.M. Yu ◽  
C.I. Lee
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Cochlear Nucleus ◽  
Phosphate Buffer ◽  
Neurodegenerative Disorder ◽  
Meriones Unguiculatus ◽  
Anteroventral Cochlear Nucleus ◽  
Critical Point Drying ◽  
Ethanol Series ◽  
Scanning Electron

Microcysts are most evident in the posteroventral and anteroventral cochlear nucleus (PVCN & AVCN) of the gerbil. They are reported as a neurodegenerative disorder or spongioform degeneration or a dynamic process related to the degree of auditory stimulation in the cochlear nucleus of the gerbil. Little information is avalable on the origin and formation of microcysts in the cochlear nucleus of the gerbil. The aim of this study was to investigate the internal morphologic changes of microcysts in the gerbil PVCN during postnatal development by scanning electron microscopy.The mongolian gerbil, Meriones unguiculatus, were sacrificed by cardiac perfusion of a saline nitrite flush, followed by a 3% glutaraldehyde in 0.1M phosphate buffer. After fixation the brain were washed in 0.1M phosphate buffer ,embedded in 5% agar, vibratome-sliced through the cochlear nucleus, and then postfixed in the 1% osmium tetroxide in 0.1M phosphate buffer for one hour. The sectioned tissues were dehydrated in a graded ethanol series to absolute ethanol and transferred to liquid carbon dioxide for critical point drying.

Development of Chloride-Mediated Inhibition in Neurons of the Anteroventral Cochlear Nucleus of Gerbil (Meriones unguiculatus)

2007 ◽  
Vol 98 (3) ◽  
pp. 1634-1644 ◽  
Author(s):  
Ivan Milenković ◽  
Mirko Witte ◽  
Rostislav Tureček ◽  
Marco Heinrich ◽  
Thomas Reinert ◽  
...  
Keyword(s):  
Cochlear Nucleus ◽  
Neuronal Development ◽  
Reversal Potential ◽  
Meriones Unguiculatus ◽  
Postnatal Life ◽  
Interaural Time Differences ◽  
Positive Direction ◽  
Gabaergic Neurotransmission ◽  
Chloride Homeostasis ◽  
Anteroventral Cochlear Nucleus

At the initial stages in neuronal development, GABAergic and glycinergic neurotransmission exert depolarizing responses, assumed to be of importance for maturation, which in turn shift to hyperpolarizing in early postnatal life due to development of the chloride homeostasis system. Spherical bushy cells (SBC) of the mammalian cochlear nucleus integrate excitatory glutamatergic inputs with inhibitory (GABAergic and glycinergic) inputs to compute signals that contribute to sound localization based on interaural time differences. To provide a fundamental understanding of the properties of GABAergic neurotransmission in mammalian cochlear nucleus, we investigated the reversal potential of the GABA-evoked currents ( EGABA) by means of gramicidin-perforated-patch recordings in developing SBC. The action of GABA switches from depolarizing to hyperpolarizing by the postnatal day 7 due to the negative shift in EGABA. Furthermore, we studied the expression pattern of the K+-Cl−-extruding cotransporter KCC2, previously shown to induce a switch from neonatal Cl− efflux to the mature Cl− influx in various neuron types, thereby causing a shift from depolarizing to hyperpolarizing GABA action. The KCC2 protein is expressed in SBC already at birth, yet its activity is attained toward the end of the first postnatal week as indicated by pharmacological inhibition. Interruption of the Cl− extrusion by [(dihydroindenyl)oxy] alkanoic acid or furosemide gradually shifted EGABA in positive direction with increasing maturity, suggesting that KCC2 could be involved in maintaining low [Cl−]i after the postnatal day 7 thereby providing the hyperpolarizing Cl−-mediated inhibition in SBC.

Morphologic changes in the anteroventral cochlear nucleus of acoustically-deprived gerbil

1995 ◽  
Vol 53 ◽  
pp. 960-961
Author(s):  
Shang-Ming Yu ◽  
Shian-Jyue Du
Keyword(s):  
Mongolian Gerbil ◽  
External Auditory Canal ◽  
Cochlear Nucleus ◽  
Neurodegenerative Disorder ◽  
Auditory Thresholds ◽  
Anteroventral Cochlear Nucleus ◽  
Time Courses ◽  
The Right ◽  
Conductive Hearing ◽  
Morphologic Changes

Microcystic lesions are reported as a neurodegenerative disorder in the cochlear nucleus of the Mongolian gerbil. These lesions resemble the spongioform degeneration. Such lesions are large holes, cavities or vacuoles and are also known as the microcysts. The microcysts develop in the neuropil or appear in the neuronal perikarya, degenerated axons and dendrites. The number and size of the microcysts is greatly reduced either by the elevation of auditory thresholds or by the conductive hearing loss induced by ligation of the external auditory canal. Furthermore, absence of the microcysts is found in the old deaf animals. This study was to investigate the morphologic changes in the anteroventral cochlear nucleus (AVCN) of the acoustically-deprived gerbil following the sequence of time courses after ligation of the external auditory canal during postnatal development.The mongolian gerbil, Meriones unguiculatus, had been acoustically deprived on the right side by a surgical ligation of the external auditory canal at postnatal day 12-14.

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