1
|
Sorensen SA, Rubel EW. Relative input strength rapidly regulates dendritic structure of chick auditory brainstem neurons. J Comp Neurol 2011; 519:2838-51. [PMID: 21500196 PMCID: PMC3196591 DOI: 10.1002/cne.22656] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Competition between presynaptic inputs has been suggested to shape dendritic form. This hypothesis can be directly tested on bitufted, auditory neurons in chicken nucleus laminaris (NL). Each NL neuron contains two relatively symmetrical dendritic arbors; the dorsal dendrites receive excitatory glutamatergic input from the ipsilateral ear, and the ventral dendrites receive corresponding input from the contralateral ear. To assess the effect of relative synaptic strength on NL dendrites, we used single-cell electroporation; electrophysiology; and live, two-photon laser scanning microscopy to manipulate both the amount and the balance of synaptic input to the two matching sets of dendrites. With simultaneous activation, both sets of dendrites changed together, either growing or retracting over the imaging period. In contrast, stimulation of only one set of dendrites (either dorsal or ventral) resulted in the unstimulated dendrites losing total dendritic branch length, whereas the stimulated dendrites exhibited a tendency to grow. In this system, balanced input leads to balanced changes in the two sets of dendrites, but imbalanced input results in differential changes. Time-lapse imaging revealed that NL dendrites respond to differential stimulation by first decreasing the size of their unstimulated dendrites and then increasing the size of their stimulated dendrites. This result suggests that the relative activity of presynaptic neurons dynamically controls dendritic structure in NL and that dendritic real estate can rapidly be shifted from inactive inputs to active inputs.
Collapse
Affiliation(s)
- Staci A Sorensen
- Allen Institute for Brain Science, Seattle, Washington 98113, USA
| | | |
Collapse
|
2
|
Prevention of normally occurring and deafferentation-induced neuronal death in chick brainstem auditory neurons by periodic blockade of AMPA/kainate receptors. J Neurosci 1997. [PMID: 9169534 DOI: 10.1523/jneurosci.17-12-04744.1997] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The role of glutamate receptors in regulating programmed neuronal death and deafferentation-induced neuronal death in the brainstem auditory nuclei was studied by in ovo drug administration to chick embryos. The nucleus laminaris (NL) undergoes programmed developmental cell death of 19% between embryonic day 9 (E9) and E17. The AMPA/kainate receptor antagonist CNQX, when administered at doses of 200-300 microg/d from E8 to E15, prevented programmed neuronal death in NL through at least posthatching day 8, without producing anatomical or behavioral abnormalities. 3-((RS)-2-Carboxypiperazin-4-yl)-propyl-1-phos-phonic acid, an antagonist of NMDA receptors, had no effect on normal cell death in the NL. CNQX, given from E8 to E15 or only from E8 to E10, also blocked the 33% neuronal loss in the nucleus magnocellularis (NM) that follows surgical destruction of the otocyst on E3, a procedure that deafferents NM neurons by preventing formation of the cochlear nerve. Treatment either with CNQX or the more highly selective NBQX from E8 to E10, before the onset of synaptic transmission in NM and NL, was also effective in preventing normal neuronal death in NL. Analysis of the effects of CNQX or NBQX on spontaneous embryonic motility at E10 showed that the doses effective in preventing neuronal death suppressed motility for <8 hr. We conclude that periodic blockade of AMPA/kainate receptors can protect CNS neurons against subsequent programmed cell death or deafferentation-induced death.
Collapse
|
3
|
Dong JF, Detta A, Bakker MH, Hitchcock ER. Direct interaction with target-derived glia enhances survival but not differentiation of human fetal mesencephalic dopaminergic neurons. Neuroscience 1993; 56:53-60. [PMID: 8232917 DOI: 10.1016/0306-4522(93)90561-s] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Regulation of the developing nervous system involves attraction, guidance and modification of innervating neurons by target cells through diffusible and membrane-related factors. The trophic effects from specific cell types remain to be investigated and characterized. In a series of experiments in which human fetal mesencephalic dopaminergic cells were co-cultured with target or non-target neurons or glial cells in direct or contiguous contact, we demonstrate that striatal glial cells (target-derived glia) can enhance dopaminergic neuron survival by up to 400% compared to either non-target cell co-cultures or mesencephalic controls. When in direct contact with striatal neurons, a greater proportion of dopaminergic neurons had a more differentiated morphology. The enhancement of dopaminergic neuron survival by target-derived glia appears to be mediated both by direct contact, possibly through target membrane-specific phenomena, and by diffusible substances, whereas non-target glia appear to exert the trophic effects predominantly through the latter mechanism. The finding that target neurons influence mainly dopaminergic neuron differentiation and target glia their survival indicates multiple, target cell type-specific regulation of innervating neuron development. These findings also have relevance to the establishment of neuronal cultures for neural transplantation.
Collapse
Affiliation(s)
- J F Dong
- Department of Neurosurgery, University of Birmingham, Midlands Centre for Neurosurgery and Neurology, Smethwick, U.K
| | | | | | | |
Collapse
|
4
|
Zhou N, Parks TN. Developmental changes in the effects of drugs acting at NMDA or non-NMDA receptors on synaptic transmission in the chick cochlear nucleus (nuc. magnocellularis). BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1992; 67:145-52. [PMID: 1380899 DOI: 10.1016/0165-3806(92)90215-i] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The developmental pharmacology of excitatory amino acid (EAA) receptors in the chick cochlear nucleus (nucleus magnocellularis, NM) was studied by means of bath application of drugs and recording of synaptically-evoked field potentials in brain slices taken from chicks aged embryonic day (E) 14 through hatching (E21). The abilities of various EAA agonists (N-methyl-D-aspartate [NMDA], kainic acid, and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid [AMPA]) to suppress postsynaptic responses by depolarization block and of EAA antagonists ((3-[RS]-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid [CCP], dizocilpine [MK-801], 6-nitro-7-sulfamoyl-benzo(F)quinoxaline-2,3 dione [NBQX], 6-cyano-7-nitroquinoxaline-2,3-dione [CNQX] and 6,7-dinitroquinoxaline-2,3-dione [DNQX]) to suppress these responses directly were assessed quantitatively. The results support the existence of NMDA receptors in NM and suggest that the ability of these receptors to influence synaptically-evoked responses declines dramatically during the last week of embryonic life. The results similarly suggest that the non-NMDA receptors in NM undergo changes in density and/or function during a period of development when the cochlear nucleus is undergoing a variety of morphological and functional transformations.
Collapse
Affiliation(s)
- N Zhou
- Department of Anatomy, University of Utah School of Medicine, Salt Lake City 84132
| | | |
Collapse
|
5
|
Sutton JK, Brunso-Bechtold JK. A Golgi study of dendritic development in the dorsal lateral geniculate nucleus of normal ferrets. J Comp Neurol 1991; 309:71-85. [PMID: 1716647 DOI: 10.1002/cne.903090106] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The development of neurons in the dorsal lateral geniculate nucleus (dLGN) of pigmented ferrets was studied by using the Golgi-Hortega technique. In adult ferrets, four dLGN cell classes were defined on the basis of somatic and dendritic morphology. Classes 1 and 2 were divided into stellate and oriented subtypes. Class 1 and 4 cells are characterized by filiform appendages, class 2 cells by club-like appendages, and class 3 cells by stalked appendages. At birth, dLGN neurons have simple dendritic arbors. During the first postnatal week, dendritic length and proximal branching density increase markedly. By postnatal day 21 (P21), dendritic morphology begins to take on mature characteristics and by the time of eye opening (P30-P35), most neurons can be classified. Also by that time, dLGN cells are covered with abundant filiform appendages. Developmental changes in appendage density were quantified for class 1 stellate cells. These data reveal that appendage density reaches a peak at P56, decreases sharply until P90, and then gradually declines to mature levels by P180. Elaboration and elimination of transient appendages occurs centrifugally; at maturity appendage density remains greater distally.
Collapse
Affiliation(s)
- J K Sutton
- Department of Neurobiology and Anatomy, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27103
| | | |
Collapse
|
6
|
Abstract
The receptors mediating excitatory neurotransmission from the cochlear nucleus (nuc. magnocellularis, NM) to third-order auditory neurons in nucleus laminaris (NL) of the chicken were studied using in vitro brain slices, bath application of drugs, and electrophysiological recording of postsynaptic field potentials. Postsynaptic responses in NL were blocked completely, in a concentration-dependent and reversible fashion, by bath application of the broad-spectrum excitatory amino acid (EAA) antagonist kynurenic acid, the 'non-NMDA' EAA receptor antagonists 6,7-dinitroquinoxaline-2,3-dione (DNQX) and 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline (NBQX), and the EAA agonists domoic acid, kainic acid, alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA), and quisqualic acid. The selective NMDA receptor antagonists 3-[-)-2-carboxypiperazin-4-yl)propyl-1-phosphonate (CPP) and dibenzocycloheptenimine (MK-801) had no effect. The results demonstrate that excitatory input from the cochlear nucleus to NL is mediated by non-NMDA (G2) EAA receptors which exhibit some of the pharmacologic features typical of the AMPA receptors defined by binding studies.
Collapse
Affiliation(s)
- N Zhou
- Department of Anatomy, University of Utah School of Medicine, Salt Lake City 84132
| | | |
Collapse
|
7
|
Moore DR. Auditory brainstem of the ferret: early cessation of developmental sensitivity of neurons in the cochlear nucleus to removal of the cochlea. J Comp Neurol 1990; 302:810-23. [PMID: 2081818 DOI: 10.1002/cne.903020412] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The role of primary afferent innervation in the maintenance of neurons in the mammalian auditory system was assessed by performing unilateral removals of the cochlea in neonatal and mature ferrets of known birth dates. Removals were performed under steroid anesthesia and resulted in the complete destruction of the organ of Corti and the loss of at least 80% of type I spiral ganglion neurons. Four main age groups [postnatal days (P)5, P24, P90, and P180] were used. Additional animals received no surgery, partial removals, or complete removals at older ages. Three months after the cochlear removal the animals were reanesthetized and perfused. The brainstem and the temporal bones were wax-embedded, frontally sectioned, and Nissl-stained. Sections of the right and left cochlear nuclei were compared quantitatively. Removal of the cochlea at P5 resulted in the loss of more than 50% of large (nongranular) neurons throughout the ipsilateral cochlear nucleus. Lesions at older ages did not produce any neuron loss. The size of the remaining neurons was reduced by 10-15% in all age groups. Partial lesions at P5 produced a graded response in the cochlear nucleus that was related to the extent of the lesion. The developmental sensitive period for the effects of cochlear removal on the ferret cochlear nucleus is therefore over before the age (P28-P30) at which the animal begins to hear. The present result differs markedly from the chicken, in which the sensitive period for removal of the cochlea persists for at least 2 months after the onset of hearing.
Collapse
Affiliation(s)
- D R Moore
- University Laboratory of Physiology, Oxford, United Kingdom
| |
Collapse
|
8
|
Schweitzer L. Differentiation of apical, basal and mixed dendrites of fusiform cells in the cochlear nucleus. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1990; 56:19-27. [PMID: 2279328 DOI: 10.1016/0165-3806(90)90159-v] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Many studies suggest that the details of morphogenesis (e.g. the length and number of dendrites) are determined by factors extrinsic to the cell, while the basic form of the neuron (e.g. the shape of the soma and the placement of the primary dendritic trunks) is determined by intrinsic factors. The following study describes the development of the dendrites of fusiform cells in the dorsal cochlear nucleus of the hamster using Golgi-stained brains from hamsters of various ages. Two basic types of dendrites are described--apical and basal--which emanate from opposite ends of the cell body and differ in their morphology. A third type of dendrite that exits the cell laterally can create a deflection in the perimeter of the cell body altering its shape. The morphology of these dendrites is described and compared to the apical and basal dendrites. Segments of laterally extending dendrites that are near apical dendrites are qualitatively and quantitatively identical to apical dendrites (that is they branch frequently and are spine-laden) and the converse is true of the segments near basal dendrites. The results suggest that during development, whether a dendritic will be apical-like or basal-like is determined by the location of its distal segment. Thus, extrinsic factors influence the overall form of these neurons.
Collapse
Affiliation(s)
- L Schweitzer
- Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, KY 40292
| |
Collapse
|
9
|
Fritzsch B. Experimental reorganization in the alar plate of the clawed toad, Xenopus laevis. I. Quantitative and qualitative effects of embryonic otocyst extirpation. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1990; 51:113-22. [PMID: 2297887 DOI: 10.1016/0165-3806(90)90263-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The area octavolateralis and the lateral line projections were examined in larval and postmetamorphic clawed toads, which had one otic vesicle removed at embryonic stage 38 (ref. 20). Premetamorphic tadpoles show a smaller octavolateral area on the operated side as compared to the contralateral control side. This area is in postmetamorphic toadlets significantly reduced as compared to the control side. The largest cells of the magnocellular vestibular nucleus show no significant difference in size to the contralateral side. A dorsolateral auditory nucleus develops prior to metamorphosis and shows in tadpoles no differences in cell size. Cell of this nucleus are in small toads only about 60% the size of cells in the contralateral nucleus. Countings in toadlets indicate a reduction of 40% in cell number on the operated side. Both tadpoles and small toads show virtually no differences in the lateral line projection compared to controls. Only rare collaterals of lateral line fibres can be traced into the neighbouring vestibular and auditory nuclei. The data show no preferential innervation of inner ear afferent deprived auditory and vestibular nuclei by lateral line afferents. In contrast, some collaterals of somatosensory fibres reach into the area deprived of octaval afferents.
Collapse
Affiliation(s)
- B Fritzsch
- University of Bielefeld, Faculty of Biology, F.R.G
| |
Collapse
|
10
|
Moore DR, Kowalchuk NE. Auditory brainstem of the ferret: effects of unilateral cochlear lesions on cochlear nucleus volume and projections to the inferior colliculus. J Comp Neurol 1988; 272:503-15. [PMID: 2843582 DOI: 10.1002/cne.902720405] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Unilateral lesions of the right cochlea were made in ferrets aged postnatal day (P)12 to P93. The extent of the lesions was assessed by counting remaining hair cells and ganglion cells in midmodiolar sections through the lesioned cochleas and by comparison with a sample of unlesioned cochleas. The neural effects of the lesions were assessed by measuring the volume of each cochlear nucleus (CN) and by counting the number of neurons in each CN that were retrogradely labeled following injections of WGA-HRP in the left inferior colliculus (IC). Survival times between lesioning and injection of the tracer ranged from 11 to 98 days. CN volume and projections to the IC were also measured in a sample of normal adult ferrets and in normal infants aged P39 to P80. Cochlear lesions resulted in a reduction of the volume of the CN on the lesioned side, relative to the other CN, in animals of all ages and survival times. The extent of the CN volume reduction was negatively correlated with the number of remaining cochlear ganglion cells. However, even where the number of ganglion cells was within the normal range, significant volume reductions occurred. The ventral CN was more severely affected by the lesions than the dorsal CN, but no difference was found between the anteroventral and posteroventral divisions of the nucleus. There was no significant difference in the extent of CN volume reductions between animals of different ages or survival times. Lesions of the right cochlea in younger animals (P14 to P24) resulted, after 90 days survival, in an increase in the number of left CN neurons projecting to the left IC. No significant increase was seen following lesions in older (P90) ferrets or following short (11 or 30 days) survival times in young (P14 to P24) ferrets. The extent of the increase in the ipsilateral CN-IC projection was not related to the number of remaining ganglion cells or to the division of the CN examined. Lesions did not affect the contralateral CN-IC projection. We conclude that cochlear lesions in infant ferrets can alter auditory brainstem morphology and connectivity. The dependence of these alterations on the age of the animal, survival time following lesion, and extent of the lesion varies markedly with the index examined.
Collapse
Affiliation(s)
- D R Moore
- University Laboratory of Physiology, Oxford, England
| | | |
Collapse
|
11
|
Jackson H, Parks TN. Induction of aberrant functional afferents to the chick cochlear nucleus. J Comp Neurol 1988; 271:106-14. [PMID: 3385006 DOI: 10.1002/cne.902710111] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Surgical extirpation of the otocyst on embryonic day (E) 3 in chick embryos prevents formation of the cochlear nerve and results in development of an aberrant axonal projection from the contralateral cochlear nucleus (nucleus magnocellularis, NM) to the deafferented NM. We have studied the morphology of this projection using horseradish peroxidase injections in NM axons and light and electron microscopy. The ability of the projection to activate its target neurons synaptically was assessed by means of extracellular microelectrode recording from in vitro preparations of the chick brainstem. The aberrant projection arises as a vertically directed branch from the contralaterally traveling NM axon at the medial border of nucleus laminaris (NL). This axonal branch forms boutonal endings that may terminate anywhere in NM but are most common in its ventral and medial regions. In our experiments, this projection is not seen on the unoperated side of experimental animals or in normal controls from E11 onward but is found on the operated sides of all experimental animals, including those with bilateral removal of the otocysts. The aberrant projection persists at least from E11 through hatching and has essentially identical features in unilaterally and bilaterally lesioned animals. The endings of the aberrant projection are boutonal in form and, in the electron microscope, exhibit all of the elements associated with normal synapses. Electrophysiological studies confirm that stimulation of the aberrant axons can elicit postsynaptic responses in NM and suggest that these synapses use an excitatory amino acid neurotransmitter.
Collapse
Affiliation(s)
- H Jackson
- Department of Anatomy, University of Utah School of Medicine, Salt Lake City 84132
| | | |
Collapse
|