The development, maturation, and maintenance of the inner ear are governed by temporal and spatial expression cascades of transcription factors that form a gene regulatory network. ISLET1 (ISL1) may be one of the major players in this cascade, and in order to study its role in the regulation of inner ear development, we produced a transgenic mouse overexpressing Isl1 under the Pax2 promoter. Pax2-regulated ISL1 overexpression increases the embryonic ISL1(+) domain and induces accelerated nerve fiber extension and branching in E12.5 embryos. Despite these gains in early development, the overexpression of ISL1 impairs the maintenance and function of hair cells of the organ of Corti. Mutant mice exhibit hyperactivity, circling behavior, and progressive age-related decline in hearing functions, which is reflected in reduced otoacoustic emissions (DPOAEs) followed by elevated hearing thresholds. The reduction of the amplitude of DPOAEs in transgenic mice was first detected at 1 month of age. By 6-9 months of age, DPOAEs completely disappeared, suggesting a functional inefficiency of outer hair cells (OHCs). The timing of DPOAE reduction coincides with the onset of the deterioration of cochlear efferent terminals. In contrast to these effects on efferents, we only found a moderate loss of OHCs and spiral ganglion neurons. For the first time, our results show that the genetic alteration of the medial olivocochlear (MOC) efferent system induces an early onset of age-related hearing loss. Thus, the neurodegeneration of the MOC system could be a contributing factor to the pathology of age-related hearing loss.
- MeSH
- analýza přežití MeSH
- embryo savčí metabolismus patologie MeSH
- ganglion spirale patologie MeSH
- kochlea inervace patologie patofyziologie MeSH
- messenger RNA genetika metabolismus MeSH
- molekulární motory metabolismus MeSH
- myši transgenní MeSH
- nedoslýchavost patologie patofyziologie MeSH
- neurony eferentní MeSH
- otoakustické emise spontánní MeSH
- počet buněk MeSH
- proteiny s homeodoménou LIM metabolismus MeSH
- sluchový práh MeSH
- stárnutí patologie MeSH
- transkripční faktor PAX2 metabolismus MeSH
- transkripční faktory metabolismus MeSH
- vnější vláskové buňky patologie MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Direct drug delivery to the cochlea is associated with the risk of irreversible damage to the ear. In this study, liposome and polymersome nanoparticles (NPs), both formed from amphiphilic molecules (lipids in liposomes and block copolymers in polymersomes), were tested as potential tools for drug delivery to the cochlea via application onto the round window membrane in adult mice (strain C3H). One day after round window membrane application, both types of NPs labeled with fluorescent markers were identified in the spiral ganglion in all cochlear turns without producing any distinct morphological or functional damage to the inner ear. NPs were detected, although to a lesser extent, in the organ of Corti and the lateral wall. The potential of liposome and polymersome NPs as therapeutic delivery systems into the cochlea via the round window membrane was evaluated using disulfiram, a neurotoxic agent, as a model payload. Disulfiram-loaded NP delivery resulted in a significant decrease in the number of spiral ganglion cells starting 2 days postapplication, with associated pronounced hearing loss reaching 20-35 dB 2 weeks postapplication as assessed through auditory brainstem responses. No changes in hair cell morphology and function (as assessed by recording otoacoustic emissions) were detected after disulfiram-loaded NP application. No effects were observed in controls where solution of free disulfiram was similarly administered. The results demonstrate that liposome and polymersome NPs are capable of carrying a payload into the inner ear that elicits a biological effect, with consequences measurable by a functional readout.
- MeSH
- apoptóza účinky léků MeSH
- Cortiho orgán účinky léků ultrastruktura MeSH
- cytotoxiny aplikace a dávkování farmakologie MeSH
- disulfiram aplikace a dávkování farmakologie MeSH
- fenestra rotunda účinky léků metabolismus ultrastruktura MeSH
- ganglion spirale cytologie účinky léků MeSH
- kaspasa 3 metabolismus MeSH
- kochlea účinky léků metabolismus ultrastruktura MeSH
- lékové transportní systémy metody MeSH
- liposomy analýza MeSH
- myši MeSH
- nanočástice analýza MeSH
- povrchově aktivní látky chemie MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Calbindin (CB) and S100 are calcium-binding proteins expressed in the inner ear in vertebrates. Information about their developmental roles is incomplete. This study investigated the expression patterns of CB and S100 in C3H mice using immunohistochemistry, from embryonic day 11 (E11) to postnatal day 10 (P10). CB was expressed in the otocyst and vestibulocochlear ganglion (VCG) from E11. In the cochlea at E17, CB immunoreactivity clearly labeled the VCG, the outer and inner hair cells, and the stria vascularis. CB staining was also present in the vestibular sensory cells, including their nerve fibers. Two days later, to this expression pattern was added the labeling of Kolliker's organ. Early postnatal CB expression encompassed VCG neurons, auditory hair cells, their afferent nerve fibers, and cells of the cochlear lateral wall. The first signs of S100 immunostaining of cochlear and vestibular epithelial cells appeared at E14. At E17 S100 immunoreactivity was found in a restricted expression pattern in the cochlea. Immunostaining was also present in the sacculus and utriculus and their afferent fibers. The Deiters', pillar and inner hair cells, and the VCG were S100-positive from E19. Postnatally, S100 staining also appeared in the inner hair cells and Deiters' cells, in some VCG neurons, and, in addition, in the spiral limbus, the spiral prominence, and the intermediate cells of the stria vascularis. This study demonstrates that the sites of CB and S100 expression in the mouse inner ear during embryonic and early postnatal development do not overlap and signal independent developmental patterns. (c) 2009 Wiley-Liss, Inc.
- MeSH
- embryo savčí MeSH
- financování organizované MeSH
- imunohistochemie MeSH
- kochlea embryologie metabolismus růst a vývoj MeSH
- myši inbrední C3H MeSH
- myši MeSH
- neurony metabolismus MeSH
- novorozená zvířata MeSH
- proteiny S100 metabolismus MeSH
- S100 kalcium vázající protein G MeSH
- stria vascularis metabolismus MeSH
- těhotenství MeSH
- tkáňová distribuce MeSH
- vláskové buňky metabolismus MeSH
- vnitřní ucho embryologie metabolismus růst a vývoj MeSH
- western blotting MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- zvířata MeSH
The effect of a low dose of vinclozolin within the development of the reproductive tract during gestation (VIN-GD 15-22) and puberty (VIN-PND 23-44) in CD1 mice was tested. We found a decrease in the anogenital distance, prostate weight and pathology of testes in both experimental groups. Sperm counts decreased to 46% (VIN-GD) and to 81% (VIN-PND), and also the acrosomal state (evaluated by antiacrosomal antibody) decreased in both groups to 89% in comparison to the control group (100%). Sperm head abnormalities increased by approximately 18% and 13%, respectively. In this connection, the expression of some genes was changed (arosome-related gene (Acr), apoptosis related genes (p53, p21)). In conclusion, a low dose of vinclozolin affected the reproductive tract, sperm parameters and expression of selected genes in both experimental groups.
- MeSH
- antagonisté androgenů toxicita MeSH
- mužské pohlavní orgány embryologie účinky léků MeSH
- myši inbrední ICR MeSH
- myši MeSH
- oxazoly toxicita MeSH
- plod účinky léků MeSH
- polymerázová řetězová reakce s reverzní transkripcí MeSH
- průmyslové fungicidy toxicita MeSH
- spermatogeneze MeSH
- těhotenství MeSH
- tělesná hmotnost účinky léků MeSH
- testis metabolismus účinky léků MeSH
- ubikvitin metabolismus MeSH
- velikost orgánu účinky léků MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- myši MeSH
- těhotenství MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
The effect of low dose of fungicide vinclozolin within development of reproductive tract during gestation (GD) and puberty (PND) in outbred CD1 mice was tested. We found a decrease in the anogenital distance, prostate weight and pathology of testes in both experimental groups. Marked negative influence has had on sperm parameters. Sperm counts decreased to 46% (GD) and to 81% (PND) and also acrosomal state (evaluated by antiacrosomal antibody) decreased in both groups to 89% in comparison to control group (100%). Sperm head abnormalities increased about 18% and 13%, respectively. In this connection the expression some genes was changed (arosome– related gene (Acr), apoptosis related genes (p53, p21)). In conclusion, low dose of vinclozolin affected the reproductive tract, sperm parameters and expression of selected genes in both experimental groups. The work was supported by the Grants of the Ministry of Education of the Czech Republic, grant No. 1M06011 and 2B06151 and in part by the Institutional Research Support AVOZ 50520701.
The Fischer 344 rat strain has been frequently used as an animal model of rapid aging. The present study was aimed at evaluating the incidence of apoptotic cells in the inner ear of 20-24-month-old F344 rats and to correlate it with cochlear function using otoacoustic emissions. Staining with cresyl violet and the enzymatic labeling (terminal deoxynucleotidyl transferase, TdT) of fragmented DNA revealed large numbers of apoptotic cells in the marginal and basal layers of the stria vascularis and in adjacent cells of the spiral ligament. The amplitudes of distortion products otoacoustic emissions (DPOAEs), which reflect functional state of the outer hair cells, were significantly reduced or totally absent in these animals. In contrast to old F344 rats, no marked DPOAE amplitude reduction and smaller numbers of apoptotic cells were found in young 4-month-old F344 rats or in aged 24-28-month-old Long Evans rats. The accumulation of apoptotic cells, mainly in the basal layer of the stria vascularis and in adjacent cells of the spiral ligament, leads to a detachment of the stria vascularis from the spiral ligament and results in the impairment of outer hair cell function. This specific type of strial deterioration suggests that aged F344 rats can serve as an animal model of strial presbycusis.
- MeSH
- apoptóza MeSH
- buněčná smrt MeSH
- druhová specificita MeSH
- financování organizované MeSH
- fragmentace DNA MeSH
- imunohistochemie MeSH
- kochlea cytologie fyziologie růst a vývoj MeSH
- krysa rodu rattus MeSH
- modely u zvířat MeSH
- potkani inbrední F344 fyziologie růst a vývoj MeSH
- sluch fyziologie MeSH
- stárnutí fyziologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
Many chemicals released into the environment can interfere with the action of the endocrine system through diverse mechanisms in animals and humans. This includes chemicals that occur naturally in plants such as phytoestrogens and also manmade chemicals (xenoestrogens). In our study we selected xenoestrogens (bisphenol-A (BPA), p-nonylphenol (NP), diethylstilbestrol (DES)) and phytoestrogens (genistein (GEN), resveratrol (RES)). All these pollutants represent of endocrine disruptors (ED). The effect of BPA, NP, DES, GEN and RES on the body weight, weight of different organs, sperm acrosomal status and in vivo fertility of CD1 mice was tested in a multigenerational study. The adult parental generation of mice and F1 and F2 generations were exposed to selected drugs for all their life. BPA and NP had a negative effect on offspring born of mice, on reproductive organs, and acrosome integrity of mice spermatozoa. Different effect was found in P, F1 and F2 generations. The fertility of mice exposed to DES was disrupted, especially in the first generation. Contrary to that, treatment by GEN and RES had no effect on fertility of CD1 mice but had some effect on reproductive parameters except of sperm integrity. Monoclonal antibodies against intra-acrosomal sperm proteins were used as biomarkers of sperm damage.
Hearing function in the Fischer 344 (F344) albino inbred strain of rats deteriorates with aging faster than in other strains, in spite of the small hair cell loss in old F344 animals [Popelar, J., Groh, D., Pelanova, J., Canlon, B., Syka, J., 2005. Age-related changes in cochlear and brainstem auditory function. Neurobiol. Aging, in press.]. This study was aimed at elucidating the structural changes in the inner ear of this rat strain during aging. Cochlear histopathology was examined in 20-24-month-old F344 rats and compared with that of young F344 rats (4 months) and of old rats of the Long-Evans (LE) strain. Hematoxylin/eosin staining in aged F344 rats showed degenerative changes in the organ of Corti, consisting of a damaged layer of marginal cells, reduced vascularization of the stria vascularis and a distorted tectorial membrane detached from the organ of Corti. Age-related changes in collagen distribution were observed with Masson's trichrome staining in the spiral ligament of old F344 rats. The results of immunohistochemical staining for type II collagen revealed a marked decrease in collagen fibers in the area connecting the spiral ligament and stria vascularis and a decrease in area IV fibrocytes in old F344 but not in LE rats. These findings may contribute to an explanation of the substantial hearing loss found in old F344 rats.
- MeSH
- azosloučeniny analýza MeSH
- barvicí látky analýza MeSH
- Cortiho orgán chemie MeSH
- eosin analýza MeSH
- fluorescenční barviva analýza MeSH
- hematoxylin analýza MeSH
- imunohistochemie metody MeSH
- kochlea * fyziologie chemie MeSH
- kolagen typ II analýza MeSH
- kolagen * analýza MeSH
- krysa rodu rattus MeSH
- membrana tectoria chemie MeSH
- methylová zeleň analýza MeSH
- potkani inbrední F344 MeSH
- stárnutí * fyziologie MeSH
- stria vascularis chemie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
