V tomto článku se budeme věnovat chronologicky objevům, resp. hypotézám, které souvisejí právě s Alzheimerovou-Fischerovou chorobou, a to hlavně v kontextu patofyziologie. V rámci pochopení návaznosti jsou jako první zmíněny patologické nálezy, jelikož na jejich základě byly hypotézy postupně vytvářeny. Vzhledem k obrovskému rozsahu jsme se však snažili vybrat pouze některé hypotézy, které jsou nejčastěji zmiňovány nebo z našeho pohledu nejzajímavější. Naším cílem není detailně zmapovat celou novodobou historii, proto se z úvodu 20. století rovnou přesuneme do jeho druhé poloviny. Demence se v tomto období postupně stávaly čím dál větším lékařským a společenským problémem, technologické možnosti zase postupně otevíraly nové možnosti výzkumu.
In this article, we will look at discoveries and hypotheses that were through time linked to Alzheimer‘s-Fischer disease, mainly in the con- text of pathophysiology. As part of the understanding of the link, pathological findings are mentioned first, as on the basis of these, the hypotheses were gradually developed. However, given the enormous scale, we have tried to select only some of the hypotheses that are most frequently mentioned or, from our point of view, the most interesting. Our goal is not to map in detail all of modern history, so we will move directly from the beginning of the 20th century to its second half. Dementia gradually became a growing medical and social problem during this period, while technological possibilities opened up new avenues of research.
- MeSH
- Alzheimerova nemoc * dějiny patofyziologie patologie MeSH
- amyloidový prekurzorový protein beta * dějiny škodlivé účinky MeSH
- dějiny 20. století MeSH
- dějiny 21. století MeSH
- glukokortikoidy škodlivé účinky MeSH
- hyperinzulinismus komplikace MeSH
- lidé MeSH
- melatonin fyziologie MeSH
- mitochondriální membrány patologie MeSH
- mozek anatomie a histologie metabolismus patologie MeSH
- mozková kůra anatomie a histologie patologie MeSH
- neurony patologie MeSH
- střevní mikroflóra MeSH
- zinek nedostatek MeSH
- Check Tag
- dějiny 20. století MeSH
- dějiny 21. století MeSH
- lidé MeSH
- Publikační typ
- historické články MeSH
In previous studies (Grécová et al., Eur J Neurosci 29:1921-1930, 2009; Bures et al., Eur J Neurosci 32:155-164, 2010), we demonstrated that after an early postnatal short noise exposure (8 min 125 dB, day 14) changes in the frequency tuning curves as well as changes in the coding of sound intensity are present in the inferior colliculus (IC) of adult rats. In this study, we analyze on the basis of the Golgi-Cox method the morphology of neurons in the IC, the medial geniculate body (MGB) and the auditory cortex (AC) of 3-month-old Long-Evans rats exposed to identical noise at postnatal day 14 and compare the results to littermate controls. In rats exposed to noise as pups, the mean total length of the neuronal tree was found to be larger in the external cortex and the central nucleus of the IC and in the ventral division of the MGB. In addition, the numerical density of dendritic spines was decreased on the branches of neurons in the ventral division of the MGB in noise-exposed animals. In the AC, the mean total length of the apical dendritic segments of pyramidal neurons was significantly shorter in noise-exposed rats, however, only slight differences with respect to controls were observed in the length of basal dendrites of pyramidal cells as well as in the neuronal trees of AC non-pyramidal neurons. The numerical density of dendritic spines on the branches of pyramidal AC neurons was lower in exposed rats than in controls. These findings demonstrate that early postnatal short noise exposure can induce permanent changes in the development of neurons in the central auditory system, which apparently represent morphological correlates of functional plasticity.
- MeSH
- akustická stimulace MeSH
- colliculus inferior růst a vývoj patologie MeSH
- dendritické trny patologie MeSH
- hluk škodlivé účinky MeSH
- metathalamus růst a vývoj patologie MeSH
- nervová síť patologie MeSH
- neurony patologie MeSH
- neuroplasticita MeSH
- novorozená zvířata MeSH
- potkani Long-Evans MeSH
- pyramidové buňky patologie MeSH
- sluchová dráha patologie MeSH
- sluchové korové centrum růst a vývoj patologie MeSH
- věkové faktory MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In the present study, adult Long-Evans rats were exposed either to natural conspecific aversive 22-kHz vocalizations or to artificial call-like stimuli with comparable frequency-temporal features, followed by c-Fos immunohistochemistry. The natural 22-kHz vocalizations was either played from a recording or produced by a foot-shocked animal located nearby (live vocalizations). In comparison with controls (non-exposed animals), c-Fos immunoreactivity was significantly increased in the inferior colliculus (IC), auditory cortex (AC), periaqueductal grey (PAG), basolateral amygdala (BA), and hippocampus (Hip) of rats exposed to either live or recorded 22-kHz natural vocalizations. Exposure to live natural vocalizations of the foot-shocked animal resulted in a similar pattern of c-Fos activity, as did exposure to the playback of the natural vocalizations. In contrast to this, foot-shocked rats (emitting the 22-kHz vocalizations) had the c-Fos positivity increased markedly in the PAG and only slightly in the AC. The expression of c-Fos also increased in the IC, AC, and in the PAG in animals exposed to the artificial call-like stimuli, when compared to controls; however, the increase was much less pronounced. In this case, c-Fos expression was not increased in the hippocampus or basolateral amygdala. Interestingly, almost no c-Fos expression was found in the medial nucleus of the geniculate body in any of the experimental groups. These findings suggest that differences exist between the processing of important natural conspecific vocalizations and artificial call-like stimuli with similar frequency-temporal features, and moreover they suggest the specific role of individual brain structures in the processing of such calls.
- MeSH
- akustická stimulace MeSH
- krysa rodu rattus MeSH
- limbický systém metabolismus účinky záření MeSH
- mapování mozku MeSH
- potkani Long-Evans MeSH
- protoonkogenní proteiny c-fos metabolismus MeSH
- sluchové korové centrum metabolismus účinky záření MeSH
- vokalizace zvířat * fyziologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
In the present study, an unbiased stereological method was used to determine the number of all neurons in Nissl stained sections of the inferior colliculus (IC), medial geniculate body (MGB), and auditory cortex (AC) in rats (strains Long Evans and Fischer 344) and their changes with aging. In addition, using the optical fractionator and western blot technique, we also evaluated the number of SMI-32-immunoreactive (-ir) neurons and levels of non-phosphorylated neurofilament proteins in the IC, MGB, AC, and visual cortex of young and old rats of the two strains. The SMI-32 positive neuronal population comprises about 10% of all neurons in the rat IC, MGB, and AC and represents a prevalent population of large neurons with highly myelinated and projecting processes. In both Long Evans and Fischer 344 rats, the total number of neurons in the IC was roughly similar to that in the AC. With aging, we found a rather mild and statistically non-significant decline in the total number of neurons in all three analyzed auditory regions in both rat strains. In contrast to this, the absolute number of SMI-32-ir neurons in both Long Evans and Fischer 344 rats significantly decreased with aging in all the examined structures. The western blot technique also revealed a significant age-related decline in the levels of non-phosphorylated neurofilaments in the auditory brain structures, 30-35%. Our results demonstrate that presbycusis in rats is not likely to be primarily associated with changes in the total number of neurons. On the other hand, the pronounced age-related decline in the number of neurons containing non-phosphorylated neurofilaments as well as their protein levels in the central auditory system may contribute to age-related deterioration of hearing function.
- Publikační typ
- časopisecké články MeSH
Aging is accompanied by the deterioration of hearing that complicates our understanding of speech, especially in noisy environments. This deficit is partially caused by the loss of hair cells as well as by the dysfunction of the stria vascularis. However, the central part of the auditory system is also affected by processes accompanying aging that may run independently of those affecting peripheral receptors. Here, we review major changes occurring in the central part of the auditory system during aging. Most of the information that is focused on age-related changes in the central auditory system of experimental animals arises from experiments using immunocytochemical targeting on changes in the glutamic-acid-decarboxylase, parvalbumin, calbindin and calretinin. These data are accompanied by information about age-related changes in the number of neurons as well as about changes in the behavior of experimental animals. Aging is in principle accompanied by atrophy of the gray as well as white matter, resulting in the enlargement of the cerebrospinal fluid space. The human auditory cortex suffers not only from atrophy but also from changes in the content of some metabolites in the aged brain, as shown by magnetic resonance spectroscopy. In addition to this, functional magnetic resonance imaging reveals differences between activation of the central auditory system in the young and old brain. Altogether, the information reviewed in this article speaks in favor of specific age-related changes in the central auditory system that occur mostly independently of the changes in the inner ear and that form the basis of the central presbycusis.
Age-related changes in the levels of major intracellular calcium buffers are known to occur in different parts of the mammalian brain, including the central auditory pathway. In the present study, we evaluate with immunohistochemistry and the western blot technique the effect that aging has on the calbindin- and calretinin-expressing system of neurons in the higher structures of the central auditory pathway, in the inferior colliculus (IC), medial geniculate body (MGB) and auditory cortex (AC) of two rat strains, the slowly aging Long-Evans and the fast aging Fischer 344. Interestingly, the age-related changes demonstrated a similar character regardless of the rat strain. In the IC of young animals, the majority of calbindin and calretinin immuno-reactive (CB and CR-ir) cells were found in the dorsal and external cortices and only sparse positive cells were present in the central nucleus of the IC. With aging, the number of CB-ir and CR-ir neurons decreased significantly in both the dorsal and external cortices. Furthermore, these declines were accompanied by an age-related reduction in the mean volumes of CB- and CR-ir neuronal somas. In the MGB of young rats, CB-ir neurons were present in abundant numbers in both the dorsal and ventral subdivisions, while CR-ir neurons were practically absent in this structure. With aging, the number and mean volume of CB-ir cells in the ventral subdivision of the MGB were significantly decreased. In comparison with the IC and MGB, age-related numerical and volumetric declines of both CB-ir and CR-ir neurons in the AC were less pronounced. Western blot protein analysis revealed a pronounced age-related decline in the levels of calbindin in both strains and in all examined brain regions. In contrast, the decline in calretinin levels with aging was less prominent, with a significant decline only in the IC of both strains. The observed age-related changes in the calbindin- and calretinin-expressing systems may contribute significantly to the deterioration of hearing function known as central presbycusis.
- MeSH
- colliculus inferior metabolismus MeSH
- druhová specificita MeSH
- imunohistochemie MeSH
- krysa rodu rattus MeSH
- metathalamus metabolismus MeSH
- mozek metabolismus MeSH
- neurony metabolismus MeSH
- potkani inbrední F344 MeSH
- potkani Long-Evans MeSH
- S100 kalcium vázající protein G metabolismus MeSH
- sluchové korové centrum metabolismus MeSH
- stárnutí metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
SMI-32 antibody recognizes a non-phosphorylated epitope of neurofilament proteins, which are thought to be necessary for the maintenance of large neurons with highly myelinated processes. We investigated the distribution and quantity of SMI-32-immunoreactive(-ir) neurons in individual parts of the rat auditory system. SMI-32-ir neurons were present in all auditory structures; however, in most regions they constituted only a minority of all neurons (10-30%). In the cochlear nuclei, a higher occurrence of SMI-32-ir neurons was found in the ventral cochlear nucleus. Within the superior olivary complex, SMI-32-ir cells were particularly abundant in the medial nucleus of the trapezoid body (MNTB), the only auditory region where SMI-32-ir neurons constituted an absolute majority of all neurons. In the inferior colliculus, a region with the highest total number of neurons among the rat auditory subcortical structures, the percentage of SMI-32-ir cells was, in contrast to the MNTB, very low. In the medial geniculate body, SMI-32-ir neurons were prevalent in the ventral division. At the cortical level, SMI-32-ir neurons were found mainly in layers III, V and VI. Within the auditory cortex, it was possible to distinguish the Te1, Te2 and Te3 areas on the basis of the variable numerical density and volumes of SMI-32-ir neurons, especially when the pyramidal cells of layer V were taken into account. SMI-32-ir neurons apparently form a representative subpopulation of neurons in all parts of the rat central auditory system and may belong to both the inhibitory and excitatory systems, depending on the particular brain region.
- MeSH
- analýza rozptylu MeSH
- colliculus inferior cytologie metabolismus MeSH
- imunohistochemie MeSH
- krysa rodu rattus MeSH
- metathalamus cytologie metabolismus MeSH
- mikroskopie MeSH
- monoklonální protilátky metabolismus MeSH
- neurofilamentové proteiny metabolismus MeSH
- neurony aferentní metabolismus MeSH
- nucleus cochlearis cytologie metabolismus MeSH
- potkani Long-Evans MeSH
- přední mozek cytologie metabolismus MeSH
- sluchová dráha cytologie MeSH
- sluchové korové centrum cytologie metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The inferior colliculus (IC) plays a strategic role in the central auditory system in relaying and processing acoustical information, and therefore its age-related changes may significantly influence the quality of the auditory function. A very complex processing of acoustical stimuli occurs in the IC, as supported also by the fact that the rat IC contains more neurons than all other subcortical auditory structures combined. GABAergic neurons, which predominantly co-express parvalbumin (PV), are present in the central nucleus of the IC in large numbers and to a lesser extent in the dorsal and external/lateral cortices of the IC. On the other hand, calbindin (CB) and calretinin (CR) are prevalent in the dorsal and external cortices of the IC, with only a few positive neurons in the central nucleus. The relationship between CB and CR expression in the IC and any neurotransmitter system has not yet been well established, but the distribution and morphology of the immunoreactive neurons suggest that they are at least partially non-GABAergic cells. The expression of glutamate decarboxylase (GAD) (a key enzyme for GABA synthesis) and calcium binding proteins (CBPs) in the IC of rats undergoes pronounced changes with aging that involve mostly a decline in protein expression and a decline in the number of immunoreactive neurons. Similar age-related changes in GAD, CB, and CR expression are present in the IC of two rat strains with differently preserved inner ear function up to late senescence (Long-Evans and Fischer 344), which suggests that these changes do not depend exclusively on peripheral deafferentation but are, at least partially, of central origin. These changes may be associated with the age-related deterioration in the processing of the temporal parameters of acoustical stimuli, which is not correlated with hearing threshold shifts, and therefore may contribute to central presbycusis.
- Publikační typ
- časopisecké články MeSH
Changes in the levels of gamma-aminobutyric acid (GABA) are known to occur in different parts of the brain during aging. In our study we attempted to define the effect that aging has on glutamate decarboxylase (GAD), the key enzyme in the synthesis of GABA, in the central parts of the auditory system. Age-related changes in GAD65 and GAD67 levels were investigated using immunohistochemistry and Western blotting in the inferior colliculus (IC), the auditory cortex (AC) and the visual cortex in Long-Evans rats. The results show that aging is associated with a decrease in the numbers of GAD65- and 67-immunoreactive neurons and the optical density of their somas in both the IC and AC. Western blot analysis revealed a pronounced age-related decline in the levels of GAD65 and 67 proteins in both the IC and AC. For comparison, in the visual cortex the decrease in both proteins was less pronounced than in the IC and AC. A similar pattern of age-related changes was found in Fischer 344 rats, a strain that manifests a rapid loss of hearing function with aging. The observed age-related decline in the levels of GAD65 and 67 may contribute significantly to the deterioration of hearing function that accompanies aging in mammals, including man.
- MeSH
- analýza rozptylu MeSH
- colliculus inferior metabolismus MeSH
- druhová specificita MeSH
- GABA fyziologie metabolismus MeSH
- glutamát dekarboxyláza metabolismus MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- potkani inbrední F344 MeSH
- potkani Long-Evans MeSH
- presbyakuze metabolismus MeSH
- protein - isoformy analýza metabolismus MeSH
- sluchové korové centrum metabolismus MeSH
- stárnutí metabolismus MeSH
- western blotting metody MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
Changes in the levels of calcium binding proteins are known to occur in different parts of the brain during aging. In our study we attempted to define the effect that aging has on the parvalbumin-expressing system of neurons in the higher parts of the central auditory system. Age-related changes in parvalbumin immunoreactivity were investigated in the inferior colliculus (IC), medial geniculate body (MGB) and auditory cortex (AC) in two rat strains, normally aging Long-Evans (LE) and fast aging Fischer 344 (F344). The results demonstrate that the changes in PV-immunoreactivity are strain-dependent with an increase in the number of PV-immunoreactive (PV-ir) neurons occurring in the inferior colliculus of old LE rats and a pronounced decline in the number of PV-ir neurons appearing in the auditory cortex of aged F344 animals. In some parts of the AC of old F344 animals no PV-ir neurons were present at all. The number of PV-ir neurons in the MGB in all examined animals was very low independent of the strain and age. The loss of PV-ir neurons in the auditory cortex of Fischer 344 rats with aging may contribute to the substantial deterioration of hearing function in this strain.
- MeSH
- colliculus inferior metabolismus MeSH
- druhová specificita MeSH
- financování organizované MeSH
- krysa rodu rattus MeSH
- metathalamus metabolismus MeSH
- neurony metabolismus MeSH
- parvalbuminy metabolismus MeSH
- potkani inbrední F344 MeSH
- potkani Long-Evans MeSH
- proteiny vázající vápník metabolismus MeSH
- sluchové korové centrum metabolismus MeSH
- stárnutí metabolismus MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
