Súhrn Východiska: Cieľom práce je študovať účinok ionizujúceho žiarenia na populáciu buniek, ktorá sa podieľa na zložení hipokampálnej formácie v mozgu dospelého potkana. Materiál a metodika: V experimente sme ožiarili dospelé samce potkanov kmeňa Wistar celotelovou frakcionovanou dávkou gama žiarenia (celková dávka 4 Gy). Po uplynutí zvolených časových intervalov (30, 60 a 90 dní po ožiarení) sme pomocou imunohistochemického farbenia identifikovali bunkové typy, ktoré sa nachádzajú v oblastiach CA1, CA3 hipokampu a v priľahlých vrstvách. Pomocou markera Ki-67 sme identifikovali proliferujúce bunky a na detekciu astrocytov sme použili marker GFAP. Výsledky: Pozoruhodný nárast v počte Ki-67-pozitívnych buniek sme zaznamenali tridsať dní po ožiarení, ktorý bol následne vystriedaný ich výrazným poklesom do 60. dňa po expozícii, najmä v oblasti CA1 a opätovným miernym nárastom do 90. dňa po radiačnom zásahu. V počte astrocytov sme zaznamenali ich dočasný úbytok tridsať dní po ožiarení a následné zvýšenie do 60. dňa. V poslednej skupine, ktorá prežívala deväťdesiat dní po expozícii, sme zistili sekundárny pokles GFAP-pozitívnych buniek v obidvoch sledovaných oblastiach. Záver: Výsledky poukazujú na to, že postradiačná odpoveď neurónov a astrocytov, ktoré sa podieľajú na zložení hippokampu, môže zohrávať určitú úlohu vo vývoji neskorých postradiačných prejavov, ktoré sú z hľadiska prognózy nepriaznivejšie.
Backgrounds: The aim of the present study was to investigate the effect of ionizing radiation on the cell population that co-forms hippocampal formation in an adult rat brain. Materials and Methods: Adult male Wistar rats were exposed to whole-body irradiation with fractionated doses of gamma rays (the total dose of 4 Gy). Thirty, 60 and 90 days after irradiation the cell-specific types housed in the CA1, CA3 subregions and adjacent layers were labelled using immunohistochemistry for specific cell phenotypes; Ki-67 marker was used for proliferating cells and GFAP for detection of astrocytes. Results: During the 30th day post-exposure, a considerable increase in the numbers of Ki-67-positive cells was seen. Moreover, significant decline in the density of neurons, mostly in the CA1 subregion, was observed on the 60th day. Slight overaccumulation of Ki-67-positive cells was seen in CA1 area 90 days after radiation treatment. Temporary decrease of GFAP-positive astrocytes was seen thirty days after irradiation, followed by their subsequent increase 60 days after exposure. Secondary decrease of GFAP-positive cells in both of regions was found in the group surviving 90 days post-irradiation. Conclusion: Results showed that radiation response of neurons and astrocytes that form the adult hippocampus may play contributory role in the development of prognostically unfavourable adverse radiation-induced late effect.
- MeSH
- antigen Ki-67 účinky léků účinky záření MeSH
- astrocyty účinky léků účinky záření MeSH
- biologie buňky MeSH
- celotělové ozáření MeSH
- dávka záření MeSH
- experimenty na zvířatech MeSH
- financování organizované MeSH
- hipokampální oblast CA1 cytologie účinky záření MeSH
- hipokampální oblast CA2 cytologie účinky záření MeSH
- hipokampální oblast CA3 cytologie účinky záření MeSH
- hipokampus cytologie účinky záření zranění MeSH
- imunohistochemie metody využití MeSH
- potkani Wistar MeSH
- proliferace buněk účinky záření MeSH
- proteiny nervové tkáně diagnostické užití účinky záření MeSH
- statistika jako téma MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
Hippocampal lesions in newborn rats alter the development of mechanisms involved in the processing of nociception. The hippocampal lesion was induced by the bilateral infusion, into the lateral cerebral ventricles, of 0.25 microL of saline containing either 0.25 micromol quinolinic acid (QUIN) and/or 0.25 micromol N-acetyl-L-aspartyl-L-glutamate (NAAG) on postnatal day 12. The same amount of sterile saline was injected into the sham-operated animals (group SHAM). It was expected that the QUIN- and NAAG-lesioned rats would exhibit some differences in thermal pain perception; however, we wanted to know if the control rats would exhibit, at least in part, similar changes in pain perception as their chemically lesioned siblings with which they were housed. Young adult NAAG-injured rats exhibited increased withdrawal latencies in the tail-flick and plantar tests, whereas young adult QUIN-injured animals exhibited only marginally decreased latencies. Nociceptive responses in the SHAM rats paralleled the littermates that had been neonatally treated with QUIN or NAAG, i.e. the responses in the SHAM(QUIN) group decreased, whereas the responses in the SHAM(NAAG) group increased. No significant changes in nociception were observed in intact animals, regardless of which group they were housed with. Our results show that social factors, which were originally demonstrated only for the pain behavior, may also influence basal nociceptive sensitivity in rats. We concluded that the "sham operation" may have had a long-term, nonspecific impact on nociceptive behavior by inducing behavioral mimicry of other animals.
- MeSH
- dipeptidy farmakologie MeSH
- financování organizované MeSH
- hipokampus zranění MeSH
- interpretace statistických dat MeSH
- krysa rodu rattus MeSH
- kyselina chinolinová farmakologie MeSH
- měření bolesti účinky léků MeSH
- nociceptory fyziologie účinky léků MeSH
- novorozená zvířata fyziologie MeSH
- reakční čas účinky léků MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
PURPOSE: Our study is focused on the magnetic resonance imaging (MRI) observation of lesion development and hippocampus related functional impairments in rats after irradiation with a Leksell Gamma knife (LGK). MATERIALS AND METHODS: We exposed 32 three-month-old Long-Evans rats to various radiation doses (25 Gy, 50 Gy or 75 Gy). The rats were scanned by a 4.7 T magnetic resonance (MR) spectrometer at several timepoints (1 - 18 months) after irradiation. The lesion size was evaluated by manual segmentation; the animals were behaviorally tested in a Morris water maze and examined histologically. RESULTS: We found that a dose of 25 Gy induced no edema, necrosis or behavioral change. The response of the rats to higher doses was not uniform; the first occurrence of lesions in the rat brains irradiated with 50 and 75 Gy was detected six months post-irradiation. Functional impairment correlated well with the lesion size and histology. CONCLUSIONS: Rat brains showed the development of expanding delayed lesions after 50 or 75 Gy doses from the LGK during the first year after irradiation.
- MeSH
- dávka záření MeSH
- financování organizované MeSH
- hipokampus patologie zranění MeSH
- krysa rodu rattus MeSH
- magnetická rezonanční tomografie MeSH
- poranění mozku etiologie patologie MeSH
- potkani Long-Evans MeSH
- radiační poranění etiologie patologie MeSH
- radiochirurgie škodlivé účinky MeSH
- vztah dávky záření a odpovědi MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
Hippocampal activity is thought to encode spatial representations in a distributed associative network. This idea predicts that partial hippocampal lesions would spare acquisition and impair retrieval of a place response as long as enough connections remained intact to encode associations. Water maze experiments supported the predictions, but the prediction of impaired retrieval was not supported when tetrodotoxin (TTX) was injected into one hippocampus and rats were tested in a place avoidance task on a rotating arena with shallow water. The rotation dissociated relevant distal stimuli from irrelevant self-motion stimuli. To explain the discrepancy, we hypothesized that the segregation of relevant and irrelevant stimuli and stimuli association into representations are distinct hippocampus-dependent operations, and whereas associative representation is more sensitive to disruption during retrieval than learning, stimulus segregation is more sensitive to disruption during learning than during retrieval. The following predictions were tested: (1) the TTX injection would spare learning but (2) impair retrieval of a place response in the water maze, which has a high associative representational demand but a low demand for segregation; (3) the injection would impair learning but (4) spare retrieval of place avoidance in the rotating arena filled with water, which has a high demand for stimulus segregation but a low associative representational demand. All four predictions were confirmed. The hypothesis also explains the pattern of sparing and impairment after the TTX injection in other place avoidance task variants, leading us to conclude that stimulus separation and association representation are dissociable functions of the hippocampus.
- MeSH
- analýza rozptylu MeSH
- anestetika lokální toxicita MeSH
- bludiště - učení fyziologie účinky léků MeSH
- časové faktory MeSH
- chování zvířat MeSH
- financování organizované MeSH
- hipokampus fyziologie účinky léků zranění MeSH
- krysa rodu rattus MeSH
- poruchy paměti patofyziologie MeSH
- potkani Long-Evans MeSH
- rozpomínání fyziologie účinky léků MeSH
- tetrodotoxin toxicita MeSH
- učení vyhýbat se fyziologie účinky léků MeSH
- úniková reakce fyziologie účinky léků MeSH
- vnímání prostoru fyziologie účinky léků MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
- MeSH
- hipokampus fyziologie zranění MeSH
- krysa rodu rattus MeSH
- percepce vzdálenosti MeSH
- prostorové chování MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- Publikační typ
- srovnávací studie MeSH
