cyclin-d1 and Cognition-Disorders

Increasing evidence has suggested cognitive impairment and neuronal apoptosis induced by anaesthetics are due to abnormal hyperphosphorylation of tau protein, but the detailed mechanism remains unknown.. Aged mice and neurons were both exposed to 2.5% sevoflurane for 2h. Spatial learning ability of the aged mice was tested with Morris water maze. The changes of neuroapoptosis, tau protein and cell-cycle-related factors (cyclin D1, p27) were determined using Western blot analysis. The effect of sevoflurane exposure on DNA synthesis was tested with immunofluorescent staining.. We found that sevoflurane significantly impaired spatial learning ability in aged mice. In addition, total tau protein. phosphorylated tau protein, Caspase-3 and cyclin D1, but not p27Kip1 were drastically increased in the hippocampus. Consistent with the results from in vivo study, sevoflurane significantly increased the expression of cyclin D1 and Brdu positive neurons in cultured hippocampal neurons. The enhancement of cyclin D1 was partially reversed by the pharmacological inhibition of hyperphosphorylation of tau.. Our results suggested that cyclin D1 overexpression may result in the neuronal apoptosis through cell cycle re-entry and the deficits in postoperative cognitive dysfunction after sevoflurane exposure. Our research will improve the current understanding of the mechanisms underlying the postoperative cognitive dysfunction by anaesthetics exposure.

Topics: Aging; Anesthetics, Inhalation; Animals; Cognition Disorders; Cyclin D1; Hippocampus; Maze Learning; Methyl Ethers; Mice; Mice, Inbred C57BL; Postoperative Period; Sevoflurane

Many patients who have received chemotherapy to treat cancer experience depressive- and anxiety-like symptoms or cognitive impairment. However, despite the evidence for this, the underlying mechanisms are still not understood. This study investigated behavioral and biochemical changes upon treatment with doxorubicin and cyclophosphamide, focusing on mental and cognitive systems, as well as neurogenesis in male rats. Doxorubicin (2 mg/kg), cyclophosphamide (50 mg/kg), and the combination of doxorubicin and cyclophosphamide were injected intraperitoneally once per week for 4 weeks. In particular, the co-administration of doxorubicin and cyclophosphamide produced anhedonia-like, anxiety-like, and spatial cognitive impairments in rats. It also reduced both the number of proliferating cells in the subgranular zone of the hippocampal dentate gyrus and their survival. Serum brain-derived neurotrophic factor (BDNF) levels were decreased along with chemotherapy-induced decreases in platelet levels. However, hippocampal BDNF levels and Bdnf mRNA levels were not decreased by this treatment. On the other hand, hippocampal cyclin D1 levels were significantly decreased by chemotherapy. These results suggest that the co-administration of doxorubicin and cyclophosphamide induces psychological and cognitive impairment, in addition to negatively affecting hippocampal neurogenesis, which may be related to hippocampal cyclin D1 levels, but not hippocampal BDNF levels.

Topics: Animals; Anxiety; Brain-Derived Neurotrophic Factor; Cognition; Cognition Disorders; Cyclin D1; Cyclophosphamide; Depression; Doxorubicin; Hippocampus; Male; Neurogenesis; Rats; Rats, Wistar

Radiation-induced brain injury occurs in many patients receiving cranial radiation therapy, and these deleterious effects are most profound in younger patients. Impaired neurocognitive functions in both humans and rodents are associated with inflammation, demyelination, and neural stem cell dysfunction. Here we evaluated the utility of lithium and a synthetic retinoid receptor agonist in reducing damage in a model of brain-focused irradiation in juvenile mice. We found that lithium stimulated brain progenitor cell proliferation and differentiation following cranial irradiation while also preventing oligodendrocyte loss in the dentate gyrus of juvenile mice. In response to inflammation induced by radiation, which may have encumbered the optimal reparative action of lithium, we used the anti-inflammatory synthetic retinoid Am80 that is in clinical use in the treatment of acute promyelocytic leukemia. Although Am80 reduced the number of cyclooxygenase-2-positive microglial cells following radiation treatment, it did not enhance lithium-induced neurogenesis recovery, and this alone was not significantly different from the effect of lithium on this proinflammatory response. Similarly, lithium was superior to Am80 in supporting the restoration of new doublecortin-positive neurons following irradiation. These data suggest that lithium is superior in its restorative effects to blocking inflammation alone, at least in the case of Am80. Because lithium has been in routine clinical practice for 60 years, these preclinical studies indicate that this drug might be beneficial in reducing post-therapy late effects in patients receiving cranial radiotherapy and that blocking inflammation in this context may not be as advantageous as previously suggested.

Topics: Animals; Behavior, Animal; Benzoates; Brain; Cell Differentiation; Cell Proliferation; Cognition Disorders; Cranial Irradiation; Cyclin D1; Cyclooxygenase 2; Dentate Gyrus; Immunohistochemistry; Inflammation; Lithium; Male; Mice; Mice, Inbred C57BL; Neural Stem Cells; Neurogenesis; Neurons; Oligodendroglia; Radiation Injuries, Experimental; Stem Cells; Tetrahydronaphthalenes