@article{SunOrtegaTanetal.2018,
  author    = {Sun, Ping and Ortega, Gabriela and Tan, Yan and Hua, Qian and Riederer, Peter F. and Deckert, J{\"u}rgen and Schmitt-B{\"o}hrer, Angelika G.},
  title     = {Streptozotocin impairs proliferation and differentiation of adult hippocampal neural stem cells in vitro-correlation with alterations in the expression of proteins associated with the insulin system},
  series = {Frontiers in Aging Neuroscience},
  volume    = {10},
  journal   = {Frontiers in Aging Neuroscience},
  number    = {145},
  doi       = {10.3389/fnagi.2018.00145},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-176741},
  year      = {2018},
  abstract  = {Rats intracerebroventricularily (icv) treated with streptozotocin (STZ), shown to generate an insulin resistant brain state, were used as an animal model for the sporadic form of Alzheimer's disease (sAD). Previously, we showed in an in vivo study that 3 months after STZ icv treatment hippocampal adult neurogenesis (AN) is impaired. In the present study, we examined the effects of STZ on isolated adult hippocampal neural stem cells (NSCs) using an in vitro approach. We revealed that 2.5 mM STZ inhibits the proliferation of NSCs as indicated by reduced number and size of neurospheres as well as by less BrdU-immunoreactive NSCs. Double immunofluorescence stainings of NSCs already being triggered to start with their differentiation showed that STZ primarily impairs the generation of new neurons, but not of astrocytes. For revealing mechanisms possibly involved in mediating STZ effects we analyzed expression levels of insulin/glucose system-related molecules such as the glucose transporter (GLUT) 1 and 3, the insulin receptor (IR) and the insulin-like growth factor (IGF) 1 receptor. Applying quantitative Real time-PCR (qRT-PCR) and immunofluorescence stainings we showed that STZ exerts its strongest effects on GLUT3 expression, as GLUT3 mRNA levels were found to be reduced in NSCs, and less GLUT3-immunoreactive NSCs as well as differentiating cells were detected after STZ treatment. These findings suggest that cultured NSCs are a good model for developing new strategies to treat nerve cell loss in AD and other degenerative disorders.},
  language  = {en}
}
@phdthesis{Sun2015,
  author    = {Sun, Ping},
  title     = {Alzheimer`s disease and brain insulin resistance: The diabetes inducing drug streptozotocin diminishes adult neurogenesis in the rat hippocampus - an in vivo and in vitro study},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-119252},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2015},
  abstract  = {Alzheimer's disease (AD) is the most prevalent neurodegenerative disease of the brain, which is characterized by a progressive loss of memory and spatial orientation. Only less than 5-10\% of AD sufferers are familial cases due to genetic mutations in the amyloid precursor protein (APP) gene or presenilin (PS) 1 and 2 genes. The cause of sporadic AD (sAD) which covers > 95\% of AD patients is still unknown. Current research found interactions between aging, diabetes and cognitive decline including dementia in general and in AD in particular. Disturbances of brain glucose uptake, glucose tolerance and utilization and impairment of the insulin/insulin receptor (IR) signaling cascade are thought to be key targets for the development of sAD. In the brain of AD patients, neural plasticity is impaired indicated by synaptic and neuronal loss. Adult neurogenesis (AN), the generation of functional neurons in the adult brain, may be able to restore neurological function deficits through the integration of newborn neurons into existing neural networks. The dentate gyrus of the hippocampus is one out of few brain regions where life-long AN exists. However, there is a big controversy in literature regarding the involvement of AN in AD pathology. Most animal studies used transgenic mice based on the Amyloid ß (Aß) hypothesis which primarily act as models for the familial form of AD. Findings from human post mortem AN studies were also inconstistent. In this thesis, we focused on the possible involvement of AN in the pathogenesis of the sporadic form of AD. Streptozotocin intracerebroventricularily (STZ icv) treated rats, which develop an insulin-resistant brain state and learning and memory deficits preceding Aß pathology act as an appropriate animal model for sAD. We used STZ treatment for both parts of my work, for the in vivo and in vitro study. In the first part of my thesis, my coworkers and I investigated STZ icv treatment effects on different stages of AN in an in vivo approach. Even if STZ icv treatment does not seem to considerably influence stem cell proliferation over a short-term (1 month after STZ icv treatment) as well as in a long-term (3 months after STZ icv treatment) period, it results in significantly less immature and newborn mature neurons 3 months after STZ icv treatment. This reduction detected after 3 months was specific for the septal hippocampus, discussed to be important for spatial learning. Subsequently we performed co-localization studies with antibodies detecting BrdU (applied appr. 27 days before sacrifice) and cell-type specific markers such as NeuN, and GFAP, we found that STZ treatment does not affect the differentiation fate of newly generated cells. Phenotype analysis of BrdU-positive cells in the hilus and molecular layer revealed that some of the BrdU-positive cells are newborn oligodendrocytes but not newborn microglia. In the second part of my thesis I worked with cultured neural stem cells (NSCs) isolated from the adult rat hippocampus to reveal STZ effects on the proliferation of of NSCs, and on the survival and differentiation of their progeny. Furthermore, this in vitro approach enabled me to study cellular mechanisms underlying the observed impaired neurogenesis in the hippocampus of STZ-treated rats. In contrast to our findings of the STZ icv in vivo study we revealed that STZ supplied with the cell culture medium inhibits the proliferation of NSCs in a dose-dependent and time-dependent manner. Moreover, performing immunofluorescence studies with antibodies detecting cell-type specific markers after triggering NSCs to differentiate, we could show that STZ treatment affects the number of newly generated neurons but not of astrocytes. Analyzing newborn cells starting to differentiate and migrate I was able to demonstrate that STZ has no effect on the migration of newborn cells. Trying to reveal cellular mechanisms underlying the negative influence of STZ on hippocampal AN, we performed qRT-PCR and immunofluorescence staining and thus could show that in NSCs the expression of glucose transporter (GLUT)3 mRNA as well as IR and GLUT3 protein levels are reduced after STZ treatment. Therefore, the inhibition of the proliferation of NSCs may be (at least partially) caused by these two molecules. Interestingly, the effect of STZ on differentiating cells was shown to be different, as IR protein expression was not significantly changed but GLUT3 protein levels were decreased in consequence of STZ treatment. In summary, this project delivered further insights into the interrelation between AN the sporadic form of sAD and thus provides a basis of new therapeutic approaches in sAD treatment through intervening AN. Discrepancies between the results of the two parts of my thesis, the in vivo and in vitro part, were certainly caused to a certain extent by the missing microenvironment in the in vitro approach with cultured NSCs. Future studies e.g. using co-culture systems could at least minimize the effect of a missing natural microenvironment of cultured NSCs, so that the use of an in vitro approach for the investigation of STZ treatment underlying cellular mechanisms can be improved.},
  subject      = {Alzheimerkrankheit},
  language  = {en}
}
@article{StraussMoskalenkoTiurbeetal.2012,
  author    = {Strauss, Armin and Moskalenko, Vasily and Tiurbe, Christian and Chodnevskaja, Irina and Timm, Stephan and Wiegering, Verena A. and Germer, Chrioph Thomas and Ulrichs, Karin},
  title     = {Goettingen Minipigs (GMP): Comparison of Two Different Models for Inducing Diabetes},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-75119},
  year      = {2012},
  abstract  = {Purpose: Preclinical experiments on large animals are indispensable for evaluating the effectiveness of diabetes therapies. Miniature swine are well suited for such studies due to their physiological and pathophysiological responses. Methods: We compare two methods for inducing diabetes in Goettingen minipigs (GMP), in five with the beta cell toxin streptozotocin (STZ) and in five other GMP by total pancreatectomy (PE). Glucose homeostasis was assessed with the intravenous glucose-tolerance test (IVGTT) and continual monitoring of interstitial glucose levels. At conclusion of the observation period, the pancreata were examined histologically. Three non-diabetic GMP served as control group. Results: The IVGTT revealed markedly diabetic profiles in both GMP groups. STZ-GMP were found to harbor residual C-peptides and scattered insulin-positive cells in the pancreas. PE-GMP survived the total pancreatectomy only with intensive postoperative care. Conclusions: Although both methods reliably induced diabetes in GMP, the PE-GMP clearly had more health problems and required a greater expenditure of time and resources. The PE-GMP model, however, was better at eliminating endogenous insulin and C-peptide than the STZ-GMP model.},
  subject      = {G{\"o}ttingen},
  language  = {en}
}
@phdthesis{Osmanovic2008,
  author    = {Osmanovic, Jelena},
  title     = {Changes in gene expression of brain insulin system in STZ icv - damaged rats - relevance to Alzheimer disease},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-29603},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2008},
  abstract  = {Ratten, die intrazerebroventricular (icv) mit Streptozotocin (STZ) behandelt werden, eignen sich gut als Tiermodelle f{\"u}r die sporadische Alzheimererkrankung (sAD). In der hier vorgelegten Arbeit wurden Ver{\"a}nderungen bez{\"u}glich der Insulinkonzentration sowie einiger Bestandteile der Insulinrezeptor (IR) - Signalkaskade in Rattengehirnen, welche icv mit STZ behandelt wurden, zu verschiedenen Zeitpunkten untersucht. Die Auswirkungen von STZ auf die zerebrale IR-Signalkaskade wurden dann mit denen von chronisch erh{\"o}hten Corticosteronkonzentrationen verglichen. In dieser Studie wurde im Hippocampus eine verminderte mRNA-Expression von Insulin, der IR sowie des insulinabbauenden Enzyms (IDE) nachgewiesen; bez{\"u}glich der tau-mRNA-Expression konnten jedoch in diesem Gehirnareal der mit STZ behandelten Ratten keine Ver{\"a}nderungen beobachtet werden. Die Resultate der Insulin-, IR- und IDE-mRNA-Expression fielen bei den mit Corticosteron behandelten Ratten {\"a}hnlich aus Im Gegensatz hierzu nahm die tau-mRNA-Expression bei Ratten, die mit Corticosterone behandelt wurden, zu, was auch f{\"u}r eine sAD kennzeichnend ist. Sowohl bei den mit STZ als auch bei den mit Corticosteronen behandelten Ratten konnten Verhaltensanomalien beobachtet werden. Die in dieser Arbeit erzielten Resultate deuten darauf hin, dass viele Merkmale einer sAD experimentell durch eine Beeintr{\"a}chtigung des Insulin/IR-Signalwegs sowie eine chronische Erh{\"o}hung der Corticosteronkonzentration hervorgerufen werden k{\"o}nnen. Dies untermauert wiederum unsere Hypothese, dass es sich bei sAD um eine neuroendokrine St{\"o}rung handelt, die mit gehirnspezifischen Fehlfunktionen in der Insulin/IR-Signalkaskade einhergeht, welche zum Teil durch erh{\"o}hte Corticosteronkonzentrationen ausgel{\"o}st werden k{\"o}nnen. Auf Grund der in dieser Arbeit erzielten Resultate stellt sich die Frage, ob \&\#61538;-Amyloid (A\&\#61538;) ein Ausl{\"o}ser oder eine Konsequenz einer sAD darstellt. Die hier vorgelegte Arbeit last den Schlus zu, dass bei sAD-Tiermodellen ein Zusammenhang zwischen prim{\"a}ren Fehlfunktionen im zerebralen Insulinsystem und dadwol sekund{\"a}r ausgeloster A\&\#61538;-Pathologie besteht. Weiterf{\"u}bende Untersuchungen wird aber notwendig um diese Aussagen zu best{\"a}tigen.},
  subject      = {Insulin},
  language  = {en}
}