Project description:This study, using a growth hormone (GH)-deficient dwarf animal model and peripheral GH replacement, investigated the effects of circulating IGF-1 during adolescence on IGF-1 levels in the brain. Our results demonstrated that hippocampal IGF-1 protein concentrations during adolescence are highly regulated by circulating IGF-1, which were reduced by GH deficiency and restored by systematic GH replacement. In contrast, IGF-1 levels in the CSF were decreased by GH deficiency but not restored by GH replacement. Furthermore, analysis of gene expression using microarrays and RT-PCR indicated that circulating IGF-1 levels did not modify the transcription of IGF-1 or its receptor in the hippocampus but did regulate genes that are involved in microvascular structure and function, brain development, and synaptic plasticity, which potentially support brain structures involved in cognitive function during this important developmental period.
Project description:This study, using a growth hormone (GH)-deficient dwarf animal model and peripheral GH replacement, investigated the effects of circulating IGF-1 during adolescence on IGF-1 levels in the brain. Our results demonstrated that hippocampal IGF-1 protein concentrations during adolescence are highly regulated by circulating IGF-1, which were reduced by GH deficiency and restored by systematic GH replacement. In contrast, IGF-1 levels in the CSF were decreased by GH deficiency but not restored by GH replacement. Furthermore, analysis of gene expression using microarrays and RT-PCR indicated that circulating IGF-1 levels did not modify the transcription of IGF-1 or its receptor in the hippocampus but did regulate genes that are involved in microvascular structure and function, brain development, and synaptic plasticity, which potentially support brain structures involved in cognitive function during this important developmental period. GH-deficient dwarf (dw/dw) and heterozygous (HZ) rats were identified at postnatal day 33-34. Starting from d35, dw/dw rats received subcutaneous injection of either 300µg GH (dw/dw+GH) or saline (dw/dw+sal) for 7d or 30d. HZ animals received saline for the same periods as controls. Animals (n=4/group for each time point) were sacrificed, the hippocampi were dissected, and total RNA were isolated for subsequent transcriptomic profiling.
Project description:Healthy adults with serum insulin like growth factor -1 (IGF-I) levels at the lowest quartile of normal ranges have increased fat metabolism and reduced glucose utlisation compared with those in the highest quartile during fasting We used gene expression in skeletal muscle to explore metabolism during fasting We selected healthy males from a bioresource based on extremes of circulating IGF-I levels on stored sera and evaluated during a 24 hour fasting
Project description:In rats, learning and memory performance decline during normal aging, which makes this rodent species a suitable model to evaluate therapeutic strategies. In aging rats, insulin-like growth factor-I (IGF-I), is known to significantly improve spatial memory accuracy as compared to control counterparts. A constellation of gene expression changes underlie the hippocampal phenotype of aging but no studies on the effects of IGF-I on the hippocampal transcriptome of old rodents have been documented. Here, we assessed the effects of IGF-I gene therapy on spatial memory performance in old female rats and compared them with changes in the hippocampal transcriptome.
Project description:Basic helix loop helix enhancer 40 (Bhlhe40) is a transcription factor expressed in rodent hippocampus, however, its role in neuronal function is not well understood. Here, we used Bhlhe40 null mice on a congenic C57Bl6/J background (Bhlhe40 KO) to investigate the impact of Bhlhe40 on neuronal excitability and synaptic plasticity. A whole genome expression array predicted that Bhlhe40 KO mice have up-regulated insulin-related pathways and down-regulated neuronal signaling-related pathways in the hippocampus. We validated that insulin degrading enzyme mRNA (Ide) and IDE protein are significantly downregulated in Bhlhe40 KO hippocampi. No significant difference was observed in hippocampal insulin levels. In hippocampal slices, we found CA1 neurons have increased miniature excitatory post-synaptic current (mEPSC) amplitude and decreased inhibitory post-synaptic current (IPSC) amplitude, indicating hyper-excitability in CA1 neurons in Bhlhe40 KO mice. At CA1 synapses, we found a reduction in long term potentiation (LTP) and long term depression (LTD), indicating an impairment in hippocampal synaptic plasticity in Bhlhe40 KO hippocampal slices. Bhlhe40 KO mice displayed no difference in seizure response to the convulsant kainic acid (KA) relative to controls. We found that while Bhlhe40 KO mice have decreased exploratory behavior they do not display alterations in spatial learning and memory. Together this suggests that Bhlhe40 plays a role in modulating neuronal excitability and synaptic plasticity ex vivo, however, Bhlhe40 alone does not play a significant role in seizure susceptibility and learning and memory in vivo. In addition, based on the reduction in IDE protein levels in these mice, there may be dysregulation of other known IDE substrates, namely insulin growth factor (Igf)-1, Igf-2, and Amyloid beta (Aβ).
Project description:Besides recent advances in neonatal care, preterm newborns still develop sex-biased behavioural alterations. Preterms fail to receive placental insulin-like growth factor-1 (IGF-1), a major fetal growth hormone in utero, and low IGF-1 serum levels correlate with preterm poor neurodevelopmental outcomes. Here, we mimicked IGF-1 deficiency of preterm newborns in mice by perinatal administration of an IGF-1 receptor antagonist. This resulted in sex-biased brain microstructural, functional, and behavioural alterations, resembling those of ex-preterm children, which we characterized performing parallel mouse/human behavioural tests. Pharmacological enhancement of GABAergic tonic-inhibition by the FDA-approved drug ganaxolone rescued functional/behavioural alterations in mice. Establishing an unprecedented mouse model of prematurity, our work dissects the mechanisms at the core of abnormal behaviours and identifies a new, readily-translatable therapeutic strategy for preterm brain disorders.
Project description:Besides recent advances in neonatal care, preterm newborns still develop sex-biased behavioural alterations. Preterms fail to receive placental insulin-like growth factor-1 (IGF-1), a major fetal growth hormone in utero, and low IGF-1 serum levels correlate with preterm poor neurodevelopmental outcomes. Here, we mimicked IGF-1 deficiency of preterm newborns in mice by perinatal administration of an IGF-1 receptor antagonist. This resulted in sex-biased brain microstructural, functional, and behavioural alterations, resembling those of ex-preterm children, which we characterized performing parallel mouse/human behavioural tests. Pharmacological enhancement of GABAergic tonic-inhibition by the FDA-approved drug ganaxolone rescued functional/behavioural alterations in mice. Establishing an unprecedented mouse model of prematurity, our work dissects the mechanisms at the core of abnormal behaviours and identifies a new, readily-translatable therapeutic strategy for preterm brain disorders.
Project description:The Norway rat has important impacts on our life. They are amongst the most used research subjects, resulting in ground-breaking advances. At the same time, wild rats live in close association with us, leading to various adverse interactions. In face of this relevance, it is surprising how little is known about their natural behaviour. While recent laboratory studies revealed their complex social skills, little is known about their social behaviour in the wild. An integration of these different scientific approaches is crucial to understand their social life, which will enable us to design more valid research paradigms, develop more effective management strategies, and to provide better welfare standards. Hence, I first summarise the literature on their natural social behaviour. Second, I provide an overview of recent developments concerning their social cognition. Third, I illustrate why an integration of these areas would be beneficial to optimise our interactions with them.