ABSTRACT: Ventral hippocampal lesion, tetrodotoxin disruption of the ventral hippocampus, and chronic administration of neuroleptics (colan-affy-rat-89421)
Project description:In pevious research we have shown that the disruption of the normal development of the ventral hippocampus in rodents leads to cellular abnormalities in the frontal cortex and behavioral deficits related to schizophenia (Neurotox Res. 2002, 4(5-6):469-475). We propose the use of gene expression analysis to investigate the molecular underpinnings of these processes which may shed light on the molecular processes relevant to human schizophrenia. In addition, we seek to characterize expression differences induced by chronic administration of antipsychotic medications, which may give insight into the molecular processes involved in ameliorating psychotic symptoms. Using both surgical and drug interventions, we aim to examine experimentally induced expression differences in the rodent brain that are relevant to human neuropsychiatric disorders. Disruption of the normal development of the vental hippocampus or chronic neuroleptic administration, will result in gene expression changes in the frontal cortex of rats. Elucidation of the molecular cascades underlying these treatments will shed light on both the pathoetiology (from the lesion experiments) and theurapeutic processes (from the antipsychotic treatment experiments) involved in human schizophrenia. We have developed 3 groups of samples:; 1] Ventral hippocampal lesion in neonatal rats (treatment and controls, total N=22); 2] Tetrodotoxin disruption of the ventral hippocampus (treatment and controls, total N=20); 3] Chronic administration of neuroleptics (multiple drugs, multiple doses, and controls, total N=63) Grand Total N=105
Project description:In pevious research we have shown that the disruption of the normal development of the ventral hippocampus in rodents leads to cellular abnormalities in the frontal cortex and behavioral deficits related to schizophenia (Neurotox Res. 2002, 4(5-6):469-475). We propose the use of gene expression analysis to investigate the molecular underpinnings of these processes which may shed light on the molecular processes relevant to human schizophrenia. In addition, we seek to characterize expression differences induced by chronic administration of antipsychotic medications, which may give insight into the molecular processes involved in ameliorating psychotic symptoms. Using both surgical and drug interventions, we aim to examine experimentally induced expression differences in the rodent brain that are relevant to human neuropsychiatric disorders. Disruption of the normal development of the vental hippocampus or chronic neuroleptic administration, will result in gene expression changes in the frontal cortex of rats. Elucidation of the molecular cascades underlying these treatments will shed light on both the pathoetiology (from the lesion experiments) and theurapeutic processes (from the antipsychotic treatment experiments) involved in human schizophrenia. We have developed 3 groups of samples: 1] Ventral hippocampal lesion in neonatal rats (treatment and controls, total N=22) 2] Tetrodotoxin disruption of the ventral hippocampus (treatment and controls, total N=20) 3] Chronic administration of neuroleptics (multiple drugs, multiple doses, and controls, total N=63) Grand Total N=105
Project description:The role of the hippocampus in learning and memory has been widely studied. However, studies of differences along the longitudinal axis indicate that the hippocampus is perhaps not a singular structure, but instead it is thought that the dorsal and ventral poles of the hippocampus have functional differences. An anatomical gradient of hippocampal inputs along the dorsal-ventral axis supports this notion. It has been recently shown that there is transcriptional differentiation along the longitudinal axis of the adult hippocampus, coinciding with functional and anatomical gradients. Understanding the development of the dorsal-ventral hippocampal axis will further our understanding of the different hippocmapal functional contributions along the longitudinal axis. However, analysis of transcriptional gradients along the dorsal ventral axis have not been studied in the neonatal rat during development. We performed an extensive bead-chip based geneome-wide analysis of transcriptional differences in dorsal, intermediate, and ventral hippocampal tissue of rats aged postnatal day 0 (P0), P9, P18 and P60.
Project description:Using whole-cell patch clamp recording and unbiased gene expression profiling in rat dissociated hippocampal neurons cultured at high density, we demonstrate here that chronic activity blockade induced by the sodium channel blocker tetrodotoxin leads to a homeostatic increase in action potential firing and down-regulation of potassium channel genes. In addition, chronic activity blockade reduces total potassium current, as well as protein expression and current of voltage-gated Kv1 and Kv7 potassium channels, which are critical regulators of action potential firing. Importantly, inhibition of N-Methyl-D-Aspartate receptors alone mimics the effects of tetrodotoxin, including the elevation in firing frequency and reduction of potassium channel gene expression and current driven by activity blockade, whereas inhibition of L-type voltage-gated calcium channels has no effect.
Project description:Chronic pain is one of the most significant and costly medical problems throughout the world. Recent evidence has confirmed the hippocampus as an active modulator of pain chronicity but the underlying mechanisms remain poorly defined. By means of in vivo electrophysiology together with chemogenetic and optogenetic manipulations in freely behaving mice, we identified a neural ensemble in the ventral hippocampal CA1 (vCA1) that showed inhibitory responses to noxious external stimuli, but not to innocuous stimuli. Following peripheral inflammation, this neuronal ensemble became responsive to innocuous stimuli and causally contributed to sensory hypersensitivity in inflammatory animals. Mimicking this inhibition of vCA1 neurons using chemogenetics in naïve mice induced chronic pain-like behavioral changes, whereas activating these vCA1 neurons in mice with chronic peripheral inflammation resulted in a striking reduction of pain-related behaviors. Pathway-specific manipulation of vCA1 projections to the basolateral amygdala (BLA) and infralimbic cortex (IL) showed that these pathways were differentially involved in pain modulation at different temporal stages of chronic inflammatory pain. These results confirm a crucial role of the ventral hippocampus and its circuits in modulating the development of chronic pain in mice.
Project description:Dorsal and ventral parts of the hippocampus despite similar histological structure are known to be involved in performance of different functions. Previous studies using next generation sequencing showed that these two hippocampal parts differ in the expression of many genes, however, stability of dorsoventral gradient of gene expression remains open question. Here, we analyzed differential expression of genes between the dorsal and ventral hippocampus of rats in polyA-enriched samples and samples subjected to depletion of ribosomal RNA. We present here a detailed analysis of differentially expressed genes between the dorsal and ventral parts of the hippocampus. Intersection of our dataset with data of previous RNAseq studies revealed 544 genes are stably differentially expressed between the hippocampal parts suggesting that, despite strongly variability between the animals and sequencing approaches, there is a subset of genes whose expression stably differs between the dorsal and ventral hippocampus. Analysis of differential splicing showed that the dorsal and ventral parts of the hippocampus express 64 genes whose splice isoforms are different between the hippocampal parts. Furthermore, we show that depletion of ribosomal RNA increases representation of transposable elements in the RNAseq libraries and helps to detect a weak predominance of expression of these elements in the ventral hippocampus.
Project description:Using NGS, we report the impact of chronic stress on the transcriptome of the dorsal and ventral hippocampus in the ewe. This study identifies specific transcriptional signatures of the dorsal VS ventral hippocampus (>220 DEG) and demonstrates a very limited transcriptional impact of stress, exclusively restricted to the dorsal hippocampus (<10 DEG).
Project description:In this study, we explored molecular alterations in the hippocampus of prenatal valproic acid (VPA)-exposed rats as a model of autism spectrum disorders (ASD). In addition, we assessed effects of chronic administration of intranasal oxytocin, a promising peptide for ASD treatment. Comparative analyses revealed that prenatal VPA exposure altered gene expression, a part of which is involved in key features including memory, developmental process, and epilepsy. Oxytocin partly improved these gene expression, which were predicted to interact with those involved in social behaviors and hippocampal-dependent memory. The present study documented molecular profiling in the hippocampus related to ASD and improvement by chronic treatment of oxytocin.
Project description:In this study, we determined the effect of chronic consistent hypoxia (CCH) and chronic intermittent hypoxia (CIH) on global gene expression in cortical and hippocampal region of developing mouse brain using long-oligo beadschip arrays. Keywords: Gene expression profile Control-Cortex: Cortical samples from 16 days old mice were analysed on whole-genome expression chips to reveal expression profile at this developmental stage. Used as control for Chronic Hypoxia Treated cortical samples. CCH-Cortex: Cortical samples from 2-week CCH treated mice were analysed on whole-genome expression chips to reveal the changes in gene expression profile following 2-week CCH treatment. CIH-Cortex: Cortical samples from 2-week CCH treated mice were analysed on whole-genome expression chips to reveal the changes in gene expression profile following 2-week CIH treatment. Control-Hippocampus: Hippocampal samples from 16 days old mice were analysed on whole-genome expression chips to reveal expression profile at this developmental stage. Used as control for Chronic Hypoxia Treated hippocampal samples. CCH-Hippocampus: Hippocampal samples from 2-week CCH treated mice were analysed on whole-genome expression chips to reveal the changes in gene expression following 2-week CCH treatment. CIH-Hippocampus: Hippocampal samples from 2-week CCH treated mice were analysed on whole-genome expression chips to reveal the changes in gene expression following 2-week CIH treatment.
Project description:The hippocampus - one of the most studied brain regions – is a key target of the stress response and vulnerable to the detrimental effects of stress. Although its intrinsic organization is highly conserved throughout its long dorsal-ventral axis, the dorsal hippocampus is linked to spatial navigation and memory formation, whereas the ventral hippocampus is linked to emotional regulation. Here, we provide the first combined transcriptomic and proteomic profiling that reveals striking differences between dorsal and ventral hippocampus. Using various acute stress challenges we demonstrate that both regions display very distinct molecular responses, and that the ventral hippocampus is particularly responsive to the effects of stress. We demonstrate that separately analyzing dorsal and ventral hippocampus greatly increases the ability to detect region-specific stress effects, and we identify an epigenetic network, which is specifically sensitive to acute stress in the ventral hippocampus.