Project description:Aims: This study aimed to identify and characterize the intrinsic properties of locus coeruleus (LC) noradrenergic neurons in male and female mice using a genetic approach. We also sought to investigate sex-specific differences in membrane properties, action potential generation, and protein expression profiles to understand the mechanisms underlying neuronal excitability variations. Methods: Utilizing a genetic mouse model by crossing Dbhcre knock-in mice with tdTomato Ai14 transgenic mice, LC neurons were identified using fluorescence microscopy. Neuronal properties, including capacitance, action potential frequency, and rheobase, were assessed using patch-clamp recordings. Spontaneous and evoked activity between sexes was compared. Proteomic analyses of individual LC neuron soma was conducted using mass-spectrometry to discern protein expression profiles. Results: Female LC noradrenergic neurons displayed greater membrane capacitance than those in male mice. Male LC neurons demonstrated greater spontaneous and evoked action potential generation compared to females. Male LC neurons exhibited a lower rheobase and achieved higher peak frequencies with similar current injections. Proteomic analysis revealed inherent differences in protein expression profiles between sexes, with male mice displaying a notably larger unique protein set compared to females. Notably, pathways pertinent to protein synthesis, degradation, and recycling, such as EIF2 and glucocorticoid receptor signaling, showed reduced expression in females. Conclusions: Male LC noradrenergic neurons exhibit higher intrinsic excitability compared to those from females. The discernible sex-based differences in excitability could be ascribed to varying protein expression profiles, especially within pathways that regulate protein synthesis and degradation. This study lays the groundwork for future studies focusing on the interplay between proteomics and neuronal function examined in individual cells.
Project description:Preclinical work has long focused only on male animals, even though sexual divergence in both baseline behaviors and drug responses clearly impact treatment outcomes in patients. Psychiatric disorders are notably divergent, with males showing higher prevalence of ADHD and ASD, and females GAD and MDD. This divergence is reflected in quantitative differences in subclincal behaviors. The Noradrenergic neurotransmitter system is targeted by many psychiatric drugs, but is relatively uncharacterized at a molecular level. We developed a mouse to profile these neurons, defining their both a baseline transcriptome, including druggable receptors, and their molecular response to stimulation. We also discovered a remarkable sexual divergence in their gene expression, including functionally increased expression of the EP3 receptor in females – a difference that can be used to modulate stress-induced anxiety in a sex specific manner. These findings underscore the need to conduct preclinical studies in a manner balanced for sex, and suggest that baseline differences in noradrenergic neurons could underlay sexually divergent behaviors.
Project description:Preclinical work has long focused only on male animals, even though sexual divergence in both baseline behaviors and drug responses clearly impact treatment outcomes in patients. Psychiatric disorders are notably divergent, with males showing higher prevalence of ADHD and ASD, and females GAD and MDD. This divergence is reflected in quantitative differences in subclincal behaviors. The Noradrenergic neurotransmitter system is targeted by many psychiatric drugs, but is relatively uncharacterized at a molecular level. We developed a mouse to profile these neurons, defining their both a baseline transcriptome, including druggable receptors, and their molecular response to stimulation. We also discovered a remarkable sexual divergence in their gene expression, including functionally increased expression of the EP3 receptor in females – a difference that can be used to modulate stress-induced anxiety in a sex specific manner. These findings underscore the need to conduct preclinical studies in a manner balanced for sex, and suggest that baseline differences in noradrenergic neurons could underlay sexually divergent behaviors.
Project description:The locus coeruleus noradrenergic (LC-NA) system plays an important role in organizing a physiological response to acute stress. However, if and how the LC affects stress-mediated transcriptomic changes in the brain is still barely understood. Here, we extensively characterize LC mediated transcriptomic response during acute stress in the hippocampus. Combining for the first time bulk mRNA-sequencing and selective chemogenetic and optogenetic manipulations of the LC-NA system
Project description:Post-mortem investigations indicate that the locus coeruleus (LC) is the initial site of hyperphosphorylated pretangle tau, a precursor to neurofibrillary tangles (NFTs) found in Alzheimer's disease (AD). The presence of pretangle tau and NFTs in the LC correlates with AD progression. LC neuron integrity and quantity are linked to cognitive states, with degeneration associated with AD. However, the mechanisms of pretangle tau-induced LC degeneration are unclear. This study examined the transcriptomic and mitochondrial profiles of LC noradrenergic neurons after transduction with pseudophosphorylated human tau. Tau hyperphosphorylation increased the somatic expression of the L-type calcium channel (LTCC), impaired mitochondria health, and led to deficits in spatial and olfactory learning. Sex-dependent alterations in gene expression were observed in rats transduced with pretangle tau. Chronic LTCC blockade prevented behavioral deficits and altered mitochondrial mRNA expression, suggesting a potential link between LTCC hyperactivity and mitochondrial dysfunction. Our research provides insights into the consequences of tau pathology in the originating structure of AD.
Project description:Background: The goal of this study was to determine the transcriptional consequences of norepinephrine transporter (NET) gene deletion in noradrenergic neuron differentiation. The norepinephrine transporter (NET) is the target of powerful mind-altering substances, such as tricyclic antidepressants and the drug of abuse, cocaine. NET function in adult noradrenergic neurons of the peripheral and central nervous systems is that of a scavenger that internalizes norepinephrine from the synaptic cleft. By contrast, norepinephrine (NE) transport has a different role in embryogenesis. It promotes differentiation of neural crest cells and locus ceruleus progenitors into noradrenergic neurons, whereas NET inhibitors, such as the tricyclic antidepressant desipramine and the drug of abuse, cocaine, inhibit noradrenergic differentiation. While NET structure und regulation of NET function is well described, little is known about downstream targets of NE transport. Results: We have determined by long serial analysis of gene expression (LongSAGE) the gene expression profiles of in vitro differentiating wild type and norepinephrine transporter-deficient (NETKO) neural crest derivatives. Comparison analyses with the wild type library (GSM 105765) have identified a number of important differentially expressed genes, including genes relevant to noradrenergic neuron differentiation and to the phenotype of NETKO mice. Furthermore we have identified novel differentially expressed genes. Conclusions: Loss of NET function during embryonic development deregulates signaling pathways that are critically involved in neural crest formation and noradrenergic neuron differentiation. The library was constructed from total RNA of 60 neural crest culture at culture day 7. The neural tubes were dissected from E9.5 embryos that lack the norepinephrine transporter gene.
Project description:TRAP translational profiling is a method that allows investigators to genetically characterize specific cell types in complex tissues such as mouse brain. Using this technique we obtained RNA-Seq data from actively translating transcripts present in neurons in the rostral pons of adult Cbln2-EGFP/Rpl10a (NIDA172) mice. This brain area includes the locus coeruleus and parabrachial nuclei. This work was supported by a grant from the National Institute on Drug Abuse P30DA035756 to N.H.