The Parkinson’s disease (PD) risk gene GTP cyclohydrolase 1 (GCH1) catalyzes the rate-limiting step in tetrahydrobiopterin (BH4) synthesis, an essential cofactor in the synthesis of monoaminergic neurotransmitters. To investigate the mechanisms by which GCH1 deficiency may contribute to PD, we generated a loss of function zebrafish gch1 mutant ( gch1-/- ), using CRISPR/Cas technology. gch1-/- zebrafish develop marked monoaminergic neurotransmitter deficiencies by 5 dpf, movement deficits by 8 dpf and lethality by 12 dpf. Tyrosine hydroxylase protein levels were markedly reduced without loss of ascending dopaminergic (DAergic) neurons. L-Dopa treatment of gch1-/- larvae improved survival without ameliorating the motor phenotype. RNAseq of gch1-/- larval brain tissue identified highly upregulated transcripts involved in innate immune response. Subsequent experiments provided morphological and functional evidence of microglial activation in gch1-/-. The results of our study suggest that GCH1 deficiency may un...

Aphasia recovery after stroke depends on the condition of the remaining, extra-lesional brain network. Network control theory provides a unique, quantitative approach to assess the interaction between brain networks. In this longitudinal, large-scale, whole-brain connectome study, we evaluated whether controllability measures of language-related regions are associated with treated aphasia recovery. Using probabilistic tractography and controlling for the effects of structural lesions, we reconstructed whole-brain diffusion tensor imaging connectomes from 68 individuals (20 female, 48 male) with chronic post-stroke aphasia who completed a 3-week language therapy. Applying principles of network control theory, we computed regional 1) average and 2) modal controllability, which decode the ability of a region to 1) spread control input through the brain network and 2) to facilitate brain state transitions. We tested the relationship between pre-treatment controllability measures of 20 language-related left he...

Astrocytes are the most abundant glial cell in the brain and perform a wide range of tasks that support neuronal function and circuit activities. There is emerging evidence that astrocytes exhibit molecular and cellular heterogeneity; however, whether distinct subpopulations perform these diverse roles remains poorly defined. Here we show that the Lunatic Fringe-GFP (Lfng-GFP) bacteria artificial chromosome mouse line from both sexes specifically labels astrocyte populations within lamina III and IV of the dorsal spinal cord. Transcriptional profiling of Lfng-GFP+ astrocytes revealed unique molecular profiles, featuring an enriched expression of Notch- and Wnt- pathway components. Leveraging CRE-DOG viral tools, we ablated Lfng-GFP+ astrocytes, which decreased neuronal activity in lamina III and IV and impaired mechanosensation associated with light touch. Together, our findings identify Lfng-GFP+ astrocytes as a unique subpopulation that occupies a distinct anatomical location in the spinal cord and direc...

Fluorescence imaging is an indispensable method for analysis of diverse cellular and molecular processes, enabling e.g. detection of ions, second messengers or metabolites. Intensity-based approaches, however, are prone to artefacts introduced by changes in fluorophore concentrations. This drawback can be overcome by fluorescence lifetime imaging (FLIM) based on time-correlated single-photon counting. FLIM often necessitates long photon collection times, resulting in strong temporal binning of dynamic processes. Recently, rapidFLIM was introduced, exploiting ultra-low dead-time photodetectors together with rapid electronics. Here, we demonstrate the applicability of rapidFLIM, combined with new and improved correction schemes, for spatiotemporal fluorescence lifetime imaging of low-emission fluorophores in a biological system. Using tissue slices of hippocampi of mice of either sex, loaded with the Na+ indicator ING2, we show that improved rapidFLIM enables quantitative, dynamic imaging of neuronal Na+ sig...

The superior colliculus (SC) is the midbrain center for integrating visual and multimodal sensory information. Neurons in the SC exhibit direction and orientation selectivity. Recent studies reported that neurons with similar preferences formed clusters in the mouse SC (Feinberg and Meister, 2014; Ahmadlou and Heimel, 2015; de Malmazet et al., 2018; Li et al., 2020) However, it remains controversial as to how these clusters are organized within the SC (Inayat et al., 2015; Chen et al., 2021). Here, we found that different brain states (i.e., awake or anesthetized with isoflurane) changed selectivity of individual SC neurons and organizations of the neuronal population in both male and female mice. Using two-photon Ca2+ imaging, we examined both individual neuronal responses and the spatial patterns of their population responses. Under isoflurane anesthesia, orientation selectivity increased and a larger number of orientation-selective cells were observed when compared to the awake condition, whereas the pr...

Hyperglycemia is a comorbidity in 60-80% of stroke patients; nevertheless, neuroprotective drugs like N-methyl-D-aspartate receptor (NMDAR) antagonists are typically assessed in normoglycemic animals at the preclinical stage before they are approved to enter clinical trials. Interestingly, as a possible explanation for the translational failure of NMDAR antagonists, it was recently reported that stroke occurring during nighttime causes smaller infarctions in rodents and therefore has a smaller window for neuroprotection. To investigate why stroke occurring during different circadian phases confers a difference in severity, we reanalyzed the published source data and found that some mice that were used in the daytime have higher blood glucose than mice that were used in the nighttime. We then repeated the experiments but found no difference in blood glucose concentration or infarct volume regardless of the circadian phase during which stroke occurs. On the other hand, induction of hyperglycemia by glucose i...

Chemical communication controls a wide range of behaviors via conserved signaling networks. Axon regeneration in response to injury is determined by the interaction between the extracellular environment and intrinsic growth potential. In this study, we investigated the role of chemical signaling in axon regeneration in Caenorhabditis elegans . We find that the enzymes involved in ascaroside pheromone biosynthesis, ACOX-1.1, ACOX-1.2, and DAF-22, participate in axon regeneration by producing a dauer-inducing ascaroside, ascr#5. We demonstrate that the chemoreceptor genes, srg-36 and srg-37 , which encode G protein-coupled receptors (GPCRs) for ascr#5, are required for adult-specific axon regeneration. Furthermore, the activating mutation in egl-30 encoding Gqα suppresses axon regeneration defective phenotype in acox-1.1 and srg-36 srg-37 mutants. Therefore, the ascaroside signaling system provides a unique example of a signaling molecule that regulates the regenerative pathway in the nervous system. SIGNIF...

Mild traumatic brain injury (mTBI) can initiate complex pathophysiological changes in the brain. Numerous cellular and molecular mechanisms underlying these pathologic changes are altered after injury, including those involved in energy utilization, excitotoxicity, ionic disturbances, and inflammation. It is thought that targeting multiple mechanisms may be necessary to produce meaningful reductions in brain pathology and to improve outcome. Previous studies have reported that the anti-diabetic drug metformin can also affect inflammatory, cell survival, and metabolic outcomes, possibly by acting on multiple targets and/or pathways. We therefore questioned whether metformin treatment can reduce pathology after repeat mild closed head injury (rmCHI) in male C57Bl/6 mice. We found that metformin, administered acutely after each head impact, resulted in markedly reduced white matter damage, astrogliosis, loss of hippocampal parvalbumin neurons, and improved mitochondrial function. In addition, both motor and c...

The co-chaperone FKBP51, encoded by the Fkbp5 gene, has been identified as central risk factor for anxiety-related disorders and stress system dysregulation. In the brain, the oval bed nucleus of the stria terminalis (ovBNST) has been implicated in stress-induced anxiety. However, the role of Fkbp5 in the ovBNST and its impact on anxiety-like behavior have remained unknown. Here we show in mice that Fkbp5 in the ovBNST is reactive to acute stress and co-expressed with the stress-regulated neuropeptides Tac2 and Crh . Subsequently, results obtained from viral-mediated manipulation indicate that Fkbp5 overexpression (OE) in the ovBNST results in an anxiolytic-like tendency regarding behavior and endocrinology, whereas a Fkbp5 knockout exposed a clear anxiogenic phenotype, indicating that native ovBNST expression and regulation is necessary for normal anxiety-related behavior. Notably, our data suggests that a stress-induced increase of Fkbp5 in the ovBNST may in fact have a protective role, leading to a tran...

To competently navigate the world, individuals must flexibly balance distinct aspects of social gaze, orienting toward others and inhibiting orienting responses, depending on the context. These behaviors are often disrupted in patient populations treated with serotonergic drugs. However, the field lacks a clear understanding of how the serotonergic system mediates social orienting and inhibiting behaviors. Here, we tested how increasing central concentrations of serotonin with the direct precursor 5-Hydroxytryptophan (5-HTP) would modulate the ability of rhesus macaques (both sexes) to use eye movements to flexibly orient to, or inhibit orienting to, faces. Systemic administrations of 5-HTP effectively increased central serotonin levels and impaired flexible orientation and inhibition. Critically, 5-HTP selectively impaired the ability of monkeys to inhibit orienting to face images, whereas it similarly impaired orienting to face and control images. 5-HTP also caused monkeys to perseverate on their gaze re...