Experimental Neurobiology最新文献

Cognitive dysfunction, a significant complication of type 2 diabetes mellitus (T2DM), can potentially manifest even from the early stages of the disease. Despite evidence of global brain atrophy and related cognitive dysfunction in early-stage T2DM patients, specific regions vulnerable to these changes have not yet been identified. The study enrolled patients with T2DM of less than five years' duration and without chronic complications (T2DM group, n=100) and demographically similar healthy controls (control group, n=50). High-resolution T1-weighted magnetic resonance imaging data were subjected to independent component analysis to identify structurally significant components indicative of morphometric networks. Within these networks, the groups' gray matter volumes were compared, and distinctions in memory performance were assessed. In the T2DM group, the relationship between changes in gray matter volume within these networks and declines in memory performance was examined. Among the identified morphometric networks, the T2DM group exhibited reduced gray matter volumes in both the precuneus (Bonferroni-corrected p=0.003) and insular-opercular (Bonferroni-corrected p=0.024) networks relative to the control group. Patients with T2DM demonstrated significantly lower memory performance than the control group (p=0.001). In the T2DM group, reductions in gray matter volume in both the precuneus (r=0.316, p=0.001) and insular-opercular (r=0.199, p=0.047) networks were correlated with diminished memory performance. Our findings indicate that structural alterations in the precuneus and insular-opercular networks, along with memory dysfunction, can manifest within the first 5 years following a diagnosis of T2DM.

Leucine-rich repeat kinase 2 (LRRK2) mutations are the most common cause of Parkinson's disease (PD). Interestingly, recent studies have reported an increased risk of stroke in patients with PD harboring LRRK2 mutations, but there is no evidence showing the functional involvement of LRRK2 in stroke. Here, we found that LRRK2 kinase activity was significantly induced in the Rose-Bengal (RB) photothrombosis-induced stroke mouse model. Interestingly, stroke infarct volumes were significantly reduced, and neurological deficits were diminished by pharmacological inhibition of LRRK2 kinase activity using MLi-2, a brain-penetrant LRRK2 kinase inhibitor. Immunohistochemical analysis showed p-LRRK2 level in stroke lesions, co-localizing with mitophagy-related proteins (PINK, Parkin, LC3B, cytochrome c), suggesting their involvement in stroke progression. Overlapping p-LRRK2 with cytochrome c/TUNEL/JC-1 (an indicator of mitochondrial membrane potential) puncta in RB photothrombosis indicated LRRK2-induced mitochondrial apoptosis, which was blocked by MLi-2. These results suggest that pharmacological inhibition of LRRK2 kinase activity could attenuate mitochondrial apoptosis, ultimately leading to neuroprotective potential in stroke progression. In conclusion, LRRK2 kinase activity might be neuro-pathogenic due to impaired mitophagy in stroke progression, and pharmacological inhibition of LRRK2 kinase activity could be beneficial in reducing the risk of stroke in patients with LRRK2 mutations.

The benefit of intranasal brain derived neurotrophic factor (BDNF) treatment on cognitive function in a neonatal postnatal day 7 (P7) mouse model of hypoxic ischemia (HI) was explored. Intranasal delivery is attractive in that it can promote widespread distribution of BDNF within both the brain and spinal cord. In this study we evaluated the effectiveness of intranasal BDNF to improve cognitive recovery following HI. HI is induced via ligation of the right carotid artery followed by a 45-minute exposure to an 8% oxygen/ 92% nitrogen mixture in an enclosed chamber. Male and female pups were subjected to a 2-hour hypothermia in a temperature-controlled chamber as a standard of care. A solution of saline (control) or recombinant human BDNF (Harlan Laboratories) was administered with a Gilson pipette at the same time each day for 7 days into each nasal cavity in awake mice beginning 24 hours after HI. We evaluated cognitive recovery using the novel object recognition (NOR) and western analysis to analyze neuro-markers and brain health such as synaptophysin and microtubule associated protein -2 (MAP2). The objective of this study was to evaluate the role and therapeutic potential of BDNF in neonatal HI recovery. Our results indicate that intranasal BDNF delivered within 24 hours after HI improved object discrimination at both 28 and 42 days after HI. Our results also demonstrate increased synaptophysin and MAP2 at day 42 in HI animals that received intranasal BDNF treatment compared to HI animals that were administered saline.

Panic disorder (PD), characterized by recurrent and intense panic attacks, presents a complex interplay between psychological and neurobiological factors. Although the amygdala and hippocampus have been studied extensively in the context of PD, the brainstem's involvement remains relatively underexplored. This study aims to address this gap by examining structural abnormalities within specific brainstem regions, including the medulla, pons, and midbrain. The study sample population comprised twenty-one adult patients diagnosed with PD and an age-gender-education-matched control group. Utilizing rigorous inclusion and exclusion criteria, confounding factors related to comorbid psychiatric conditions and brain structure abnormalities were minimized. Our findings revealed a significant reduction in medulla volume among PD patients, a finding that persisted even after correcting for individual differences in total intracranial volume. The medulla's role in cardiovascular regulation and autonomic function, coupled with its involvement in fear responses, underscores its potential significance in the pathophysiology of PD. This study elucidates the medulla's structural abnormalities as a potential biomarker for PD. Understanding the role of the brainstem in PD could pave the way for more targeted and effective interventions for this condition.

Autoimmune encephalitis (AIE) is a type of immunoreactive encephalitic disorder and is recognized as the most prevalent noninfectious encephalitis. Nevertheless, the rarity of definitive AIE diagnosis through biopsy or autopsy represents a significant hurdle to understanding and managing the disease. In this article, we present the pathological findings of AIE and review the literature based on a distinct case of AIE presenting as CD8+ T-lymphocyte predominant encephalitis. We describe the clinical progression, diagnostic imaging, laboratory data, and autopsy findings of an 80-year-old deceased male patient. The patient was diagnosed with pulmonary tuberculosis 6 months before death and received appropriate medications. A week before admission to the hospital, the patient manifested symptoms such as a tendency to sleep, decreased appetite, and confusion. Although the patient temporally improved with medication including correction of hyponatremia, the patient progressed rapidly and died in 6 weeks. The brain tissue revealed lymphocytic infiltration in the gray and white matter, leptomeninges, and perivascular infiltration with a predominance of CD8+ T lymphocytes, suggesting a case of AIE. There was no detectable evidence of viral infection or underlying neoplasm. The autopsy revealed that this patient also had Alzheimer's disease, atherosclerosis, arteriolosclerosis, and aging-related tau astrogliopathy. This report emphasizes the pivotal role of pathological examination in the diagnosis of AIE, especially when serological autoantibody testing is not available or when a patient is suspected of having multiple diseases.

In this study, we show that ANKS1A is specifically expressed in the brain endothelial cells of adult mice. ANKS1A deficiency in adult mice does not affect the differentiation, growth, or patterning of the cerebrovascular system; however, its absence significantly impacts the cerebrovascular system of the aged brain. In aged ANKS1A knock-out (KO) brains, vessel lesions exhibiting cerebral cavernous malformations (CCMs) are observed. In addition, CCM-like lesions show localized peripheral blood leakage into the brain. The CCM-like lesions reveal immune cells infiltrating the parenchyma. The CCM-like lesions also contain significantly fewer astrocyte endfeets and tight junctions, indicating that the integrity of the BBB has been partially compromised. CCM-like lesions display increased fibronectin expression in blood vessels, which is also confirmed in cultured endothelial cells deficient for ANKS1A. Therefore, we hypothesize that ANKS1A may play a role in maintaining or stabilizing healthy blood vessels in the brain during aging.

Loss of inhibition is suggested to cause pathological pain symptoms. Indeed, some human case reports suggest that lesions including the thalamic reticular nucleus (TRN) which provides major inhibitory inputs to other thalamic nuclei, may induce thalamic pain, a type of neuropathic pain. In support, recent studies demonstrated that activation of GABAergic neurons in the TRN reduces nociceptive responses in mice, reiterating the importance of the TRN in gating nociception. However, whether biochemically distinct neuronal types in the TRN differentially contribute to gating nociception has not been investigated. We, therefore, investigated whether the activity of parvalbumin (PV) and somatostatin (SOM) expressing neurons in the somatosensory TRN differentially modulate nociceptive behaviors using optogenetics and immunostaining techniques. We found that activation of PV neurons in the somatosensory TRN significantly reduced nociceptive behaviors, while activation of SOM neurons in the TRN had no such effect. Also, selective activation of PV neurons, but not SOM neurons, in the TRN activated relatively more PV neurons in the primary somatosensory cortex, which delivers inhibitory effect in the cortex, when measured with cFos and PV double staining. Results of our study suggest that PV neurons in the somatosensory TRN have a stronger influence in regulating nociception and that their activations may provide further inhibition in the somatosensory cortex by activating cortical PV neurons.

Rab40 proteins are an atypical subgroup of Rab GTPases containing a unique suppressor of the cytokine signaling (SOCS) domain that is recruited to assemble the CRL5 E3 ligase complex for proteolytic regulation in various biological processes. A nonsense mutation deleting the C-terminal SOCS box in the RAB40B gene was identified in a family with axonal peripheral neuropathy (Charcot-Marie-Tooth disease type 2), and pathogenicity of the mutation was assessed in model organisms of zebrafish and Drosophila. Compared to control fish, zebrafish larvae transformed by the human mutant hRAB40B-Y83X showed a defective swimming pattern of stalling with restricted localization and slower motility. We were consistently able to observe reduced labeling of synaptic markers along neuromuscular junctions of the transformed larvae. In addition to the neurodevelopmental phenotypes, compared to normal hRAB40B expression, we further examined ectopic expression of hRAB40B-Y83X in Drosophila to show a progressive decline of locomotion ability. Decreased ability of locomotion by ubiquitous expression of the human mutation was reproduced not with GAL4 drivers for neuron-specific expression but only when a pan-glial GAL4 driver was applied. Using the ectopic expression model of Drosophila, we identified a genetic interaction in which Cul5 down regulation exacerbated the defective motor performance, showing a consistent loss of SOCS box of the pathogenic RAB40B. Taken together, we could assess the possible gain-of-function of the human RAB40B mutation by comparing behavioral phenotypes in animal models; our results suggest that the mutant phenotypes may be associated with CRL5-mediated proteolytic regulation.

The μ-opioid receptor (MOR) is a class of opioid receptors characterized by a high affinity for β-endorphin and morphine. MOR is a G protein-coupled receptor (GPCR) that plays a role in reward and analgesic effects. While expression of MOR has been well established in neurons and microglia, astrocytic MOR expression has been less clear. Recently, we have reported that MOR is expressed in hippocampal astrocytes, and its activation has a critical role in the establishment of conditioned place preference. Despite this critical role, the expression and function of astrocytic MOR from other brain regions are still unknown. Here, we report that MOR is significantly expressed in astrocytes and GABAergic neurons from various brain regions including the hippocampus, nucleus accumbens, periaqueductal gray, amygdala, and arcuate nucleus. Using the MOR-mCherry reporter mice and Imaris analysis, we demonstrate that astrocytic MOR expression exceeded 60% in all tested regions. Also, we observed similar MOR expression of GABAergic neurons as shown in the previous distribution studies and it is noteworthy that MOR expression is particularly in parvalbumin (PV)-positive neurons. Furthermore, consistent with the normal MOR function observed in the MOR-mCherry mouse, our study also demonstrates intact MOR functionality in astrocytes through iGluSnFr-mediated glutamate imaging. Finally, we show the sex-difference in the expression pattern of MOR in PV-positive neurons, but not in the GABAergic neurons and astrocytes. Taken together, our findings highlight a substantial astrocytic MOR presence across various brain regions.

In preclinical research on Alzheimer's disease and related tauopathies, tau phosphorylation analysis is routinely employed in both cellular and animal models. However, recognizing the sensitivity of tau phosphorylation to various extrinsic factors, notably temperature, is vital for experimental accuracy. Hypothermia can trigger tau hyperphosphorylation, while hyperthermia leads to its dephosphorylation. Nevertheless, the rapidity of tau phosphorylation in response to unintentional temperature variations remains unknown. In cell cultures, the most significant temperature change occurs when the cells are removed from the incubator before harvesting, and in animal models, during anesthesia prior to euthanasia. In this study, we investigate the kinetics of tau phosphorylation in N2a and SH-SY5Y neuronal cell lines, as well as in mice exposed to anesthesia. We observed changes in tau phosphorylation within the few seconds upon transferring cell cultures from their 37°C incubator to room temperature conditions. However, cells placed directly on ice post-incubation exhibited negligible phosphorylation changes. In vivo, isoflurane anesthesia rapidly resulted in tau hyperphosphorylation within the few seconds needed to lose the pedal withdrawal reflex in mice. These findings emphasize the critical importance of preventing temperature variation in researches focused on tau. To ensure accurate results, we recommend avoiding anesthesia before euthanasia and promptly placing cells on ice after removal from the incubator. By controlling temperature fluctuations, the reliability and validity of tau phosphorylation studies can be significantly enhanced.