Publications by authors named "Kosei Ojika"

The cholinergic efferent network from the medial septal nucleus to the hippocampus is crucial for learning and memory. This study aimed to clarify whether hippocampal cholinergic neurostimulating peptide (HCNP) has a rescue function in the cholinergic dysfunction of HCNP precursor protein (HCNP-pp) conditional knockout (cKO). Chemically synthesized HCNP or a vehicle were continuously administered into the cerebral ventricle of HCNP-pp cKO mice and littermate floxed (control) mice for two weeks via osmotic pumps.

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Cholinergic activation can enhance glutamatergic activity in the hippocampus under pathologic conditions, such as Alzheimer's disease. The aim of the present study was to elucidate the relationship between glutamatergic neural functional decline and cholinergic neural dysfunction in the hippocampus. We report the importance of hippocampal cholinergic neurostimulating peptide (HCNP) in inducing acetylcholine synthesis in the medial septal nucleus.

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Article Synopsis
  • The medial septal nucleus sends cholinergic signals to the hippocampus, crucial for learning and memory, and can produce theta oscillations that help encode new information.
  • HCNP (hippocampal cholinergic neurostimulating peptide) triggers acetylcholine production in the medial septal nuclei and is derived from a protein known as HCNP-pp.
  • In a study with knockout mice lacking HCNP-pp, researchers found reduced theta power in the CA1 region of the hippocampus and fewer cholinergic axons, indicating that HCNP plays a vital role in maintaining cholinergic activity in the septo-hippocampal network.
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  • HCNP regulates acetylcholine production by increasing choline acetyltransferase levels in the septal hippocampus, affecting both in vitro and in vivo environments.
  • HCNP-pp transgenic mice exhibit depressive behaviors and show enhanced long-term potentiation (LTP) of synaptic transmission in the hippocampus compared to wild-type mice, suggesting stronger neural activity.
  • The facilitation of LTP in HCNP-pp Tg mice is influenced by muscarinic modulation, indicating a potential link between HCNP-pp and glutamatergic postsynaptic function.
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  • Dopamine influences synaptic plasticity in the primary motor cortex (M1) and its effects were studied using a paired associative stimulation (PAS) protocol in patients with Parkinson's disease (PD) and multiple system atrophy (MSA-P).
  • Both patient groups without dopamine therapy showed no significant increase in motor-evoked potentials (MEPs) following the PAS protocol, indicating a lack of cortical plasticity without medication.
  • Dopamine replacement therapy in PD restored the MEP increase, suggesting that it's the activation of the cortico-striatal circuit, rather than dopamine itself, that is crucial for enhancing cortical plasticity in M1.
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  • The study investigates how subcortical nuclei contribute to coordinating human behavior, focusing on whether the connectivity of cortico-subcortical circuits is organized in a 'funneling' manner or through 'parallel processing'.
  • Using fMRI, researchers analyzed brain activity in 25 healthy volunteers while they performed finger movements, identifying key areas activated during the task.
  • The results indicated that there is both overlap and distinct connections between motor cortices and subcortical areas (like the striatum and thalamus), providing evidence for the 'information funneling' hypothesis and suggesting that parallel processing also exists but is not the sole principle in the basal ganglia.
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Hippocampal cholinergic neurostimulating peptide (HCNP) induces the synthesis of acetylcholine in the medial septal nucleus in vitro and in vivo. The precursor, HCNP-pp, is a multifunctional protein participating in important signaling pathways, such as MAPK/ERK kinase (MEK) and G-protein-coupled receptor kinase 2 (GRK2). We recently demonstrated that HCNP-pp colocalizes with collapsin response mediator protein-2 (CRMP-2) at presynaptic terminals in the hippocampus, suggesting that HCNP-pp may play an important role in presynaptic function in association with CRMP-2.

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Article Synopsis
  • HCNP stimulates acetylcholine production in the medial septal nucleus both in lab settings (in vitro) and living organisms (in vivo).
  • HCNP-pp, a precursor protein, engages in various signaling pathways and is linked to increased levels of CRMP-2 in the hippocampus of genetically modified mice.
  • Research shows that HCNP-pp is found at synapses alongside CRMP-2 and enhances synaptic protein levels, indicating its crucial role in presynaptic function within the hippocampus.
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Hippocampal cholinergic neurostimulating peptide (HCNP) is known to promote differentiation of septohippocampal cholinergic neurons. The HCNP precursor protein (HCNP-pp) may play several roles, for example, as an ATP-binding protein, a Raf kinase inhibitor protein, and a phosphatidylethanolamine-binding protein, as well as a precursor for HCNP. This study therefore aimed to elucidate the involvement of HCNP-pp in specific neural lineages after stroke using a hypoxic-ischemic (HI) rat model of brain ischemia.

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The acquisition of new motor skills is essential throughout daily life and involves the processes of learning new motor sequence and encoding elementary aspects of new movement. Although previous animal studies have suggested a functional importance for striatal dopamine release in the learning of new motor sequence, its role in encoding elementary aspects of new movement has not yet been investigated. To elucidate this, we investigated changes in striatal dopamine levels during initial skill-training (Day 1) compared with acquired conditions (Day 2) using (11)C-raclopride positron-emission tomography.

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Objective: Selective impairment of executive function has been shown in Parkinson's Disease (PD) patients undergoing Deep Brain Stimulation (DBS) of the Subthalamic Nucleus (STN). However, some patients experience difficulties in daily life, such as dissension in interpersonal relationships or a loss of lifestyle balance, in the short term after surgery. Our hypothesis is that these difficulties might be related to executive dysfunction.

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  • This text discusses a unique case of reversible cerebral vasoconstriction syndrome (RCVS) occurring in a patient with Takayasu's arteritis (TA), which presented with intense headaches and seizures.
  • Imaging studies showed signs of posterior reversible encephalopathy syndrome and significant vasoconstriction in various arteries.
  • The authors suggest that RCVS should be considered when diagnosing thunderclap headaches with related vascular abnormalities in patients with connective tissue diseases like Takayasu's arteritis.
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  • The study investigated how positive remodeling of carotid artery plaques can predict future strokes, using advanced imaging techniques like MDCT angiography and black-blood MRI.
  • 17 symptomatic and 11 asymptomatic cases were analyzed, revealing that plaques with positive remodeling had a significantly higher stroke occurrence compared to those with negative remodeling.
  • The research indicates that combining measurements of remodeling ratios and MR signal intensity may enhance stroke risk prediction, while traditional biological markers were not effective for this purpose.
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We previously reported a novel peptide, Hippocampal Cholinergic Neurostimulating Peptide (HCNP), which induces acetylcholine synthesis by increasing the amount of choline acetyltransferase (ChAT) in medial septal nuclei. The HCNP precursor protein (HCNP-pp), composed of 186 amino acids, is an inhibitory factor of the c-Raf/MEK cascade and may be involved in fetal rat brain development via the inhibition of phosphorylation of Erk. To clarify the involvement of HCNP in hippocampal cholinergic circuitry, we previously generated HCNP-pp transgenic (HCNP-pp Tg) mice using the promoter of the α subunit of Ca(2+) calmodulin-dependent protein kinase II (CaMKIIα).

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We have previously reported a novel peptide, hippocampal cholinergic neurostimulating peptide (HCNP), which induces acetylcholine synthesis by increasing the amount of cholineacetyltransferase (ChAT) in medial septal nuclei. The HCNP precursor protein, composed of 186 amino acids, is an inhibitory factor of the c-Raf/ MEK cascade and may be involved in the development of the fetal rat brain via the inhibition of Erk phosphorylation. To clarify the involvement of HCNP in hippocampal cholinergic circuitry, we previously generated HCNP precursor protein (HCNP-pp) transgenic mice using the promoter of the alpha subunit of Ca(2+) calmodulin-dependent protein kinase II (CaMKIIalpha).

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Background: : Stroke patients experience postural instability that can impede functional improvements in their gait. However, the precise functions of the dominant and non-dominant hemispheres in controlling static standing posture and weight-bearing remain unclear.

Objective: : To investigate differences in balancing ability between right-handed patients with right and left hemispheric lesions.

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Hippocampal cholinergic neurostimulating peptide (HCNP), originally purified from young rat hippocampus, has been known to promote the differentiation of septo-hippocampal cholinergic neurons. Recently, the precursor protein of HCNP (HCNP-pp) has also received attention as a multifunctional protein with roles, in addition to serving as the HCNP precursor, such as acting as an ATP-binding protein, a Raf kinase inhibitor protein (RKIP), and phosphatidylethanolamine-binding protein (PEBP). In particular, the function of RKIP has attracted attention over several years for its role in controlling cellular proliferation and metastasis in cancer cells.

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We report a 64-year-old man diagnosed with Lambert-Eaton myasthenic syndrome (LEMS) associated with pulmonary squamous cell carcinoma. Circulating anti-P/Q-type voltage-gated calcium channel (VGCC) antibody was detected, and the patient was treated with 3,4-diaminopyridine. At age 61, chest radiograph revealed a tumor shadow in the right upper lung field.

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Acetylcholine modulates neural activity in the hippocampal glutamatergic pathway via the induction of phosphorylated Erk and may act as a novel transmitter in septohippocampal memory formation. However, how acetylcholine synthesis in the septal nucleus is regulated is unknown. We have purified a peptide from the hippocampus of the young adult rat, named hippocampal cholinergic neurostimulating peptide (HCNP) that induces acetylcholine synthesis in vitro in the septal nucleus.

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Background: Minocycline, a second-generation tetracycline with anti-inflammatory and anti-apoptotic properties, has been shown to promote therapeutic benefits in experimental stroke. However, equally compelling evidence demonstrates that the drug exerts variable and even detrimental effects in many neurological disease models. Assessment of the mechanism underlying minocycline neuroprotection should clarify the drug's clinical value in acute stroke setting.

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We present two cases of young adults with acute disseminated encephalomyelitis (ADEM) who developed severe conscious and motor disturbances. Despite their similar initial clinical course and MRI findings, their motor function outcomes were quite different. In both cases, fluid attenuated inversion recovery (FLAIR) sequenced MRI showed multiple symmetric hyperintense lesions in the internal capsule and the brainstem at the subacute stage.

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We report a case of a 62-year-old man with limbic encephalitis associated with diffuse large B cell lymphoma. He was hospitalized for the assessment of cognitive disturbance and changes in characteristics. Neurological examination revealed disturbance of recall and recent memory.

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Hippocampal cholinergic neurostimulating peptide (HCNP), which enhances acetylcholine synthesis and induces cholinergic phenotype development of the septohippocampal system, is derived from HCNP precursor protein (HCNPpp), also known as phosphatidylethanolamine binding protein (PEBP) and Raf kinase inhibitor protein (RKIP). Our previous study demonstrated that expression of HCNPpp mRNA was decreased in the hippocampi of autopsied brains of Alzheimer's disease (AD) patients, indicating the association of HCNP with the pathogenesis of AD. To clarify the involvement of gene variations in the promoter region of the gene encoding HCNPpp in this mRNA reduction, we analyzed DNA polymorphisms or mutations within this gene promoter region in AD patients by direct sequencing.

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