Amidated and Ibuprofen-Conjugated Kyotorphins Promote Neuronal Rescue and Memory Recovery in Cerebral Hypoperfusion Dementia Model

Anti-Aging Activity of Andaliman (Zanthoxylum Acanthopodium DC) Fruit Ethanol Extract on Brain Weight and p16INK4a Expression of Hippocampus in Aging Model Rats

BACKGROUND

Physiological aging and due to oxidative stress in long term will have an impact on cellular response disorders, can caused aging of hippocampus and senility. Brain weight is known to decrease with age and p16INK4a as aging biomarkers have been investigated. Andaliman is one of typical herbal plants from North Sumatra has been widely used as an antioxidant, anti-inflammatory and anti-aging.

OBJECTIVE

This study was evaluated effect of andaliman (Zanthoxylum acanthopodium DC) fruit ethanol extract (AEE) on brain weight and p16INK4a expression in aging model rats.

METHODS

This study was carried out experimentally of 24 male wistar rats. The treatment group consisted of 4 groups; KN= negatif control (normal), KP= positif control (aging model rat), P1 and P2= aging model rat + AEE at dose 150 and 300mg/kgbw, respectively. The aging model rats were D-galactose-induced at dose of 150mg/kgbw for 8 weeks. Brain weigth were recorded by digital scales. p16INK4a expression using immunohistochemical methods. The data analysis with Anova test.

RESULTS

This study showed differences brain weight between groups (p=0.523). Brain weight in P1 (1.34±0,06) and P2 (1.30±0.09) tendency increased than KP (1.29±0.62). The p16INK4a expression between groups significant difference (p=0.041), continued with post hoc Least Significant Difference (LSD) showed p16INK4a expression in KN significant decreased than KP (p=0.027). Likewise, p16INK4a expression in P2 was significant decreased than KP (p=0.010).

CONCLUSION

Andaliman ethanol extract at a dose 300mg/kgbw for 8 weeks was improved aging process caused D-galactose induced.

The effects of visual context on visual-vestibular mismatch revealed by electrodermal and postural response measures

BACKGROUND

No objective criteria exist for diagnosis and treatment of visual-vestibular mismatch (VVM).

OBJECTIVE

To determine whether measures of electrodermal activity (EDA) and trunk acceleration will identify VVM when exposed to visual-vestibular conflict.

METHODS

A modified VVM questionnaire identified the presence of VVM (+ VVM) in 13 of 23 young adults (34 ± 8 years) diagnosed with vestibular migraine. Rod and frame tests and outcome measures for dizziness and mobility were administered. Participants stood on foam while viewing two immersive virtual environments. Trunk acceleration in three planes and electrodermal activity (EDA) were assessed with wearable sensors. Linear mixed effect (LME) models were used to examine magnitude and smoothness of trunk acceleration and tonic and phasic EDA. Welch's t-test and associations between measures were assessed with a Pearson Correlation Coefficient. Effect sizes of group mean differences were calculated.

RESULTS

Greater than 80% of all participants were visually dependent. Outcome measures were significantly poorer in the + VVM group: tonic EDA was lower (p < 0.001) and phasic EDA higher (p < 0.001). Postural accelerations varied across groups; LME models indicated a relationship between visual context, postural, and ANS responses in the + VVM group.

CONCLUSIONS

Lower tonic EDA with + VVM suggests canal-otolith dysfunction. The positive association between vertical acceleration, tonic EDA, and visual dependence suggests that increased vertical segmental adjustments are used to compensate. Visual context of the spatial environment emerged as an important control variable when testing or treating VVM.

Don't forget the little brain: A framework for incorporating the cerebellum into the understanding of cognitive aging

With the rapidly growing population of older adults, an improved understanding of brain and cognitive aging is critical, given the impacts on health, independence, and quality of life. To this point, we have a well-developed literature on the cortical contributions to cognition in advanced age. However, while this work has been foundational for our understanding of brain and behavior in older adults, subcortical contributions, particularly those from the cerebellum, have not been integrated into these models and frameworks. Incorporating the cerebellum into models of cognitive aging is an important step for moving the field forward. There has also been recent interest in this structure in Alzheimer's dementia, indicating that such work may be beneficial to our understanding of neurodegenerative disease. Here, I provide an updated overview of the cerebellum in advanced age and propose that it serves as a critical source of scaffolding or reserve for cortical function. Age-related impacts on cerebellar function further impact cortical processing, perhaps resulting in many of the activation patterns commonly seen in aging.

The Minocycline Ameliorated the Synaptic Plasticity Impairment in Vascular Dementia

Chronic cerebral hypoperfusion (CCH) leads to vascular dementia with progressive hippocampal damage and cognitive impairments. In the present study, we compared early and late Minocycline (MINO) treatment on cognitive function, long and short-term synaptic-plasticity following CCH. We used bilateral common carotid arteries occlusion model (2VO) for induction of hypoperfusion. Male Sprague-Dawley rats were divided into 5 following groups (each having 2 subgroups): 2VO + V (vehicle), 2VO+MINO-E (early treatment of MINO on days 0 to 3 after 2VO), 2VO+MINO-L (late-treatment on days 21 to 32 after 2VO), control, and sham. Passive-avoidance (PA) and radial arm maze (RAM) tests were used to investigate learning and memory. Long term and short term synaptic plasticity were assessed by field potential recording, the brains were removed after recording and preserved for histological study to count pyramidal cells in CA1 region.Cerebral hypoperfusion could impair memory performance, synaptic plasticity, and basal synaptic transmission (BST) along with hippocampal cell loss. Thus, we found a significant reduction in step-through latency (STL) of PA test with a higher number of working and reference errors in RAM in CCH rats. However, only late treatment with MINO improved memory performance, synaptic plasticity, hippocampal cell loss, and increased neurotransmitter pool (NP) in CCH rats, but early treatment could not produce long-lasting beneficial effects 32 days after 2VO. MINO may improve synaptic plasticity and memory performance in hypo-perfused rats directly and indirectly by increasing NP and/or suppressing inflammatory factors, respectively.

The Neuroprotective Action of Amidated-Kyotorphin on Amyloid β Peptide-Induced Alzheimer's Disease Pathophysiology

Kyotorphin (KTP, l-tyrosyl-l-arginine) is an endogenous dipeptide initially described to have analgesic properties. Recently, KTP was suggested to be an endogenous neuroprotective agent, namely for Alzheimer’s disease (AD). In fact, KTP levels were shown to be decreased in the cerebrospinal fluid of patients with AD, and recent data showed that intracerebroventricular (i.c.v.) injection of KTP ameliorates memory impairments in a sporadic rat model of AD. However, this administration route is far from being a suitable therapeutic strategy. Here, we evaluated if the blood-brain permeant KTP-derivative, KTP-NH₂, when systemically administered, would be effective in preventing memory deficits in a sporadic AD animal model and if so, which would be the synaptic correlates of that action. The sporadic AD model was induced in male Wistar rats through i.c.v. injection of amyloid β peptide (Aβ). Animals were treated for 20 days with KTP-NH₂ (32.3 mg/kg, intraperitoneally (i.p.), starting at day 3 after Aβ administration) before memory testing (Novel object recognition (NOR) and Y-maze (YM) tests). Animals were then sacrificed, and markers for gliosis were assessed by immunohistochemistry and Western blot analysis. Synaptic correlates were assessed by evaluating theta-burst induced long term potentiation (LTP) of field excitatory synaptic potentials (fEPSPs) recorded from hippocampal slices and cortical spine density analysis. In the absence of KTP-NH₂ treatment, Aβ-injected rats had clear memory deficits, as assessed through NOR or YM tests. Importantly, these memory deficits were absent in Aβ-injected rats that had been treated with KTP-NH₂, which scored in memory tests as control (sham i.c.v. injected) rats. No signs of gliosis could be detected at the end of the treatment in any group of animals. LTP magnitude was significantly impaired in hippocampal slices that had been incubated with Aβ oligomers (200 nM) in the absence of KTP-NH₂. Co-incubation with KTP-NH₂ (50 nM) rescued LTP toward control values. Similarly, Aβ caused a significant decrease in spine density in cortical neuronal cultures, and this was prevented by co-incubation with KTP-NH₂ (50 nM). In conclusion, the present data demonstrate that i.p. KTP-NH₂ treatment counteracts Aβ-induced memory impairments in an AD sporadic model, possibly through the rescuing of synaptic plasticity mechanisms.

CE-MS with electrokinetic supercharging and application to determination of neurotransmitters

Electrokinetic supercharging (EKS) is known as one of the most effective online electrophoretic preconcentration techniques, though pairing with it with mass spectrometry has presented challenges. Here, EKS is successfully paired with ESI-MS/MS to provide a sensitive and robust method for analysis of biogenic amines in biological samples. Injection parameters including electric field strength and the buffer compositions used for the separation and focusing were investigated to achieve suitable resolution, high sensitivity, and compatibility with ESI-MS. Using EKS, the sensitivity of the method was improved 5000-fold compared to a conventional hydrodynamic injection with CZE. The separation allowed for baseline resolution of several neurotransmitters within 16 min with LODs down to 10 pM. This method was applied to targeted analysis of seven biogenic amines from rat brain stem and whole Drosophila tissue. This is the first method to use EKS with CE-ESI-MS/MS to analyze biological samples.

Gradual Cerebral Hypoperfusion Impairs Fear Conditioning and Object Recognition Learning and Memory in Mice: Potential Roles of Neurodegeneration and Cholinergic Dysfunction

In the present study, male C57BL/6J mice were subjected to gradual cerebral hypoperfusion by implanting an ameroid constrictor (AC) on the left common carotid artery (CCA) and a stenosis on the right CCA. In the sham group, all surgical procedures were kept the same except no AC was implanted and stenosis was not performed. One month following the surgical procedures, fear conditioning and object recognition tests were conducted to evaluate learning and memory functions and motor functions were assessed using a balance beam test. At the experimental endpoint, mice were perfused and brains were collected for immunostaining and histology. Learning and memory as well as motor functions were significantly impaired in the hypoperfusion group. The immunoreactivity to choline acetyltransferase was decreased in dorsal striatum and basal forebrain of the hypoperfusion group indicating that cholinergic tone in these brain regions was compromised. In addition, an increased number of Fluoro-Jade positive neurons was also found in cerebral cortex, dorsal striatum and hippocampus indicating neurodegeneration in these brain regions. Based on this pattern of data, we argued that this mouse model would be a useful tool to investigate the therapeutic interventions for the treatment of vascular dementia. Additionally, this model could be employed to exploit the effect of microvascular occlusions on cognitive impairment in the absence and presence of Alzheimer's disease pathology.

(S)-Oxiracetam is the Active Ingredient in Oxiracetam that Alleviates the Cognitive Impairment Induced by Chronic Cerebral Hypoperfusion in Rats

Chronic cerebral hypoperfusion is a pathological state that is associated with the cognitive impairments in vascular dementia. Oxiracetam is a nootropic drug that is commonly used to treat cognitive deficits of cerebrovascular origins. However, oxiracetam is currently used as a racemic mixture whose effective ingredient has not been identified to date. In this study, we first identified that (S)-oxiracetam, but not (R)-oxiracetam, was the effective ingredient that alleviated the impairments of spatial learning and memory by ameliorating neuron damage and white matter lesions, increasing the cerebral blood flow, and inhibiting astrocyte activation in chronic cerebral hypoperfused rats. Furthermore, using MALDI-MSI and LC-MS/MS, we demonstrated that (S)-oxiracetam regulated ATP metabolism, glutamine-glutamate and anti-oxidants in the cortex region of hypoperfused rats. Altogether, our results strongly suggest that (S)-oxiracetam alone could be a nootropic drug for the treatment of cognitive impairments caused by cerebral hypoperfusion.

Neuropeptide Kyotorphin Impacts on Lipopolysaccharide-Induced Glucocorticoid-Mediated Inflammatory Response. A Molecular Link to Nociception, Neuroprotection, and Anti-Inflammatory Action

Neuropeptide kyotorphin (KTP) is a potent analgesic if administered directly into the brain. In contrast, KTP-amide (KTP-NH₂) is analgesic, neuroprotective, and anti-inflammatory following systemic administration, albeit its mechanism of action is unknown. The aim of this study was to shed light on the mechanism of action of KTP-NH₂ at the molecular level. KTP-NH₂ does not inhibit the enkephalinases angiotensin-converting-enzyme and dipeptidyl-peptidase 3. Intravital microscopy showed that KTP-NH₂ decreased the number of rolling leukocytes in a mouse model of inflammation induced by lipopolysaccharide (LPS). Pretreatment with metyrapone abrogated the action of KTP-NH₂. Interestingly, stimulating rolling leukocytes using CXCL-1 is also counteracted by the KTP-NH₂, but this effect is not abrogated by metyrapone. We conclude that KTP-NH₂ has dual action: a glucocorticoid-mediated action, which is dominant in the full-fledged LPS-induced inflammation model, and a glucocorticoid-independent mechanism, which is predominant in models in which leukocyte rolling is stimulated but inflammation is not totally developed.

Pharmacological Potential of the Endogenous Dipeptide Kyotorphin and Selected Derivatives

The endogenous peptide kyotorphin (KTP) has been extensively studied since it was discovered in 1979. The dipeptide is distributed unevenly over the brain but the majority is concentrated in the cerebral cortex. The putative KTP receptor has not been identified yet. As many other neuropeptides, KTP clearance is mediated by extracellular peptidases and peptide transporters. From the wide spectrum of biological activity of KTP, analgesia was by far the most studied. The mechanism of action is still unclear, but researchers agree that KTP induces Met-enkephalins release. More recently, KTP was proposed as biomarker of Alzheimer disease. Despite all that, KTP limited pharmacological value prompted researchers to develop derivatives more lipophilic and therefore more prone to cross the blood–brain barrier (BBB), and also more resistant to enzymatic degradation. Conjugation of KTP with functional molecules, such as ibuprofen, generated a new class of compounds with additional biological properties. Moreover, the safety profile of these derivatives compared to opioids and their efficacy as neuroprotective agents greatly increases their pharmacological value.

Endothelium-Mediated Action of Analogues of the Endogenous Neuropeptide Kyotorphin (Tyrosil-Arginine): Mechanistic Insights from Permeation and Effects on Microcirculation

Kyotorphin (KTP) is an endogenous peptide with analgesic properties when administered into the central nervous system (CNS). Its amidated form (l-Tyr-l-Arg-NH2; KTP-NH2) has improved analgesic efficacy after systemic administration, suggesting blood-brain barrier (BBB) crossing. KTP-NH2 also has anti-inflammatory action impacting on microcirculation. In this work, selected derivatives of KTP-NH2 were synthesized to improve lipophilicity and resistance to enzymatic degradation while introducing only minor changes in the chemical structure: N-terminal methylation and/or use of d amino acid residues. Intravital microscopy data show that KTP-NH2 having a d-Tyr residue, KTP-NH2-DL, efficiently decreases the number of leukocyte rolling in a murine model of inflammation induced by bacterial lipopolysaccharide (LPS): down to 46% after 30 min with 96 μM KTP-NH2-DL. The same molecule has lower ability to permeate membranes (relative permeability of 0.38) and no significant activity in a behavioral test which evaluates thermal nociception (hot-plate test). On the contrary, methylated isomers at 96 μM increase leukocyte rolling up to nearly 5-fold after 30 min, suggesting a proinflammatory activity. They have maximal ability to permeate membranes (relative permeability of 0.8) and induce long-lasting antinociception.