The Effect of Lutein on Ischemia-reperfusion-induced Vasculitic Neuropathic Pain and Neuropathy in Rats

Lutein, a versatile carotenoid: Insight on neuroprotective potential and recent advances

BACKGROUND

Neurodegenerative diseases (NDDs) are a diverse group of neurological disorders with progressive neuronal loss at specific brain regions, leading to impaired cognitive functioning, loss of neuroplasticity, severe neurological impairment, and dementia. The incidence of neurodegenerative diseases is increasing at an alarming rate with current treatments struggling to barely prolong the inevitable. The desperation to discover a therapeutic agent to treat neurodegenerative diseases and to aid in the process of healthy recovery has opened a gateway into natural pigments.

HYPOTHESIS

The xanthophyll pigment lutein may bear the potential as a therapeutic agent against NDDs.

RESULTS

Lutein plays an important role in brain development, cognitive functioning, and improving neuroplasticity. In vitro and in vivo studies revealed the neuroprotective properties of lutein against NDDs such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and cerebral ischemia. The neuroprotective effect of lutein is evidenced by the reduction of free radicals and the simultaneous strengthening of the endogenous antioxidant systems by activating the NRF-2/ERK/AKT pathway. Further, it effectively suppressed mitochondrial aberrations, excitotoxicity, overaccumulation of metals, and its resultant complications. The immunomodulatory activity of lutein prevents neuroinflammation by hindering NF-κB nuclear translocation, regulation of NIK/IKK, PI3K/AKT, MAPK/ERK, JNK pathways, and ICAM-1 downregulation. Lutein also rescued the dysregulated cholinergic system and resolved memory defects. Along with its neuroprotective properties, lutein also improved neuroplasticity by enabling neurogenesis through increased GAP-43, NCAM, and BDNF levels.

CONCLUSION

Lutein exhibits strong neuroprotective activities against various NDDs. Though the investigations are in the exploratory phase, this review presents the consolidation of scattered evidence of the neuroprotective properties of lutein and urges its further exploration in clinical studies.

Effect of peripheral blood mononuclear cells on ischemia-reperfusion injury of sciatic nerve of adult male albino rat: histological, immunohistochemical, and ultrastructural study

Ischemia/reperfusion (I/R) injury of sciatic nerve is a serious condition that results in nerve fiber degeneration, and reperfusion causes oxidative injury. Peripheral blood mononuclear cells (PBMNCs) have neuroregenerative power. This study was carried out to evaluate the potential ameliorative effect of PBMNCs on changes induced by I/R injury of the sciatic nerve. Fifty adult male albino rats were divided into donor and experimental groups that were subdivided into four groups: group I (control group), group II received 50 µL PBNMCs once intravenously via the tail vein, group III rubber tourniquet was placed around their Rt hind limb root for 2 hours to cause ischemia, group IV was subjected to limb ischemia as group III, then they were injected with 50 ul PBMNCs as group II before reperfusion. I/R injury showed disorganization of nerve fascicles with wide spaces in between nerve fibers. The mean area of collagen fibers, iNOS immunoexpression, and number of GFAP-positive Schwann cells of myelinated fibers showed a highly significant increase, while a highly significant reduction in the G-ratio and neurofilament immunoexpression was observed. Myelin splitting, invagination, evagination, and myelin figures were detected. PBMNC-treated group showed a marked improvement that was confirmed by histological, immunohistochemical, and ultrastructural findings.

Extraction, identification and application of gliadin from gluten: Impact of pH on physicochemical properties of unloaded- and lutein-loaded gliadin nanoparticles

In the present study, high purity gliadin was extracted from gluten by the marginally modified Osborne method and the effect of different pHs in the aqueous ethanol on the physicochemical properties of unloaded gliadin nanoparticles (UGNs) and lutein-loaded gliadin nanoparticles (LGNs) was investigated. The results revealed that the formation of UGNs and LGNs at diverse pHs was driven by a conjunction of hydrogen bonding, electrostatic interactions and hydrophobic effects, but their dominant roles varied at different pHs. pH also significantly impacted the surface hydrophobicity, secondary structure and aromatic amino acid microenvironment of UGNs and LGNs. LGNs at pH 5.0 and at pH 9.0 exhibited better loading capacity and could reach 9.7884 ± 0.0006 % and 9.7360 ± 0.0017 %, respectively. These two samples also had greater photostability and thermal stability. Half-lives of LGNs at pH 5.0 were 2.185 h and 54.579 h, respectively. Half-lives of LGNs at pH 9.0 were 2.937 h and 49.159 h, respectively. LGNs at pH 5.0 and LGNs at pH 9.0 also had higher bioaccessibility of lutein, with 15.98 ± 0.04 % and 15.27 ± 0.03 %, respectively. These findings yielded precious inspirations for designing innovative lutein delivery system.

Characterization of Inhibitory Capability on Hyperpolarization-Activated Cation Current Caused by Lutein (β,ε-Carotene-3,3'-Diol), a Dietary Xanthophyll Carotenoid

Lutein (β,ε-carotene-3,3'-diol), a xanthophyll carotenoid, is found in high concentrations in the macula of the human retina. It has been recognized to exert potential effectiveness in antioxidative and anti-inflammatory properties. However, whether and how its modifications on varying types of plasmalemmal ionic currents occur in electrically excitable cells remain incompletely answered. The current hypothesis is that lutein produces any direct adjustments on ionic currents (e.g., hyperpolarization-activated cation current, Ih [or funny current, If]). In the present study, GH3-cell exposure to lutein resulted in a time-, state- and concentration-dependent reduction in Ih amplitude with an IC50 value of 4.1 μM. There was a hyperpolarizing shift along the voltage axis in the steady-state activation curve of Ih in the presence of this compound, despite being void of changes in the gating charge of the curve. Under continued exposure to lutein (3 μM), further addition of oxaliplatin (10 μM) or ivabradine (3 μM) could be effective at either reversing or further decreasing lutein-induced suppression of hyperpolarization-evoked Ih, respectively. The voltage-dependent anti-clockwise hysteresis of Ih responding to long-lasting inverted isosceles-triangular ramp concentration-dependently became diminished by adding this compound. However, the addition of 10 μM lutein caused a mild but significant suppression in the amplitude of erg-mediated or A-type K+ currents. Under current-clamp potential recordings, the sag potential evoked by long-lasting hyperpolarizing current stimulus was reduced under cell exposure to lutein. Altogether, findings from the current observations enabled us to reflect that during cell exposure to lutein used at pharmacologically achievable concentrations, lutein-perturbed inhibition of Ih would be an ionic mechanism underlying its changes in membrane excitability.