Glutamate antibodies restore the balance of IL-6 and IL-10 in brain structures in aging C57BL/6 mice with memory impairment induced by the neurotoxic fragment Αβ₂₅₋₃₅

Abstract

Introduction. The antiamnestic properties of polyclonal monospecific glutamate antibodies have previously been demonstrated in experimental models of Alzheimer's disease and in aging animals. It is now generally recognized that neuroinflammation plays an important role in the progression of neuropathological changes observed in AD, a distinctive feature of which is the activation of glial cells (astrocytes, microglia), accompanied by increased synthesis and release of proinflammatory cytokines. Of particular interest are the proinflammatory interleukin IL-6, which is considered a key marker of cellular aging and chronic inflammation, and the anti-inflammatory IL-10, which primarily exerts anti-inflammatory effects. The aim of this study was to investigate the effect of glutamate antibodies on the content in IL-6 and IL-10 in the brain structures (prefrontal cortex and hippocampus) of aging mice with induced memory impairment caused by intranasal administration of a fragment of the β-amyloid protein Aβ_25-35.

Methods. The study was performed on 12-month-old C57BL/6 mice. To reproduce the cognitive impairment characteristic of AD, intranasal administration of the neurotoxic β-amyloid protein (Aβ), fragment 25-35, was used. The animals were divided into 4 groups: the 1st control group received intranasal (i/n) saline in a volume of 4 μl, the 2nd experimental group – i/n solution of 4 μl of Aβ_25-35 solution at a dose of 60 μg/kg, the 3rd – simultaneously i/n Aβ_25-35 at the same dose and glutamate antibodies (GLU-AT) at a dose of 250 μg/kg in a volume of 4 μl and the 4th group – i/n GLU-AT at a dose of 250 μg/kg in a volume of 4 μl. Intranasal administration of solutions was carried out daily for 14 days. Twenty-four hours after the last administration of the solutions, memory impairment, the main indicator of cognitive dysfunction development caused by i/n administration of Aβ_25-35, was assessed in the passive avoidance reflex conditioned reflex test using a standard method. At the end of the experiment, the animals were decapitated, and the prefrontal cortex and hippocampus were isolated; the material was stored at -85°C. The IL-6 and IL-10 content in the brain structures was determined by ELISA (Cloud-Clone Corp. test system) using an ImmunoChem-2100 ELISA reader at a wavelength of 450 nm. Interleukin concentrations were normalized per 1 mg of brain tissue.

Results. Intranasal administration of Aβ_25-35 to mice for 14 days resulted in significant impairment of memory processes, an increase in proinflammatory IL-6 levels in the prefrontal cortex, and a significant decrease in IL-10 levels in the prefrontal cortex and hippocampus. Coadministration of Aβ_25-35 and GLU-AT resulted in a significant decrease in IL-6 levels in both the prefrontal cortex and hippocampus and an increase in IL-10 levels in these brain structures.

Conclusion. Conclusion. Intranasal 14-day administration of glutamate antibodies together with the neurotoxic fragment Aβ_25-35 had a protective effect: an increase in mnestic function of the brain to the level in the control group, a decrease in IL-6 content, and an increase in IL-10 levels in the prefrontal cortex and hippocampus to control values. The obtained data indicate that antibodies to glutamate restore the balance of pro- and anti-inflammatory cytokines, in particular IL-6 and IL-10.