Diosgenin ameliorates cellular and molecular changes in multiple sclerosis in C57BL/6 mice.

Multiple sclerosis (MS) is especially known as a demyelinating disease of the central nervous system. Current treatments for MS are mostly based on controlling neuroinflammation and there are no treatments to promote the remyelination process at present. Diosgenin is a known herbal anti-inflammatory and antioxidant agent, which has also been shown to stimulate the growth of myelin in vitro. However, there is no or little evidence about diosgenin effects; specially on myelination, neuroprotection and its corresponding mechanisms in vivo in experimental autoimmune encephalomyelitis (EAE) as the most valid experimental model of MS. In this study, the therapeutic effect of diosgenin on clinical signs of EAE, and the corresponding cellular and molecular mechanisms have been examined with emphasis on myelination and neuroprotection mechanisms. EAE was induced using myelin oligodendrocyte glycoprotein (MOG) antigen in C57BL/6 mice. Diosgenin was gavaged (100 mg/kg) daily with the onset of paralysis signs (half tail paralysis) until the 18th post-immunization day in the treatment group. Blood and spinal cord tissue sampling was performed on post-immunization day 18. Lumbar spinal cord inflammation, demyelination, and axonal degeneration were assessed using Hematoxylin and Eosin (H & E), Luxol Fast Blue (LFB), and Bielschowsky's silver staining methods, respectively. Serum and spinal cord tissue level of tumor necrosis factor alpha (TNFα) and tissue levels of matrix metalloproteinase 9 (MMP-9) and interleukin 17 (IL-17) as inflammatory markers, microtubule-associated proteins 1A/1B light chain 3A (MAP1LC3A), and activity dependent neuroprotector homeobox (ADNP) as neuroprotective markers were assayed using enzyme linked immunosorbent assay (ELISA) method. The clinical score of EAE in the diosgenin treatment group was significantly reduced compared to the EAE group on days 15 to 18 after induction of the EAE (p < 0.001). Inflammation, demyelination and axonal loss scores also decreased significantly in the diosgenin treatment group compared to the EAE group (p < 0.05). Serum and spinal cord tissue level of TNFα and tissue level of MMP-9 considerably decreased in the diosgenin treatment group in comparison with the EAE group (p < 0.01). Diosgenin treatment had no significant effects on the tissue levels of IL-17, ADNP and MAP1LC3A. Therefore, diosgenin improved the clinical signs of EAE through lowering neuroinflammation, demyelination and axonal degeneration, but did not significantly affect the neuroprotective factors in this study. As a result, diosgenin could be a good candidate for new MS treatment strategies that, in addition to their anti-inflammatory effects, also enhance myelination.

Scutellarin alleviates lipopolysaccharide-induced cognitive deficits in the rat: Insights into underlying mechanisms.

Inflammation is a common hallmark of neurodegenerative disorders. Systemic inflammation is usually associated with cognitive deficits. Scutellarin is a flavone with established antioxidant, anti-inflammatory, and neuroprotective effects. In this study, the effect of this flavone in prevention of lipopolysaccharide (LPS)-induced cognitive deficit was evaluated. LPS was i.p. injected at a dose of 500µg/kg/day and scutellarin was administered i.p. at doses of 5, 25, or 50mg/kg/day. Treatment of LPS-injected rats with scutellarin dose-dependently ameliorated deficits of spatial recognition memory in Y maze, discrimination index in novel object discrimination task, and retention and recall index in passive avoidance test. Additionally, scutellarin lowered hippocampal malondialdehyde (MDA) and potentiated antioxidant defense elements comprising superoxide dismutase (SOD), catalase, and glutathione (GSH) in addition to reduction of acetylcholinesterase (AChE) activity. Furthermore, scutellarin decreased hippocampal nuclear factor-kappaB (NF-κB), tumor necrosis factor α (TNFα), interleukin 6 (IL-6) and elevated nuclear factor (erythroid-derived 2)-like 2 (Nrf2). Inappropriate alterations of authophagy markers including beclin-1, LC3 II, mTOR, and P62 were also prevented in the presence of scutellarin. Our findings demonstrate that scutellarin alleviates LPS-induced cognitive disturbances, however, the precise mechanism remains still speculative.

S-allyl cysteine improves clinical and neuropathological features of experimental autoimmune encephalomyelitis in C57BL/6 mice.

Multiple sclerosis (MS) is a deleterious autoimmune and demyelinating disorder of the central nervous system with debilitating sensory and motor complications. There is still no definite cure for it and the main focus for its treatment mostly pivots around subsiding its severity and recurrence. Experimental autoimmune encephalomyelitis (EAE) is an established animal model of MS. S-allyl cysteine (SAC) is the active and main constituent of aged garlic extract with anti-inflammatory and neuroprotective property. This study was conducted to evaluate its possible protective effect in EAE model of MS. SAC was administered p.o. at a dose of 50 mg/kg/day to female C57BL/6 mice immunized with myelin oligodendrocytic glycoprotein (MOG35-55). Results showed that SAC is capable to alleviate clinical signs and severity of the disease and improved lumbar spinal cord tissue level of tumor necrosis factor α (TNFa), interleukin 17 (IL-17), activity-dependent neuroprotector homeobox (ADNP), microtubule-associated proteins 1A/1 B light chain 3A (MAP1LC3A), and matrix metalloproteinase 9 (MMP-9). In addition, SAC attenuated inflammatory cell infiltration, axonal demyelination, and axonal loss in lumbar spinal cord in EAE group, as demonstrated by H & E, Luxol fast blue (LFB), and Bielschowsky silver staining, respectively. Taken together, SAC could mitigate severity of MOG35-55-induced EAE as a valid model of MS via amelioration of pathogenic molecular mechanisms responsible for neuroinflammation and axonal damage.

The anti-aging protein klotho alleviates injury of nigrostriatal dopaminergic pathway in 6-hydroxydopamine rat model of Parkinson's disease: Involvement of PKA/CaMKII/CREB signaling.

Parkinson's disease (PD) is a prevalent movement disorder in the elderly. PD is hallmarked with progressive deterioration of mesencephalic dopaminergic neurons and development of debilitating motor and non-motor clinical symptoms. Klotho protein is the product of an aging-suppressor gene that its overexpression could protect neurons against oxidative injury. This study was undertaken to explore whether exogenous klotho could alleviate injury of nigrostriatal dopaminergic pathway in 6-hydroxydopamine (6-OHDA) rat model of PD. Intrastriatal 6-OHDA-lesioned rats were pretreated with klotho at a dose of 10µg/rat. Results showed that klotho mitigates apomorphine-induced rotational behavior and reduces the latency to initiate and the total time in the narrow beam test. In addition, beneficial effect of klotho was attenuated following i.c.v. microinjection of protein kinase A (PKA) inhibitor H-89 and Ca(2+)/calmodulin-dependent protein kinase II (CamKII) inhibitor KN-62. Additionally, klotho significantly lowered striatal levels of malondialdehyde (MDA), reactive oxygen species (ROS), glial fibrillary acid protein (GFAP), α synuclein, phospho-cAMP-response element binding protein (pCREB), and DNA fragmentation. Furthermore, klotho was capable to prevent degeneration of tyrosine hydroxylase (TH)-positive neurons within substantia nigra pars compacta (SNC). Collectively, these findings denote neuroprotective potential of exogenous klotho in 6-OHDA rat model of PD through alleviation of astrogliosis, apoptosis, and oxidative stress. It was also obtained that part of its protective effect is dependent on PKA/CaMKII/CREB signaling cascade.

Age-Related Differences in Neuropathic Pain Behavior and Spinal Microglial Activity after L5 Spinal Nerve Ligation in Male Rats.

INTRODUCTION: Several studies have reported the involvement of age-related changes in the development of neuropathic pain behaviors. However, limited data are available on the role of age in establishing and maintaining chronic neuropathic pain after peripheral nerve injury. METHODS: In the present study, we examined age-related neuropathic behavior among rats in 4 age groups: pups (4 weeks old; weight, 60-80 g), juvenile rats (6 weeks old; weight, 120-140 g), and mature rats (10-12 weeks old; weight, 200-250 g). Because the exact contribution of spinal microglia and its association with the development of neuropathic pain remains unknown, we also evaluated the expression of spinal Iba1, a microglial marker, by using western blotting before and 5 days after spinal nerve ligation (SNL) as well as after the daily IP administration of minocycline (30 mg/kg). RESULTS: Our results showed that SNL-induced mechanical allodynia but not thermal hyperalgesia in mature rats but not in pups (P<0.05 and P<0.01, respectively). The expression of spinal Iba1 in the juvenile rats was significantly lower than that in pups and mature rats (P<0.01). Moreover, administration of minocycline decreased the expression of spinal Iba1 in the pup rats more than in juvenile rats (P<0.001) and in the juvenile rats more than in the mature rats (P<0.05). CONCLUSION: These data suggest that the development of neuropathic behaviors and microglial activation after SNL could be age dependent.