Harpagophytum procumbens Extract Ameliorates Allodynia and Modulates Oxidative and Antioxidant Stress Pathways in a Rat Model of Spinal Cord Injury.

Spinal cord injury (SCI) is a deliberating disorder with impairments in locomotor deficits and incapacitating sensory abnormalities. Harpagophytum procumbens (Hp) is a botanical widely used for treating inflammation and pain related to various inflammatory and musculoskeletal conditions. Using a modified rodent contusion model of SCI, we explored the effects of this botanical on locomotor function and responses to mechanical stimuli, and examined possible neurochemical changes associated with SCI-induced allodynia. Following spinal cord contusion at T10 level, Hp (300 mg/kg, p.o.) or vehicle (water) was administered daily starting 24 h post-surgery, and behavioral measurements made every-other day until sacrifice (Day 21). Hp treatment markedly ameliorated the contusion-induced decrease in locomotor function and increased sensitivity to mechanical stimuli. Determination of Iba1 expression in spinal cord tissues indicated microglial infiltration starting 3 days post-injury. SCI results in increased levels of 4-hydroxynonenal, an oxidative stress product and proalgesic, which was diminished at 7 days by treatment with Hp. SCI also enhanced antioxidant heme oxygenase-1 (HO-1) expression. Concurrent studies of cultured murine BV-2 microglial cells revealed that Hp suppressed oxidative/nitrosative stress and inflammatory responses, including production of nitric oxide and reactive oxygen species, phosphorylation of cytosolic phospholipases A2, and upregulation of the antioxidative stress pathway involving the nuclear factor erythroid 2-related factor 2 and HO-1. These results support the use of Hp for management of allodynia by providing resilience against the neuroinflammation and pain associated with SCI and other neuropathological conditions.

Multi-Focal Neuronal Ultrastructural Abnormalities and Synaptic Alterations in Mice after Low-Intensity Blast Exposure.

Service members during military actions or combat training are exposed frequently to primary blast generated by explosive weaponry. The majority of military-related neurotrauma are classified as mild and designated as "invisible injuries" that are prevalent during current conflicts. While the previous experimental blast injury studies using moderate- to high-intensity exposures focused mainly on gross and microscopic neuropathology, our previous studies have shown that low-intensity blast (LIB) exposures resulted in nanoscale subcellular myelin and mitochondrial damages and subsequent behavioral disorders in the absence of gross or detectable cellular damage. In this study, we used transmission electron microscopy to delineate the LIB effects at the ultrastructural level specifically focusing on the neuron perikaryon, axons, and synapses in the cortex and hippocampus of mice at seven and 30 days post-injury (DPI). We found dysmorphic dark neuronal perikaryon and "cytoplasmic aeration" of dendritic processes, as well as increased microtubular fragmentation of the myelinated axons along with biochemically measured elevated tau/phosphorylated tau/Aß levels. The number of cortical excitatory synapses decreased along with a compensatory increase of the post-synaptic density (PSD) thickness both at seven and 30 DPI, while the amount of hippocampal CA1 synapses increased with the reduced PSD thickness. In addition, we observed a significant increase in protein levels of PSD95 and synaptophysin mainly at seven DPI indicating potential synaptic reorganization. These results demonstrated that a single LIB exposure can lead to ultrastructural brain injury with accompanying multi-focal neuronal organelle alterations. This pre-clinical study provides key insights into disease pathogenesis related to primary blast exposure.

Ultrastructural brain abnormalities and associated behavioral changes in mice after low-intensity blast exposure.

Explosive blast-induced mild traumatic brain injury (mTBI), a "signature wound" of recent military conflicts, commonly affects service members. While past blast injury studies have provided insights into TBI with moderate- to high-intensity explosions, the impact of primary low-intensity blast (LIB)-mediated pathobiology on neurological deficits requires further investigation. Our prior considerations of blast physics predicted ultrastructural injuries at nanoscale levels. Here, we provide quantitative data using a primary LIB injury murine model exposed to open field detonation of 350 g of high-energy explosive C4. We quantified ultrastructural and behavioral changes up to 30 days post blast injury (DPI). The use of an open-field experimental blast generated a primary blast wave with a peak overpressure of 6.76 PSI (46.6 kPa) at a 3-m distance from the center of the explosion, a positive phase duration of approximate 3.0 milliseconds (ms), a maximal impulse of 8.7 PSI × ms and a sharp rising time of 9 × 10-3 ms, with no apparent impact/acceleration in exposed animals. Neuropathologically, myelinated axonal damage was observed in blast-exposed groups at 7 DPI. Using transmission electron microscopy, we observed and quantified myelin sheath defects and mitochondrial abnormalities at 7 and 30 DPI. Inverse correlations between blast intensities and neurobehavioral outcomes including motor activities, anxiety levels, nesting behavior, spatial learning and memory occurred. These observations uncover unique ultrastructural brain abnormalities and associated behavioral changes due to primary blast injury and provide key insights into its pathogenesis and potential treatment.