Experimental neurology
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Experimental neurology · Jul 2019
Repetitive closed-head impact model of engineered rotational acceleration (CHIMERA) injury in rats increases impulsivity, decreases dopaminergic innervation in the olfactory tubercle and generates white matter inflammation, tau phosphorylation and degeneration.
Traumatic brain injury (TBI) affects at least 3 M people annually. In humans, repetitive mild TBI (rmTBI) can lead to increased impulsivity and may be associated with chronic traumatic encephalopathy. To better understand the relationship between repetitive TBI (rTBI), impulsivity and neuropathology, we used CHIMERA (Closed-Head Injury Model of Engineered Rotational Acceleration) to deliver five TBIs to rats, which were continuously assessed for trait impulsivity using the delay discounting task and for neuropathology at endpoint. ⋯ Consistent with diffuse axonal injury generated by CHIMERA, white matter inflammation, tau immunoreactivity and degeneration were observed in the optic tract and corpus callosum. Finally, pronounced grey matter microgliosis was observed in the olfactory tubercle. Our results provide insight into the mechanisms by which rTBI leads to post-traumatic psychiatric-like symptoms in a novel rat TBI platform.
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Experimental neurology · Jul 2019
Upregulation of interleukin-6 on Cav3.2 T-type calcium channels in dorsal root ganglion neurons contributes to neuropathic pain in rats with spinal nerve ligation.
The T-type calcium channels Cav3.2, one of the low voltage-activated (LVA) calcium channels, have been found to play important roles in the neuronal excitability. Recently, we and others have demonstrated that accumulation of Cav3.2 channels in the dorsal root ganglion (DRG) neurons and sensory nerves contributes to neuropathic pain after peripheral nerve injury. In the present study, we aimed to further investigate the regulation of Cav3.2 channels by interleukin-6 (IL-6) in DRG neurons in neuropathic pain rats after spinal nerve ligation (SNL). ⋯ Furthermore, inhibition of IL-6 trans-signaling reduced the upregulation of Cav3.2 T-type channel induced by FIL-6 (a fusion protein of IL-6 and sIL-6R) in primary cultured DRG neurons in vitro. In vivo, inhibition of IL-6 trans-signaling reversed the upregulation of Cav3.2, reduced the hyperexcitability of L5 DRG neurons and alleviated mechanical allodynia in SNL rats. Our results suggest that IL-6 upregulates Cav3.2 T-type channels expression and function through the IL-6/sIL-6R trans-signaling pathway in DRG neurons, thus contributes to the development of neuropathic pain in SNL rats.
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Experimental neurology · Jul 2019
Impairment of pericyte-endothelium crosstalk leads to blood-brain barrier dysfunction following traumatic brain injury.
The blood-brain barrier (BBB) constitutes a neurovascular unit formed by microvascular endothelial cells, pericytes, and astrocytes. Brain pericytes are important regulators of BBB integrity, permeability, and blood flow. Pericyte loss has been implicated in injury; however, how the crosstalk among pericytes, endothelial cells, and astrocytes ultimately leads to BBB dysfunction in traumatic brain injury (TBI) remains elusive. ⋯ Similarly, pericyte-endothelium integrity impairment in FPI animals greatly increases the permeability of small-molecular-weight sodium fluorescein and high-molecular-weight-tracer Evans blue across the BBB. In addition, the injury-inflicted animals show significantly higher levels of S100β and NSE in the blood samples compared with controls. In conclusion, our data provide an insight that brain trauma causes an early impairment of pericyte-endothelium integrity and results in BBB dysregulation that initiates pathological consequences associated with TBI.
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Experimental neurology · Jul 2019
Neuroprotective effects of inter-alpha inhibitor proteins after hypoxic-ischemic brain injury in neonatal rats.
Hypoxic-ischemic (HI) brain injury is one of the most common neurological problems occurring in the perinatal period. Hypothermia is the only approved intervention for neonatal HI encephalopathy. However, this treatment is only partially protective, has a narrow therapeutic time window after birth and only can be used to treat full-term infants. ⋯ Delayed treatment with IAIPs 6 h after HI did not improve histopathological brain injury in males or females, but resulted in higher (P < 0.050) brain weights compared with the placebo-treated HI males. Therefore, treatment with IAIPs immediately after HI improved brain weights and reduced neuropathological brain injury and cell death in male rats, and reduced infarct volume in both male and female neonatal rats. We conclude that IAIPs exert neuroprotective effects after exposure to HI in neonatal rats and may exhibit some sex-related differential effects.
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Experimental neurology · Jul 2019
FGF21 promotes functional recovery after hypoxic-ischemic brain injury in neonatal rats by activating the PI3K/Akt signaling pathway via FGFR1/β-klotho.
Perinatal asphyxia often results in neonatal cerebral hypoxia-ischemia (HI), which is associated with high mortality and severe long-term neurological deficits in newborns. Currently, there are no effective drugs to mitigate the functional impairments post-HI. Previous studies have shown that fibroblast growth factor 21 (FGF21) has a potential neuroprotective effect against brain injury. ⋯ In isolated primary cortical neurons, the rhFGF21 treatment protected primary neurons from oxygen-glucose deprivation (OGD) insult by inhibiting neuronal apoptosis and promoting neuronal survival. Both our in vivo and in vitro results reveal that rhFGF21 could inhibit neuronal apoptosis by activating the PI3K/Akt signaling pathway via FGF21/FGFR1/β-klotho complex formation. Therefore, rhFGF21 may be a promising therapeutic agent for promoting functional recovery after HI-induced neonatal brain injury.