Kallikrein-related peptidase 6: a biomarker for traumatic brain injury in the rat.

Background: Establishment of a traumatic brain injury (TBI)-sensitive biomarker or identification of a key therapeutic agent would significantly improve clinicians' efforts to diagnose and treat TBI, thereby promoting improved outcomes for patients. Numerous studies support the role of kallikrein-6 (Klk6) as a critical component of neuroinflammation and demyelination. This study assesses whether Klk6 is implicated in the secondary mechanisms of TBI and subsequently if serum levels of Klk6 are useable as a biomarker.

Zinc supplementation provides behavioral resiliency in a rat model of traumatic brain injury.

Depression, anxiety, and impairments in learning and memory are all associated with traumatic brain injury (TBI). Because of the strong link between zinc deficiency, depression, and anxiety, in both humans and rodent models, we hypothesized that dietary zinc supplementation prior to injury could provide behavioral resiliency to lessen the severity of these outcomes after TBI. Rats were fed a marginal zinc deficient (5 ppm), zinc adequate (30 ppm), or zinc supplemented (180 ppm) diet for 4 weeks followed by a moderately-severe TBI using the well-established model of controlled cortical impact (CCI).

Vitamin D deficiency reduces the benefits of progesterone treatment after brain injury in aged rats.

Administration of the neurosteroid progesterone (PROG) has been shown to be beneficial in a number of brain injury models and in two recent clinical trials. Given widespread vitamin D deficiency and increasing traumatic brain injuries (TBIs) in the elderly, we investigated the interaction of vitamin D deficiency and PROG with cortical contusion injury in aged rats. Vitamin D deficient (VitD-deficient) animals showed elevated inflammatory proteins (TNFα, IL-1β, IL-6, NFκB p65) in the brain even without injury.

Progesterone and its metabolite allopregnanolone differentially regulate hemostatic proteins after traumatic brain injury.

Our laboratory has shown in numerous experiments that the neurosteroids progesterone (PROG) and allopregnanolone (ALLO) improve molecular and functional outcomes after traumatic brain injury (TBI). As coagulopathy is an important contributor to the secondary destruction of nervous tissue, we hypothesized that PROG and ALLO administration may also have a beneficial effect on coagulation protein expression after TBI. Adult male Sprague-Dawley rats were given bilateral contusions of the medial frontal cortex followed by treatments with PROG (16 mg/kg), ALLO (8 mg/kg), or vehicle (22.

Progesterone improves acute recovery after traumatic brain injury in the aged rat.

Recent evidence has demonstrated that treatment with progesterone can attenuate many of the pathophysiological events following traumatic brain injury (TBI) in young adult rats, but this effect has not been investigated in aged animals. In this study, 20-month-old male Fischer 344 rats with bilateral contusions of the frontal cortex (n = 4 per group) or sham operations received 8, 16, or 32 mg/kg of progesterone or vehicle. Locomotor activity was measured at 72 h to assess behavioral recovery.

Neurosteroids reduce inflammation after TBI through CD55 induction.

The inflammatory cascade that follows traumatic brain injury may lead to secondary cell death and can impede recovery of function. Complement factors and their convertases are increased in glia after brain injury and lead to the production of inflammatory products that kill vulnerable neurons. Progesterone and its metabolite allopregnanolone (5alpha-pregnan-3beta-ol-20-one) have been shown to reduce the expression of inflammatory cytokines in the acute stages of brain injury, although how they do this is not completely understood.

The enantiomer of progesterone acts as a molecular neuroprotectant after traumatic brain injury.

Previous work shows that neurosteroid enantiomers activate specific molecular receptors that relay neuroprotection. However, the actions of the enantiomer of progesterone (ent-PROG) at the PROG receptor (PR) are unknown. PR binding and transcriptional assays were performed to determine the actions of ent-PROG at the classical PR.

Slow-release and injected progesterone treatments enhance acute recovery after traumatic brain injury.

The benefits of continuous progesterone release via subcutaneous silastic capsule implants were compared to daily subcutaneous injections in a rat model of traumatic brain injury (TBI). Adult male Sprague-Dawley rats received either bilateral frontal cortex contusions or sham surgery. Rats were injected with progesterone or vehicle at 1 and 6 h post-injury, then once every 24 h for six days with tapering of the dose over the final two treatments.

Tapered progesterone withdrawal promotes long-term recovery following brain trauma.

We previously demonstrated that after traumatic brain injury (TBI), acute progesterone withdrawal (AW) causes an increase in anxiety behaviors and cerebro-cellular inflammation compared to tapered progesterone withdrawal (TW). Our current study investigates the behavioral and cellular effects of AW two weeks after termination of treatments to determine the longer-term influence of withdrawal after injury. Adult, male Sprague-Dawley rats received either bilateral frontal cortex contusion (L) or sham (S) surgery.

Expression profiling of p53-target genes in copper-mediated neuronal apoptosis.

Copper toxicity associated with Wilson's disease is known to cause neuronal damage and death in the basal ganglia and frontal cortex leading to Parkinson-like symptoms and cognitive deficits. Our previous work in cultured human NTERA-2-N neurons showed that copper-induced neuronal apoptosis is dependent on the induction and nuclear translocation of the tumor suppressor protein, p53. Because p53 acts as a DNA-binding transcription factor, this work used an oligonucleotide array to identify p53 target genes that are differentially regulated in copper-loaded neurons.

Copper alters the conformation and transcriptional activity of the tumor suppressor protein p53 in human Hep G2 cells.

The tumor suppressor protein p53 plays a role in the molecular response to DNA damage by acting as a DNA-binding transcription factor that regulates specific target genes to arrest the cell cycle, induce repair mechanisms, and initiate apoptotic cell death. To test the effect of copper on the transcriptional activity of p53, Hep G2 cells were transiently transfected with a luciferase reporter gene downstream from multiple p53 response elements. Co-transfection with the p53 gene resulted in a 6-fold increase in luciferase activity, showing that p53 acts as a transcription factor in this system.

Effect of retinoic acid on ferritin H expression during brain development and neuronal differentiation.

We have previously shown that brain ferritin H expression, which has been associated with iron utilization, is developmentally regulated. Because retinoic acid (RA) regulates gene expression and is involved in cellular differentiation, we tested the hypothesis that RA regulates ferritin H during brain development and neuronal differentiation. RA, administered to rats on postnatal day 1, produced a 4-fold increase in brain ferritin H mRNA (p < 0.

Moderate zinc deficiency increases cell death after brain injury in the rat.

Zinc supplementation has been used clinically to reduce Zn losses and protein turnover in patients suffering from traumatic brain injury. Despite the known role of zinc in cell survival and integrity, the influence of zinc status on central nervous system wound healing in the weeks and months after brain injury has not been addressed. In this investigation, we examined cell death after unilateral cortical stab wounds in adult rats (n = 5 per group) that were provided diets containing adequate zinc (30 mg Zn/kg diet), supplemental zinc (180 mg/kg), or moderately deficient zinc (5 mg/kg).

Zinc inhibits the nuclear translocation of the tumor suppressor protein p53 and protects cultured human neurons from copper-induced neurotoxicity.

High concentrations of the trace metal zinc (Zn) have previously been shown to provide transient protection of cells from apoptotic death. The molecular mechanisms responsible for this protection are not known. Thus, this work explored the ability of Zn to protect human neurons in culture (NT2-N) from Cu-mediated death and tested the hypotheses that the tumor-suppressor protein p53 plays a role in Cu-induced neuronal death and is part of the mechanism of Zn protection.