Neuropharmacology
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Impact to the head or rapid head acceleration-deceleration can cause traumatic brain injury (TBI) with a characteristic pathology of traumatic axonal injury (TAI) and secondary damage in white matter tracts. Myelin and oligodendrocyte lineage cells have significant roles in the progression of white matter pathology after TBI and in the potential for plasticity and subsequent recovery. The myelination pattern of specific brain regions, such as frontal cortex, may also increase susceptibility to neurodegeneration and psychiatric symptoms after TBI. ⋯ Thus, effective remyelination and myelin remodeling may be neurobiological substrates of plasticity in neuronal circuits that require long-distance communication. This perspective integrates findings from multiple contexts to propose a model of myelin and oligodendrocyte lineage cell relevance in white matter injury after TBI. This article is part of the Special Issue entitled 'Oligodendrocytes in Health and Disease'.
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Recently we reported that fluoxetine (10 mg/kg) improves functional recovery by attenuating blood spinal cord barrier (BSCB) disruption after spinal cord injury (SCI). Here we investigated whether a low-dose of fluoxetine (1 mg/kg) and vitamin C (100 mg/kg), separately not possessing any protective effect, prevents BSCB disruption and improves functional recovery when combined. After a moderate contusion injury at T9 in rat, a low-dose of fluoxetine and vitamin C, or the combination of both was administered intraperitoneally immediately after SCI and further treated once a day for 14 d. ⋯ Co-treatment with fluoxetine and vitamin C also significantly inhibited the expression and activation of MMP-9 at 8 h and 1 d after injury, respectively, and the infiltration of neutrophils (at 1 d) and macrophages (at 5 d) and the expression of inflammatory mediators (at 2 h, 6 h, 8 h or 24 h after injury) were significantly inhibited by co-treatment with fluoxetine and vitamin C. Furthermore, the combination of fluoxetine and vitamin C attenuated apoptotic cell death at 1 d and 5 d and improved locomotor function at 5 weeks after SCI. These results demonstrate the synergistic effect combination of low-dose fluoxetine and vitamin C on BSCB disruption after SCI and furthermore support the effectiveness of the combination treatment regimen for the management of acute SCI.
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The poor aqueous solubility of progesterone (PROG) limits its potential use as a therapeutic agent. We designed and tested EIDD-1723, a novel water-soluble analog of PROG with >100-fold higher solubility than that of native PROG, as candidate for development as a field-ready treatment for traumatic brain injury (TBI). The pharmacokinetic effects of EIDD-1723 on morphological and functional outcomes in rats with bilateral cortical impact injury were evaluated. ⋯ EIDD-1723 significantly reduced cerebral edema and improved recovery from motor, sensory and spatial learning deficits as well as, or better than, native PROG. Pharmacokinetic investigation after a single i.m. injection in rats revealed that EIDD-1723 was rapidly converted to the active metabolite EIDD-036, demonstrating first-order elimination kinetics and ability to cross the blood-brain barrier. Our results suggest that EIDD-1723 represents a substantial advantage over current PROG formulations because it overcomes storage, formulation and delivery limitations of PROG and can thereby reduce the time between injury and treatment.
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High fat (HF) diet-induced obesity has been shown to augment behavioral responses to psychostimulants that target the dopamine system. The purpose of this study was to characterize dopamine terminal changes induced by a HF diet that correspond with enhanced locomotor sensitization to amphetamine. C57BL/6J mice had limited (2hr 3 d/week) or extended (24 h 7 d/week) access to a HF diet or standard chow for six weeks. ⋯ Additionally, we observed reduced membrane dopamine transporter (DAT) levels after HF, and a shift in DAT localization to the cytosol was detected with limited access to HF. This study showed that different patterns of HF exposure produced distinct dopamine terminal adaptations to repeated AMPH, which differed from chow fed mice, and enhanced sensitization to AMPH. Locomotor sensitization in chow fed mice coincided with elevated DAT function and increased AMPH potency; however, the enhanced behavioral response to AMPH after HF exposure was unique in that it coincided with reduced DAT function and diet pattern-specific adaptations.
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Mounting evidences indicate the functional interactions between neuropeptide FF (NPFF) and opioids, including the endogenous opioids. In the present work, EN-9, a chimeric peptide containing the functional domains of the endogenous opioid endomorphin-2 (EM-2) and NPFF, was synthesized and pharmacologically characterized. In vitro cAMP assay demonstrated that EN-9 was a multifunctional agonist of κ-opioid, NPFF1 and NPFF2 receptors. ⋯ At supraspinal level, only high dose of EN-9 (60 nmol, i.c.v.) inhibited gastrointestinal transit via NPFF receptors. Similarly, systemic administration of EN-9 also inhibited gastrointestinal transit at high doses (10 and 30 mg/kg, i.v.). Taken together, the multifunctional agonist of κ-opioid and NPFF receptors EN-9 produced a potent, non-tolerance forming antinociception with limited side effects.