Pharmacological Characterization of a Novel Neuroactive Steroid Prodrug, NTS-104, and Its Neuroprotective Activity in Experimental Stroke Models.

BACKGROUND: Ischemic stroke affects about 700 000 patients per year in the United States, and to date, there are no effective pharmacological agents that promote recovery. Here, we studied the pharmacokinetics, pharmacodynamics, and efficacy of NTS-105, a novel neuroactive steroid, and NTS-104, a prodrug of NTS-105, in 2 models of ischemic stroke. METHODS: The pharmacodynamics and pharmacokinetics of NTS-104/105 were investigated in naive and stroke rats, and models of embolic and transient middle cerebral artery occlusion were used to investigate the dose-related effects of NTS-104. All rats were randomly assigned into the experimental groups, and all outcome measurements were performed blindly. RESULTS: Blood plasma and brain pharmacokinetic analysis revealed that NTS-104 rapidly converted to NTS-105, which reached peak concentration at ≈1 hour after dosing and distributed similarly to normal and ischemic brains. NTS-104 administration 4 hours after embolic middle cerebral artery occlusion led to a dose-dependent improvement of neurological outcomes and a dose-dependent reduction of infarct volumes relative to vehicle-treated animals. A single dose level study confirmed that NTS-104 administered 4 hours after transient middle cerebral artery occlusion was also neuroprotective. Quantitative ELISA revealed that NTS-104 treatment resulted in time- and dose-dependent changes in AKT activation and cytokine levels within the ischemic brain, which included reductions of IL-6, VEGF, ICAM-1, IL-1ß, MCP-1, RAGE, and GM-CSF. Time- and dose-dependent reductions in IL-6 and GM-CSF were also observed in the plasma along with an elevation of galectin-1. CONCLUSIONS: NTS-104 is a novel prodrug that converts to a novel neuroactive steroid, NTS-105, which improves functional outcomes in experimental ischemic stroke models.

NTS-105 decreased cell death and preserved long-term potentiation in an in vitro model of moderate traumatic brain injury.

Traumatic brain injury (TBI) is a major cause of hospitalization and death. To mitigate these human costs, the search for effective drugs to treat TBI continues. In the current study, we evaluated the efficacy of the novel neurosteroid, NTS-105, to reduce post-traumatic pathobiology in an in vitro model of moderate TBI that utilizes an organotypic hippocampal slice culture. NTS-105 inhibited activation of the androgen receptor and the mineralocorticoid receptor, partially activated the progesterone B receptor and was not active at the glucocorticoid receptor. Treatment with NTS-105 starting one hour after injury decreased post-traumatic cell death in a dose-dependent manner, with 10 nM NTS-105 being most effective. Post-traumatic administration of 10 nM NTS-105 also prevented deficits in long-term potentiation (LTP) without adversely affecting neuronal activity in naïve cultures. We propose that the high potency pleiotropic action of NTS-105 beneficial effects at multiple receptors (e.g. androgen, mineralocorticoid and progesterone) provides significant mechanistic advantages over native neurosteroids such as progesterone, which lacked clinical success for the treatment of TBI. Our results suggest that this pleiotropic pharmacology may be a promising strategy for the effective treatment of TBI, and future studies should test its efficacy in pre-clinical animal models of TBI.

Improvement in edema and cognitive recovery after moderate traumatic brain injury with the neurosteroid prodrug NTS-104.

Neuroactive steroids reduce mortality, decrease edema, and improve functional outcomes in preclinical and clinical traumatic brain injury (TBI) studies. In this study, we tested the efficacy of two related novel neuroactive steroids, NTS-104 and NTS-105, in a rat model of TBI. NTS-104 is a water-soluble prodrug of NTS-105, a partial progesterone receptor agonist. To investigate the effects of NTS-104 on TBI recovery, adult male Sprague Dawley rats received moderate parasagittal fluid-percussion injury or sham surgery and were treated with vehicle or NTS-104 (10 â€‹mg/kg, intramuscularly) at 4, 10, 24, and 48 â€‹h post-TBI. The therapeutic time window was also assessed using the neuroactive steroid NTS-105 (3 â€‹mg/kg, intramuscularly). Edema in the parietal cortex and hippocampus, measured at 3 days post-injury (DPI), was reduced by NTS-104 and NTS-105. NTS-105 was effective in reducing edema when given at 4, 10, or 24 â€‹h post-injury. Sensorimotor deficits in the cylinder test at 3 DPI were ameliorated by NTS-104 and NTS-105 treatment. Cognitive recovery, assessed with cue and contextual fear conditioning and retention of the water maze task assessed subacutely 1-3 weeks post-injury, also improved with NTS-104 treatment. Cortical and hippocampal atrophy at 22 DPI did not improve, indicating that NTS-104/NTS-105 may promote post-TBI cognitive recovery by controlling edema and other processes. These results demonstrate that NTS-104/NTS-105 is a promising therapeutic approach to improve motor and cognitive recovery after moderate TBI.

Neurosteroid Receptor Modulators for Treating Traumatic Brain Injury.

Traumatic brain injury (TBI) triggers wide-ranging pathology that impacts multiple biochemical and physiological systems, both inside and outside the brain. Functional recovery in patients is impeded by early onset brain edema, acute and chronic inflammation, delayed cell death, and neurovascular disruption. Drug treatments that target these deficits are under active development, but it seems likely that fully effective therapy may require interruption of the multiplicity of TBI-induced pathological processes either by a cocktail of drug treatments or a single pleiotropic drug. The complex and highly interconnected biochemical network embodied by the neurosteroid system offers multiple options for the research and development of pleiotropic drug treatments that may provide benefit for those who have suffered a TBI. This narrative review examines the neurosteroids and their signaling systems and proposes directions for their utility in the next stage of TBI drug research and development.

Human tissue kallikrein in the treatment of acute ischemic stroke.

Acute ischemic stroke (AIS) remains a major cause of death and disability throughout the world. The most severe form of stroke results from large vessel occlusion of the major branches of the Circle of Willis. The treatment strategies currently available in western countries for large vessel occlusion involve rapid restoration of blood flow through removal of the offending blood clot using mechanical or pharmacological means (e.g. tissue plasma activator; tPA). This review assesses prospects for a novel pharmacological approach to enhance the availability of the natural enzyme tissue kallikrein (KLK1), an important regulator of local blood flow. KLK1 is responsible for the generation of kinins (bradykinin and kallidin), which promote local vasodilation and long-term vascularization. Moreover, KLK1 has been used clinically as a direct treatment for multiple diseases associated with impaired local blood flow including AIS. A form of human KLK1 isolated from human urine is approved in the People's Republic of China for subacute treatment of AIS. Here we review the rationale for using KLK1 as an additional pharmacological treatment for AIS by providing the biochemical mechanism as well as the human clinical data that support this approach.

Evaluation and tracking of Alzheimer's disease severity using resting-state magnetoencephalography.

We have conducted multicenter clinical studies in which brain function was evaluated with brief, resting-state magnetoencephalography (MEG) scans. A study cohort of 117 AD patients and 123 elderly cognitively normal volunteers was recruited from community neurology clinics in Denver, Colorado and Minneapolis, Minnesota. Each subject was evaluated through neurological examination, medical history, and a modest battery of standard neuropsychological tests. Brain function was measured by a one-minute, resting-state, eyes-open MEG scan. Cross-sectional analysis of MEG scans revealed global changes in the distribution of relative spectral power (centroid frequency of healthy subjects = 8.24 ± 0.2 Hz and AD patients = 6.78 ± 0.25 Hz) indicative of generalized slowing of brain signaling. Functional connectivity patterns were measured using the synchronous neural interactions (SNI) test, which showed a global increase in the strength of functional connectivity (cO2 value of healthy subjects = 0.059 ± 0.0007 versus AD patients = 0.066 ± 0.001) associated with AD. The largest magnitude disease-associated changes were localized to sensors near posterior and lateral cortical regions. Part of the cohort (31 AD and 46 cognitively normal) was evaluated in an identical fashion approximately 10 months after the first assessments. Follow-up scans revealed multiple MEG scan features that correlated significantly with changes in neuropsychological test scores. Linear combinations of these MEG scan features generated an accurate multivariate model of disease progression over 10 months. Our results demonstrate the utility of brief resting-state tests based on MEG. The non-invasive, rapid and convenient nature of these scans offers a new tool for translational AD research and early phase development of novel treatments for AD.