Differences in outcomes following an intensive upper-limb rehabilitation program for patients with common central nervous system-acting drug prescriptions

Background: Difficulty using the upper-limb is a major barrier to independence for many patients post-stroke or brain injury. High dose rehabilitation can result in clinically significant improvements in function even years after the incident; however, there is still high variability in patient responsiveness to such interventions that cannot be explained by age, sex, or time since stroke. Methods: This retrospective study investigated whether patients prescribed certain classes of central nervous system-acting drugs—γ-aminobutyric acid (GABA) agonists, antiepileptics, and antidepressants—differed in their outcomes on the three-week intensive Queen Square Upper-Limb program. For 277 stroke or brain injury patients (167 male, median age 52 years (IQR: 21), median time since incident 20 months (IQR: 26)) upper-limb impairment and activity was assessed at admission to the program and at six months post-discharge, using the upper limb component of the Fugl-Meyer, Action Research Arm Test, and Chedoke Arm and Hand Activity Inventory. Drug prescriptions were obtained from primary care physicians at referral. Specification curve analysis was used to protect against selective reporting results and add robustness to the conclusions of this retrospective study. Results: Patients with GABA agonist prescriptions had significantly worse upper-limb scores at admission but no evidence for a significant difference in program-induced improvements was found. Additionally, no evidence of significant differences in patients with or without antiepileptic drug prescriptions on either admission to, or improvement on, the program was found in this study. Although no evidence was found for differences in admission scores, patients with antidepressant prescriptions experienced reduced improvement in upper-limb function, even when accounting for anxiety and depression scores. Conclusions: These results demonstrate that, when prescribed typically, there was no evidence that patients prescribed GABA agonists performed worse on this high-intensity rehabilitation program. Patients prescribed antidepressants, however, performed poorer than expected on the Queen Square Upper-Limb rehabilitation program. While the reasons for these differences are unclear, identifying these patients prior to admission may allow for better accommodation of differences in their rehabilitation needs.

Pharmacokinetics, pharmacodynamics, safety, tolerability, and mass balance of single and continuous intravenous infusion of SPT-07A in healthy volunteers

PURPOSE

SPT-07A is an intravenous injection of (+)-2-borneol being developed for the treatment of acute ischemic stroke. This study aimed to investigate the pharmacokinetics, pharmacodynamics, safety, tolerability, and mass balance of SPT-07A after sequentially administered single and multiple infusions of SPT-07A at 10 mg, 20 mg, or 40 mg.

METHODS

This phase I, double-blind, randomized, placebo-controlled, dose-escalation study was conducted in 36 Chinese healthy volunteers. Each cohort enrolled 12 eligible subjects, who were 9:3 randomized to receive SPT-07A or matching placebo during the two study occasions, that is, an initial single-dose occasion followed by a 7-day multiple-dose occasion with a dosing interval of 12 h. Pharmacokinetic, pharmacodynamic assessments regarding effects on the central nervous system (CNS) were performed pre-dose and several times post-dose. Safety and tolerability were evaluated throughout the study for each cohort.

RESULTS

Following single intravenous (i.v.) administration of 10 mg to 40 mg SPT-07A, the plasma SPT-07A concentration reached its peak by the end of infusion. Thereafter, the plasma concentration declined in a multiphase exponential manner with an average terminal elimination half-life of 3.85 to 8.93 h. The exposure parameters of SPT-07A increased dose proportionally. Steady state of SPT-07A was reached after 12-hourly i.v. administrations for 4 days with minimal accumulations. No significant difference of change-from-baseline was observed in the pharmacodynamic measurements between each of the three SPT-07A-treated groups and the placebo group. A total of 41 adverse events (AEs) were reported in 77.8% subjects at 10 mg (7/9), 20 mg (7/9), and 40 mg (7/9), respectively. The AE incidence in placebo group was also 77.8% (7/9). All AEs were mild or moderate in severity and self-limited. SPT-07A was mainly excreted in human urine in glucuronic acid conjugate forms. The total urine recovery rate approximated 84.69% of the administered dose.

CONCLUSIONS

SPT-07A was safe and well tolerated after single and multiple intravenous administrations of SPT-07A in the range of 10 mg to 40 mg. SPT-07A presented linear pharmacokinetics in human. Based on plasma exposure, the doses of 10-40 mg twice daily resulted in exposure levels comparable with those obtained at doses demonstrating potential efficacy on AIS animal models and were thus recommended as therapeutic exploratory doses in the phase II clinical trial.

Conditioned Aversion and Neuroplasticity Induced by a Superagonist of Extrasynaptic GABAA Receptors: Correlation With Activation of the Oval BNST Neurons and CRF Mechanisms

THIP (gaboxadol), a superagonist of the δ subunit-containing extrasynaptic GABA_A receptors, produces persistent neuroplasticity in dopamine (DA) neurons of the ventral tegmental area (VTA), similarly to rewarding drugs of abuse. However, unlike them THIP lacks abuse potential and induces conditioned place aversion in mice. The mechanism underlying the aversive effects of THIP remains elusive. Here, we show that mild aversive effects of THIP were detected 2 h after administration likely reflecting an anxiety-like state with increased corticosterone release and with central recruitment of corticotropin-releasing factor corticotropin-releasing factor receptor 1 (CRF₁) receptors. A detailed immunohistochemical c-Fos expression mapping for THIP-activated brain areas revealed a correlation between the activation of CRF-expressing neurons in the oval nucleus of the bed nuclei of stria terminalis and THIP-induced aversive effects. In addition, the neuroplasticity of mesolimbic DA system (24 h after administration) and conditioned place aversion by THIP after four daily acute sessions were dependent on extrasynaptic GABA_A receptors (abolished in δ-GABA_A receptor knockout mice) and activation of the CRF₁ receptors (abolished in wildtype mice by a CRF₁ receptor antagonist). A selective THIP-induced activation of CRF-expressing neurons in the oval part of the bed nucleus of stria terminalis may constitute a novel mechanism for inducing plasticity in a population of VTA DA neurons and aversive behavioral states.

The neural basis of motion sickness

Although motion of the head and body has been suspected or known as the provocative cause for the production of motion sickness for centuries, it is only within the last 20 yr that the source of the signal generating motion sickness and its neural basis has been firmly established. Here, we briefly review the source of the conflicts that cause the body to generate the autonomic signs and symptoms that constitute motion sickness and provide a summary of the experimental data that have led to an understanding of how motion sickness is generated and can be controlled. Activity and structures that produce motion sickness include vestibular input through the semicircular canals, the otolith organs, and the velocity storage integrator in the vestibular nuclei. Velocity storage is produced through activity of vestibular-only (VO) neurons under control of neural structures in the nodulus of the vestibulo-cerebellum. Separate groups of nodular neurons sense orientation to gravity, roll/tilt, and translation, which provide strong inhibitory control of the VO neurons. Additionally, there are acetylcholinergic projections from the nodulus to the stomach, which along with other serotonergic inputs from the vestibular nuclei, could induce nausea and vomiting. Major inhibition is produced by the GABA_B receptors, which modulate and suppress activity in the velocity storage integrator. Ingestion of the GABA_B agonist baclofen causes suppression of motion sickness. Hopefully, a better understanding of the source of sensory conflict will lead to better ways to avoid and treat the autonomic signs and symptoms that constitute the syndrome.

Arbaclofen in fragile X syndrome: results of phase 3 trials

Background

Arbaclofen improved multiple abnormal phenotypes in animal models of fragile X syndrome (FXS) and showed promising results in a phase 2 clinical study. The objective of the study is to determine safety and efficacy of arbaclofen for social avoidance in FXS.

Methods

Two phase 3 placebo-controlled trials were conducted, a flexible dose trial in subjects age 12–50 (209FX301, adolescent/adult study) and a fixed dose trial in subjects age 5–11 (209FX302, child study). The primary endpoint for both trials was the Social Avoidance subscale of the Aberrant Behavior Checklist-Community Edition, FXS-specific (ABC-C_FX). Secondary outcomes included other ABC-C_FX subscale scores, Clinical Global Impression-Improvement (CGI-I), Clinical Global Impression-Severity (CGI-S), and Vineland Adaptive Behavior Scales, Second Edition (Vineland-II) Socialization domain score.

Results

A total 119 of 125 randomized subjects completed the adolescent/adult study (n = 57 arbaclofen, 62 placebo) and 159/172 completed the child study (arbaclofen 5 BID n = 38; 10 BID n = 39; 10 TID n = 38; placebo n = 44). There were no serious adverse events (AEs); the most common AEs included somatic (headache, vomiting, nausea), neurobehavioral (irritability/agitation, anxiety, hyperactivity), decreased appetite, and infectious conditions, many of which were also common on placebo. In the combined studies, there were 13 discontinuations (n = 12 arbaclofen, 1 placebo) due to AEs (all neurobehavioral). The adolescent/adult study did not show benefit for arbaclofen over placebo for any measure. In the child study, the highest dose group showed benefit over placebo on the ABC-C_FX Irritability subscale (p = 0.03) and Parenting Stress Index (PSI, p = 0.03) and trends toward benefit on the ABC-C_FX Social Avoidance and Hyperactivity subscales (both p < 0.1) and CGI-I (p = 0.119). Effect size in the highest dose group was similar to effect sizes for FDA-approved serotonin reuptake inhibitors (SSRIs).

Conclusions

Arbaclofen did not meet the primary outcome of improved social avoidance in FXS in either study. Data from secondary measures in the child study suggests younger patients may derive benefit, but additional studies with a larger cohort on higher doses would be required to confirm this finding. The reported studies illustrate the challenges but represent a significant step forward in translating targeted treatments from preclinical models to clinical trials in humans with FXS.

Diabetic encephalopathy-related depression: experimental evidence that insulin and clonazepam restore antioxidant status in rat brain

There is increasing evidence suggesting that oxidative stress plays an important role in the development of many chronic and degenerative conditions such as diabetic encephalopathy and depression. Considering that diabetic rats and mice present higher depressive-like behaviour when submitted to the forced swimming test and that treatment with insulin and/or clonazepam is able to reverse the behavioural changes of the diabetic rats, the present work investigated the antioxidant status, specifically total antioxidant reactivity and antioxidant potential of insulin and clonazepam, as well as the effect of this drugs upon protein oxidative damage and reactive species formation in cortex, hippocampus and striatum from diabetic rats submitted to forced swimming test. It was verified that longer immobility time in diabetic rats and insulin plus clonazepam treatment reversed this depressive-like behaviour. Moreover, data obtained in this study allowed to demonstrate through different parameters such as protein carbonyl content, 2'7'-dichlorofluorescein oxidation, catalase, superoxide dismutase, glutathione peroxidase assay, total radical-trapping antioxidant potential and total antioxidant reactivity that there is oxidative stress in cortex, hippocampus and striatum from diabetic rats under depressive-like behaviour and highlight the insulin and/or clonazepam effect in these different brain areas, restoring antioxidant status and protein damage.

Effects of muscimol inactivations of functional domains in motor, premotor, and posterior parietal cortex on complex movements evoked by electrical stimulation

Parietal and frontal cortex are central to controlling forelimb movements. We previously showed that movements such as reach, grasp, and defense can be evoked from primary motor (M1), premotor (PMC), and posterior parietal (PPC) cortex when 500-ms trains of electrical pulses are delivered via microelectrodes. Stimulation sites that evoked a specific movement clustered into domains, which shared a topographic pattern in New World monkeys and prosimian galagos. Matched functional domains in parietal and frontal cortex were preferentially interconnected. We reasoned that matched functional domains form parallel networks involved in specific movements. To test the roles of domains in M1, PMC, and PPC, we systematically inactivated with muscimol domains in one region and determined if functional changes occurred in matching domains in other regions. The most common changes were higher current thresholds for stimulation-evoked movements and shorter, not fully developed, trajectories of movements. Inactivations of an M1 functional domain greatly reduced or abolished movements evoked from the matching domains in PMC or PPC, whereas movements evoked from nonmatching domains remained mostly unaffected. In contrast, inactivating PMC or PPC domains did not consistently abolish the ability to evoke movements from matching M1 domains. However, inactivation of PMC domains suppressed or altered the movements evoked from PPC domains. Thus movement sequences evoked from PMC depend on M1 and movement sequences evoked from PPC depend on both M1 and PMC. Overall, the results support the conclusion that PPC, PMC, and M1 are subdivided into functional domains that are hierarchically related within parallel networks.

Medial prefrontal cortex inactivation attenuates the diurnal rhythm in amphetamine reward

Psychostimulant reward, as assessed via the conditioned place preference (CPP) paradigm, exhibits a daily rhythm with peaks in the late dark and early light periods, and a nadir near the light-to-dark transition. While this diurnal rhythm is correlated with neural activity in several corticolimbic structures, the brain regions mediating this behavioral rhythm remain unknown. Here, we examine the role of the ventral medial prefrontal cortex (mPFC). The effects of excitotoxic mPFC lesions on daily rhythms in amphetamine CPP were examined at previously observed peak (zeitgeber time [ZT] 23) and nadir times (ZT11). mPFC lesions encompassing the prelimbic and infralimbic subregions increased the CPP for amphetamine at the nadir time, thereby eliminating the daily rhythm in amphetamine reward. To examine the effects of transient mPFC inactivation, rats received intra-mPFC infusions of GABA receptor agonists during the acquisition or expression phases of CPP testing. Inactivation of the ventral mPFC at either of these phases also eliminated the daily rhythm in amphetamine-induced CPP via an increase in drug-paired chamber dwell time at the baseline nadir. Together, these results indicate that the ventral mPFC plays a critical role in mediating the diurnal rhythm in amphetamine CPP during both the acquisition and expression of learned reward-context associations. Moreover, as the loss of rhythmicity occurs via an increase at the nadir point, these results suggest that excitatory output from the ventral mPFC normally inhibits context-elicited reward seeking prior to the light-to-dark transition.