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Biomedical subjects

Donald G Stein

Publications and source records attributed to Donald G Stein.

At least 19 recordsLinked to original sources

ProTECT: a randomized clinical trial of progesterone for acute traumatic brain injury.

STUDY OBJECTIVE: Laboratory evidence indicates that progesterone has potent neuroprotective effects. We conducted a pilot clinical trial to assess the safety and potential benefit of administering progesterone to patients with acute traumatic brain injury. METHODS: This phase II, randomized, double-blind, placebo-controlled trial was conducted at an urban Level I trauma center. One hundred adult trauma patients who arrived within 11 hours of injury with a postresuscitation Glasgow Coma Scale score of 4 to 12 were enrolled with proxy consent. Subjects were randomized on a 4:1 basis to receive either intravenous progesterone or placebo. Blinded observers assessed patients daily for the occurrence of adverse events and signs of recovery. Neurologic outcome was assessed 30 days postinjury. The primary safety measures were differences in adverse event rates and 30-day mortality. The primary measure of benefit was the dichotomized Glasgow Outcome Scale-Extended 30 days postinjury. RESULTS: Seventy-seven patients received progesterone; 23 received placebo. The groups had similar demographic and clinical characteristics. Laboratory and physiologic characteristics were similar at enrollment and throughout treatment. No serious adverse events were attributed to progesterone. Adverse and serious adverse event rates were similar in both groups, except that patients randomized to progesterone had a lower 30-day mortality rate than controls (rate ratio 0.43; 95% confidence interval 0.18 to 0.99). Thirty days postinjury, the majority of severe traumatic brain injury survivors in both groups had relatively poor Glasgow Outcome Scale-Extended and Disability Rating Scale scores. However, moderate traumatic brain injury survivors who received progesterone were more likely to have a moderate to good outcome than those randomized to placebo. CONCLUSION: In this small study, progesterone caused no discernible harm and showed possible signs of benefit.

Accidents, Traffic↗

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. Additionally, the neuroprotective effects of ent-PROG in traumatic brain injury (TBI) were investigated and compared to the actions of PROG and its metabolite allopregnanolone (ALLO), both of which have been shown to have neuroprotective properties when given after TBI. Binding studies performed in COS cells over-expressing the PR showed that ent-PROG inhibited PROG binding to the PR. In contrast, ent-PROG did not activate PR-mediated transcription. Rats received bilateral medial frontal cortex injury followed by treatments at 1, 6, 24 and 48h with PROG, ALLO or ent-PROG. Brains were processed for edema, protein and enzyme activity. ent-PROG treatment in vivo decreased cerebral edema, cell death mediators, inflammatory cytokines, and reactive gliosis, and increased antioxidant activity. These findings suggest that the progestin-mediated pro-survival response seen with TBI is regulated either independently of the classical PR or via nongenomic PR-regulated actions.

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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. Progesterone-packed silastic capsules were implanted post-injury while the animals were anesthetized. Behavioral assays for anxiety and locomotor activity were evaluated pre- and post-TBI. Brains were extracted eight days post-TBI and prepared for molecular assays. Decreased GABAA-4 levels complemented a decrease in anxiety behaviors on the Elevated Plus Maze for capsule compared to progesterone-injected animals prior to daily injections. All groups with implanted capsules increased locomotor activity compared to those given progesterone injections. In conclusion, steady-state progesterone treatment after TBI decreases edema and anxiety and increases activity, thus enhancing behavioral recovery. A continuous mode of pharmacological administration may prove to be more beneficial in translational and clinical testing than bolus injections over the same period of time.

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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. Rats were injected at 1 and 6 h post-injury, then every 24 h for six days. Vehicle (V)-treated rats were given 9 injections of 22.5% cyclodextrin, whereas AW rats received 9 injections of 16 mg/kg progesterone and TW rats received 7 injections of P at 16 mg/kg, followed by one at 8 mg/kg and one at 4 mg/kg. On day 8, sensory neglect and locomotor activity tests were initiated. Animals were killed 22 days post-TBI and the brains prepared for either molecular or histological analysis. Western blotting revealed increased brain-derived neurotrophic factor (BDNF) and heat shock protein 70 (HSP70) in TW vs. AW animals. P53 was increased in VL animals, whereas all progesterone-treated groups were equivalent to shams. TW animals had markedly decreased sensory neglect compared to AW animals and increased center time in locomotor activity assays. In addition, lesion reconstruction revealed a decreased lesion size for TWL over AWL over VL animals. Glial fibrillary acidic protein (GFAP) immunofluorescent staining followed this pattern as well. In conclusion, after TBI, AW affects select behaviors and molecular markers in the chronic recovery period.

Anesthetics↗

Allopregnanolone, a progesterone metabolite, is more effective than progesterone in reducing cortical infarct volume after transient middle cerebral artery occlusion.

STUDY OBJECTIVE: We compare the effects of postinjury administration of allopregnanolone, a metabolite of progesterone, to progesterone in an animal model of transient middle cerebral artery occlusion. METHODS: Focal cerebral ischemia was induced in age-matched, adult, male, Sprague-Dawley rats by using an intraluminal filament and suture method to occlude the right middle cerebral artery. After 120 minutes of middle cerebral artery occlusion, the occluding filament was withdrawn to allow reperfusion. Laser-Doppler flowmetry was used to monitor cerebral blood flow for the entire 2-hour period of occlusion and for 5 minutes after reperfusion. Animals subjected to middle cerebral artery occlusion received injections of allopregnanolone (8 mg/kg, n=6), progesterone (8 mg/kg, n=6) and vehicle (2-hydroxypropyl-beta-cyclodextrin, n=7) at 2 hours (intraperitoneally 5 minutes before reperfusion) and 6 hours (subcutaneously) postocclusion. Brains were removed at 72 hours post-middle cerebral artery occlusion, sectioned into coronal slices, and stained with 2,3,5-triphenyltetrazolium chloride (TTC). In a blinded analysis, infarct volume was calculated by using computer-aided morphometry to measure brain areas not stained with TTC. RESULTS: After progesterone or allopregnanolone treatment, stained sections revealed a significant reduction in cortical, caudate-putamen, and hemispheric infarct volumes (percentage of contralateral structure) compared with vehicle-injected controls. Cortical infarction (percentage of contralateral cortex) was 37.47%+/-10.57% (vehicle), 25.49%+/-7.38% (progesterone; P<.05 from vehicle), and 11.40%+/-7.09% (allopregnanolone; P<.05 from vehicle; P<.05 from progesterone). Caudate-putamen infarction (percentage of contralateral caudate-putamen) was 78.02%+/-22.81% (vehicle), 48.41%+/-22.44% (progesterone; P<.05 from vehicle), and 50.44%+/-10.90% (allopregnanolone; P<.05 from vehicle). Total hemispheric infarction (percentage of contralateral hemisphere) was 24.37%+/-6.69% (vehicle), 15.95%+/-3.59% (progesterone; P<.05 from vehicle), and 11.54%+/-3.71% (allopregnanolone; P<.05 from vehicle). No significant differences in cerebral blood flow between groups and time points during ischemia and early reperfusion were observed, suggesting that the relative ischemic insult was equivalent among all groups. CONCLUSION: Although progesterone and allopregnanolone are effective in reducing infarct pathology, allopregnanolone is more potent than progesterone in attenuating cortical damage. Our results suggest that both neurosteroids should be examined for safety and efficacy in a clinical trial for ischemic stroke.

Analysis of Variance↗

Progesterone administration modulates AQP4 expression and edema after traumatic brain injury in male rats.

This study investigates whether progesterone administration regulates AQP4 and GFAP expression in rats with bilateral contusion injuries of the medial frontal cortex. Male rats were given 0 or 16 mg/kg injections of progesterone at 1, 6, 24, and 48 h post-injury. Brains were extracted at 24 h or 72 h post-injury and assayed for cerebral edema and AQP4 and GFAP expression using Western blot analysis. Progesterone treatments reduced brain water content significantly in the brain-injured groups. There was no significant change in AQP4 expression 24 h after progesterone treatment compared to lesion + vehicle animals. However, progesterone significantly reduced AQP4 expression at 72 h post-injury in the tissue bounded by the lateral ventricles and the peri-contusion areas compared to lesion+ vehicle rats, but increased AQP4 expression in the tissue surrounding the third ventricle. Also progesterone effects on GFAP expression varied according to brain region. Our results can be taken to show that the expression of AQP4 protein after TBI is time-dependent, region-specific, and possibly implicated in the formation and resolution of TBI-induced cerebral edema.

Analysis of Variance↗

Progesterone treatment inhibits the inflammatory agents that accompany traumatic brain injury.

Progesterone given after traumatic brain injury (TBI) has been shown to reduce the initial cytotoxic surge of inflammatory factors. We used Western blot techniques to analyze how progesterone might affect three inflammation-related factors common to TBI: complement factor C3 (C3), glial fibrillary acidic protein (GFAP), and nuclear factor kappa beta (NFkappaB). One hour after bilateral injury to the medial frontal cortex, adult male rats were given injections of progesterone (16 mg/kg) for 2 days. Brains were harvested 48 h post-TBI, proteins were extracted from samples, each of which contained tissue from both the contused and peri-contused areas, then measured by Western blot densitometry. Complete C3, GFAP, and NFkappaB p65 were increased in all injured animals. However, in animals given progesterone post-TBI, NFkappaB p65 and the inflammatory metabolites of C3 (9 kDa and 75 kDa) were decreased in comparison to vehicle-treated animals. Measures of NFkappaB p50 showed no change after injury or progesterone treatment, and progesterone did not alter the expression of GFAP. The therapeutic benefit of post-TBI progesterone administration may be due to its salutary effect on inflammatory proteins known to increase immune cell invasion and cerebral edema.

Analysis of Variance↗

Tapered progesterone withdrawal enhances behavioral and molecular recovery after traumatic brain injury.

Systemic injections of the neurosteroid progesterone improve cognitive recovery after traumatic brain injury (TBI) and stroke, and decrease molecular indicators of neuronal damage. Suddenly withdrawing progesterone after repeated dosing (PW) exacerbates ischemia and causes increased anxiety, seizure susceptibility, and excitotoxicity. Adult male Sprague-Dawley rats received either bilateral medial frontal cortex contusions or sham surgery. Injections were administered at 1 and 6 h post-injury, then every 24 h for 7 days. Vehicle-treated rats received 2-hydroxypropyl-beta-cyclodextrin (HBC). Acute PW (AW) rats received a full 16 mg/ml of progesterone for 7 days, and tapered PW (TW) rats received 5 days at full dosage, then 2 days with progressively halved dosages. Anxiety behaviors were observed pre- and post-surgery, and compared to levels at the peak of withdrawal. AW rats with lesions exhibited significantly more anxiety than any other treatment group, while both lesion- and sham-operated TW rats were indistinguishable from vehicle-treated intact animals. After behavioral tests were complete, the brains were extracted and prepared for Western blotting. TNFalpha, cFos, Caspase-3, and NFkappaB, among others, were investigated. While all progesterone treatments resulted in improved molecular recovery, TW animals had significantly fewer active markers for apoptosis and inflammation than AW animals. In conclusion, although progesterone treatment decreases inflammation and apoptosis, acute withdrawal increases activity in some apoptotic and inflammatory pathways and increases anxiety behavior during the acute healing phase. A tapered withdrawal of the hormone further enhances short-term recovery after TBI.

2-Hydroxypropyl-beta-cyclodextrin↗

The neurosteroids progesterone and allopregnanolone reduce cell death, gliosis, and functional deficits after traumatic brain injury in rats.

This report compares the effects of progesterone and its metabolite, allopregnanolone, on the early injury cascade (apoptosis) and long-term functional deficits after TBI. Progesterone (16 mg/kg) or allopregnanolone (4, 8, or 16 mg/kg) were injected at 1 h, 6 h, and then for 5 consecutive days after bilateral contusions of the frontal cortex in adult male rats. Within one day after injury, progesterone and allopregnanolone reduced both the expression of pro-apoptotic proteins caspase-3 and Bax, and apoptotic DNA fragmentation. Progesterone and allopregnanolone also reduced the size of glial fibrillary acid protein (GFAP)-positive astrocytes at the lesion site 24 h after injury. Compared to sham-operated controls at 19 days after injury, injured rats given either progesterone or any of three doses of allopregnanolone had equivalent numbers of ChAT-positive cells in the nucleus basalis magnocellularis. At 19 days post-injury, rats given progesterone or allopregnanolone (8 mg/kg) showed improved performance in a spatial learning task compared to injured rats given only the vehicle. These results provide evidence of the anti-apoptotic and anti-astrogliotic effects of progesterone and allopregnanolone and help to explain why better cognitive performance is observed after injury when animals are given either neurosteroid.

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The membrane-associated progesterone-binding protein 25-Dx is expressed in brain regions involved in water homeostasis and is up-regulated after traumatic brain injury.

After traumatic brain injury, progesterone has important neuroprotective effects in the nervous system. There is better functional outcome and less oedema formation in pseudopregnant rat females (high levels of endogenous progesterone) than in males. In addition to intracellular progesterone receptors, membrane binding sites of the hormone such as 25-Dx may also be involved in neuroprotection. In the present study we investigated the distribution of the membrane-associated progesterone-binding protein 25-Dx in rat brain. Immunohistochemical analysis showed that 25-Dx is particularly abundant in the hypothalamic area, circumventricular organs, and ependymal cells of the lateral walls of the third and lateral ventricles. A strong signal was also detected in the meninges. Double immunofluorescence immunolabelling and confocal microscopy showed that 25-Dx is co-expressed with vasopressin in neurones of the paraventricular, supraoptic and retrochiasmatic nuclei. Levels of 25-Dx expression were higher in pseudopregnant females than in males. After traumatic brain injury, 25-Dx expression was up-regulated in neurones and induced in astrocytes, which play an important role in regulating water and ion homeostasis. The expression of 25-Dx in structures involved in CSF production (choroid plexus) and in osmoregulation (circumventricular organs, hypothalamus and meninges), and its up-regulation after brain damage, point to a novel and potentially important role of this progesterone-binding protein in the maintenance of water homeostasis after traumatic brain injury.

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The case for progesterone.

Recent clinical trials in hormone therapy (HT) for women approaching or past menopause have been disappointing. Most women who have been taking conjugated equine estrogens combined with synthetic progestins have been encouraged to stop these supplements because of increased health risks. The results of the clinical trials may be accurate about the risks associated with the synthetic compounds and combinations, but the data do not reflect what might have been the case if 17beta-estradiol had been tested with natural progesterone instead of synthetic medroxyprogesterone acetate. For the most part, in almost all work on HT, estrogens have been given the primary focus despite the fact that progesterone has important properties that can enhance the repair of neurodegenerative and traumatic injuries to the central nervous system. This article reviews some of those properties and discusses the evidence suggesting that, if HT is to be reconsidered, progesterone should be given more attention as a potent neurotrophic agent that may play an important role in reducing or preventing motor, cognitive, and sensory impairments that can accompany senescence in both males and females.

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Neural progenitor cell transplants promote long-term functional recovery after traumatic brain injury.

Studies demonstrating the versatility of neural progenitor cells (NPCs) have recently rekindled interest in neurotransplantation methods aimed at treating traumatic brain injury (TBI). However, few studies have evaluated the safety and functional efficacy of transplanted NPCs beyond a few months. The purpose of this study was to assess the long-term survival, migration, differentiation and functional significance of NPCs transplanted into a mouse model of TBI out to 1 year post-transplant. NPCs were derived from E14.5 mouse brains containing a transgene-expressing green fluorescent protein (GFP) and cultured as neurospheres in FGF2-containing medium. Neurospheres were injected into the ipsilateral striatum of adult C57BL/6 mice 1 week following unilateral cortical impact injury. Behavioral testing revealed significant improvements in motor abilities in NPC-treated mice as early as 1 week, and the recovery was sustained out to 1 year post-transplant. In addition, mice receiving NPC transplants showed significant improvement in spatial learning abilities at 3 months and 1 year, whereas an intermediate treatment effect on this behavioral parameter was detected at 1 month. At 14 months post-transplant, GFP(+) NPCs were observed throughout the injured hippocampus and adjacent cortical regions of transplanted brains. Immunohistochemical analysis revealed that the majority of transplanted cells co-labeled for NG2, an oligodendrocyte progenitor cell marker, but not for neuronal, astrocytic or microglial markers. In conclusion, transplanted NPCs survive in the host brain up to 14 months, migrate to the site of injury, enhance motor and cognitive recovery, and may play a role in trophic support following TBI.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗

Effects of progesterone on the inflammatory response to brain injury in the rat.

The effects of progesterone on the cellular inflammatory response to frontal cortex injury were examined on postsurgical days 1, 3, 5, 7 and 9 in male rats treated with progesterone (4 mg/kg) and/or vehicle. Rats with bilateral contusions showed increased levels of edema on days 1, 3 and 5, more reactive astrocytes on days 3, 5, 7 and 9, and more macrophages/activated microglia on days 1, 3, 5 and 9 compared to shams. The number of neurons in the medial dorsal nucleus (MDN) of the thalamus reduced on days 5 and 9 after injury compared to shams. Progesterone reduced edema levels and increased the accumulation of macrophages/activated microglia compared to vehicle controls (p<0.025); however, these changes in the inflammatory response were not related to MDN neuronal survival. Our results confirm the possibility that one way progesterone mediates its neuroprotective effects following injury is through its actions on the inflammatory response.

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Progesterone and allopregnanolone reduce inflammatory cytokines after traumatic brain injury.

Following a traumatic brain injury (TBI), the excessive release of interleukin-1beta (IL-1beta) and tumor necrosis factor alpha (TNF-alpha) is a major cause of cerebral edema, which, in turn, can cause permanent neuronal loss and cognitive deficits in laboratory rats. This study examined the changes in expression of the proinflammatory cytokines IL-1beta and TNF-alpha after progesterone (8 mg/kg) or allopregnanolone (4 mg/kg) treatment in brain-injured rats at 3, 8, and 12 h and 6 days post-injury. Adult male rats received either bilateral prefrontal cortical contusion or sham surgery. The hormones were given intraperitoneally at 1 and 6 h, and continued once per day for up to 5 days. The gene expression of IL-1beta and TNF-alpha was measured by mRNA using real-time quantitative reverse transcripted polymerase chain reaction (RT-PCR). The protein concentrations of IL-1beta and TNF-alpha were measured using enzyme-linked immunosorbent assay (ELISA) to confirm the translation from mRNA to protein. The results indicated that progesterone and allopregnanolone reduce both IL-1beta and TNF-alpha at 3 h post-injury, when the expression of these cytokines peaks. At 8 and 12 h post-injury, IL-1beta and TNF-alpha gene expression in injured rats was still elevated compared to shams. By the sixth day post-injury, cytokine expression was back to the level of intact rats. We conclude that progesterone and allopregnanolone may attenuate the production of proinflammatory cytokines early after TBI, and this may be one mechanism by which progesterone and allopregnanolone reduce cerebral edema and promote functional recovery from TBI.

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Unilateral frontal lobe contusion and forelimb function: chronic quantitative and qualitative impairments in reflexive and skilled forelimb movements in rats.

Traumatic brain injury induced by mechanical impacts of the head can be modeled in rats in order to investigate acute and chronic therapy. Because frontal lobe contusion affects the neural representation of the forelimb in both the neocortex and basal ganglia, the purpose of the present experiments was to examine the chronic changes in reflexive and skilled forelimb induced by the injury. Contusions produced a cavity in the sensorimotor cortex, accompanied by shrinkage of the pyramidal tract, loss of cells in the dorsolateral striatum, and enlargement of the lateral ventricle. There were substantial individual differences in lesion size despite use of two different contusion forces, but all rats receiving contusions displayed chronic forelimb deficits. Reflexive tests of forelimb use (limb posture, placing, and support) indicated that impairments were most pronounced in the forelimb contralateral to the lesion. Tests of limb preference indicated that the contusion rats displayed a forelimb asymmetry: they were more likely to lean on their ipsilateral-to-lesion forelimb for support when rearing in a test cylinder, and this impairment was amplified in a home cage test. They also displayed a preference for the forelimb ipsilateral to the lesion when reaching for food, although both forelimbs were equally impaired on measures of success when reaching for food from a tray and reaching for a single food pellet on a shelf. A qualitative analysis from frame-by-frame video records indicated that when reaching for single pellets, impairments in forelimb use primarily affected the contralateral-to-lesion limb, especially limb aiming, supination, and food pellet release. Impairments in the ipsilateral-to-lesion forelimb were generally, but not exclusively, secondary to postural abnormalities. The wide range of chronic impairments in forelimb use following contusion injuries are discussed in relation to the anatomical and behavioral origins of the impairments and the potential use of forelimb tests in the assessment of therapy for traumatic brain injury to the frontal cortex.

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Allopregnanolone, a progesterone metabolite, enhances behavioral recovery and decreases neuronal loss after traumatic brain injury.

PURPOSE: In the current study we investigated whether allopregnanolone, a metabolite of progesterone, could replicate progesterone's beneficial effects in promoting spatial learning ability after bilateral medial prefrontal cortex contusions in rats. Allopregnanolone has been shown to enhance GABA neurotransmission, whereas its isomer epiallopregnanolone does not have this property. Thus, epiallopregnanolone was chosen as a control substance to examine further the role of GABA transmission in post-trauma neuroprotection. METHODS: After the contusion, rats were given 4 mg/kg treatment of either allopregnanolone or epiallopregnanolone for five consecutive days beginning 1 hr post-injury. Control groups only received vehicle treatment at the same time points. A spatial learning task (Morris Water Maze, MWM) was performed at 7 days post-injury for 10 days. Subsequent histological analyses of brain tissue were conducted to determine quantitatively the neuronal losses in both the mediodorsal nucleus of the thalamus (MDN) and the nucleus basalis magnocellularis (NBM). RESULTS: Allopregnanolone-treated rats showed better performance in the MWM compared to the vehicle-treated injury group. The histological analyses also revealed that the allopregnanolone-treated injury group had less neuronal loss in both the MDN and the NBM compared to the vehicle-treated injury group. In contrast, epiallopregnanolone did not facilitate MWM performance or reduce neuronal loss in the MDN and the NBM after TBI. CONCLUSION: Based on our findings, we suggest that allopregnanolone may mediate the effects of progesterone in promoting cognitive and morphological recovery from TBI through, among others, its direct or indirect effects on GABA-modulated neurons in the MDN and the NBM.

Analysis of Variance↗

Behavioral effects and anatomic correlates after brain injury: a progesterone dose-response study.

Evidence suggests that progesterone enhances functional recovery in rats after medial frontal cortical contusions; however, a high dose of progesterone exacerbates tissue loss in a stroke model when administered chronically (7-10 days) prior to injury [Stroke 31 (2000) 1173)]. This study attempts to determine progesterone's dose-response effects on behavioral performance and GABA-A receptor expression following a cortical contusion. Male rats received injections of 0, 8, 16, or 32 mg/kg progesterone in 22.5% 2-hydroxypropyl-beta-cyclodextrin following cortical impact. Lesion 8 mg/kg and lesion 16 mg/kg groups displayed less thigmotaxis in the Morris water maze (MWM) than 0 and 32 mg/kg groups and were not significantly impaired relative to shams on other water maze measures. Increased variability in the 32 mg/kg group during somatosensory neglect testing was the only evidence indicating that a high dose of progesterone was disruptive to a few animals. These results suggest that low and moderate doses of progesterone are optimal for facilitating recovery of select behaviors and that postinjury progesterone treatment permits a wider dose range than preinjury treatment. Progesterone did not affect lesion size, but a strong negative correlation was observed between thalamic GABA-A receptor density and water maze performance. Future studies could explore causes for this relationship.

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The delayed administration of dehydroepiandrosterone sulfate improves recovery of function after traumatic brain injury in rats.

The goal of the current study was to test the hypothesis that dehydroepiandrosterone-sulfate (DHEAS), a pro-excitatory neurosteroid, could facilitate recovery of function in male rats after delayed treatment following TBI. DHEAS has been found to play a major role in brain development and aging by influencing the migration of neurons, arborization of dendrites, and formation of new synapses. These characteristics make it suitable as a potential treatment to enhance neural repair in response to CNS injury. In our study, behavioral tests were conducted concurrently with DHEAS administration (0, 5, 10, or 20 mg/kg) starting seven days post-injury (PI). These assays included 10 days of Morris Water Maze testing (MWM; 7d PI), 10 days of Greek-Cross (GC; 21d PI), Tactile Adhesive Removal task (TAR; PI days: 6, 13, 20, 27, 34), and spontaneous motor behavior testing (SMB; PI days: 2, 4, 6, 12, 19, 26, 33). Brain-injured rats showed an improvement in performance in all tasks after 5, 10, or 20 mg/kg DHEAS. The most effective dose of DHEAS in the MWM was 10 mg/kg, while in the GC it was 20 mg/kg, in TAR 5 mg/kg, and all doses, except for vehicle, were effective at reducing injury-induced SMB hyperactivity. In no task did DHEAS-treated animals perform worse than the injured controls. In addition, DHEAS had no significant effects on behavioral performance in the sham-operates. These results can be interpreted to demonstrate that after a 7-day delay, the chronic administration of DHEAS to injured rats significantly improves behavioral recovery on both sensorimotor and cognitive tasks.

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