Neuroprotective effects of progesterone following stroke in aged rats

Inter-synergized Neuroprotection of Costunolide Engineered Bone Marrow Mesenchymal Stem Cells Targeting System

Treatment of stroke remains difficult due to the unsatisfactory or unlocalized delivery of small molecule- and cell-based therapeutics in injured brain tissues. This is particularly the case for costunolide (Cos), which is highly neuroprotective and anti-inflammatory but finds great difficulty in reaching the brain. Here, we present that Cos induces the differentiation of bone marrow mesenchymal stem cells (bMSCs) into glia-like cells (C-bMSCs) capable of secreting neurotrophic factors and homing to injured brain tissues. By taking advantage of the homing effect, Cos and C-bMSCs were simultaneously funneled into the damaged brain by: (i) preparing Cos micelles (Cos-M) through entrapping Cos into the amphiphilic copolymer mPEG-PLGA [poly(ethylene oxide) monomethyl ether-poly(lactide-co-glycolide)], and (ii) incorporating Cos-M into C-bMSCs to give an intravenously injectable cell-like composite termed Cos@C-bMSCs, which displayed the inter-synergized neuroprotective efficacy in the cerebral ischemia reperfusion (CIR) injured rats. As desired, in the injured brain area, Cos@C-bMSCs simultaneously released Cos and C-bMSCs (glia-like cells) to repair the injured brain and to secret neurotrophic factors such as nerve growth factor (NGF). In view of the availability and reliability of autologous MSCs, the proof-of-concept design, development, and in vivo efficacy of Cos@C-bMSCs signify a movement in our management of brain damages.

Progesterone modulates the expression of spinal ephrin-B2 after peripheral nerve injury: New insights into progesterone mechanisms

Recent studies have shown that the ephrin/Eph signaling pathway may contribute to the pathology of neuropathic pain. Drugs like progesterone may be used to counteract both thermal hyperalgesia and mechanical allodynia in different models of neuropathic pain. The present study was designed to determine progesterone's modulatory role on neuropathic pain and spinal expression of ephrin-B2 following chronic constriction nerve injury (CCI). Thirty-six adult male Wistar rats were used. The sciatic nerve was chronically constricted. Progesterone (5 mg/kg and 15 mg/kg) was administrated for 10 days (from day 1 up to day10) following sciatic constriction. Behavioral tests were performed before surgery (day 0) and on days 1, 3, 7, and 14 after CCI and before progesterone administration on the same days. Western blotting was performed on days 3, 7, and 14th post-surgery. The findings showed that after CCI, the expression of spinal cord ephrin-B2 increased significantly in parallel with mechanical allodynia and thermal hyperalgesia. Post-injury administration of progesterone (15 mg/kg but not 5) decreased mechanical allodynia, thermal hyperalgesia, and the expression of spinal ephrin-B2. It is concluded that post-injury repeated administration of progesterone could be an effective way of alleviating neuropathic pain by suppressing ephrin-B2 activation and helps to make the better design of steroid-based therapies to inhibit pain after peripheral injury.

High fat-low protein diet induces metabolic alterations and cognitive dysfunction in female rats

Approximately one-third of the world population is suffering from MetS, and the same is expected to rise in the years to come. Worldwide, most of the staple diets contain high amounts of carbohydrates, fats and comparatively low quantities of proteins. The goal of this study was to evaluate the effect of high fat-low protein diet in the development of the metabolic syndrome and associated cognitive deficits in the female rats. The rats fed with high fat-low protein diet (HFLPD) and 15% oral fructose solution for 24 weeks. Body weight, food intake, water intake, fasting blood glucose, oral glucose tolerance, glycosylated hemoglobin (HbA_1C), and serum lipid profile were measured after every 4 weeks. Serum insulin, HOMA-IR index, rectal temperature, and systolic blood pressure were measured to confirm the manifestation of the hallmarks of metabolic syndrome. Behavioral tests for locomotion, anxiety, learning, and spatial memory were performed from the 12th week to till the end of the study. At the 24th week, oxidative stress assays and histopathology of liver, kidney, brain, and WAT were also performed. HFLPD significantly altered the physiologic and metabolic parameters which contributed to the manifestation of MetS. HFLPD also impaired the cognitive functions along with significant structural changes in the liver, kidney, WAT, and brain. The findings of this study reveal that HFLPD has the potential to induce the physiological, metabolic and histological alterations in rats, which eventually led to the development of MetS and also disrupted the cognitive functions in female rats.

Steroids in Stroke with Special Reference to Progesterone

Both sex and steroid hormones are important to consider in human ischemic stroke and its experimental models. Stroke initiates a cascade of changes that lead to neural cell death, but also activates endogenous protective processes that counter the deleterious consequences of ischemia. Steroids may be part of these cerebroprotective processes. One option to provide cerebroprotection is to reinforce these intrinsic protective mechanisms. In the current review, we first summarize studies describing sex differences and the influence of steroid hormones in stroke. We then present and discuss our recent results concerning differential changes in endogenous steroid levels in the brains of male and female mice and the importance of progesterone receptors (PR) during the early phase after stroke. In the third part, we give an overview of experimental studies, including ours, that provide evidence for the pleiotropic beneficial effects of progesterone and its promising cerebroprotective potential in stroke. We also highlight the key role of PR signaling as well as potential additional mechanisms by which progesterone may provide cerebroprotection.

Contributions of sex to cerebrovascular function and pathology

Sex differences exist in how cerebral blood vessels function under both physiological and pathological conditions, contributing to observed sex differences in risk and outcomes of cerebrovascular diseases (CBVDs), such as vascular contributions to cognitive impairment and dementia (VCID) and stroke. Throughout most of the lifespan, women are protected from CBVDs; however, risk increases following menopause, suggesting sex hormones may play a significant role in this protection. The cerebrovasculature is a target for sex hormones, including estrogens, progestins, and androgens, where they can influence numerous vascular functions and pathologies. While there is a plethora of information on estrogen, the effects of progestins and androgens on the cerebrovasculature are less well-defined. Estrogen decreases cerebral tone and increases cerebral blood flow, while androgens increase tone. Both estrogens and androgens enhance angiogenesis/cerebrovascular remodeling. While both estrogens and androgens attenuate cerebrovascular inflammation, pro-inflammatory effects of androgens under physiological conditions have also been demonstrated. Sex hormones exert additional neuroprotective effects by attenuating oxidative stress and maintaining integrity and function of the blood brain barrier. Most animal studies utilize young, healthy, gonadectomized animals, which do not mimic the clinical conditions of aging individuals likely to get CBVDs. This is also concerning, as sex hormones appear to mediate cerebrovascular function differently based on age and disease state (e.g. metabolic syndrome). Through this review, we hope to inspire others to consider sex as a key biological variable in cerebrovascular research, as greater understanding of sex differences in cerebrovascular function will assist in developing personalized approaches to prevent and treat CBVDs.

Does progesterone have protective effects on ovarian ischemia-reperfusion injury?

Objective:

The aim of the present study was to evaluate the effects of progesterone (PG) against ovarian ischemia-reperfusion (I/R) injury through the evaluation of biochemical and histopathologic parameters.

Material and Methods:

Twenty-one female Wistar albino rats were divided into three groups. Group 1: Sham; group 2: I/R; group 3: I/R+PG (8 mg/kg). PG was administered intraperitoneally to the rats in group 3, 30 minutes before a detorsion operation. Ovarian I/R injury was evaluated in serum and tissue by using biochemical parameters including malondialdehyde (MDA), total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index, neutrophil gelatinase-associated lipocalin (NGAL) and immunofluorescence staining by using a terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay.

Results:

Serum and tissue TOS levels were significantly lower in group 3 than in group 2. Tissue TAS levels were higher in group 3 than in group 2 (p<0.001). NGAL and MDA levels were similar between the groups. Histologic score, including vascular congestion, hemorrhage, polymorphonuclear neutrophils, and interstitial edema, was higher in group 2. Pre-treatment with PG decreased the score, but this difference was not statistically significant. The number of apoptotic cells was higher in group 2 than in groups 1 and 3. The TUNEL-positive cell number decreased with PG in group 3.

Conclusion:

Preoperative PG treatment might exert protective effects on ovarian I/R injury through its anti-apoptotic and antioxidative properties.

ALDH2 Protects Against Ischemic Stroke in Rats by Facilitating 4-HNE Clearance and AQP4 Down-Regulation

Aldehyde dehydrogenase 2 (ALDH2) is a new therapeutic target in the central nervous system. However, the association between ALDH2 and brain edema following ischemic stroke (IS) remains unclear. The present study was investigated to whether active ALDH2 can attenuate brain edema by using a rat model of IS, with the aim of clarifying the underlying mechanisms involved. Rats were administered the ALDH2 agonist Alda-1, vehicle or the ALDH2 inhibitor cyanamide (CYA) 15 min prior to a 1.5 h middle cerebral artery occlusion (MCAO) surgery. The effects of ALDH2 were subsequently investigated 24 h after reperfusion by evaluating neurological function, infarct sizes, brain edema volumes, 4-hydroxy-2-nonenal (4-HNE) levels, and aquaporin 4 (AQP4) protein expression. The results demonstrated that increasing ALDH2 activity significantly improved neurological deficits, reduced infarct sizes, and attenuated brain edema after MCAO. Alda-1 administration led to decreased 4-HNE levels and inhibited AQP4 protein expression in the peri-infarct section of the brain. Whereas, CYA administration increased 4-HNE levels, AQP4 expression, and simultaneously aggravated brain edema following MCAO. In conclusion, increasing ALDH2 activity can improve brain edema, infarct volumes, and reduce neurological impairment in a rat IS model. The therapeutic benefits of ALDH2 are related to 4-HNE clearance and AQP4 down-regulation.

A Role of Endogenous Progesterone in Stroke Cerebroprotection Revealed by the Neural-Specific Deletion of Its Intracellular Receptors

Treatment with progesterone protects the male and female brain against damage after middle cerebral artery occlusion (MCAO). However, in both sexes, the brain contains significant amounts of endogenous progesterone. It is not known whether endogenously produced progesterone enhances the resistance of the brain to ischemic insult. Here, we used steroid profiling by gas chromatography-tandem mass spectrometry (GC-MS/MS) for exploring adaptive and sex-specific changes in brain levels of progesterone and its metabolites after MCAO. We show that, in the male mouse brain, progesterone is mainly metabolized via 5α-reduction leading to 5α-dihydroprogesterone (5α-DHP), also a progesterone receptor (PR) agonist ligand in neural cells, then to 3α,5α-tetrahydroprogesterone (3α,5α-THP). In the female mouse brain, levels of 5α-DHP and 3α,5α-THP are lower and levels of 20α-DHP are higher than in males. After MCAO, levels of progesterone and 5α-DHP are upregulated rapidly to pregnancy-like levels in the male but not in the female brain. To assess whether endogenous progesterone and 5α-DHP contribute to the resistance of neural cells to ischemic damage, we inactivated PR selectively in the CNS. Deletion of PR in the brain reduced its resistance to MCAO, resulting in increased infarct volumes and neurological deficits in both sexes. Importantly, endogenous PR ligands continue to protect the brain of aging mice. These results uncover the unexpected importance of endogenous progesterone and its metabolites in cerebroprotection. They also reveal that the female reproductive hormone progesterone is an endogenous cerebroprotective neurosteroid in both sexes.SIGNIFICANCE STATEMENT The brain responds to injury with protective signaling and has a remarkable capacity to protect itself. We show here that, in response to ischemic stroke, levels of progesterone and its neuroactive metabolite 5α-dihydroprogesterone are upregulated rapidly in the male mouse brain but not in the female brain. An important role of endogenous progesterone in cerebroprotection was demonstrated by the conditional inactivation of its receptor in neural cells. These results show the importance of endogenous progesterone, its metabolites, and neural progesterone receptors in acute cerebroprotection after stroke. This new concept could be exploited therapeutically by taking into account the progesterone status of patients and by supplementing and reinforcing endogenous progesterone signaling for attaining its full cerebroprotective potential.

BDNF expression is up-regulated by progesterone in human umbilical cord mesenchymal stem cells

OBJECTIVE

To investigate whether promotion of neuronal differentiation of human umbilical cord mesenchymal stem cells (HUMSCs) by progesterone (PROG) involves changes in brain-derived neurotrophic factor (BDNF) levels.

METHODS

We used rat brain tissue extracts to mimic the brain microenvironment. Quantitative sandwich enzyme-linked immunosorbent assay was performed to measure levels of BDNF in cultured medium with or without PROG.

RESULTS

Progesterone increased levels of BDNF in HUMSCs.

CONCLUSION

Progesterone enhancement of brain-derived neurotrophic factor levels may be involved in PROG activated-pathways to promote neuronal differentiation of HUMSCs.

Progesterone improves long-term functional and histological outcomes after permanent stroke in older rats

Previous studies have shown progesterone to be beneficial in animal models of central nervous system injury, but less is known about its longer-term sustained effects on recovery of function following stroke. We evaluated progesterone's effects on a panel of behavioral tests up to 8 weeks after permanent middle cerebral artery occlusion (pMCAO). Male Sprague-Dawley rats 12m.o. were subjected to pMCAO and, beginning 3h post-pMCAO, given intraperitoneal injections of progesterone (8mg/kg) or vehicle, followed by subcutaneous injections at 8h and then every 24h for 7 days, with tapering of the last 2 treatments. The rats were then tested on functional recovery at 3, 6 and 8 weeks post-stroke. We observed that progesterone-treated animals showed attenuation of infarct volume and improved functional outcomes at 8 weeks after stroke on grip strength, sensory neglect, motor coordination and spatial navigation tests. Progesterone treatments significantly improved motor deficits in the affected limb on a number of gait parameters. Glial fibrillary acidic protein expression was increased in the vehicle group and considerably lowered in the progesterone group at 8 weeks post-stroke. With repeated post-stroke testing, sensory neglect and some aspects of spatial learning performance showed spontaneous recovery, but on gait and grip-strength measres progesterone given only in the acute stage of stroke (first 7 days) showed sustained beneficial effects on all other measures of functional recovery up to 8 weeks post-stroke.

The Importance of Considering Sex Differences in Translational Stroke Research

Stroke is the second leading cause of death worldwide, and differences between men and women have been documented in incidence, prevalence, and outcome. Here, we reviewed the literature on sex differences in stroke severity, mortality, functional outcome, and response to therapies after ischemic stroke. Many of the sex differences in stroke severity and mortality are explained by differences in baseline demographics such as older age in women. However, women account for more stroke deaths, consistently suffer from worse stroke outcomes, and are more often institutionalized and permanently disabled than men. These sex differences in functional outcome are equalized after treatment with tissue plasminogen activator (tPA) and women may benefit more from treatment than men. However, this may depend on race, as African-American women have less of a response to tPA than other groups. Regarding endovascular treatments, the few existing studies that have investigated sex differences in stroke outcome point to equal benefit in both sexes; however, many clinical trials are relatively underpowered to detect sex differences. Further, we considered sex-specific effects in animal models of stroke and present recommendations for the performance of stroke studies in female animals. The male-biased use of research animals is distinguished from the clinical situation where there is a disproportionate and growing female stroke population. Stroke in women is greatly understudied, and including both sexes is especially important in both preclinical and clinical studies that evaluate potential stroke therapies.

Progesterone Changes VEGF and BDNF Expression and Promotes Neurogenesis After Ischemic Stroke

Studies have shown that progesterone enhances functional recovery after ischemic stroke, but the underlying mechanisms are not completely understood. Therefore, we investigated the effect of progesterone on vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), and neurogenesis in a rodent stroke model. Rats underwent permanent middle cerebral artery occlusion (pMCAO) and then received intraperitoneal injections of progesterone (15 mg/kg) or vehicle at 1 h followed by subcutaneous injections at 6, 24, and 48 h. We examined VEGF and BDNF expression by Western blotting and/or immunostaining and microvessel density by lectin immunostaining. Neurogenesis in the subventricular zone was determined by immunostaining of Ki67 and doublecortin, and double BrdU/Nestin immunostaining. We calculated brain water content with the wet-dry weight method on day 3 and assessed neurologic deficits with the modified neurological severity score on days 1, 3, 7, and 14. Progesterone-treated rats showed a significant decrease in VEGF expression, but an increase in BDNF expression, compared with that of vehicle-treated pMCAO rats on day 3 post-occlusion. Progesterone did not alter the microvessel density, but it reduced brain water content compared with that in vehicle-treated rats on day 3 post-occlusion. Progesterone treatment increased the numbers of newly generated neurons in the subventricular zone and doublecortin-positive cells in the peri-infarct region on day 7 post-occlusion. In addition, progesterone improved neurologic function on days 7 and 14 post-occlusion. Our data suggest that the enhancement of endogenous BDNF and subsequent neurogenesis could partially underlie the neuroprotective effects of progesterone.

Sex-Specific Effects of Progesterone on Early Outcome of Intracerebral Hemorrhage

BACKGROUND

Preclinical evidence suggests that progesterone improves recovery after intracerebral hemorrhage (ICH); however, gonadal hormones have sex-specific effects. Therefore, an experimental model of ICH was used to assess recovery after progesterone administration in male and female rats.

METHODS

ICH was induced in male and female Wistar rats via stereotactic intrastriatal injection of clostridial collagenase (0.5 U). Animals were randomized to receive vehicle or 8 mg/kg progesterone intraperitoneally at 2 h, then subcutaneously at 5, 24, 48, and 72 h after injury. Outcomes included relevant physiology during the first 3 h, hemorrhage and edema evolution over the first 24 h, proinflammatory transcription factor and cytokine regulation at 24 h, rotarod latency and neuroseverity score over the first 7 days, and microglial activation/macrophage recruitment at 7 days after injury.

RESULTS

Rotarod latency (p = 0.001) and neuroseverity score (p = 0.01) were improved in progesterone-treated males, but worsened in progesterone-treated females (p = 0.028 and p = 0.008, respectively). Progesterone decreased cerebral edema (p = 0.04), microglial activation/macrophage recruitment (p < 0.001), and proinflammatory transcription factor phosphorylated nuclear factor-x03BA;B p65 expression (p = 0.0038) in males but not females, independent of tumor necrosis factor-α, interleukin-6, and toll-like receptor-4 expression. Cerebral perfusion was increased in progesterone-treated males at 4 h (p = 0.043) but not 24 h after injury. Hemorrhage volume, arterial blood gases, glucose, and systolic blood pressure were not affected.

CONCLUSIONS

Progesterone administration improved early neurobehavioral recovery and decreased secondary neuroinflammation after ICH in male rats. Paradoxically, progesterone worsened neurobehavioral recovery and did not modify neuroinflammation in female rats. Future work should isolate mechanisms of sex-specific progesterone effects after ICH.

Progesterone treatment in two rat models of ocular ischemia

PURPOSE

To determine whether the neurosteroid progesterone, shown to have protective effects in animal models of traumatic brain injury, stroke, and spinal cord injury, is also protective in ocular ischemia animal models.

METHODS

Progesterone treatment was tested in two ocular ischemia models in rats: a rodent anterior ischemic optic neuropathy (rAION) model, which induces permanent monocular optic nerve stroke, and the middle cerebral artery occlusion (MCAO) model, which causes transient ischemia in both the retina and brain due to an intraluminal filament that blocks the ophthalmic and middle cerebral arteries. Visual function and retinal histology were assessed to determine whether progesterone attenuated retinal injury in these models. Additionally, behavioral testing and 2% 2,3,5-triphenyltetrazolium chloride (TTC) staining in brains were used to compare progesterone's neuroprotective effects in both retina and brain using the MCAO model.

RESULTS

Progesterone treatment showed no effect on visual evoked potential (VEP) reduction and retinal ganglion cell loss in the permanent rAION model. In the transient MCAO model, progesterone treatment reduced (1) electroretinogram (ERG) deficits, (2) MCAO-induced upregulation of glutamine synthetase (GS) and glial fibrillary acidic protein (GFAP), and (3) retinal ganglion cell loss. As expected, progesterone treatment also had significant protective effects in behavioral tests and a reduction in infarct size in the brain.

CONCLUSIONS

Progesterone treatment showed protective effects in the retina following MCAO but not rAION injury, which may result from mechanistic differences with injury type and the therapeutic action of progesterone.

Hydrogen sulfide induces neuroprotection against experimental stroke in rats by down-regulation of AQP4 via activating PKC

Hydrogen sulfide (H2S) is now known as an important neuromodulator in the central nervous system. The aim of the current study was to investigate whether exogenous H2S gas can attenuate brain edema induced by experimental stroke and to clarify the potential mechanisms. Rats underwent 2-h middle cerebral artery occlusion (MCAO) and received 40 ppm or 80 ppm H2S inhalation for 3h at the beginning of reperfusion. The effects of H2S were investigated by evaluating neurological function, infarct size, brain edema volume, and aquaporin4 (AQP4) protein expression at 24h after reperfusion. Moreover, to explore the possible mechanisms for the neuroprotective effects of H2S, protein kinase C (PKC) activity was detected and a PKC inhibitor, Go6983, was used via intracerebral ventricular injection. Our results showed that 40 ppm or 80 ppm H2S inhalation significantly reduced neurological deficits, infarct size, and brain edema after MCAO. The expression of AQP4 in the peri-infarct area of brain was also inhibited after inhalation of H2S. PKC was activated by H2S treatment and the PKC inhibitor attenuated the neuroprotection of H2S with an increased AQP4 expression at the same time. In conclusion, H2S inhalation attenuates brain edema, reduces infarct volume, and improves neurologic function in a rat experimental stroke model. The therapeutic benefits of H2S inhalation are associated with down-regulation of AQP4 expression via activating PKC.

Progesterone and allopregnanolone in the central nervous system: response to injury and implication for neuroprotection

Progesterone is a well-known steroid hormone, synthesized by ovaries and placenta in females, and by adrenal glands in both males and females. Several tissues are targets of progesterone and the nervous system is a major one. Progesterone is also locally synthesized by the nervous system and qualifies, therefore, as a neurosteroid. In addition, the nervous system has the capacity to bio-convert progesterone into its active metabolite allopregnanolone. The enzymes required for progesterone and allopregnanolone synthesis are widely distributed in brain and spinal cord. Increased local biosynthesis of pregnenolone, progesterone and 5α-dihydroprogesterone may be a part of an endogenous neuroprotective mechanism in response to nervous system injuries. Progesterone and allopregnanolone neuroprotective effects have been widely recognized. Multiple receptors or associated proteins may contribute to the progesterone effects: classical nuclear receptors (PR), membrane progesterone receptor component 1 (PGRMC1), membrane progesterone receptors (mPR), and γ-aminobutyric acid type A (GABAA) receptors after conversion to allopregnanolone. In this review, we will succinctly describe progesterone and allopregnanolone biosynthetic pathways and enzyme distribution in brain and spinal cord. Then, we will summarize our work on progesterone receptor distribution and cellular expression in brain and spinal cord; neurosteroid stimulation after nervous system injuries (spinal cord injury, traumatic brain injury, and stroke); and on progesterone and allopregnanolone neuroprotective effects in different experimental models including stroke and spinal cord injury. We will discuss in detail the neuroprotective effects of progesterone on the nervous system via PR, and of allopregnanolone via its modulation of GABAA receptors.

Evaluating the translational potential of progesterone treatment following transient cerebral ischaemia in male mice

Background

Progesterone is neuroprotective in numerous preclinical CNS injury models including cerebral ischaemia. The aim of this study was two-fold; firstly, we aimed to determine whether progesterone delivery via osmotic mini-pump would confer neuroprotective effects and whether such neuroprotection could be produced in co-morbid animals.

Results

Animals underwent transient middle cerebral artery occlusion. At the onset of reperfusion, mice were injected intraperitoneally with progesterone (8 mg/kg in dimethylsulfoxide). Adult and aged C57 Bl/6 mice were dosed additionally with subcutaneous infusion (1.0 μl/h of a 50 mg/ml progesterone solution) via implanted osmotic minipumps. Mice were allowed to survive for up to 7 days post-ischaemia and assessed for general well-being (mass loss and survival), neurological score, foot fault and t-maze performance. Progesterone reduced neurological deficit [F_(1,2) = 5.38, P = 0.027] and number of contralateral foot-faults [F_(1,2) = 7.36, P = 0.0108] in adult, but not aged animals, following ischaemia. In hypertensive animals, progesterone treatment lowered neurological deficit [F_(1,6) = 18.31, P = 0.0001], reduced contralateral/ipsilateral alternation ratio % [F_(1,2) = 17.05, P = 0.0006] and time taken to complete trials [F_(1,2) = 15.92, P = 0.0009] for t-maze.

Conclusion

Post-ischemic progesterone administration via mini-pump delivery is effective in conferring functional improvement in a transient MCAO model in adult mice. Preliminary data suggests such a treatment regimen was not effective in producing a protective effect in aged mice. However, in hypertensive mice, who received post-ischemic progesterone intraperitoneally at the onset of reperfusion had better functional outcomes than control hypertensive mice.

Progesterone attenuates aquaporin-4 expression in an astrocyte model of ischemia/reperfusion

Previous studies have suggested that progesterone may be involved in neuroprotection by preventing brain edema. In this study, we assessed the effects of progesterone on aquaporin-4 (AQP4) expression in an ischemia/reperfusion model of cultured rat astrocytes, and further explored the possible role of the protein kinase C (PKC) pathway in this course. We evaluate primary culture astrocytes exposed to 4 h oxygen-glucose deprivation (OGD) followed by 24 h reperfusion (OGD4h/R24h) as a means of simulating cortex ischemia and reperfusion, and test the effect of progesterone on AQP4 expression in response to OGD4h/R24h. Besides, the cell viability was assessed by MTT reduction and lactate dehydrogenase release assay, accompanied by cell morphology survey. At a concentration of 1 and 2 μM, progesterone significantly attenuated AQP4 at the level of both protein and mRNA and ameliorated the cell viability of astrocytes from OGD/reperfusion injury. Moreover, this effect was blocked by the PKC inhibitor Ro31-8220, which was employed before the OGD. These results indicate that progesterone exerts the protective effects and attenuates AQP4 expression in an astrocyte model of ischemia/reperfusion depending on the PKC signal pathway.

New aspects of progesterone interactions with the actin cytoskeleton and neurosteroidogenesis in the cerebellum and the neuronal growth cone

The impact of progesterone on neuronal tissues in the central (CNS) and peripheral (PNS) nervous system is of significant scientific and therapeutic interest. Glial and neuronal cells of vertebrates express steroidogenic enzymes, and are able to synthesize progesterone de novo from cholesterol. Progesterone is described to have neuroprotective, neuroreparative, anti-degenerative, and anti-apoptotic effects in the CNS and the PNS. Thus, the first clinical studies promise new therapeutic options using progesterone in the treatment of patients with traumatic brain injury. Additionally, experimental data from different animal models suggest further positive effects of progesterone on neurological diseases such as cerebral ischemia, peripheral nerve injury and amyothropic lateral sclerosis. In regard to this future clinical use of progesterone, we discuss in this review the underlying physiological principles of progesterone effects in neuronal tissues. Mechanisms leading to morphological reorganizations of neurons in the CNS and PNS affected by progesterone are addressed, with special focus on the actin cytoskeleton. Furthermore, new aspects of a progesterone-dependent regulation of neurosteroidogenesis mediated by the recently described progesterone binding protein PGRMC1 in the nervous system are discussed.

Progesterone attenuates experimental subarachnoid hemorrhage-induced vasospasm by upregulation of endothelial nitric oxide synthase via Akt signaling pathway

Cerebral vasospasm is the leading cause of mortality and morbidity in patients after aneurysmal subarachnoid hemorrhage (SAH). However, the mechanism and adequate treatment of vasospasm are still elusive. In the present study, we evaluate the effect and possible mechanism of progesterone on SAH-induced vasospasm in a two-hemorrhage rodent model of SAH. Progesterone (8 mg/kg) was subcutaneously injected in ovariectomized female Sprague-Dawley rats one hour after SAH induction. The degree of vasospasm was determined by averaging the cross-sectional areas of basilar artery 7 days after first SAH. Expressions of endothelial nitric oxide synthase (eNOS) and phosphorylated Akt (phospho-Akt) in basilar arteries were evaluated. Prior to perfusion fixation, there were no significant differences among the control and treated groups in physiological parameters recorded. Progesterone treatment significantly (P < 0.01) attenuated SAH-induced vasospasm. The SAH-induced suppression of eNOS protein and phospho-Akt were relieved by progesterone treatment. This result further confirmed that progesterone is effective in preventing SAH-induced vasospasm. The beneficial effect of progesterone might be in part related to upregulation of expression of eNOS via Akt signaling pathway after SAH. Progesterone holds therapeutic promise in the treatment of cerebral vasospasm following SAH.

Progesterone in experimental permanent stroke: a dose-response and therapeutic time-window study

Currently, the only approved treatment for ischaemic stroke is tissue plasminogen activator, a clot-buster. This treatment can have dangerous consequences if not given within the first 4 h after stroke. Our group and others have shown progesterone to be beneficial in preclinical studies of stroke, but a progesterone dose-response and time-window study is lacking. We tested male Sprague-Dawley rats (12 months old) with permanent middle cerebral artery occlusion or sham operations on multiple measures of sensory, motor and cognitive performance. For the dose-response study, animals received intraperitoneal injections of progesterone (8, 16 or 32 mg/kg) at 1 h post-occlusion, and subcutaneous injections at 6 h and then once every 24 h for 7 days. For the time-window study, the optimal dose of progesterone was given starting at 3, 6 or 24 h post-stroke. Behavioural recovery was evaluated at repeated intervals. Rats were killed at 22 days post-stroke and brains extracted for evaluation of infarct volume. Both 8 and 16 mg/kg doses of progesterone produced attenuation of infarct volume compared with the placebo, and improved functional outcomes up to 3 weeks after stroke on locomotor activity, grip strength, sensory neglect, gait impairment, motor coordination and spatial navigation tests. In the time-window study, the progesterone group exhibited substantial neuroprotection as late as 6 h after stroke onset. Compared with placebo, progesterone showed a significant reduction in infarct size with 3- and 6-h delays. Moderate doses (8 and 16 mg/kg) of progesterone reduced infarct size and improved functional deficits in our clinically relevant model of stroke. The 8 mg/kg dose was optimal in improving motor, sensory and memory function, and this effect was observed over a large therapeutic time window. Progesterone shows promise as a potential therapeutic agent and should be examined for safety and efficacy in a clinical trial for ischaemic stroke.

Progesterone and cerebral ischaemia: the relevance of ageing

Cerebral stroke is a leading cause of long-term disability and a major cause of death in the developed world. The total incidence of stroke is projected to rise substantially over the next 20 years as a result of the rising elderly population. Although age is one of the most significant prognostic markers for poor outcome after stroke, very few experimental studies have been conducted in aged animals. Importantly, sex differences in both vulnerability to stroke and outcome after cerebral ischaemia have frequently been reported and attributed to the action of steroid hormones. Progesterone is a candidate neuroprotective factor for stroke, although the majority of pre-clinical studies have focused on using young, healthy adult animals. In terms of cerebral stroke, males and postmenopausal females represent the groups at highest risk of cerebral stroke and these categories can be modelled using either aged or ovariectomised female animals. In this review, we discuss the importance of conducting experimental studies in aged animals compared to young, healthy animals, as well as the impact this has on experimental outcomes. In addition, we focus on reviewing the studies that have been conducted to date examining the neuroprotective potential of progesterone in aged animals. Importantly, the limited studies that have been conducted in aged animals do lend further support to progesterone as a therapeutic option after ischaemic stroke that warrants further investigation.

Bone marrow mononuclear cells exert long-term neuroprotection in a rat model of ischemic stroke by promoting arteriogenesis and angiogenesis

Transplanted bone marrow-derived mononuclear cells (BMMNCs) can promote arteriogenesis and angiogenesis by incorporating into vascular walls and differentiating into smooth muscle cells (SMCs) and endothelial cells (ECs). Here, we explored whether BMMNCs can enhance arteriogenesis and angiogenesis and promote long-term functional recovery in a rat model of permanent middle cerebral artery occlusion (pMCAO). Sprague-Dawley rats were injected with vehicle or 1×10(7) BMMNCs labeled with BrdU via femoral vein 24 h after induction of pMCAO. Functional deficits were assessed weekly through day 42 after pMCAO, and infarct volume was assessed on day 7. We visualized the angioarchitecture by latex perfusion on days 14 and 42. BMMNC transplantation significantly reduced infarct volume and neurologic functional deficits compared with untreated or vehicle-treated ischemic groups. In BMMNC-treated rats, BrdU-positive cells were widely distributed in the infarct boundary zone, were incorporated into vessel walls, and enhanced the growth of leptomeningeal anastomoses, the circle of Willis, and basilar arteries. BMMNCs were shown to differentiate into SMCs and ECs from day 14 after stroke and preserved vascular repair function for at least 6 weeks. Our data indicate that BMMNCs can significantly enhance arteriogenesis and angiogenesis, reduce infarct volume, and promote long-term functional recovery after pMCAO in rats.

Revisiting the roles of progesterone and allopregnanolone in the nervous system: resurgence of the progesterone receptors

Progesterone is commonly considered as a female reproductive hormone and is well-known for its role in pregnancy. It is less well appreciated that progesterone and its metabolite allopregnanolone are also male hormones, as they are produced in both sexes by the adrenal glands. In addition, they are synthesized within the nervous system. Progesterone and allopregnanolone are associated with adaptation to stress, and increased production of progesterone within the brain may be part of the response of neural cells to injury. Progesterone receptors (PR) are widely distributed throughout the brain, but their study has been mainly limited to the hypothalamus and reproductive functions, and the extra-hypothalamic receptors have been neglected. This lack of information about brain functions of PR is unexpected, as the protective and trophic effects of progesterone are much investigated, and as the therapeutic potential of progesterone as a neuroprotective and promyelinating agent is currently being assessed in clinical trials. The little attention devoted to the brain functions of PR may relate to the widely accepted assumption that non-reproductive actions of progesterone may be mainly mediated by allopregnanolone, which does not bind to PR, but acts as a potent positive modulator of γ-aminobutyric acid type A (GABA(A) receptors. The aim of this review is to critically discuss effects of progesterone on the nervous system via PR, and of allopregnanolone via its modulation of GABA(A) receptors, with main focus on the brain.

Progesterone's role in neuroprotection, a review of the evidence

The sex hormone progesterone has been shown to improve outcomes in animal models of a number of neurologic diseases, including traumatic brain injury, ischemia, spinal cord injury, peripheral nerve injury, demyelinating disease, neuromuscular disorders, and seizures. Evidence suggests it exerts its neuroprotective effects through several pathways, including reducing edema, improving neuronal survival, and modulating inflammation and apoptosis. In this review, we summarize the functional outcomes and pathophysiologic mechanisms attributed to progesterone treatment in neurologic disease. We then comment on the breadth of evidence for the use of progesterone in each neurologic disease family. Finally, we provide support for further human studies using progesterone to treat several neurologic diseases.

Neuroprotective effects of the SCR1-3 functional domain of CR1 on acute cerebral ischemia and reperfusion injury in rats

OBJECTIVE

Complement receptor type 1 (CR1), one of the most potent inhibitors in complement activation, shows a protective effect on cerebral ischemia/reperfusion (CI/R) injury due to its ability to bind C3b and C4b and to inactivate C3/C5 convertases. So far, no study assessed the effect of the first three short consensus repeats (SCR1-3) with low molecular weight, one of the most active functional domains of CR1, binding C4b with a powerful decay-acceleration effect on classical and alternative C3/C5 convertases pathways. Therefore, we aim to assess this effect on CI/R injury in the present study.

METHODS

Seventy-five adult male Sprague-Dawley rats were randomly divided into three groups: sham operation group (n = 15), CI/R group (n = 30), and CI/R group treated with CR1-SCR1-3 protein (n = 30). After middle cerebral artery occlusion (MCAO) for 1 hour and reperfusion for 24 hours, neurological motor deficits, cerebral infarct size, and biochemical parameters including myeloperoxidase (MPO), malondialdehyde (MDA), and superoxide dismutase (SOD) were assessed. Meanwhile, tissues in cerebral cortex were collected and processed for western blotting, immunohistochemistry, and HE staining.

RESULTS

CR1-SCR1-3 could improve neurological functions in brain with a 26.8% decrease in neurological motor deficit score and could lead to a 63.8% reduction in cerebral infarct size. Besides, pretreatment using CR1-SCR1-3 could prevent neutrophil infiltration and alleviate inflammation severity and subsequent tissue damage. Decreased C4b expression and action, as well as improved morphological changes, were also observed in cerebral tissues of CI/R+CR1-SCR1-3 rats.

CONCLUSION

CR1-SCR1-3 protein could possess a neuroprotective effect on acute CI/R injury.

Comparison of the therapeutic effects of bone marrow mononuclear cells and microglia for permanent cerebral ischemia

In this study we transplanted bone marrow mononuclear cells (BM-MNCs) or microglia into rats that had undergone permanent cerebral ischemia and observed the distribution or morphology of transplanted cells in vivo. In addition, we compared the effects of BM-MNCs and microglia on infarct volume, brain water content, and functional outcome after permanent cerebral ischemia. BM-MNCs and microglia were obtained from femur and brain, respectively, of newborn rats. Adult rats were injected with vehicle or 3 million BM-MNCs or microglia via the tail vein 24h after permanent middle cerebral artery occlusion (pMCAO). The distribution or morphologic characteristics of transplanted BM-MNCs (double stained with BrdU/Cd34 or BrdU/CD45) and microglia (double stained with BrdU/Iba-1) were detected with immunofluorescent staining at 3 or 7 and 14 days after pMCAO. Functional deficits were assessed by the modified neurologic severity score at 1, 3, 7 and 14 days after pMCAO. Brain water content was assessed at 3 days, and infarct volume was determined at 14 days. We observed more BrdU/CD45 and BrdU/Iba-1 double-stained cells than BrdU/CD34 double-stained cells around the infarcted area. Some infused microglia showed the morphology of innate microglia at 7 days after pMCAO, and the number increased at 14 days. BM-MNC-treated rats showed significantly reduced infarct volume and brain water content compared to vehicle- and microglia-treated rats. In addition, BM-MNC treatment reduced neurologic deficit scores compared to those in the other groups. The results provide evidence that infusion of BM-MNCs, but not microglia, is neuroprotective after permanent cerebral ischemia.

Progesterone attenuates cerebral edema in neonatal rats with hypoxic-ischemic brain damage by inhibiting the expression of matrix metalloproteinase-9 and aquaporin-4

The aim of this study was to investigate the effects of progesterone (PROG) on blood-brain barrier (BBB) permeability, cerebral edema and the expression of matrix metalloproteinase-9 (MMP-9) and aquaporin-4 (AQP-4) in neonatal rats with hypoxic-ischemic brain damage (HIBD) and to explore the mechanism of its neuroprotective effect. Sixty 7-day-old Wistar rats were divided into sham surgery, hypoxic ischemia (HI) and drug prophylaxis (PROG) groups. HIBD animal models were established. All the animals were sacrificed after 24 h. The BBB was assessed using Evans blue. Cerebral moisture capacity was determined using the dry-wet method. MMP-9 was detected in the brain tissues using enzyme-linked immunosorbent assay. The expression of AQP-4 and MMP-9 in the cerebral cortex was observed using immunohistochemistry and real-time polymerase chain reaction. The MMP-9 levels in the cortex, BBB permeability, cerebral moisture capacity and expression of AQP-4 and MMP-9 in the HI group were significantly higher compared with those in the sham surgery group (P<0.01), and they were significantly lower in the drug prophylaxis group compared with those in the HI group (P<0.05). In conclusion, PROG reduces BBB damage and cerebral edema and inhibits MMP-9 generation to protect rat brains against HIBD. The protective effect of PROG may be correlated with downregulated expression of AQP-4 and MMP-9 in the cerebral cortex.

Method parameters' impact on mortality and variability in rat stroke experiments: a meta-analysis

Background

Even though more than 600 stroke treatments have been shown effective in preclinical studies, clinically proven treatment alternatives for cerebral infarction remain scarce. Amongst the reasons for the discrepancy may be methodological shortcomings, such as high mortality and outcome variability, in the preclinical studies. A common approach in animal stroke experiments is that A) focal cerebral ischemia is inflicted, B) some type of treatment is administered and C) the infarct sizes are assessed. However, within this paradigm, the researcher has to make numerous methodological decisions, including choosing rat strain and type of surgical procedure. Even though a few studies have attempted to address the questions experimentally, a lack of consensus regarding the optimal methodology remains.

Methods

We therefore meta-analyzed data from 502 control groups described in 346 articles to find out how rat strain, procedure for causing focal cerebral ischemia and the type of filament coating affected mortality and infarct size variability.

Results

The Wistar strain and intraluminal filament procedure using a silicone coated filament was found optimal in lowering infarct size variability. The direct and endothelin methods rendered lower mortality rate, whereas the embolus method increased it compared to the filament method.

Conclusions

The current article provides means for researchers to adjust their middle cerebral artery occlusion (MCAo) protocols to minimize infarct size variability and mortality.

Progesterone inhibition of neuronal calcium signaling underlies aspects of progesterone-mediated neuroprotection

Progesterone is being utilized as a therapeutic means to ameliorate neuron loss and cognitive dysfunction following traumatic brain injury. Although there have been numerous attempts to determine the means by which progesterone exerts neuroprotective effects, studies describing the underlying molecular mechanisms are lacking. What has become clear, however, is the notion that progesterone can thwart several physiological processes that are detrimental to neuron function and survival, including inflammation, edema, demyelination and excitotoxicity. One clue regarding the means by which progesterone has restorative value comes from the notion that these aforementioned biological processes all share the common theme of eliciting pronounced increases in intracellular calcium. Thus, we propose the hypothesis that progesterone regulation of calcium signaling underlies its ability to mitigate these cellular insults, ultimately leading to neuroprotection. Further, we describe recent findings that indicate neuroprotection is achieved via progesterone block of voltage-gated calcium channels, although additional outcomes may arise from blockade of various other ion channels and neurotransmitter receptors. This article is part of a Special Issue entitled 'Neurosteroids'.

Current therapeutic strategies to mitigate the eNOS dysfunction in ischaemic stroke

Impairment of endothelial nitric oxide synthase (eNOS) activity is implicated in the pathogenesis of endothelial dysfunction in many diseases including ischaemic stroke. The modulation of eNOS during and/or following ischaemic injury often represents a futile compensatory mechanism due to a significant decrease in nitric oxide (NO) bioavailability coupled with dramatic increases in the levels of reactive oxygen species that further neutralise NO. However, applications of a number of therapeutic agents alone or in combination have been shown to augment eNOS activity under a variety of pathological conditions by potentiating the expression and/or activity of Akt/eNOS/NO pathway components. The list of these therapeutic agents include NO donors, statins, angiotensin-converting enzyme inhibitors, calcium channel blockers, phosphodiesterase-3 inhibitors, aspirin, dipyridamole and ellagic acid. While most of these compounds exhibit anti-platelet properties and are able to up-regulate eNOS expression in endothelial cells and platelets, others suppress eNOS uncoupling and tetrahydrobiopterin (an eNOS stabiliser) oxidation. As the number of therapeutic molecules that modulate the expression and activity of eNOS increases, further detailed research is required to reveal their mode of action in preventing and/or reversing the endothelial dysfunction.

Progesterone and low-dose vitamin D hormone treatment enhances sparing of memory following traumatic brain injury

Progesterone (PROG) has been shown to protect the brain from traumatic injury and is now in Phase III clinical trials. Our work shows that PROG's beneficial effects can be reduced in vitamin D hormone (VDH)-deficient subjects. VDH can modulate neuronal apoptosis, trophic factors, inflammation, oxidative stress, excitotoxicity, and myelin and axon repair. We investigated whether VDH combined with PROG could improve behavioral outcomes more than PROG alone in VDH-sufficient rats given bilateral contusions of the medial frontal cortex. PROG and different doses of VDH (1 μg/kg, VDH1; 2.5 μg/kg, VDH2; 5 μg/kg, VDH3) were injected intraperitoneally 1 h post-injury. Eight additional doses of PROG were given subcutaneously over 8 days with tapering over the last 2 days. Neurobehavioral tests, necrotic cavity, neuronal death and activation of astrocytes were evaluated 21 days post-injury. We found that PROG and PROG + VDH preserve spatial memory processing. VDH1 + PROG improved performance in acquisition more effectively than PROG alone, indicating that the low VDH dose is optimal for combination therapy. There were no significant differences in necrotic cavity size among the groups. The density of positive staining for reactive astrocytes (glial fibrillary acidic protein (GFAP)) increased and the cell bodies and processes of GFAP-positive cells were enlarged in the PROG + VDH1 group. Our data indicate that the combination of PROG and VDH is more effective than PROG alone in preserving spatial and reference memory, and that PROG plus low-dose VDH can activateGFAP reactions up to 21 days after injury. This effect may be one of the mechanisms underlying PROG's neuroprotective effects in combination with VDH.

Protective effect of hydroalcoholic extract of Mimusops elengi Linn. flowers against middle cerebral artery occlusion induced brain injury in rats

ETHNOPHARMACOLOGICAL RELEVANCE

In the traditional Indian and Thai system of medicine, Mimusops elengi Linn., flower is used as brain tonic and to calm anxiety and panic attacks.

AIM OF THE STUDY

The present study was designed to investigate the neuroprotective effect of hydroalcoholic extract of Mimusops elengi (ME) against cerebral ischemic reperfusion injury in rats.

MATERIALS AND METHODS

Male rats were pretreated with ME (100 and 200mg/kg) for seven days and focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) method. After 60min of MCAO and 24h of reperfusion, a battery of behavioral tests assessed the extent of neurological deficits. Infarct volume and brain edema were measured in TTC stained brain sections and the extent of blood brain barrier (BBB) disruption was observed by Evan's blue extravasation. Oxidative and nitrative stress parameters were estimated in the brain homogenates. Further, simultaneous quantification of five polyphenolic biomarkers were done using HPLC.

RESULTS

Pretreatment with ME at doses of 100 and 200mg/kg significantly improved the neurobehavioral alterations and reduced the infarct volume, edema and extent of BBB disruption induced by ischemia reperfusion injury. It also prevented the alteration in the antioxidant status and reduced the nitrite levels when compared to ischemic animals. Further, HPLC studies revealed that ME contains five bioactive polyphenolic compounds.

CONCLUSIONS

These results clearly indicate the neuroprotective effect of ME against stroke like injury. The observed protective effect might be attributed to the polyphenolic compounds and their antioxidant and anti-inflammatory property.

Novel actions of progesterone: what we know today and what will be the scenario in the future?

Objectives

This article is aimed to review the novel actions of progesterone, which otherwise is considered as a female reproductive hormone. The article focuses on its important physiological actions in males too and gives an overview of its novel perspectives in disorders of central and peripheral nervous system.

Key findings

Progesterone may have a potential benefit in treatment of traumatic brain injury, various neurological disorders and male related diseases like benign prostatic hypertrophy (BPH), prostate cancer and osteoporosis. Norethisterone (NETA), a progesterone derivative, decreases bone mineral loss in male castrated mice suggesting its role in osteoporosis. In the future, progesterone may find use as a male contraceptive too, but still needs confirmatory trials for safety, tolerability and acceptability. Megestrol acetate, a progesterone derivative is preferred in prostatic cancer. Further, it may find utility in nicotine addiction, traumatic brain injury (recently entered Phase III trial) and Alzheimer's disease, diabetic neuropathy and crush injuries. Studies also suggest role of progesterone in stroke, for which further clinical trials are needed. The non genomic actions of progesterone may be in part responsible for these novel actions.

Summary

Although progesterone has shown promising role in various non-hormonal benefits, further clinical studies are needed to prove its usefulness in conditions like stroke, traumatic brain injury, neuropathy and crush injury. In male related illnesses like BPH and prostatic Ca, it may prove a boon in near future. New era of hormonal male contraception may be initiated by use of progesterone along with testosterone.

Is progesterone a worthy candidate as a novel therapy for traumatic brain injury?

Although progesterone is critical to a healthy pregnancy, it is now known to have other important functions as well. Recent research demonstrates that this hormone is also a potent neurosteroid that can protect damaged cells in the central and peripheral nervous systems and has rapid actions that go well beyond its effects on the classical intranuclear progesterone receptor. Based on years of preclinical research demonstrating its safety and effectiveness in animal models of central nervous system injury the hormone was recently tested in two Phase II clinical trials for traumatic brain injury (TBI). A US National Institutes of Health-sponsored, nationwide Phase III clinical trial is now evaluating progesterone for moderate-to-severe TBI in 1200 patients. An industry-sponsored Phase III international trial is also under way, and planning for a trial using progesterone to treat pediatric brain injury has begun. Preclinical data suggest that progesterone may also be effective in stroke and some neurodegenerative disorders.

Investigation of the mechanisms of progesterone protection following oxygen-glucose deprivation in organotypic hippocampal slice cultures

This study aimed to test the hypothesis that progesterone is neuroprotective against oxygen-glucose deprivation (OGD) through its conversion to the active metabolite allopregnanolone (AlloP) and the potentiation of GABA(A) receptors. Organotypic hippocampal cultures were exposed to 2h of OGD and the resulting cell death was quantified 24h later using combined propidium iodide and Hoechst immunostaining. Initially, we confirmed, that both progesterone and AlloP were protective in terms of reducing cell death following OGD in hippocampal cultures and for both, the optimal level of protection was observed at a concentration of 0.1μM. However, the protective effect of progesterone was absent in the presence of finasteride (10μM) which inhibits the metabolism of progesterone to active metabolites, including AlloP. In addition, the concurrent application of picrotoxin (100μM), a potent GABA(A) receptor antagonist, prevented the protection previously seen by either progesterone or AlloP alone. These results indicate that progesterone protects hippocampal cultures from cell death following OGD largely due to its conversion to AlloP and that GABA(A) receptors are important mediators of the protective effects of both progesterone and AlloP.

Progesterone is neuroprotective following cerebral ischaemia in reproductively ageing female mice

Gender differences in both vulnerability to stroke and outcome following cerebral ischaemia have frequently been observed and attributed to the action of steroid hormones. Progesterone is a candidate neuroprotective factor for stroke; however, studies are lacking which: (i) study those groups representing high risk i.e. postmenopausal females; (ii) administer progesterone solely post-ischaemia; and (iii) combine histopathological and functional assessments. Postmenopausal females, along with males, represent the group at highest risk of cerebral stroke and can be modelled using aged or ovariectomized animals. In the current study, we aimed to determine the neuroprotective effects of progesterone administration following cerebral ischaemia in aged and ovariectomized mice. Following transient middle cerebral artery occlusion, progesterone was administered at 1, 6 and 24 h post-ischaemia to aged and ovariectomized female mice. At 48 h post-ischaemia, progesterone significantly reduced the lesion volume (P < 0.05) but had no effect on neurological outcome in aged female mice. Whereas in ovariectomized mice, at 48 h post-ischaemia, progesterone treatment had no effect on the amount of lesion volume present but did significantly improve neurological outcome. In a further study of ovariectomized mice, allowed to survive for 7 days post-ischaemia, progesterone treatment significantly improved motor outcome as assessed using both the rotarod and grid test. In fact, by 7 days post-ischaemia, progesterone-treated ovariectomized mice did not differ significantly in performance compared with shams, whereas vehicle-treated ovariectomized mice displayed a significant functional impairment following ischaemia. The current study has demonstrated that progesterone has different neuroprotective effects whether it is administered to aged or ovariectomized female mice and emphasizes the need to combine histopathological and functional outcomes within the same study. In addition, as progesterone-only treatment may not improve all outcomes in all groups, therapies that combine progesterone with other neuroprotective candidates should be investigated to maximize benefit following stroke.

Effects of progesterone on intestinal inflammatory response and mucosa structure alterations following SAH in male rats

BACKGROUND

Subarachnoid hemorrhage (SAH) can induce a persistent inflammatory response, histopathologic changes in the gut. This study investigated whether progesterone administration modulates intestinal proinflammatory cytokine expression and structure alternations following SAH in male rats.

MATERIALS AND METHODS

A total of 48 male rats were randomly divided into four groups: control group (n = 12), SAH group (n = 12), SAH+vehicle group (n = 12) and SAH+progesterone group (n = 12). We measured intestinal wet/dry weight ratio; the concentrations of IL-1β, TNF-α, and IL-6 by enzyme-linked immunosorbent assay; intestinal mucosal morphologic changes by histopathologic study and electron microscopy.

RESULTS

Administration of progesterone following SAH could increase the appetite scores of SAH rats and decrease concentrations of proinflammatory cytokines and wet/dry weight ratio in the gut. SAH-induced damage of gut structure was ameliorated after progesterone supplementation.

CONCLUSIONS

The results of the present study suggest that the therapeutic benefit of post-SAH progesterone supplementation might be due to its inhibitory effects on intestinal proinflammatory cytokine expression and gut structure amelioration.

Progesterone influences postischemic synaptogenesis in the CA1 region of the hippocampus in rats

Synaptogenesis is considered necessary for learning and memory. Recently, it has been suggested that progesterone (PROG) effects synaptogenesis of the cerebellar Purkinje cell, helps alleviate symptoms of multiple sclerosis and helps arrest spinal cord neurodegeneration. However, it is unclear whether PROG influences synaptic plasticity in central nervous system neurons after global cerebral ischemia. The purpose of the present study was to reveal PROG's influence on postischemic synaptogenesis in the CA1 region of the hippocampus in rats. Global cerebral ischemia was induced in male Sprague-Dawley rats by the 4-vessel occlusion (4-VO) method. To determine the amount of synaptogenesis, growth-associated protein 43 (GAP-43) and synaptophysin (SYP) expression were examined by immunohistochemical, reverse transcription-polymerase chain reaction (RT-PCR) and western blot techniques. Histological and behavioral tests were used to indicate the effect of PROG on global cerebral ischemia. Recovery times were 3, 7, 14, 21, and 35 days after surgery. We found that PROG increased the expression of GAP-43 and SYP. In addition, there was a significant increase in neuronal cell density and improvement ability to remain on an accelerating rotarod observed in the 4-VO rats treated with PROG compared to vehicle. We propose that PROG helped enable synaptogenesis in the CA1 region of therat hippocampus after global cerebral ischemia in rats.

Progesterone prevents development of neuropathic pain in a rat model: Timing and duration of treatment are critical

BACKGROUND

Progesterone is emerging as an important protective agent against various injuries to the nervous system. Neuroprotective and remyelinating effects have been documented for this neurosteroid, which is synthesized by, and acts on, the central and peripheral nervous systems. Neuropathic pain is a severe, persistent condition that is generally resistant to treatment, and poses major personal, social, and economic burdens. The purpose of this study was to determine if single-dose or repeated progesterone administration would alleviate tactile hypersensitivity in a rat model of neuropathic pain, and to determine if early versus late initiation of treatment has an effect on the outcome.

METHODS

Rats were unilaterally implanted with a polyethylene cuff around the sciatic nerve, and sensitivity to von Frey filament stimulation was measured over approximately 12 weeks.

RESULTS

Rats given progesterone starting one hour after cuff implantation, and daily until day 4, exhibited tactile hypersensitivity similar to that of vehicle-treated rats for the duration of the study. When progesterone was started one hour after cuff implantation and given daily until day 10, rats exhibited no tactile hypersensitivity in the later part of the study, after treatment had stopped. When progesterone treatment was initiated at 20 days, once the model had been fully established, and given daily for 4 or even 11 days, no differences in withdrawal thresholds were observed compared with controls. Progesterone did not have any effect on withdrawal thresholds when given as a single dose, as measured at 30, 60 and 90 minutes after administration.

CONCLUSION

These results indicate that progesterone, when administered immediately after nerve injury, and for a sufficient period of time, can prevent the development of neuropathic pain, and may offer new strategies for the treatment of this highly debilitating condition.

Protection against ischemic stroke damage by synergistic treatment with amlodipine plus atorvastatin in Zucker metabolic rat

Ischemic stroke is a major neurologic disorder and a leading cause of disability and death in the world. We compared neuroprotective effects of single or combination therapy of amlodipine (AM) and atorvastatin (AT) in such a metabolic syndrome model Zucker rat. The animals were pretreated with vehicle, AM, AT, or the combination of AM plus AT for 28days, and physical and serum parameters were analyzed, then 90min of transient middle cerebral artery occlusion (tMCAO), was performed followed by immunohistochemical analyses at 24h. Without affecting serum levels of lipids, adiponectin, and leptin, the combination therapy of AM plus AT ameliorated the post-ischemic brain weight increase. The single treatment with AM or AT itself exerted neuroprotective effects with reducing inductions of MMP-9 and AT2R, as well as with preserving collagen IV, and the combination therapy of AM plus AT showed a further synergistic benefit against acute ischemic neural damages. Single AT was more protective on these 3 molecules than single AM at this time point of 24h after tMCAO. Thus, the combination therapy with AM plus AT extended the neuroprotectives effect of single treatment with AM or AT on a part of neurovascular unit and a hypertension-related receptor.

Neuroprotective effect of liquiritin against focal cerebral ischemia/reperfusion in mice via its antioxidant and antiapoptosis properties

Our present study was conducted to investigate whether liquiritin (7-hydroxy-2-[4-[3,4,5-trihydroxy-6-(hydroxymethyl) oxan-2-yl] oxyphenyl]-chroman-4-one, 1), an active component of Glycyrrhiza uralensis Fisch., exerts a neuroprotective effect against focal cerebral ischemia/reperfusion (I/R) in male Institute of Cancer Research (ICR) mice. On the establishment of mice with middle cerebral artery occlusion (MCAO) for 2 h and reperfusion for 22 h, liquiritin at the doses of 40, 20, and 10 mg/kg was administered before MCAO once a day intragastrically for a subsequent 3 days. Neurological deficits and infarct volume were measured, respectively. The levels of malondialdehyde (MDA) and carbonyl, activities of superoxide anion (SOD), catalase (CAT) and glutathion peroxidase (GSH-Px) and reduced glutathione/oxidized disulfide (GSH/GSSG) ratio in brain were estimated spectrophotometrically. 8-Hydroxy-2'-deoxyguanosine (8-OHdG) and terminal deoxynucleotidyl transferase-mediated DuTP-biotin nick end labeling (TUNEL)-positive cells were detected by immunohistochemical analysis. Our results showed that the neurological deficits, infarct volume, and the levels of MDA and carbonyl decreased, the ratio of GSH/GSSG and the activities of SOD, CAT, and GSH-Px were compensatorily up-regulated, and 8-OHdG and TUNEL-positive cells decreased after 22 h of reperfusion in liquiritin-treated groups. These findings suggest that liquiritin might be a potential agent against cerebral I/R injury in mice by its antioxidant and antiapoptosis properties.