Hormone replacement therapy and ischemic stroke severity in women: A case-control study

Stroke Hormones and Outcomes in Women (SHOW) Study: Is the ‘Healthy-User Effect’ Valid for Women after Stroke?

Aims: To determine differences in stroke severity and outcomes in women using hormone therapy (HT) versus nonusers at baseline, and to investigate whether there is a ‘healthy-user effect’ of HT in women with stroke. Materials and methods: A total of 133 women over the age of 18 years with acute ischemic stroke were enrolled and categorized based on their use of HT at the time of stroke. Initial stroke severity was assessed at admission, and disability and activities of daily living were assessed at 6-month intervals for 2 years. Results: A total of 30% of the cohort were HT users. HT users were less likely to have hypertension and were leaner than nonusers. There were no differences in initial stroke severity, mortality or any of the functional status outcomes based on HT use at baseline. Conclusion: There did appear to be a healthy-user effect for HT users at baseline, but following stroke, there were no significant differences in long-term outcomes.

Impact of comorbidities on ischemic stroke outcomes in women

BACKGROUND AND PURPOSE

We assessed the association of prestroke comorbidities with long-term stroke outcomes among women with ischemic stroke.

METHODS

Prestroke comorbid conditions in 133 women admitted with acute ischemic stroke were scored with the Charlson Index (CI). We assessed whether the CI and other specific conditions were associated with modified Rankin Score (mRS) at 90 days or more poststroke.

RESULTS

After adjustment for initial NIHSS and age, higher CI was the sole factor independently associated with poorer 90 day mRS scores. When CI was excluded, coronary disease and diabetes were independently associated with poorer outcome.

CONCLUSIONS

The extent of comorbidities as assessed by the CI is independently associated with 90-day mRS among women with ischemic stroke, but the individual comorbidities of CHD and DM were each associated with functional outcome.

Neurotoxicity assessment using zebrafish

INTRODUCTION

Transparency is a unique attribute of zebrafish that permits direct assessment of drug effects on the nervous system using whole mount antibody immunostaining and histochemistry.

METHODS

To assess pharmacological effects of drugs on the optic nerves, motor neurons, and dopaminergic neurons, we performed whole mount immunostaining and visualized different neuronal cell types in vivo. In addition, we assessed neuronal apoptosis, proliferation, oxidation and the integrity of the myelin sheath using TUNEL staining, immunostaining and in situ hybridization. The number of dopaminergic neurons was examined and morphometric analysis was performed to quantify the staining signals for myelin basic protein and apoptosis.

RESULTS

We showed that compounds that induce neurotoxicity in humans caused similar neurotoxicity in zebrafish. For example, ethanol induced defects in optic nerves and motor neurons and affected neuronal proliferation; 6-hydroxydopamine caused neuronal oxidation and dopaminergic neuron loss; acrylamide induced demyelination; taxol, neomycin, TCDD and retinoic acid induced neuronal apoptosis.

DISCUSSION

Effects of drug treatment on different neurons can easily be visually assessed and quantified in intact animals. These results support the use of zebrafish as a predictive model for assessing neurotoxicity.

Differences in brain volumes among males and female hormone-therapy users and nonusers

Numerous studies have shown gender differences in the brain volumes of elderly adults. Some evidence shows that higher estrogen levels may be neuroprotective, suggesting that hormone therapy (HT) may in part be responsible for these gender differences; however, few studies have examined the relation between HT and brain volumes. Brain volumes of caudate, putamen, hippocampus, gray matter, white matter, white-matter lesions, and cerebrospinal fluid were measured on magnetic resonance imaging scans. A comprehensive neuropsychological battery was administered. Women were separated into two groups based on HT use, and we used multiple regression analyses to compare these groups with one another and with men. Results of brain-volume measurements showed that HT users had significantly less gray matter and more cerebrospinal fluid than nonusers. Results of the neuropsychological testing showed that HT users performed better on the Shipley Vocabulary Test than males did.

Estrogens and experimental ischemic stroke: a systematic review

Estrogens are believed to provide females with endogenous protection against cerebrovascular events although clinical trials studying long-term hormone replacement have yielded disappointing results. In contrast, estrogens might be neuroprotective after experimental ischemia. We performed a systematic review of controlled experimental studies that administered estrogens before, or after, cerebral ischemia and measured lesion volume. Relevant studies were found from searching PubMed, Embase and Web of Science. From 161 identified publications, 27 studies using 1,304 experimental subjects were analyzed using the Cochrane Review Manager software. Estrogens reduced lesion volume in a dose-dependent manner, after either transient (P<0.001) or permanent (P<0.001) ischemia and whether administered before or up to 4 h after ischemia onset; no studies assessed efficacy for later time periods. The effect size for estrogens decreased with increasing quality scores for studies of transient ischemia. Estrogens reduced lesion volume when administered to ovariectomized females and young adult males, but had no effect in intact females. Limited data were present for aged animals and the full dose-response relationship was not available in all experimental groups. On the basis of these data, estrogens are a candidate treatment for ischemic stroke, although further preclinical studies are also warranted.

Statin Use and Sex-Specific Stroke Outcomes in Patients With Vascular Disease

Background and Purpose— Although statins reduce the risk of stroke in patients with coronary heart disease, possible differing effects of statins on stroke outcomes based on sex remain uncertain. We investigated the relationships between statin use and sex-specific stroke incidence, severity, and mortality.

Methods— Data from 3 trials of oral glycoprotein IIb/IIIa inhibitors (first and second Sibrafiban versus aspirin to Yield Maximum Protection from ischemic Heart events postacute cOroNary sYndromes [SYMPHONY] and Blockade of the glycoprotein IIb/IIIa Receptor to Avoid Vascular Occlusion [BRAVO]) were pooled and stroke outcomes compared among 8191 baseline statin users versus 14 752 nonusers. Time-to-event data were modeled with proportional hazards regression. Stroke severity was assessed retrospectively with the Canadian Neurological Scale (CNS) based on records with scoreable neurological examinations.

Results— A total of 217 subjects had strokes (0.95%). Statin users had a lower risk of stroke in unadjusted (hazard ratio [HR], 0.69; 95% CI, 0.51 to 0.92) and risk-adjusted models (HR, 0.72; 95% CI, 0.53 to 0.97). There was no difference in stroke mortality with statin use ( P =0.8). CNS scores could be assigned to 106 of the subjects, with no difference in severity among statin users and nonusers (median CNS=10.5 in users versus CNS=9.75 in nonusers; P =0.14). Women had more severe strokes than men (median CNS=10.5 in men versus 9.5 in women; Poisson regression P =0.035). Women had more severe strokes after adjustment for statin use ( P =0.03) and the combination of statin use, atrial fibrillation, and age ( P =0.03).

Conclusions— In patients included in these clinical trials of oral glycoprotein IIb/IIIa inhibitors, statin use is associated with a reduced risk of stroke but not severity or mortality. Women had more severe strokes than men, a difference that was not explained by baseline characteristics or statin use.

Modulatory effects of progesterone on inducible nitric oxide synthase expression in vivo and in vitro

Nitric oxide (NO) is produced in the CNS following injury-induced expression of inducible nitric oxide synthase (iNOS), yet its role as protective or damaging is unclear. Previous studies investigating the therapeutic potential of female sex steroids in stroke and trauma suggest that NO from this source is harmful, since oestradiol and progesterone decreased the level of iNOS expression in vitro and improved neurological outcome. We investigated the effects of progesterone on stroke-induced expression of iNOS in mice, as well as cytokine-induced expression of iNOS and its transcriptional activators in cells relevant to injury. We observed a significant reduction in stroke-induced iNOS transcript in progesterone-treated mice and in cultured macrophages. In contrast, progesterone significantly amplifed cytokine-induced iNOS mRNA in cultured primary astrocytes, although the expression of protein was decreased. We sequenced upstream of the 1.5 kb reported iNOS promoter region and identified a potential progesterone response element (PRE). Astrocytes transiently transfected with iNOS promoter/CAT reporter gene constructs containing the PRE displayed a significant increase in induction of CAT expression after progesterone treatment, and this was diminished in cells transfected with a construct containing a disrupted PRE. These observations suggest the involvement of iNOS in the neuroprotective effects of progesterone.

Progesterone enhances functional recovery after middle cerebral artery occlusion in male mice

Sex differences have been observed in the outcome after ischemia that are believed to be attributable to sex steroid hormones. The present study investigated the possible benefits of progesterone administration after focal cerebral ischemia. Male mice underwent 60-minute middle cerebral artery occlusion (MCAO) and received progesterone (8 mg/kg, intraperitoneally) or vehicle (dimethyl sulfoxide) 1, 6, and 24 hours after MCAO. The lesion volume at 48 hours after MCAO was significantly reduced (P < 0.05) in progesterone-treated mice compared with vehicle-treated mice. All other mice underwent tests of well being (survival rate and body weight recovery), motor ability (grid test and rotarod), and cognitive ability (water maze) for up to 21 days. MCAO significantly worsened outcome in all of these tests compared with shams. Progesterone treatment was beneficial in that compared with vehicle, it significantly improved survival rate, weight recovery, and motor ability. This improvement was most apparent during water maze testing, where progesterone-treated mice were indistinguishable from shams in terms of acquiring the task. These results indicate beneficial effects of progesterone administration after cerebral ischemia and illustrate the need to further investigate the mechanisms of progesterone action.

A comparative review of the risks and benefits of hormone replacement therapy regimens

The Women's Health Initiative (a large, randomized, placebo-controlled trial) investigated the effect of conjugated equine estrogens combined with medroxyprogesterone acetate on specific potential long-term benefits and risks. A review of the clinical studies that have investigated different types and regimens of estrogens combined with progestins was conducted to assess how applicable the results of the Women's Health Initiative are to hormone replacement therapy regimens in general. The studies that were reviewed were limited to randomized clinical trials and observational studies that have been published over the last 15 years (1987-2002) and to meta-analyses and reviews that may have included the literature before 1987. The increased risks for venous thromboembolism, stroke, coronary heart disease, and breast cancer that were identified in the Women's Health Initiative trial have also been reported with postmenopausal hormone therapies that contain a variety of estrogen and progestin products. The beneficial effects that were noted in the Women's Health Initiative, with respect to reductions in fractures and colorectal cancer, have not been evaluated in large, randomized controlled trials that use different estrogen/progestin combinations; however, observational trials that used a variety of estrogen or hormone replacement therapy products and randomized clinical studies that evaluated bone mineral density (an excellent predictor of fracture risk) with different estrogen/hormone replacement therapy regimens would suggest that results would be similar to those found in the Women's Health Initiative. Although the relief of menopausal symptoms, the primary reason women seek treatment, was not included in the overall benefit/risk analysis of the Women's Health Initiative, numerous trials suggest that all therapies are effective. Overall, these data indicate that the benefit/risk analysis that was reported in the Women's Health Initiative can be generalized to all postmenopausal hormone replacement therapy products.

Testosterone increases neurotoxicity of glutamate in vitro and ischemia-reperfusion injury in an animal model

Increasing evidence has demonstrated striking sex differences in the outcome of neurological injury. Whereas estrogens contribute to these differences by attenuating neurotoxicity and ischemia-reperfusion injury, the effects of testosterone are unclear. The present study was undertaken to determine the effects of testosterone on neuronal injury in both a cell-culture model and a rodent ischemia-reperfusion model. Glutamate-induced HT-22 cell-death model was used to evaluate the effects of testosterone on cell survival. Testosterone was shown to significantly increase the toxicity of glutamate at a 10 microM concentration, whereas 17beta-estradiol significantly attenuated the toxicity at the same concentration. In a rodent stroke model, ischemia-reperfusion injury was induced by temporal middle cerebral artery occlusion (MCAO) for 1 h and reperfusion for 24 h. To avoid the stress-related testosterone reduction, male rats were castrated and testosterone was replaced by testosterone pellet implantation. Testosterone pellets were removed at 1, 2, 4, or 6 h before MCAO to determine the duration of acute testosterone depletion effects on infarct volume. Ischemic lesion volume was significantly decreased from 239.6 +/- 25.9 mm(3) in control to 122.5 +/- 28.6 mm(3) when testosterone pellets were removed at 6 h before MCAO. Reduction of lesion volume was associated with amelioration of the hyperemia during reperfusion. Our in vitro and in vivo studies suggest that sex differences in response to brain injury are partly due to the consequence of damaging effects of testosterone.