Microparticles generated during chronic cerebral ischemia deliver proapoptotic signals to cultured endothelial cells.

Circulating microparticles (MPs) are involved in many physiological processes and numbers are increased in a variety of cardiovascular disorders. The present aims were to characterize levels of MPs in a rodent model of chronic cerebral hypoperfusion (CCH) and to determine their signaling properties. MPs were isolated from the plasma of rats exposed to CCH and quantified by flow cytometry. When MPs were added to cultured endothelial cells or normal rat kidney cells they induced cell death in a time and dose dependent manner. Analysis of pellets by electron microscopy indicates that cell death signals are carried by particles in the range of 400 nm in diameter or less. Cell death involved the activation of caspase 3 and was not a consequence of oxidative stress. Inhibition of the Fas/FasL signaling pathway also did not improve cell survival. MPs were found to contain caspase 3 and treating the MPs with a caspase 3 inhibitor significantly reduced cell death. A TNF-α receptor blocker and a TRAIL neutralizing antibody also significantly reduced cell death. Levels of circulating MPs are elevated in a rodent model of chronic cerebral ischemia. MPs with a diameter of 400 nm or less activate the TNF-α and TRAIL signaling pathways and may deliver caspase 3 to cultured cells.

First report of severe tolpyralate sensitivity in corn (Zea mays) discovers a novel genetic factor conferring crop response to a herbicide.

BACKGROUND: Tolpyralate, a relatively new inhibitor of 4-hydroxyphenylpyruvate dioxygenase (HPPD), is registered for postemergence use in all types of corn (Zea mays L.) and has a record of excellent crop tolerance. A report of severe crop injury to sweet corn inbred (XSEN187) led to the following objectives: (i) determine whether sensitivity to tolpyralate in XSEN187 exists, and if confirmed, (ii) determine the genetic basis of tolpyralate sensitivity, and (iii) screen other corn germplasm for sensitivity to tolpyralate. RESULTS: Inbred XSEN187 was confirmed sensitive to tolpyralate. Inclusion of methylated seed oil or nonionic surfactant in the spray volume was necessary for severe crop injury. Tolpyralate sensitivity in XSEN187 is not conferred by alleles at Nsf1, a cytochrome P450-encoding gene (CYP81A9) conferring tolerance to many corn herbicides. Evidence suggests that tolpyralate sensitivity in XSEN187 is conferred by a single gene mapped to the Chr05: 283 240-1 222 909 bp interval. Moreover, tolpyralate sensitivity was observed in 48 other sweet corn and field corn inbreds. CONCLUSIONS: Severe sensitivity to tolpyralate exists in sweet corn and field corn germplasm when the herbicide is applied according to label directions. Whereas the corn response to several other herbicides, including HPPD-inhibitors, is conferred by the Nsf1 locus, corn sensitivity to tolpyralate is the result of a different locus. The use of tolpyralate should consider herbicide tolerance in inbred lines from which corn hybrids were derived, whereas alleles that render corn germplasm sensitive to tolpyralate should be eliminated from breeding populations, inbreds, and commercial cultivars. © 2023 Illinois Foundation Seeds, Inc and The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Microparticles: biomarkers and beyond.

Membrane microparticles are submicron fragments of membrane shed into extracellular space from cells under conditions of stress/injury. They may be distinguished from other classes of extracellular vesicles (i.e. exosomes) on the basis of size, content and mechanism of formation. Microparticles are found in plasma and other biological fluids from healthy individuals and their levels are altered in various diseases, including diabetes, chronic kidney disease, pre-eclampsia and hypertension among others. Accordingly, they have been considered biomarkers of vascular injury and pro-thrombotic or pro-inflammatory conditions. In addition to this, emerging evidence suggests that microparticles are not simply a consequence of disease, but that they themselves may contribute to pathological processes. Thus microparticles appear to serve as both markers and mediators of pathology. The present review examines the evidence for microparticles as both biomarkers of, and contributors to, the progression of disease. Approaches for the detection of microparticles are summarized and novel concepts relating to the formation of microparticles and their biological effects are examined.

A systematic literature review on the clinical efficacy of low dose naltrexone and its effect on putative pathophysiological mechanisms among patients diagnosed with fibromyalgia.

Background: Low dose naltrexone (LDN) is used off-label by many individuals with fibromyalgia to help manage their pain. There is no current systematic literature review summarising the evidence to support this use of LDN. The objectives of this study were to evaluate if patients with fibromyalgia prescribed LDN have reduced pain scores and greater quality of life compared with those allocated to placebo in randomized controlled trials. Secondly to determine if changes in inflammatory markers and brain structure and function are observed among patients with fibromyalgia taking LDN. Methods: Systematic literature searches were conducted in MEDLINE, Embase Classic + Embase, APA PsychInfo, and The Cochrane Library from inception to May 2022. Reference lists from the selected papers were cross-checked with database search results. Results: Three studies met our inclusion criteria for the assessment of efficacy, and two studies on potential LDN mechanisms. Results indicated some evidence to suggest LDN reduces pain and increases quality of life. One study reported baseline erythrocyte sedimentation rate (ESR) predicted LDN response (≥30% reduction in fibromyalgia symptoms) and a second study showed plasma concentrations of inflammatory biomarkers were lower after LDN treatment. To our knowledge, there are no brain imaging studies reporting the effect of LDN in patients with fibromyalgia. All studies were based on small sample sizes, were restricted to women and the risk of bias was assessed to be high. There is also some evidence of publication bias. Conclusion: The strength of evidence from randomized controlled trials to support the use of LDN among patients with fibromyalgia is low. Two small studies suggest ESR and cytokines may be involved in the mechanism by which LDN exerts its effects. Two trials (INNOVA and FINAL) are currently in progress, but further work is needed among men and different ethnic groups.

Biological-physical interactions are fundamental to understanding and managing coastal dynamics.

There is an urgent need to address coastal dynamics as a fundamental interaction between physical and biological processes, particularly when trying to predict future biological-physical linkages under anticipated changes in environmental forcing. More integrated modelling, support for observational networks and the use of management interventions as controlled experimental exercises should now be vigorously pursued.

Identification of tidal trapping of microplastics in a temperate salt marsh system using sea surface microlayer sampling.

Microplastics are contaminants of increasing global environmental concern. Estuaries are a major transport pathway for land-derived plastics to the open ocean but are relatively understudied compared to coastal and open marine environments. The role of the "estuarine filter", by which the supply of sediments and contaminants to the sea is moderated by processes including vegetative trapping and particle flocculation, remains poorly defined for microplastics land to sea transfer. Here, we focus on the sea surface microlayer (SML) as a vector for microplastics, and use SML sampling to assess microplastic trapping in a temperate marsh system in Southampton Water, UK. The SML is known to concentrate microplastics relative to the underlying water and is the first part of rising tidal waters to traverse intertidal and upper tidal surfaces. Sampling a salt marsh creek at high temporal resolution allowed assessment of microplastics in-wash and outflow from the salt marsh, and its relationship with tidal state and bulk suspended sediment concentrations (SSC), over spring and neap tides. A statistically significant decrease in microplastics abundance from the flood tide to the ebb tide was found, and a weak positive relationship with SSC observed.

Rescue of neurons from ischemic injury by peroxisome proliferator-activated receptor-gamma requires a novel essential cofactor LMO4.

Activation of peroxisome proliferator-activated receptor-gamma (PPARgamma) signaling after stroke may reduce brain injury, but this effect will depend on the levels of receptor and cofactors. Here, we showed that the direct effect of PPARgamma signaling to protect neurons from ischemic injury requires a novel cofactor LMO4, because this effect was lost in LMO4-null cortical neurons. PPARgamma agonist also failed to reduce cerebral infarction after transient focal ischemia in CaMKIIalphaCre/LMO4loxP mice with LMO4 ablated in neurons of the forebrain. Expressing LMO4 in LMO4-null cortical neurons rescued the PPARgamma-protective effect. PPARgamma signaling activates the promoter of the antioxidant gene SOD2 and this process requires LMO4. Addition of a superoxide dismutase mimetic MnTBAP [manganese(III)tetrakis(4-benzoic acid)porphyrin] bypassed the deficiency in PPARgamma signaling and was able to directly rescue LMO4-null cortical neurons from ischemic injury. Like LMO4, PPARgamma and PGC1alpha (PPARgamma coactivator 1alpha) levels in neurons are elevated by hypoxic stress, and absence of LMO4 impairs their upregulation. Coimmunoprecipitation and mammalian two-hybrid assays revealed that LMO4 interacts in a ligand-dependent manner with PPARgamma. LMO4 augments PPARgamma-dependent gene activation, in part, by promoting RXRalpha (retinoid X receptor-alpha) binding to PPARgamma and by increasing PPARgamma binding to its target DNA sequence. Together, our results identify LMO4 as an essential hypoxia-inducible cofactor required for PPARgamma signaling in neurons. Thus, upregulation of LMO4 expression after stroke is likely to be an important determinant of neuron survival.

Living beyond our physiological means: small vessel disease of the brain is an expression of a systemic failure in arteriolar function: a unifying hypothesis.

BACKGROUND AND PURPOSE: It is our premise that the pathophysiology of small vessel disease in the brain is similar to small vessel disease in other heavily perfused tissues and that the presence of small vessel disease elsewhere in the body foretells its presence in the brain as well as its consequences on cognitive function. The hypothesis presented in this article is that small vessel disease is a systemic condition of aging that is exacerbated by vascular risk factors, which results from dysfunction of arteriolar perfusion. This condition, which we term systemic arteriolar dysfunction, affects the brain as well as a number of extracranial systems. SUMMARY OF REVIEW: Recent literature is synthesized to suggest a possible etiology of this condition, highlighting the multiple pathways that may conspire to produce the endothelial and other vascular changes seen in systemic arteriolar dysfunction. CONCLUSIONS: Regardless of the etiology, we emphasize that small vessel disease is a systemic condition with major healthcare consequences, requiring a new paradigm in the way we practice medicine. Because this condition can be decelerated by control of vascular risk factors, doing so may significantly reduce morbidity, mortality, and healthcare costs.

ATP release by way of connexin 36 hemichannels mediates ischemic tolerance in vitro.

Spreading depression (SD) is a self-propagating wave of neuronal and glial depolarization that may occur in virtually any gray matter region in the brain. One consequence of SD is an increased tolerance to ischemia. It has been shown that during cortical SD ATP is released into the extracellular space and activation of purinergic receptors leads to the induction of ischemic tolerance. In the present study we show that depolarization of cultured neurons induces ischemic tolerance which is mediated by purinergic receptor activation. Depolarization causes the release of ATP into the extracellular medium, which may be prevented by treatment with the connexin hemichannel blockers flufenamic acid and quinine, but not the pannexin hemichannel blocker carbenoxolone. Knockdown of connexin 36 expression by siRNA greatly reduces the amount of ATP released during depolarization and the subsequent degree of ischemic tolerance. We conclude that during depolarization neurons release ATP by way of connexin 36 hemichannels.

Cortical spreading depression releases ATP into the extracellular space and purinergic receptor activation contributes to the induction of ischemic tolerance.

Cortical Spreading Depression (CSD) is a well-studied model of preconditioning that provides a high degree of tolerance to a subsequent ischemic event in the brain. The present study was undertaken in order to determine whether the release of ATP during CSD could contribute to the induction of ischemic tolerance. Direct measurement of ATP levels during CSD indicates that with each CSD wave ATP is released into the extracellular space at levels exceeding 100 microM. Cultures of rat primary cortical neurons exposed to low levels of extracellular ATP developed tolerance to subsequent oxygen-glucose deprivation (OGD) or metabolic hypoxia. The preconditioning effect requires new protein synthesis and develops with time, suggesting that a complex genomic response is required for the induction of tolerance. Multiple purinergic receptors are involved in mediating tolerance, with P2Y receptor activation having the greatest effect. Although extracellular adenosine or glutamate may make a small contribution, most of the tolerance was found to be induced independently of adenosine or glutamate receptor activation. Multiple signal transduction pathways mediate the response to extracellular ATP with the protein kinase A pathway and activation of phospholipase C contributing the most. The results are consistent with the proposal that CSD releases ATP into the extracellular space and the subsequent activation of P2Y receptors makes a major contribution to the induction of ischemic tolerance in the brain.

Characterization of stanniocalcin 2, a novel target of the mammalian unfolded protein response with cytoprotective properties.

Accumulation of misfolded proteins in the endoplasmic reticulum (ER) induces a highly conserved homeostatic response in all eukaryotic cells, termed the unfolded-protein response (UPR). Here we describe the characterization of stanniocalcin 2 (STC2), a mammalian homologue of a calcium- and phosphate-regulating hormone first identified in fish, as a novel target of the UPR. Expression of STC2 gene is rapidly upregulated in cultured cells after exposure to tunicamycin and thapsigargin, by ATF4 after activation of the ER-resident kinase PERK. In addition, STC2 expression is also activated in neuronal cells by oxidative stress and hypoxia but not by several cellular stresses unrelated to the UPR. In contrast, expression of another homologue, STC1, is only upregulated by hypoxia independent of PERK or ATF4 expression. In vivo studies revealed that rat cortical neurons rapidly upregulate STC2 after transient middle cerebral artery occlusion. Finally, siRNA-mediated inhibition of STC2 expression renders N2a neuroblastoma cells and HeLa cells significantly more vulnerable to apoptotic cell death after treatment with thapsigargin, and overexpression of STC2 attenuated thapsigargin-induced cell death. Consequently, induced STC2 expression is an essential feature of survival component of the UPR.

Regulation of expression of early growth response transcription factors in rat primary cortical neurons by extracellular ATP.

The zinc finger transcription factor early growth response-1 (Egr-1, NGFI-A, zif268, Krox 24, TIS8, ZENK) is upregulated immediately in the brain by cortical spreading depression (CSD) and other preconditioning stimuli and thus might participate in regulation of the overall genomic response to preconditioning. In the present study, the induction of expression of Egr-1 and other early growth response family members was characterized in rat primary cortical neuronal cultures. In neuronal cultures in vitro, depolarization or exposure to extracellular glutamate caused a 4-fold increase in egr-1 mRNA while exposure to extracellular ATP caused a 10-fold increase. The presence of mRNA encoding for multiple types of purinergic receptors was confirmed by RT-PCR. A number of nucleotide agonists proved effective in eliciting an increase in egr-1 mRNA. Over a limited range of concentration, the most effective agonists were ATP > ADP > alpha, beta-methylene ATP > UTP > cAMP > UDP > AMP > adenosine. Pertussis toxin, suramin, reactive blue 2, PPADS, DPCPX and inhibitors of Protein Kinase C, Protein Kinase A and PI3 kinase significantly reduced the upregulation of egr-1 by exposure to extracellular ATP. These findings suggest that neuronal metabotropic purinergic receptor activation contributes to the induction of early growth response transcription factors and may provide a target that can be manipulated to increase ischemic tolerance of the brain in vivo.

Microparticles generated during chronic cerebral ischemia increase the permeability of microvascular endothelial barriers in vitro.

Numbers of circulating microparticles (MPs) are elevated in a variety of cardiovascular disorders, and recent studies indicate that they are involved in inflammatory intercellular signaling. In the present study the signaling properties of MPs were assessed in an in vitro model of the blood brain barrier. MPs isolated from the plasma of rats exposed to chronic cerebral ischemia caused a significant reduction in the transendothelial electrical resistance (TEER) when applied to in vitro endothelial barriers, while MPs isolated from an equal volume of plasma from unoperated or sham operated rats did not. The reduction in TEER was attenuated by treating endothelial barriers prior to exposure to MPs with the caspase 3 inhibitor AC-DEVD-CHO, the TNF-α inhibitor SPD304, the tumor necrosis factor alpha-converting enzyme (TACE, ADAM 17) inhibitor TAPI-0-1 and the Rho kinase (ROCK) inhibitor Y-27632, and by treating the MPs themselves with these inhibitors prior to applying them to cultured cells. This observation indicates that MPs generated during cerebral ischemia contain pro-TNF-α, active TACE and active ROCK. ROCK and Ras homolog gene family member A (RhoA) were detected in MPs by western blot. The growth factor VEGF stimulated transcellular transport in endothelial barriers while exposure to MPs did not. We conclude that the increase in permeability of artificial barriers induced by MPs is primarily due to enhanced apoptosis induced by activation of the TNF-α pathway and activated caspase 3 and Rho kinases delivered to endothelial cells by MPs.

Cilostazol reduces blood brain barrier dysfunction, white matter lesion formation and motor deficits following chronic cerebral hypoperfusion.

Cerebral small vessel disease (CSVD) is a pathological process leading to lacunar infarcts, leukoaraiosis and cerebral microbleeds. Dysfunction of the blood brain barrier (BBB) has been proposed as a mechanism in the progression cerebral small vessel disease. A rodent model commonly used to study some aspects of CSVD is bilateral common carotid artery occlusion (BCCAO) in the rat. In the present study it was determined that gait impairment, as determined by a tapered beam test, and BBB permeability increased following BCCAO. Cilostazol, a type III phosphodiesterase inhibitor, has been shown to have anti-apoptotic effects and prevent white matter vacuolation and rarefaction induced by BCCAO in rats. In this study the protective effect of cilostazol administration on the increase BBB permeability following BCCAO was determined as well as the effect on plasma levels of circulating microparticles (MPs), cerebral white matter rarefaction, glial activation and gait disturbance. The effect of cilostazol on in vitro endothelial barriers was also evaluated. Cilostazol treatment improved BBB permeability and reduced gait disturbance, visual impairment and microglial activation in optic tract following BCCAO in vivo. It also reduced the degree of cell death and the reduction in trans-endothelial electrical resistance (TEER) in artificial endothelial barriers in vitro induced by MP treatment of in vitro barriers.

Cortical spreading depression modifies components of the inflammatory cascade.

As more information becomes available regarding the role of inflammation following stroke, it is apparent that some inflammatory mediators are detrimental and others are beneficial to the progression of ischemic injury. Cortical spreading depression (CSD) is known to impart some degree of ischemic tolerance to the brain and to influence the expression of many genes. Many of the genes whose expression is altered by CSD are associated with inflammation, and it appears likely that modulation of the inflammatory response to ischemia by CSD contributes to ischemic tolerance. Understanding which inflammatory processes are influenced by CSD may lead to the identification of novel targets in the effort to develop an acute treatment for stroke.

Tongue protrusion: a simple test for neurological recovery in rats following focal cerebral ischemia.

A simple tongue protrusion (TP) test is described for rats following focal ischemia induced by middle cerebral artery occlusion (MCAO). MCAO resulted in a dramatic decrease in TP that correlated with a concomitant decline in neurological performance in standard 5- and 20-point tests and deficits in performance in the Morris water maze and the accelerating rotarod. TP values also correlated with infarct size at 7 and 24 days following MCAO. This simple and inexpensive test, that monitors the ability of rats to lick food out of a glass tube, is easily administered, can be administered frequently without changing baseline performance, is not susceptible to behavioral compensation and should not interfere with other tests used concurrently to evaluate neurological deficit. The TP test may, therefore, serve as a useful addition to the battery of tests commonly used to assess neurological damage in rats, particularly in models of stroke.

The effects of high- and low-risk environments on cognitive function in rats following 2-vessel occlusion of the carotid arteries: a behavioral study.

In a prospective study of environmental factors affecting cognitive recovery from stroke, adult male rats were reared for 3 months in a high-risk (relatively isolated, low activity, high-fat diet, high-stress) or low-risk (social, healthy diet, low-stress, physically active) environment. They then received cognitive testing to assess various aspects of learning and memory before undergoing 2-vessel occlusion (2VO) of the carotid arteries, or sham surgery. Rats were returned to their respective environments post-operatively. Relative to pre-operative levels, 2VO rats exhibited significant cognitive losses that were consistently greater in the high-risk group than its low-risk counterpart. As well, the high-risk 2VO group was impaired, relative to the low-risk 2VO group on tests of new learning introduced post-operatively. At 3-month follow-up testing, rats that had undergone 2VO surgery exhibited further decline on some tests but recovery on others, with recovery generally slower in the high-risk 2VO group. The high-risk environment also affected rats' pre-operative cognitive performance and, to a lesser extent, their performance following sham surgery. Overall, the study shows that rats experiencing cerebral ischemia are more likely to experience severe cognitive deficits if exposed to a high-risk environment and recover more slowly than ischemic rats in a more favorable environment. The results underscore the importance of lifestyle factors with respect to the impact of stroke on cognition and in assessing prospects for recovery of function.

Microparticles induce cell cycle arrest through redox-sensitive processes in endothelial cells: implications in vascular senescence.

BACKGROUND: Chronic disease accelerates endothelial dysfunction in aging, a process associated with cell senescence. However, the mechanisms underlying this process are unclear. We examined whether endothelial cell (EC)-derived microparticles (MPs) facilitate EC senescence and questioned the role of reactive oxygen species in this process. METHODS AND RESULTS: Senescence was induced by sequential passaging of primary mouse ECs. Cells retained phenotypic characteristics of ECs from passage 4 through passage 21. Passage 21 ECs exhibited features of senescence, including increased staining of senescence-associated ß-galactosidase (SA-ßgal), a greater percentage of cells in G(1)/G(0) phase of the cell cycle, and increased phosphorylation of p66(Shc) (P<0.05). Microparticle formation from passage 21 ECs was increased versus passage 4 ECs (∼2.2-fold increase versus passage 4, P<0.05), and the Rho kinase inhibitor fasudil blocked this increase. Exposure of passage 4 ECs to MPs shifted cells from a proliferating to a nonproliferating phenotype, as indicated by cell cycle analysis and increased senescence-associated ß-galactosidase staining. MPs increased EC generation of O(2) (•-) (∼2.7-fold) and H(2)O(2) (∼2.6-fold), effects blocked by apocynin (nicotinamide adenine dinucleotide phosphate oxidase inhibitor) and rotenone (mitochondrial oxidase inhibitor) but not by allopurinol (xanthine oxidase inhibitor). MPs increased expression of cell cycle proteins p 21 cip1 and p16ink4a and stimulated phosphorylation of p66(Shc) in ECs (P<0.05 versus untreated ECs). Pretreatment with the reactive oxygen species scavenger sodium 4,5-dihydroxybenzene-1,3-disulfonate (tiron) abrogated the prosenescent effects of MPs. CONCLUSIONS: MPs promote EC senescence through nicotinamide adenine dinucleotide phosphate oxidase- and mitochondrial-derived reactive oxygen species. Such redox-sensitive processes may be important in vascular dysfunction in aging. (J Am Heart Assoc. 2012;1:e001842 doi: 10.1161/JAHA.112.001842.).

C-reactive protein expression in a rodent model of chronic cerebral hypoperfusion.

White matter lesions (WML) are a clinically significant, common feature of the aging brain and have been associated with cognitive decline and depression. They are a manifestation of cerebral small vessel disease, which is associated with the progression of vascular dementia. Recent research has been focused on identifying biomarkers which may have a correlation with WML. Previous population based studies have indicated a relation between the serum level of the acute phase protein, C-reactive protein (CRP), and WML. However no previous studies have demonstrated its expression and relation to WML in brain tissue itself. Here we use the rodent model of permanent bilateral common carotid artery ligation (BCCAL) to assess CRP expression during chronic cerebral hypoperfusion (CCH). Our results show that CRP is up-regulated at the mRNA and protein levels in brain tissue from BCCAL animals. The expression of CRP mRNA was upregulated on day 3 following surgery. Because previous studies, as well as the present study, have shown that microglial activity is prominent after the third day of CCH, we sought to determine the role of microglia in CRP expression. Results indicate that cultured microglia express mRNA and protein for CRP and this expression is increased when cells are treated with interleukin-1ß (IL-1ß), interleukin-6 (IL-6) or a combination of the two.. This finding could indicate a possible role for CRP in the progression of small vessel disease in the brain and provide a therapeutic target.

Protection conferred by Corticotropin-releasing hormone in rat primary cortical neurons against chemical ischemia involves opioid receptor activation.

Different studies have supported neuroprotective effects of Corticotropin-releasing hormone (CRH) against various excitotoxic and oxidative insults in vitro. However, the physiological mechanisms involved in this protection remain largely unknown. The present study was undertaken to determine the impact of CRH administration (at concentrations ranging from 200 fmol to 2 nmol) before and at delayed time intervals following potassium cyanide (KCN)-induced insult in rat primary cortical neurons. A second objective aimed to determine whether kappa and delta opioid receptor (KOR and DOR) blockade, using nor-binaltorphimine and naltrindole respectively (10 microM), could alter CRH-induced cellular protection. Our findings revealed that CRH treatments before or 3 and 8 h following KCN insult conferred significant protection against cortical injury, an effect blocked in cultures treated with alpha-helical CRH (9-41) prior to KCN administration. In addition, KOR and DOR blockade significantly reduced CRH-induced neuronal protection observed 3 but not 8 h post-KCN insult. Using western blotting, we demonstrated increased dynorphin, enkephalin, DOR and KOR protein expression in CRH-treated primary cortical neurons, and immunocytochemistry revealed the presence of opioid peptides and receptors in cortical neurons. These findings suggest protective effects of CRH against KCN-induced neuronal damage, and the contribution of the opioid system in modulating CRH actions.