Elevation of neuronal expression of NAIP reduces ischemic damage in the rat hippocampus.

We show here that transient forebrain ischemia selectively elevates levels of neuronal apoptosis inhibitory protein (NAIP) in rat neurons that are resistant to the injurious effects of this treatment. This observation suggests that increasing NAIP levels may confer protection against ischemic cell death. Consistent with this proposal, we demonstrate that two other treatments that increase neuronal NAIP levels, systemic administration of the bacterial alkaloid K252a and intracerebral injection of an adenovirus vector capable of overexpressing NAIP in vivo, reduce ischemic damage in the rat hippocampus. Taken together, these findings suggest that NAIP may play a key role in conferring resistance to ischemic damage and that treatments that elevate neuronal levels of this antiapoptotic protein may have utility in the treatment of stroke.

Complications and predisposing factors from a decade of total laryngectomy.

BACKGROUND: Total laryngectomy is often utilised to manage squamous cell carcinoma of the larynx or hypopharynx. This study reports on surgical trends and outcomes over a 10-year period. METHOD: A retrospective review of patients undergoing total laryngectomy for squamous cell carcinoma was performed (n = 173), dividing patients into primary and salvage total laryngectomy cohorts. RESULTS: A shift towards organ-sparing management was observed. Primary total laryngectomy was performed for locoregionally advanced disease and utilised reconstruction less than salvage total laryngectomy. Overall, 11 per cent of patients developed pharyngocutaneous fistulae (primary: 6 per cent; salvage: 20 per cent) and 11 per cent neopharyngeal stenosis (primary: 9 per cent; salvage: 15 per cent). Pharyngocutaneous fistulae rates were higher in the reconstructed primary total laryngectomy group (24 per cent; 4 of 17), compared with primary closure (3 per cent; 3 of 90) (p = 0.02). Patients were significantly more likely to develop neopharyngeal stenosis following pharyngocutaneous fistulae in salvage total laryngectomy (p = 0.01) and reconstruction in primary total laryngectomy (p = 0.02). Pre-operative haemoglobin level and adjuvant treatment failed to predict pharyngocutaneous fistulae development. CONCLUSION: Complications remain hard to predict and there are continuing causes of morbidity. Additionally, prior treatment continues to affect surgical outcomes.

APAF1 is a key transcriptional target for p53 in the regulation of neuronal cell death.

p53 is a transcriptional activator which has been implicated as a key regulator of neuronal cell death after acute injury. We have shown previously that p53-mediated neuronal cell death involves a Bax-dependent activation of caspase 3; however, the transcriptional targets involved in the regulation of this process have not been identified. In the present study, we demonstrate that p53 directly upregulates Apaf1 transcription as a critical step in the induction of neuronal cell death. Using DNA microarray analysis of total RNA isolated from neurons undergoing p53-induced apoptosis a 5-6-fold upregulation of Apaf1 mRNA was detected. Induction of neuronal cell death by camptothecin, a DNA-damaging agent that functions through a p53-dependent mechanism, resulted in increased Apaf1 mRNA in p53-positive, but not p53-deficient neurons. In both in vitro and in vivo neuronal cell death processes of p53-induced cell death, Apaf1 protein levels were increased. We addressed whether p53 directly regulates Apaf1 transcription via the two p53 consensus binding sites in the Apaf1 promoter. Electrophoretic mobility shift assays demonstrated p53-DNA binding activity at both p53 consensus binding sequences in extracts obtained from neurons undergoing p53-induced cell death, but not in healthy control cultures or when p53 or the p53 binding sites were inactivated by mutation. In transient transfections in a neuronal cell line with p53 and Apaf1 promoter-luciferase constructs, p53 directly activated the Apaf1 promoter via both p53 sites. The importance of Apaf1 as a p53 target gene in neuronal cell death was evaluated by examining p53-induced apoptotic pathways in primary cultures of Apaf1-deficient neurons. Neurons treated with camptothecin were significantly protected in the absence of Apaf1 relative to those derived from wild-type littermates. Together, these results demonstrate that Apaf1 is a key transcriptional target for p53 that plays a pivotal role in the regulation of apoptosis after neuronal injury.

Purinergic modulation of human corpus cavernosum relaxation.

The activation of P2Y(6) receptors has been previously reported to cause vascular smooth muscle constriction and relaxation. The aim of our study was to determine the effect of P2Y(6) receptor subtype activation on human cavernosal function. Cavernosal tissue was obtained from 23 patients undergoing gender reassignment surgery. Immunohistochemistry (IHC) and Western blotting were used to determine the presence of P2Y(6) receptors in corpus cavernosal tissue. The effects of UDP (a selective P2Y(6) receptor agonist) before and after the addition of distilled water (control), cibacron blue 3GA (CB, a P2Y(6) receptor antagonist; 10(-4) m) or N-nitro-L-arginine methyl esther (L-NAME, a NO synthase inhibitor; 10(-4) m) were assessed on phenylephrine (PE; 10(-4) m) pre-contracted cavernosal strips using organ baths. Electrical field stimulation (EFS; 0.5-32 Hz) was performed in the absence and presence of CB to determine neuronal-mediated P2Y(6) receptor responses. IHC and Western blotting revealed the presence of P2Y(6) receptors on cavernosal sections. UDP at 10(-4) m and 10(-3) m induced a 5% and 16% relaxation of the PE-mediated response (both p < 0.0001), respectively, which was significantly blocked by CB (48% reduction of the UDP 10(-3) m response, p < 0.002) but not affected by L-NAME. EFS-induced relaxations of pre-contraction strips were not significantly altered by CB. We have found the presence of P2Y(6) receptors in human cavernosal tissues, that when activated induce cavernosal smooth muscle cell relaxation via non-neuronal and non-nitric oxide dependent mechanism. Further investigation is needed to establish whether P2Y(6) receptors play a physiological role in penile erection.

In vitro and in vivo effects of vardenafil (a PDE-5 Inhibitor) on corpus cavernosal smooth muscle relaxation in diabetic rabbits.

INTRODUCTION: Diabetes mellitus is associated with impaired cavernosal smooth muscle relaxation (CSMR) and the development of erectile dysfunction (ED). Vardenafil, a phosphodiesterase type 5 inhibitor has been used to treat ED. The aim of this study was to assess the in vitro and in vivo effects of vardenafil on diabetic rabbit CSMR. METHODS: Organ bath studies were used. RESULTS: Sodium nitroprusside (SNP)- and electrical field stimulation (EFS)-induced CSMR in diabetic rabbits given the vehicle was significantly impaired when compared with controls. The in vitro addition of vardenafil significantly enhanced SNP-induced CSMR in diabetic animals given the vehicle. SNP-induced CSMR in diabetic animals given in vivo vardenafil was significantly increased when compared with the diabetic untreated group. The in vitro addition of vardenafil significantly enhanced SNP and EFS-induced CSMR in cavernosal tissue taken from diabetic animals given vardenafil in vivo. CONCLUSIONS: The present findings suggest that the combination of in vitro and in vivo vardenafil enhance diabetic CSMR, reinforcing the use of vardenafil for the treatment of diabetes-induced ED.

Regional differences in the expression of nitric oxide synthase and specific receptors in the vascular tissues of control and diabetic rabbits: a pilot study.

BACKGROUND: Atherosclerosis can influence the expression of endothelial nitric oxide synthase (eNOS) as well as endothelin-1 (ET-1) and 5-hydroxytryptamine (5HT; serotonin) receptors. Diabetes has an effect on the onset, severity and pattern of atherosclerosis with a predilection for more distal arteries. We aimed to identify regional differences in the distribution of eNOS activity, ET-1 and 5HT receptors in vascular tissues obtained from control and diabetic rabbits. MATERIALS AND METHODS: The mid abdominal aorta, right renal and right femoral arteries were harvested from 12 adult rabbits (6 months old, 3-3.9 kg); 8 controls and 4 diabetic (induced using alloxan 7 months previously). Samples were stored in liquid nitrogen for Western immunoblotting for eNOS as well as ET-1 and 5HT receptors. RESULTS: Significant differences were found in the distribution of eNOS, ET-1 and 5HT between the aorta, renal and femoral arteries in the controls. The number of ET-1 receptors was significantly higher (aorta; p=0.016, renal; p=0.004, femoral; p=0.05,) whereas, the expression of eNOS was significantly lower (aorta; p =0.004, renal; p =0.004, femoral; p =0.008) when comparing arteries from normal rabbits with these from diabetics ones. The number of 5HT receptors was higher in arteries from diabetic rabbits but this was not statistically significantly. CONCLUSION: The "regional" distribution of eNOS activity as well as ET-1 and 5HT receptors in control rabbits varies significantly according to the vessel assessed. Further studies are needed to evaluate the effect of blocking these receptors (e.g. on the risk of re-stenosis). Regional receptor differences may explain why diabetes is linked with a predilection for atherosclerosis (and possibly calcification) in distal arteries.

Changes in cholinergic and purinergic neurotransmission in the diabetic rabbit bladder.

BACKGROUND: Diabetes mellitus (DM)-associated alterations in bladder function have been attributed to changes in autonomic receptors and alterations in detrusor structure and function. The changes in cholinergic and purinergic neurotransmission in the DM rabbit bladder were evaluated. MATERIALS AND METHODS: DM was induced with alloxan in adult male New Zealand White rabbits. At 6 months, detrusor and bladder neck muscle strips were obtained and mounted in organ baths. Transmural electrical field stimulation (EFS: supramaximal voltage, 0.1 ms duration, 10 s trains) was performed in the presence of atropine (10(-6) M) or alpha, beta-methylene ATP (10(-6) M), and after adding tetrodotoxin10(-6) M. Purinergic, alpha, beta-methylene ATP-sensitive, and cholinergic, atropine-sensitive, components were calculated independently and compared with those from controls. RESULTS: Both normal and DM detrusor and bladder neck strips contracted in a frequency-dependent fashion in response to transmural EFS. A plot of EFS vs. detrusor contractility showed a decrease (ANOVA < 0.001) in the cholinergic nerve-mediated component, whereas the purinergic nerve-mediated component was increased (ANOVA < 0.001) in the DM detrusor compared to the control. The total EFS- and KCl-induced responses were unaltered in the DM group compared to the controls. There was no difference in purinergic, alpha, beta-methylene ATP-sensitive, and cholinergic, atropine-sensitive, components in strips from the bladder neck for both normal and DM rabbits. CONCLUSION: These results suggest that an enhancement of purinergic and a reduction of cholinergic neurotransmission occur in the detrusor muscle of the diabetic rabbit. These changes may contribute to the pathophysiology of diabetic cystopathy.

The effect of dietary protein restriction on the progression of diabetic nephropathy. A 12-month follow-up.

Eight patients with insulin-dependent diabetes mellitus and progressive renal dysfunction as determined by serial serum creatinine values were placed on a diet containing 40 g of high-biologic-value protein. Selected factors of renal function were determined over a 12-month interval. After the first 12 months of the protein-limited diet, creatinine clearance was not significantly changed. The rate of decline in renal function during the dietary protein restriction slowed from the rate over the prior 12 months in seven patients. Five of these seven demonstrated improvement in renal function. Daily urinary protein excretion decreased significantly, from 2105 +/- 1355 to 142 +/- 164 mg/d (2.11 +/- 1.36 to 0.14 +/- 0.16 g/d). Body weight did not change significantly, whereas serum albumin level increased significantly from a mean of 3.5 +/- 0.6 to 4.3 +/- 0.3 g/dL (35 +/- 6 to 43 +/- 3 g/L). These findings suggest that dietary protein restriction has a beneficial role in treating patients with diabetic nephropathy.

Nitric oxide and penile erection: is erectile dysfunction another manifestation of vascular disease?

There is convincing evidence that the prevalence of erectile dysfunction is increased among men with ischaemic heart disease. This association may be attributed to the fact that both erectile dysfunction and ischaemic heart disease share similar risk factors (e.g. hypertension, dyslipidaemia, diabetes and smoking). Nitric oxide (NO) activity is adversely affected, in penile and vascular tissue, by these risk factors. It is therefore not surprising that a defect in NO activity is thought to play a role in the pathogenesis of both erectile dysfunction and ischaemic heart disease. We consider this evidence and propose that defective NO activity provides a unifying explanation for the association between these two conditions. Further research in this area may improve our understanding of the pathogenesis of cardiovascular diseases as a whole.

Anatomy and electrophysiology of neurons terminating in the corpora allata of the cockroach Diploptera punctata.

Intracellular recording and dye injection were used to study the structure and electrophysiological properties of individual neurons that project to the corpora allata of the cockroach, Diploptera punctata. Neurons in the pars intercerebralis generate long-duration, tetrodotoxin-sensitive action potentials. Dye injection revealed two cell types. One type extends axons to the contralateral nervi corporis cardiaci I, some of which innervate the corpora allata, and another type extends a major axon down each of the circumoesophageal connectives. Neurons in the pars lateralis also generate long-duration action potentials. These neurons extend axons to the ipsilateral nervi corporis cardiaci II, which continue on to terminate in the corpora cardiaca and the corpora allata. Small groups of all the above neuronal types are dye and electrically coupled. Penetration and dye injection into nerve terminals in the corpora allata and corpora cardiaca confirmed the innervation of the corpora allata by neurons located in the pars intercerebralis and pars lateralis and revealed a third class of neurons that have terminals in the corpora allata: intrinsic neurons of the corpora cardiaca.

Spectrum of gas within the kidney. Emphysematous pyelonephritis and emphysematous pyelitis.

Renal emphysema is an important clinical entity that is not addressed frequently in the medical literature. The affected patients may have gas within the renal parenchyma, emphysematous pyelonephritis, or confined to the collecting system, emphysematous pyelitis. Two patients that illustrate the spectrum of this entity are described. The literature has been reviewed to determine the clinical features of each disorder and to provide a schema for diagnosis and management. Emphysematous pyelonephritis is seen primarily in diabetic patients, whereas emphysematous pyelitis is recognized most often in association with urinary tract obstruction. The diagnosis is made radiographically by demonstrating renal gas on plain abdominal roentgenography or intravenous pyelography. Location and extent of renal gas are best evaluated by computed tomographic scanning. Intraparenchymal gas usually requires nephrectomy, whereas successful therapy of gas limited to the collecting system involves medical management, with a drainage procedure when obstruction coexists.

Normal and pathological erectile function: the potential clinical role of endothelin-1 antagonists.

Erectile dysfunction (ED) is a common problem, particularly in older men. The production of penile erection involves an interplay between autonomic nerves and locally released vasoactive mediators. Endothelin-1 (ET-1) is a peptide released from endothelium in the corpus cavernosum, which causes smooth muscle contraction. Recent studies have investigated the physiological significance of ET-1 in the control of erectile function and it may play a role in detumescence. There is also much evidence to link ET-1 to risk factors for ED. ET-1 antagonists may prove beneficial in the treatment of ED and also in prevention of long term deterioration of erectile function. These antagonists may also find a role when used in combination with agents, which are established for the treatment of ED.

Endogenous expression of inhibitor of apoptosis proteins in facial motoneurons of neonatal and adult rats following axotomy.

The inhibitor of apoptosis protein family members inhibit cell death resulting from a variety of apoptotic stimuli. However, the endogenous expression of neuronal inhibitor of apoptosis proteins following axonal injury has not been thoroughly examined. Neonatal facial motoneurons are highly susceptible to axotomy-induced apoptosis, whereas adult facial motoneurons survive axotomy. We hypothesized that the endogenous expression of inhibitor of apoptosis proteins may be involved in the differential susceptibility of adult and neonatal facial motoneurons to axonal injury. In this study, we examined the expression of two endogenous inhibitor of apoptosis proteins, neuronal apoptosis inhibitory protein and x-linked inhibitory apoptosis protein, in adult and neonatal rat facial motoneurons following axotomy. Analyses using reverse-transcription polymerase chain reaction and in situ hybridization indicated that neuronal apoptosis inhibitory protein mRNA was increased in neonatal facial nuclei 24 h post axotomy. In the adult, neuronal apoptosis inhibitory protein mRNA expression increased at 1, 3, 7 and 14 days post axotomy, while little change in the expression of X-linked inhibitory apoptosis protein mRNA was detected at any age or time point time point analyzed. Interestingly, immunohistochemistry using antibodies for neuronal apoptosis inhibitory protein and X-linked inhibitory apoptosis protein, revealed the level of these proteins was higher in the neonatal motoneurons when compared with the adult. Furthermore, immunohistochemistry and western blot for neuronal apoptosis inhibitory protein revealed, in contrast to the observed increase in neuronal apoptosis inhibitory protein mRNA, a decline in the expression of neuronal apoptosis inhibitory protein following axotomy in the adult, whereas no change in neuronal apoptosis inhibitory protein was detected in neonatal facial motoneurons. X-linked inhibitory apoptosis protein, as analyzed by immunohistochemistry and western blot, remained unchanged by axotomy in neonatal motoneurons and adult motoneurons. These results indicate differential expression and/or turnover of inhibitor of apoptosis proteins in neonatal versus adult facial motoneurons, and suggest the level of inhibitor of apoptosis protein expression alone is not an indicator of cell fate following axotomy.

Effects of neomycin on galactose absorption across rat jejunum.

The effects of neomycin sulphate on galactose absorption have been studied using in vivo and in vitro preparations of rat small intestine. Neomycin (10(-3)M) produced an increase in the maximum transport capacity (Jmax) for the active component of absorption in vivo. The apparent Kt for absorption was unaffected. The antibiotic caused a dose-dependent increase in the potential difference across the mucosal membrane (Vm) measured in vitro, a maximal effect being seen at a concentration of 10(-4)M. Furthermore, the magnitude of the depolarization induced by the addition of galactose (4 mM) to the mucosal fluid was enhanced by neomycin (10(-4)M). Phlorhizin (10(-4)M) abolished the galactose-induced depolarization in both the absence and presence of the antibiotic. It is concluded that neomycin increases the electrical driving force for Na+ during Na+-coupled galactose entry into the enterocyte.

Differential changes of adrenoceptor- and muscarinic receptor-linked prostacyclin synthesis by the aorta and urinary bladder of the diabetic rat.

1. The effect of experimental diabetes mellitus (DM; hyperglycaemic, non-ketototic; 2 months duration) in the rat on receptor-linked prostacyclin (PGI2) synthesis (measured as 6-oxo-PGF1 alpha by radioimmunoassay) was studied in the aorta and urinary bladder using adrenaline, angiotensin II (AII) and acetylcholine (ACh). Signal transduction systems were studied via stimulation of PGI2 synthesis with phorbol ester dibutyrate (PDBU; a protein kinase C activator [PKC]), Ca2+ ionophore A23187 (A23187) and thapsigargin (both elevate intracellular Ca2+, activating phospholipase A2 [PLA2]) and arachidonate (AA; substrate for PGI2 synthesis). 2. In response to adrenaline, AII and phorbol ester, aortic PGI2 release was markedly reduced (all > 75%) in diabetic rats compared to controls. EC50s of the dose-response curves for adrenaline, AII and PDBU were also markedly increased in aortae from DM rats compared to controls. Although there was decreased output of PGI2 in response to A23187 by aortae from diabetic rats compared to controls, there was no difference in the EC50s (mean +/- s.e. mean: diabetic, 2.7 +/- 0.2 x 10(-6) M; controls 2 +/- 0.18 x 10(-6) M). There were no differences in PGI2 release (or in the EC50s) in response to thapsigargin or AA between aortae from diabetic and control rats. 3. In the urinary bladder, there was a marked increase in PGI2 output in response to ACh and a marked decrease in EC50s for the ACh-PGI2 dose-response curves in diabetic rats (EC50 = 5.8 +/- 0.32 x 10(-7) M) compared to controls (EC50 = 2.2 +/- 0.15 x 10(-6) M). Although there was an increase in PGI2 output in the urinary bladders from diabetic rats in response to A23187, there were no differences in the EC50s (control, 1.8 +/- 0.2 x 10-6 M; diabetic, 1.1 +/- 0.15 X 10-6 M). In the urinary bladders, there were no differences in PGI2 output (or the EC50s) in response to PDBU, thapsigargin or AA between diabetic or control rats.4. These data indicate that: (i) reduced PGI2 synthesis coupled to adrenoceptors and AII receptors in the aortae of diabetic rats may be due to diminished PKC activity and not to changes in receptor density and/or affinity, Ca2+ stores, PLA2, cyclo-oxygenase or PGI2 synthase; (ii) the diametrically opposite effect of DM on ACh-stimulated PGI2 synthesis is not due to an increase in PKC activity, but possibly to an increase in muscarine receptor number and/or affinity; (iii) changes in receptor-linked PGI2 synthesis are not ubiquitous in experimental DM and may be organ-specific.

Hyperglucagonaemia: effects on active nutrient uptake by the rat jejunum.

The effects of chronic (72 h) glucagon treatment on active nutrient uptake by the rat jejunum have been determined using in-vitro electrophysiological and autoradiographic methods together with an in-vivo technique which measures absorption across a cannulated segment of upper jejunum. Glucagon caused a marked increase in the potential difference across the brush border membrane from a mean value of -47.6 mV under control conditions to -54.2 mV following treatment with the hormone (P less than 0.025). A similar hyperpolarization was also noted after 24 h glucagon administration. The magnitude of the depolarization induced by the addition of D-galactose (4 mmol/l) to the mucosal fluid was increased from 6.0 to 14.3 mV following 72 h glucagon treatment (P less than 0.05). Phloridzin (0.1 mmol/l) abolished the galactose-induced depolarization in both control and treated animals. Glucagon induced significant increases of 49.9 and 61.0% respectively for glucose and galactose absorption measured under in-vivo conditions. Autoradiographic studies revealed that following glucagon treatment, L-valine uptake occurred earlier during enterocyte migration along the villus. This resulted in an enhanced accumulation of the amino acid at the villus tip. We conclude that glucagon increases nutrient transport across the small intestine. The raised electrical gradient for Na+- coupled nutrient entry into the enterocyte is likely to be a major factor in the transport response.

Distribution of 125I-labelled insulin-binding sites in peripheral tissues of the normal and diabetic rat: an autoradiographic study.

In-vitro autoradiography was used to demonstrate the regional distribution of 12I-labelled insulin-binding sites in the liver, kidney and heart of normal rats and rats made diabetic with streptozotocin. The distribution of insulin-binding sites in the liver of control rats was uniformly high, while in the kidney of control rats there was weak 125I-labelled insulin binding in the medulla and dense binding in the cortex. In the hearts of control rats a high density of 125I-labelled insulin-binding sites was evident both in the atrial and ventricular muscle. Non-ketotic diabetes mellitus caused a marked increase in 125I-labelled insulin-binding sites in both the liver and kidney with the former tissue exhibiting a time-dependent (7 to 62 days) increase. There was no apparent effect of diabetes on insulin-binding sites in the heart. Since experimental diabetes causes (1) a decrease in circulating insulin concentration and (2) impaired insulin action at many target tissues, the increase in 125I-labelled insulin-binding sites observed in the present study may represent a compensatory 'up regulation' of insulin receptors.

First report of the isolation of an adult worm of the genus Brachylaima (Digenea: Brachylaimidae), from the gastrointestinal tract of a human.

A 78-year-old woman presented with an 18-month history of intermittent diarrhoea. Examination of her stools revealed brachylaimid eggs, which were present in three separate specimens over a week. After treatment with praziquantel a degenerate adult Brachylaima species was recovered from her faeces. She lived in a rural area of South Australia and ate vegetables grown in her own garden which had been infested with helicid snails. In south Australia these introduced European helicid snails are commonly infected with brachylaimid intermediate larval stages and are considered to be the source of the human infection.

Endothelin-1 and nitric oxide in the pathogenesis of urinary tract disorders secondary to bladder outlet obstruction.

Bladder outlet obstruction (BOO) is a common disorder that is associated with urinary tract symptoms. Nitric oxide (NO), synthesized by NO synthase (NOS) is a potent vasodilator that is present throughout the urinary tract and the corpus cavernosum. Endothelin-1 (ET-1) conversely is a potent vasoconstrictor peptide that is similarly distributed throughout the urinary tract. ET-1 and NO as well as possessing opposing actions regulate each other's synthesis. The disruption of the balance between ET-1 and NO is associated with various vascular pathologies. However, their potential roles in the pathogenesis of urinary tract disorders, secondary to BOO, is not well established. New Zealand White rabbits with BOO are considered to be a suitable model of the human condition. Hence, using this model, we systematically investigated the potential roles of ET-1 and NO in the pathogenesis of the various urological disorders associated with BOO. In this review we discuss the results of our studies, which support the concept that an imbalance between ET-1 and NO may be associated with the pathogenesis of urinary tract disorders secondary to BOO. We also discuss the potential clinical implications of this association. This review is based on the Bard Silver Medal Lecture given (by MAK) at the 2002 British Association of Urological Surgeons (BAUS) annual meeting.

Cortical spreading depression transiently activates MAP kinases.

Cortical spreading depression (CSD) has been shown to have neuroprotective effects when administered in advance of cerebral ischemia. The mechanism by which CSD induces its neuroprotective effect however remains to be elucidated. Since MAP kinases have been shown to impart neuroprotection in ischemic preconditioning paradigms, we attempted to determine the role CSD may have in the activation of MAPK. We show that CSD is capable of increasing the phosphorylation of ERK in a MEK-dependent manner. This phosphorylation is, however, transient, as phosphorylated ERK levels return to control levels 45 min after 2 h of CSD elicitation. Immunohistochemical analysis reveals that the phosphorylated form of ERK is located ubiquitously in cells of the CSD-treated cortex while CSD-elicited MEK phosphorylation resides solely in the nuclei. These data suggest that CSD may act via the MAP kinase pathways to mediate preconditioning.