International Expert Consensus Document on Takotsubo Syndrome (Part II): Diagnostic Workup, Outcome, and Management.

The clinical expert consensus statement on takotsubo syndrome (TTS) part II focuses on the diagnostic workup, outcome, and management. The recommendations are based on interpretation of the limited clinical trial data currently available and experience of international TTS experts. It summarizes the diagnostic approach, which may facilitate correct and timely diagnosis. Furthermore, the document covers areas where controversies still exist in risk stratification and management of TTS. Based on available data the document provides recommendations on optimal care of such patients for practising physicians.

International Expert Consensus Document on Takotsubo Syndrome (Part I): Clinical Characteristics, Diagnostic Criteria, and Pathophysiology.

Takotsubo syndrome (TTS) is a poorly recognized heart disease that was initially regarded as a benign condition. Recently, it has been shown that TTS may be associated with severe clinical complications including death and that its prevalence is probably underestimated. Since current guidelines on TTS are lacking, it appears timely and important to provide an expert consensus statement on TTS. The clinical expert consensus document part I summarizes the current state of knowledge on clinical presentation and characteristics of TTS and agrees on controversies surrounding TTS such as nomenclature, different TTS types, role of coronary artery disease, and etiology. This consensus also proposes new diagnostic criteria based on current knowledge to improve diagnostic accuracy.

Downregulation of growth hormone 1 gene in the cerebellum and prefrontal cortex of rats with depressive-like behavior.

Depressive-like behaviors in animals are usually assessed by standardized behavioral tests such as the forced swimming test (FST). However, individual variation in test performance may obscure group differences and thereby hinder the discovery of genes responsible for depression. Few reports have shown the influence of individual variability in identifying the genes associated with depressive-like behaviors. In this study, we conducted microarray analysis to identify genes differentially expressed in the prefrontal cortex (PFC) and cerebellum of rats stratified by FST immobility ratio (% immobility in 5 min) into a control group [immobility ratio: -1 to +1 standard deviation (SD) from the mean] and a depressive group (immobility ratio: +1 to +2 SDs above the mean). Genes differentially expressed in both the cerebellum and PFC of the depressive group were Alas2, Gh1, Hba-a2, Hbb, Hbb-b1, Hbe2, LOC689064, Mrps10, Mybpc, Olf6415, and Pfkb1. Ingenuity Pathway Analysis identified Gh1 as a hub gene in the networks of differentially expressed genes in both brain regions. This study indicates that the depressive-like behavior may be related to the decrease of Gh1 expression in the cerebellum and PFC.

Reduction of cortical excitability and increase of thalamic activity in a low-frequency rTMS treatment for chronic tinnitus.

Low-frequency repetitive transcranial magnetic stimulation (rTMS) has received increasing attention for the treatment of tinnitus, but its therapeutic mechanisms are unclear. We performed low-frequency rTMS treatment for a patient with chronic tinnitus and examined changes of cortical excitability and cerebral blood flow using paired-pulse TMS and single-photon emission computed tomography. After the rTMS treatment, tinnitus loudness was decreased, cortical excitability was reduced, and blood flow in the thalamus was increased. Our results suggest that low-frequency rTMS treatment reduces tinnitus loudness by an inhibitory effect on the cortical excitability and a remote activation effect on the thalamus through the corticothalamic networks.

Cardiovascular responses to microinjections of endomorphin-2 into the nucleus of the solitary tract are attenuated in the spontaneously hypertensive rat.

Stimulation of µ1-opioid receptors (M1ORs) in the medial nucleus solitarius (mNTS) by endomorphin-2 (EM2) elicits decreases in mean arterial pressure (MAP), heart rate (HR) and greater splanchnic nerve activity (GSNA) in Wistar rats. We tested the hypothesis that EM2-induced responses in the mNTS may be attenuated in the spontaneously hypertensive rat (SHR). Experiments were carried out in urethane-anesthetized, artificially ventilated, adult male SHR and Wistar-Kyoto rats (WKY). Alterations in responses to chemical stimulation of the hypothalamic arcuate nucleus (ARCN) after bilateral blockade of M1ORs in the mNTS were also studied. In SHR, microinjections of EM2 into the mNTS elicited smaller decreases in MAP, HR and GSNA compared to those elicited in WKY; smaller cardiovascular responses in SHR can be explained by lower expression of M1OR mRNA in the NTS of SHR compared to WKY. Decreases in MAP and GSNA and increases in HR were elicited by microinjections of N-methyl-D-aspartic acid (NMDA) into the ARCN of WKY. Bilateral blockade of M1ORs in the mNTS attenuated the decreases in MAP and GSNA and exaggerated the increases in HR elicited by the ARCN stimulation in WKY but not in SHR. Tonic inhibitory activity of neuropeptide Y/gamma-aminobutyric acid (NPY/GABA) neurons in the ARCN is attenuated in SHR; this observation may explain increases in MAP, GSNA and HR elicited by microinjections of NMDA into the ARCN of SHR. These results demonstrate that attenuation of EM2-induced responses in the mNTS of SHR may contribute to the excitatory responses elicited by ARCN stimulation in SHR.

Amlodipine has a preventive effect on temporal left ventricular hypokinesia after emotional stress compared with an angiotensin II receptor blocker.

PURPOSE: We previously reported that α- and ß-blockers protected against emotional stress-induced cardiac dysfunction, but the protective effects of other antihypertensive drugs is unknown. The purpose of this study is to evaluate the ability of a calcium channel blocker, amlodipine, to prevent temporal left ventricular hypokinesia after emotional stress compared with an angiotensin II receptor blocker, olmesartan medoxomil. METHODS: Rats premedicated with amlodipine (0.2 mg/kg), olmesartan (0.8 mg/kg), or vehicle were restrained for 30 min (immobilization stress: IMO) to reproduce emotional stress and then anesthetized to release stress. We measured the fractional area change (FAC) using echocardiography (SONOS5500) with a s12 probe (frequency 5-12 MHz, frame rate 120 Hz) and blood pressure and heart rate at the end of IMO and every 10 for 60 min after IMO. RESULTS: During IMO, FAC in the amlodipine or the olmesartan group was as high as that in the vehicle group. At 20 min after IMO, FAC in the amlodipine group was significantly higher than in the other two groups (84 ± 8 vs. 60 ± 7 or 68 ± 15 %, p < 0.05). During IMO, blood pressure in the amlodipine or the olmesartan group was significantly lower than with vehicle (119 ± 6 and 110 ± 7 vs. 124 ± 5 mmHg, p < 0.05). After IMO, blood pressure in the olmesartan group was significantly lower than in the other two groups. CONCLUSION: Acute administration of amlodipine could prevent a sudden drop in cardiac function after acute stress like IMO, but olmesartan did not. Amlodipine might have a protective effect on temporal left ventricular hypokinesia after emotional stress, which might not be related to decreased blood pressure.

Stress cardiomyopathy.

Recently, an increasing number of cases of stress cardiomyopathy, mainly occurring in elderly women, have been documented in many parts of the world. In Japan, this disease is known as takotsubo cardiomyopathy (named after the fishing pot used for trapping octopus). Symptoms of this condition are akin to those of acute myocardial infarction, but no obstructive lesions are found in the coronary arteries, and left ventricular apical ballooning is present. Stress cardiomyopathy is now a well-recognized cause of acute heart failure, lethal ventricular arrhythmias, and ventricular rupture. Although the precise mechanism of onset of this condition is still controversial, two major pathogenic mechanisms have been proposed: catecholamine cardiotoxicity and neurogenic stunned myocardium. We summarize the findings of studies conducted to date on stress cardiomyopathy-from bench to bedside and bedside to bench.

Cardiac and vascular gene profiles in an animal model of takotsubo cardiomyopathy.

We investigated cardiac and vascular gene profiles in response to immobilization stress (IMO) in rats, an animal model of emotional stress-induced takotsubo cardiomyopathy using microarray analysis, followed by re-confirmation with real-time reverse transcription-polymerase chain reaction. Expression levels of the identified genes were further estimated by pretreatment with an α1-adrenoceptor blocker and/or a ß1-adrenoceptor blocker. In response to IMO, expression of 46 genes was significantly altered in the heart and that of 49 genes was significantly altered in the aorta. Pathway analysis with DAVID Bioinformatics Resources indicated that regulation of transcription and response to endogenous stimulation were the top two scoring pathways. Altered expression of cardiac genes was blunted by pretreatment with a ß1-adrenoceptor blocker or α1 + ß1-adrenoceptor blockers. In contrast, that of aortic genes was blunted by pretreatment with an α1-adrenoceptor blocker or α1 + ß1-adrenoceptor blockers. Activation of α1-adrenoceptor in the blood vessels or activation of ß1-adrenoceptors in the heart were mainly responsible for emotional stress-induced alteration of cardiac and vascular gene profiles.

Connexin-43 redistribution and gap junction activation during forced restraint protects against sudden arrhythmic death in rats.

BACKGROUND: Connexin-43 (Cx43) expression is reduced or redistributed in heart disease. Restraint or other emotional stressors might cause sudden death in persons with such diseases, but the mechanism of death and its connection to Cx43 during restraint remain unknown. Whether Cx43 distribution or gap junction (GJ) function during restraint is involved in sudden arrhythmic death in rats is addressed in this study. METHODS AND RESULTS: Male Sprague-Dawley rats underwent immobilization (IMO), and individual electrocardiographic responses were monitored by telemetry. Heart sections were used to examine ventricular Cx43 distribution, and GJ intercellular communication (GJIC) activity was assessed using a dye-transfer assay. IMO induced the translocation of Cx43 into to the GJ-rich fraction, with a peak at 60 min. During IMO, Cx43 immunofluorescence was enhanced at intercalated discs, in association with GJIC activation, and premature ventricular contractions (PVCs) increased. In the presence of the GJ inhibitor, carbenoxolone (0.25 mg.kg(-1).h(-1)), IMO induced lethal ventricular tachycardia or fibrillation in 21.7% of rats, in association with QRS prolongation and increased PVCs. CONCLUSIONS: IMO causes Cx43 translocation to intercalated discs, thereby reducing vulnerability to lethal arrhythmias via enhancing GJ coupling.

Restraint stress induces connexin-43 translocation via α-adrenoceptors in rat heart.

BACKGROUND: Immobilization (IMO) confers emotional stress in animals and humans. It was recently reported that IMO in rats induced translocation of connexin-43 (Cx43) to gap junctions (GJs) and attenuated arrhythmogenesis with GJ inhibition, and Cx43 translocation in the ischemic heart was also shown. Few reports show the contribution of adrenoceptors to Cx43 upregulation in cardiomyocytes, but the involvement of adrenoceptors and ischemia in Cx43 translocation in IMO remains elusive. METHODS AND RESULTS: Male Sprague-Dawley rats underwent IMO and the ventricular distribution of Cx43 was examined by western blotting. IMO induced translocation of Cx43 to the GJ-enriched membrane fraction, with a peak at 60min. The IMO-induced Cx43 translocation was inhibited by pretreatment with the α(1)-adrenoceptor blockers, prazosin (1mg/kg, PO) and bunazosin (4mg/kg, PO), but not with either the ß(1)-blocker, metoprolol (10mg/kg, IP), or the ß(1+2)-blocker, propranolol (1mg/kg, PO). The translocation was inhibited by the nitric oxide, donor isosorbide dinitrate (100µg·kg(-1)·min(-1), IV), possibly through sympathetic inhibition. Hypoxia inducible factor-1α was not redistributed by IMO. The ß-blockers, but not the α-blockers, inhibited the premature ventricular contractions (PVCs) induced by IMO. CONCLUSIONS: Translocation of Cx43 to the GJ-enriched fraction occurs via the α(1)-adrenoceptor pathway, independently of ischemia. The ß-adrenoceptor pathway contributes to the inducing of PVCs in IMO.

Subjective Loudness Using External Noise Reflects the Loudness and Distress of Tinnitus: A Cross-Sectional Study.

OBJECTIVES: Subjective tinnitus loudness has been measured using loudness matches, which compare tinnitus loudness with pure tones from an audiometer. When patients compare the sound pressure of certain noises with the tinnitus loudness, however, there may be remarkable differences from the measurements according to loudness matches. Subjective loudness (SubL) is an estimation of the sound pressure of tinnitus loudness by comparison of noises considered to be most similar to tinnitus loudness of patient. We examine whether SubL is inferior to loudness matches in measurement of subjective tinnitus loudness. DESIGN: Single-group cross-sectional study. PATIENTS: Included in this study were a clinical group of 111 patients with the chief complaint of subjective tinnitus. Seven of the 111 patients were excluded due to missing audiometry or questionnaire data. METHODS: Patients assessed the tinnitus loudness and related distress using visual analogue scales (VAS-L and VAS-S) and answered the Tinnitus Handicap Inventory (THI). Hearing acuity, tinnitus pitch, and loudness were then measured using an audiometer. RESULTS: VAS-L, VAS-S, and THI scores significantly correlated with loudness match using Goodwin's method (SL2) and SubL. Subgroup analysis based on patient ages indicated that all correlations of SL2 with VAS-L, VAS-S, and THI scores were no longer seen in patients more than 60 years of age. Meanwhile, SubL correlated with VAS-L, VAS-S, and THI scores in all subgroups. CONCLUSIONS: SubL was a good reflection of self-reported loudness and distress of tinnitus. It may therefore be a simple and easy means of assessing tinnitus loudness and associated distress during pre-examination without an audiometer.

Lansoprazole prevents the progression of liver fibrosis in non-alcoholic steatohepatitis model rats.

OBJECTIVES: We previously demonstrated that lansoprazole provided hepatoprotection in a drug-induced hepatitis animal model partially through the Nrf2/HO-1 pathway. Here, we examined whether lansoprazole could also provide hepatoprotection in a rat model of non-alcoholic steatohepatitis (NASH). METHODS: Six-week-old rats were fed a normal chow or a choline-deficient amino acid-defined (CDAA) diet to establish a rat model of NASH. The groups fed a CDAA diet for 5 weeks were subcutaneously administered either a vehicle or a lansoprazole suspension for 4 weeks beginning the second week of the experiment. KEY FINDINGS: Bridging fibrosis was observed in the livers of almost all the NASH model rats (six of seven), but it was not always observed in NASH model rats (one of seven) continuously administered lansoprazole. The serum aspartate aminotransferase level elevated by the CDAA diet was significantly decreased following lansoprazole administration. Lansoprazole also increased the expression of Nrf2, but not HO-1, in the liver of NASH model rats. Lansoprazole decreased the level of activated TGF-ß protein. Furthermore, interleukin-6 gene and protein expression were decreased. CONCLUSIONS: Lansoprazole inhibits hepatic fibrogenesis, at least during the early stages, in CDAA diet-induced NASH model rats. The mechanisms might be associated with cytokine suppression but not the inhibition of reactive oxygen species.

Estrogen alters c-Fos response to immobilization stress in the brain of ovariectomized rats.

Estrogen receptors are widely expressed in the brain, where estrogen modulates central nervous function. In this study, we investigated the effect of estrogen on the emotional stress response in the brain by comparing the CNS patterns of c-Fos expression in response to immobilization stress (IMO) in ovariectomized rats with placebo treatment (OVX + Pla) vs. ovariectomized rats supplemented with 17beta-estradiol (OVX + E2). Increased c-Fos immunoreactive neurons in response to IMO were observed in cerebral cortex, septum, thalamus, hypothalamus, midbrain, pons and medulla oblongata in accordance with previous findings. When OVX + E2/Stress were compared with OVX + Pla/Stress, the numbers of c-Fos immunoreactive cells were significantly lower in the lateral septum, paraventricular hypothalamic nucleus, dorsomedial hypothalamic nucleus, medial amygdaloid nucleus, lateral periaqueductal gray, laterodorsal tegmental nucleus and locus coeruleus, while they were significantly higher in paraventricular thalamic nucleus and nucleus of the solitary tract. These data suggest that neuronal activities in these areas are influenced bidirectionally by systemic estrogen level.

Persistent median artery in the hand: a report with a brief review of the literature.

We encountered a persistent median artery in the forearms and hands bilaterally in a 78-year-old Japanese male cadaver during dissection practice at Wakayama Medical University. The brachial arteries divided into the ulnar and radial arteries. The ulnar artery gave off the median and posterior interosseous arteries at the same point, although the anterior interosseous artery was not found. The median artery ran along the median nerve and bifurcated in the hand. In the superficial layer of the palm, one branch of the median artery ran to the ulnar side of the thumb, whereas the other passed to the second interdigital space. The ulnar artery reached the third and fourth interdigital spaces and the ulnar side of the little finger, and showed no anastomosis with the median artery in the superficial layer of the palm. The radial artery did not give off the superficial palmar branch. Therefore, the formation of the superficial palmar arch was incomplete. In the deep layer of the palm, the radial artery formed the deep palmar arch with the deep palmar branch of the ulnar artery and gave off the princeps pollicis artery. In the dorsum of hand, the radial artery passed over the first dorsal interosseous muscle to the index finger and communicated with the palmar pollical artery from the median artery in the first interosseous space. The present study reports an unusual variation of the persistent median artery in the hand and briefly reviews the literature about the median artery.

Cyclooxygenase 2 expression in rat corneas after ethanol exposure.

PURPOSE: To evaluate the effects of ethanol exposure of the cornea on inflammation in corneal epithelium. SETTING: Department of Ophthalmology, Wakayama Medical University, Wakayama, Japan. METHODS: One cornea of Wistar rats (n = 60) was exposed to ethanol 20% for 30 seconds. The animals were killed 0.5, 1.0, 1.5, 2.0, 6.0, 12.0, 24.0, 48.0, or 72.0 hours or 7 days after treatment. The paraffin section or cryosection of the treated eyes was processed for histology; immunohistochemistry for cyclooxygenase 2 (COX2); p65 subunit of nuclear factor kappa B (NF-kappaB), which is the major transcription factor involved in COX2 expression; phospho-IkappaB; or in situ hybridization for COX2 mRNA. RESULTS: In the uninjured corneas, faint immunoreactivity for COX2 was detected in the basal cells of the corneal epithelium, but not in other cell layers. Cyclooxygenase 2 mRNA was not observed in the injured epithelium; it was expressed 2 hours after ethanol exposure, but not 3 hours or later after treatment. The COX2 protein was detected in the corneal epithelium throughout the epithelial layers from 3 to 72 hours, but not at 7 days. The p65 of NF-kappaB translocated to the nuclei of corneal epithelium 3 to 24 hours after treatment but was not seen in the nuclei 48 hours after treatment. Phospho-I kappaB was detected in corneal epithelium 6 hours after treatment, but not 12 hours or later. CONCLUSION: Ethanol exposure activated NF-kappaB and upregulated COX2 expression, which may cause inflammation in corneal tissue.

No involvement of the nerve growth factor gene locus in hypertension in spontaneously hypertensive rats.

Sympathetic hyper-innervation and increased levels of nerve growth factor (NGF), an essential neurotrophic factor for sympathetic neurons, have been observed in the vascular tissues of spontaneously hypertensive rats (SHRs). Such observations have suggested that the pathogenesis of hypertension might involve a qualitative or quantitative abnormality in the NGF protein, resulting from a significant mutation in the gene's promoter or coding region. In the present study, we analyzed the nucleotide sequences of the cis-element of the NGF gene in SHRs, stroke-prone SHRs (SHRSPs), and normotensive Wistar-Kyoto (WKY) rats. The present analyses revealed some differences in the 3-kb promoter region, coding exon, and 3' untranslated region (3'UTR) for the NGF gene among those strains. However, the observed differences did not lead to changes in promoter activity or to amino acid substitution; nor did they represent a link between the 3'UTR mutation of SHRSPs and elevated blood pressure in an F2 generation produced by crossbreeding SHRSPs with WKY rats. These results suggest that the NGF gene locus is not involved in hypertension in SHR/ SHRSP strains. The present study also revealed two differences between SHRs and WKY rats, as found in cultured vascular smooth muscle cells and in mRNA prepared from each strain. First, SHRs had higher expression levels of c-fos and c-jun genes, which encode the component of the AP-1 transcription factor that activates NGF gene transcription. Second, NGF mRNAs prepared from SHRs had a longer 3'UTR than those prepared from WKY rats. Although it remains to be determined whether these events play a role in the hypertension of SHR/SHRSP strains, the present results emphasize the importance of actively searching for aberrant trans-acting factor(s) leading to the enhanced expression of the NGF gene and NGF protein in SHR/SHRSP strains.

Transcriptional activation in lens epithelial cells following an ocular blunt trauma.

PURPOSE: To determine whether an ocular blunt trauma activates anterior ocular segment (cornea and lens) by examining the expression patterns of c-fos and c-jun mRNAs in these tissues of an eye of adult rat following a blunt trauma. SETTING: Department of Ophthalmology, Wakayama Medical University School of Medicine, Kimiidera, Wakayama, Japan. METHODS: Adult Wistar rats (n=36) were generally anesthetized by ether inhalation. One eye was hit with an iron sphere (30 gram) that fell to the eye from 1 m. After the procedure, the animals were killed and the affected eye was enucleated at 15, 30, 60, 120, and 180 minutes. In situ hybridization using radiolabeled oligoprobes was used to detect mRNAs of c-fos and c-jun in tissue. RESULTS: The c-fos and c-jun mRNAs were not detected in the epithelium of uninjured cornea and lens by in situ hybridization. The mRNAs for c-fos and c-jun were then detected in corneal epithelium from 15 to 60 minutes posttreatment, and were no longer observed thereafter. In lens epithelium, mRNA for c-fos or c-jun were transiently detected from 15 to 60 minutes or 30 minutes posttreatment, respectively. CONCLUSION: The c-fos and c-jun mRNAs were transiently expressed in corneal and lens epithelial cells after blunt trauma. Ocular blunt trauma activates corneal and lens epithelial cells without apparent corneal ablation or direct injury in the lens epithelium. Such activation in lens epithelium might be involved in cataractogenesis.

Semaphorin 4A induces growth cone collapse of hippocampal neurons in a Rho/Rho-kinase-dependent manner.

Semaphorins are a family of secreted and membrane-bound proteins, known to control axonal pathfinding. It was recently demonstrated that Semaphorin 4A (Sema4A) is crucially involved in immune cell activation. However, the role of Sema4A in the nervous system has not yet been clarified. To examine if Sema4A can function as a chemo-repulsive cue to growth cones of developing hippocampal neurons, a growth cone collapse assay with recombinant Sema4A was performed in primary hippocampal neurons cultured from E17 mice. In these primary hippocampal neurons, Sema4A induced a significant growth cone collapse as compared with the culture without Sema4A. The Sema4A-induced growth cone collapse could be blocked by Y-27632, a Rho-kinase inhibitor. Furthermore, immunocytochemical analysis with antibodies against Sema4A demonstrated the binding of recombinant Sema4A to the growth cones of hippocampal neurons. Thus, our data indicated that Sema4A could function as a chemo-repulsive cue by activating a receptor whose signal is transmitted to Rho-kinase and induced growth cone collapse of hippocampal neurons.

The kinase domain of death-associated protein kinase is inhibitory for tubulointerstitial fibrosis in chronic obstructive nephropathy.

Death-associated protein kinase (DAPK) is a Ca2+/calmodulin-dependent serine/threonine kinase that is thought to mediate apoptosis. We have shown that the kinase domain of DAPK is crucial for the induction of renal tubular cell apoptosis in chronic obstructive uropathy (COU) created by unilateral ureteral ligation. DAPK-mutant mice, generated by deletion of 74 amino acids from the catalytic kinase domain, were used to investigate the role of the DAPK kinase domain in renal fibrosis following COU. Interstitial collagen and alpha-smooth muscle actin (alpha-SMA) expressions in situ were compared between obstructed kidneys in wild-type and mutant mice. As a result, tubulointerstitial fibrosis, as quantified by interstitial collagen expression, was significantly augmented in mutant kidneys compared with wild-type kidneys following COU. Furthermore, deletion of the kinase domain from DAPK significantly increased the appearance of alpha-SMA-positive myofibroblasts in the renal interstitium during COU. Thus, our results suggest that the kinase domain deleted by gene targeting plays a suppressive role for the development of renal fibrosis through inhibition of the tubular epithelial-to-mesenchymal transition in a mouse model of COU.

STAT6 deficiency inhibits tubulointerstitial fibrosis in obstructive nephropathy.

To elucidate the contribution of signal transducer and activator of transcription (STAT) 6 to the pathophysiology of chronic renal injury, STAT6-/- mice were subjected to unilateral ureteral ligation together with wild-type control mice. STAT6-/- kidneys had more apoptotic cells and a greater influx of F4/80-positive cells than wild-type kidneys following ureteral obstruction. There was a much larger alpha-smooth muscle actin-positive area in STAT6-/- kidneys than in wild-type kidneys after ureteral ligation. However, renal fibrosis, as quantified by Masson-Trichrome staining, was not significantly exaggerated in STAT6-/- kidneys compared with wild-type kidneys. The accumulation of collagen I was significantly less in STAT6-/- kidneys than in wild-type kidneys. These observations indicate that the STAT6 signal transduction pathway exerts a protective role on renal cell apoptosis in chronic obstructive uropathy. Our findings also suggest that the STAT6 pathway may have a promotive effect on renal fibrosis by activating collagen synthesis following ureteral obstruction.