Malat1 deficiency prevents hypoxia-induced lung dysfunction by protecting the access to alveoli.

Hypoxia is common in lung diseases and a potent stimulator of the long non-coding RNA Metastasis-Associated Lung Adenocarcinoma Transcript 1 (MALAT1). Herein, we investigated the impact of Malat1 on hypoxia-induced lung dysfunction in mice. Malat1-deficient mice and their wild-type littermates were tested after 8 days of normoxia or hypoxia (10% oxygen). Hypoxia decreased elastance of the lung by increasing lung volume and caused in vivo hyperresponsiveness to methacholine without altering the contraction of airway smooth muscle. Malat1 deficiency also modestly decreased lung elastance but only when tested at low lung volumes and without altering lung volume and airway smooth muscle contraction. The in vivo responsiveness to methacholine was also attenuated by Malat1 deficiency, at least when elastance, a readout sensitive to small airway closure, was used to assess the response. More impressively, in vivo hyperresponsiveness to methacholine caused by hypoxia was virtually absent in Malat1-deficient mice, especially when hysteresivity, a readout sensitive to small airway narrowing heterogeneity, was used to assess the response. Malat1 deficiency also increased the coefficient of oxygen extraction and decreased ventilation in conscious mice, suggesting improvements in gas exchange and in clinical signs of respiratory distress during natural breathing. Combined with a lower elastance at low lung volumes at baseline, as well as a decreased propensity for small airway closure and narrowing heterogeneity during a methacholine challenge, these findings represent compelling evidence suggesting that the lack of Malat1 protects the access to alveoli for air entering the lung.

Developmental expression patterns of erythropoietin and its receptor in mouse brainstem respiratory regions.

Erythropoietin (EPO) is a hypoxia-inducible hormone, classically known to enhance red blood cell production upon binding its receptor (EPOR) present on the surface of the erythroid progenitor cells. EPO and its receptor are also expressed in the central nervous system (CNS), exerting several non-hematopoietic actions. EPO also plays an important role in the control of breathing. In this review, we summarize the known physiological actions of EPO in the neural control of ventilation during postnatal development and at adulthood in rodents under normoxic and hypoxic conditions. Furthermore, we present the developmental expression patterns of EPO and EPORs in the brainstem, and with the use of in situ hybridization (ISH) and immunofluorescence techniques we provide original data showing that EPOR is abundantly present in specific brainstem nuclei associated with central chemosensitivity and control of ventilation in the ventrolateral medulla, mainly on somatostatin negative cells. Thus, we conclude that EPO signaling may act through glutamatergic neuron populations that are the primary source of rhythmic inspiratory excitatory drive. This work underlies the importance of EPO signaling in the central control of ventilation across development and adulthood and provides new insights on the expression of EPOR at the cellular level.

Roles of oestradiol receptor alpha and beta against hypertension and brain mitochondrial dysfunction under intermittent hypoxia in female rats.

AIM: Chronic intermittent hypoxia (CIH) induces systemic (hypertension) and central alterations (mitochondrial dysfunction underlying cognitive deficits). We hypothesized that agonists of oestradiol receptors (ER) α and ß prevent CIH-induced hypertension and brain mitochondrial dysfunction. METHODS: Ovariectomized female rats were implanted with osmotic pumps delivering vehicle (Veh), the ERα agonist propylpyraoletriol (PPT - 30 µg/kg/day) or the ERß agonist diarylpropionitril (DPN - 100 µg/kg/day). Animals were exposed to CIH (21%-10% FI O2 - 10 cycles/hour - 8 hours/day - 7 days) or normoxia. Arterial blood pressure was measured after CIH or normoxia exposures. Mitochondrial respiration and H2 O2 production were measured in brain cortex with high-resolution respirometry, as well as activity of complex I and IV of the electron transport chain, citrate synthase, pyruvate, and lactate dehydrogenase (PDH and LDH). RESULTS: Propylpyraoletriol but not DPN prevented the rise of arterial pressure induced by CIH. CIH exposures decreased O2 consumption, complex I activity, and increased H2 O2 production. CIH had no effect on citrate synthase activity, but decreased PDH activity and increased LDH activity indicating higher anaerobic glycolysis. Propylpyraoletriol and DPN treatments prevented all these alterations. CONCLUSIONS: We conclude that in OVX female rats, the ERα agonist prevents from CIH-induced hypertension while both ERα and ERß agonists prevent the brain mitochondrial dysfunction and metabolic switch induced by CIH. These findings may have implications for menopausal women suffering of sleep apnoea regarding hormonal therapy.

Role of Estradiol Receptor Beta (ERß) on Arterial Pressure, Respiratory Chemoreflex and Mitochondrial Function in Young and Aged Female Mice.

We tested the hypothesis that ERß is involved in respiratory control in female mice. We used young adult (5-6 months-old) and aged (17-18 months-old) ERßKO or wild-type controls (WT) female mice to assess arterial blood pressure (via a tail-cuff sensor) and indices of respiratory pattern (sighs and apneas - recorded by whole body plethysmography at rest). We also measured respiratory parameters at rest and in response to brief (<10 min) exposure to hypoxia (12% O2) or hypercapnia (5% CO2). Because ERß is localized in mitochondria, and because estradiol and ERß agonist increase mitochondrial O2 consumption, we assessed the mitochondrial respiration (with a high-resolution oxygraph system) and the in vitro activity of the complex I of the electron transfer chain in samples of brain cortex in aged wild-type and ERßKO female mice. Compared to young WT mice, young ERßKO mice had elevated arterial blood pressure, but similar ventilatory responses to hypoxia and hypercapnia. In old ERßKO female mice compared to old WT mice, the arterial blood pressure was lower, the frequency of sighs was higher and the frequency of apneas was lower, and the hypoxic and hypercapnic ventilatory responses were reduced. In old ERßKO mice mitochondrial respiration and complex I activities in the brain cortex were lower than in WT mice. We conclude that ERß has age-specific effects on vascular and respiratory functions in female mice.

Increased ventilation in female erythropoietin-deficient mouse line is not progesterone and estrous stage-dependent.

Previous studies suggest that chronic erythropoietin (Epo) deficiency in male mice does not alter normoxic/hypoxic ventilation. As effects of Epo are sex specific and as progesterone could be a respiratory stimulant, we evaluated the impact of Epo deficiency and its possible interaction with progesterone in ventilatory control in female mice during estrous cycle phases. Compared to wild type (WT) animals, Epo-TAgh female mice exhibited higher ventilation in hypoxia. However, when data were separated into luteal and follicular phases of the estrous cycle, basal ventilation and hypoxic ventilation were not different in both mice strains. As progesterone is known to be a potent respiratory stimulant, additional experiments were performed to elucidate its role. Interestingly, after mifepristone treatment, HVR was not modified in WT and Epo-TAgh mice, showing that the ventilatory stimulation observed in females was not directly mediated by progesterone. We conclude that Epo-TAgh female mice show no estrous stage-dependent increase of ventilatory control and progesterone independent response to hypoxia.

Efectividad del cambio de tratamiento desde Metadona a Buprenorfina/Naloxona en dependientes a opiáceos, Bilbao - España / Effectiveness of treatment change from methadone to Buprenorphine / Naloxone in opiate dependents, Bilbao - Spain

A nivel mundial la dependencia a opiáceos es un problema vigente, y los pacientes afectados por esta condición requieren programas de tratamiento sustitutivo farmacológico, que utilizan tradicionalmente Metadona. Actualmente, existe debate sobre el hecho de que la Buprenorfina/Naloxona podria ser utilizada como un reemplazo adecuado del fármaco tradicional. Las investigaciones aún no son totalmente concluyentes, faltando estudios que prueben los resultados en la práctica clínica. Objetivos: Determinar la efectividad del tratamiento con Buprenorfina/Naloxona como reemplazo de la metadona en pacientes dependientes de opiáceos tratados en un Módulo de Asistencia Psicosocial en la ciudad de Bilbao, España. Métodos: Se realizó un estudio cuasiexperimental, cuantitativo, longitudinal, prospectivo, con 21 pacientes dependientes de opiáceos que formaban parte del Programa de mantenimiento con Metadona con dosis inferiores o iguales a 40 mg/día, en quienes se sustituyó ese tratamiento por el de Buprenorfina/Naloxona (8mg/2mg) siguiendo para esto los criterios de la Guía para el tratamiento de la adicción a opiáceos con Buprenorfina/Naloxona de la Sociedad Científica Española de estudios sobre alcohol, el alcoholismo y otras toxicomanías del 2010. Resultados: Después de tres meses de cambio de terapéutica a Buprenorfina/Naloxona se evidencio una reducción estadísticamente significativa en el consumo de opiáceos ilegales, medido a través de los controles de substancias en orina desde un promedio de 2,67 controles positivos con metadona, a 2,24 controles con Buprenorfina/Naloxona. La adherencia, se mantuvo similar a la previa, presentando además una retención del 100% de los pacientes. La calidad de vida, medida con el Test TECVASP, presento una mejora estadísticamente significativa, desde una puntuación de 76,76 cuando recibían Metadona (DE 6,41) hasta 90,33 (DE 5,77 ) con la nueva terapéutica. Conclusiones: Cambiar la terapia de mantenimiento con Metadona, en pacientes dependientes de opioides, por buprenorfina/naloxona es una buena opción, ya que tiene una efectividad similar en términos de adherencia y retención, y produce una mayor reducción en el uso de opiáceos ilegales, al tiempo que mejora la calidad de vida del paciente.

At the global level, opioid dependence is an ongoing problem, and patients with this condition require pharmacological substitution treatment programs, which traditionally use methadone. Currently there is debate over whether Buprenorphine / Naloxone could be used as a suitable replacement for the traditional drug. The investigations are not yet totally conclusive, lacking studies that prove the results in the clinical practice. Objectives: To determine the effectiveness of treatment with Buprenorphine / Naloxone as a replacement for Methadone in opioid dependent patients treated in a Psychosocial Assistance Module in the city of Bilbao, Spain. Methods: A quasi-experimental, quantitative, longitudinal, prospective study was conducted with 21 opioid-dependent patients that were part of the maintenance program with Methadone at doses lower than or equal to 40 mg / day, in which treatment was replaced by that of Buprenorphine / Naloxone (8 mg/2 mg) following for this the criteria of the Guide for the treatment of the addiction to opiates with Buprenorphine / Naloxone of the Spanish Scientific Society of studies on alcohol, alcoholism and other drug addictions of 2010. Results: After a three-month change in therapy to Buprenorphine / Naloxone, a statistically significant reduction in illegal opioid use was observed, measured through urine substance controls from an average of 2.67 methadone-positive controls 2.24 controls with Buprenorphine / Naloxone. The Adherence remained similar to the previous one, presenting a retention of 100% of the patients. Quality of life, measured with the TECVASP test, showed a statistically significant improvement, from a score of 76.76 when receiving Methadone (DE 6.41) to 90.33 (DE 5.77) with the new therapy. Conclusions: Changing maintenance therapy with methadone, in opioid-dependent patients, by buprenorphine/naloxone is a good option, because it has a similar effectiveness in terms of adherence and retention, and produces a greater reduction in the use of illegal opiates, and the same time improves the quality of life of the patient.

Pharmacological, but not genetic, alteration of neural Epo modifies the CO2/H+ central chemosensitivity in postnatal mice.

Cerebral erythropoietin (Epo) plays a crucial role for respiratory control in newborn rodents. We showed previously that soluble Epo receptor (sEpoR: an Epo antagonist) reduces basal ventilation and hypoxic hyperventilation at postnatal day 10 (P10) and in adult mice. However, at these ages (P10 and adulthood), Epo had no effect on central chemosensitivity. Nevertheless, it is known that the sensitivity to CO2/H+ during the mammalian respiratory network maturation process is age-dependent. Accordingly, in this study we wanted to test the hypothesis that cerebral Epo is involved in the breathing stimulation induced by the activation of central CO2/H+ chemoreceptors at earlier postnatal ages. To this end, en bloc brainstem-spinal cord preparations were obtained from P4 mice and the fictive breathing response to CO2-induced acidosis or metabolic acidosis was analyzed. This age (P4) was chosen because previous research from our laboratory showed that Epo altered (in a dose- and time-dependent manner) the fictive ventilation elicited in brainstem-spinal cord preparations. Moreover, as it was observed that peripheral chemoreceptors determined the respiratory sensitivity of central chemoreceptors to CO2, the use of this technique restricts our observations to central modulation. Our results did not show differences between preparations from control and transgenic animals (Tg21: overexpressing cerebral Epo; Epo-TAgh: cerebral Epo deficient mice). However, when Tg21 brainstem preparations were incubated for 1h with sEpoR, or with inhibitors of ERK/Akt (thus blocking the activation of the Epo molecular pathway), the fictive breathing response to CO2-induced acidosis was blunted. Our data suggest that variation of the Epo/sEpoR ratio is central to breathing modulation during CO2 challenges, and calls attention to clinical perspectives based on the use of Epo drugs at birth in hypoventilation cases.

Inhibition of Protein Kinases AKT and ERK1/2 Reduce the Carotid Body Chemoreceptor Response to Hypoxia in Adult Rats.

The carotid body is the main mammalian oxygen-sensing organ regulating ventilation. Despite the carotid body is subjected of extensive anatomical and functional studies, little is yet known about the molecular pathways signaling the neurotransmission and neuromodulation of the chemoreflex activity. As kinases are molecules widely involved in motioning a broad number of neural processes, here we hypothesized that pathways of protein kinase B (AKT) and extracellular signal-regulated kinases ½ (ERK1/2) are implicated in the carotid body response to hypoxia. This hypothesis was tested using the in-vitro carotid body/carotid sinus nerve preparation ("en bloc") from Sprague Dawley adult rats. Preparations were incubated for 60 min in tyrode perfusion solution (control) or containing 1 µM of LY294002 (AKT inhibitor), or 1 µM of UO-126 (ERK1/2 inhibitor). The carotid sinus nerve chemoreceptor discharge rate was recorded under baseline (perfusion solution bubbled with 5 % CO(2) balanced in O(2)) and hypoxic (perfusion solution bubbled with 5 % CO(2) balanced in N(2)) conditions. Compared to control, both inhibitors significantly decreased the normoxic and hypoxic carotid body chemoreceptor activity. LY294002- reduced carotid sinus nerve discharge rate in hypoxia by about 20 %, while UO-126 reduces the hypoxic response by 45 %. We concluded that both AKT and ERK1/2 pathways are crucial for the carotid body intracellular signaling process in response to hypoxia.

Estudio de Rodilla Flotante en pacientes del Hospital Clínico Viedma / Floating Knee Study in Patients of Hospital Clínico Viedma

Se denomina "Rodilla Flotante" a la combinación de fractura de fémur y tibia ipsilaterales. La incidencia exacta se desconoce, pero tiene un abordaje terapéutico complejo, una alta tasa de complicaciones y una elevada mortalidad. El presente estudio busca determinar los aspectos relacionados con esta patología en nuestro medio y analizarlos de una manera integral, realizándose para esto un estudio descriptivo y longitudinal retrospectivo abarcando 18 meses (de julio 2008 a diciembre 2009) que incluye a 17 pacientes con diagnóstico de "Rodilla Flotante" ingresados en el Servicio de Ortopedia y Traumatología del Hospital Clínico Viedma. Los resultados mostraron que esta lesión equivale al 1,9 % de los casos atendidos por este servicio. Siendo el 82,35% hombres. La edad promedio fue de 34 años. El mecanismo de producción más frecuente: accidentes en motocicleta (41,2%), seguido de atropellados (29,4%). En cuanto a la clasificación la mayor parte fue tipo I de Fraser (68,8%). El tratamiento quirúrgico definitivo se aplicó entre el 5º y 14° día en el 73.3%, mayormente usando clavos centro medulares en fémur y tibia. Los resultados del tratamiento fueron: excelentes 40%, buenos 33.3%, regulares 20% y pobres en el 6,6% según la escala de Karlstrom y Olerud. Las lesiones asociadas:TEC (80%), fracturas de pelvis (60%), trauma abdominal cerrado (60%) y trauma de tórax (33,3%). Dentro de las complicaciones, un paciente falleció por falla multiorgánica, otro concluyó en amputación, y cinco presentaron infección. Por lo que se concluye que en general los aspectos relacionados con esta patología, su presentación y tratamiento en nuestro medio, son similares a los que se encuentran descritos en la literatura médica.  .

"Floating knee" refers to the combination of fracture of femur and tibia ipsilateral .The exact incidence is unknown, but has a complex therapeutic approach, a high rate of complications and high mortality. This study pretends to determine aspects of this disease in our environment and to analyze them in a comprehensive manner, making this a retrospective descriptive study longitudinal spanning 18 months (from July 2008 to December 2009) includes 17 patients with diagnosis of "Floating knee" entered in the service of Orthopedics and Traumatology of the Hospital Clinico Viedma. The results showed that this injury is equivalent to 1.9% of the cases covered by this service. 82.35% corresponds to men.The middle age was 34 years. The most common mechanism: motoreyele accident (41,18%), followed by hasty (29.41%). The most common classification was Fraser type I (68.82%). The definitive surgical treatment apply between 5º and 14° day on the 73.3%, mostly using medullar center nail in femur and tibia. The results of the treatment were: excellent 40%, good 33.3%, regular 20% and poor in 6.6 % according to the scale of Karlstrom and Olerud. Associated injuries: TEC (80%), fracture of pelvis (60%), closed abdominal trauma (60%) and chest trauma (33.3%). In the complications, one patient died of multiorganic fail, another concluded in amputation, and five presented infection. The research group concluded that aspects of this disease, its presentation and treatment in our environment, are in general similar to those that are described in the medical literature.

Impaired ventilatory acclimatization to hypoxia in female mice overexpressing erythropoietin: unexpected deleterious effect of estradiol in carotid bodies.

Apart from enhancing the production of red blood cells, erythropoietin (Epo) alters the ventilatory response when oxygen supply is reduced. We recently demonstrated that Epo's beneficial effect on the ventilatory response to acute hypoxia is sex dependent, with female mice being better able to cope with reduced oxygenation. In the present work, we hypothesized that ventilatory acclimatization to chronic hypoxia (VAH) in transgenic female mice (Tg6) harboring high levels of Epo in the brain and blood will also be improved compared with wild-type (WT) animals. Surprisingly, VAH was blunted in Tg6 female mice. To define whether this phenomenon had a central (brain stem respiratory centers) and/or peripheral (carotid bodies) origin, a bilateral transection of carotid sinus nerve (chemodenervation) was performed. This procedure allowed the analysis of the central response in the absence of carotid body information. Interestingly, chemodenervation restored the VAH in Tg6 mice, suggesting that carotid bodies were responsible for the blunted response. Coherently with this observation, the sensitivity to oxygen alteration in arterial blood (Dejour test) after chronic hypoxia was lower in transgenic carotid bodies compared with the WT control. As blunted VAH occurred in female but not male transgenic mice, the involvement of sex female steroids was obvious. Indeed, measurement of sexual female hormones revealed that the estradiol serum level was 4 times higher in transgenic mice Tg6 than in WT animals. While ovariectomy decreased VAH in WT females, this treatment restored VAH in Tg6 female mice. In line with this observation, injections of estradiol in ovariectomized Tg6 females dramatically reduced the VAH. We concluded that during chronic hypoxia, estradiol in carotid bodies suppresses the Epo-mediated elevation of ventilation. Considering the increased application of recombinant Epo for a variety of disorders, our data imply the need to take the patient's hormonal status into consideration.

Histamine H1 receptor promotes atherosclerotic lesion formation by increasing vascular permeability for low-density lipoproteins.

OBJECTIVE: Enhanced endothelial permeability leading to intimal accumulation of low-density lipoproteins (LDL) stimulates the formation of atherosclerotic lesions. Histamine is known to increase vascular permeability. Whether this affects the formation of atherosclerotic lesions, however, remains elusive. METHODS AND RESULTS: Apolipoprotein E-null (ApoE(-/-)) mice treated with a histamine H1 receptor but not an H2 receptor antagonist developed 40% fewer atherosclerotic lesions in the aorta than placebo-treated controls. Similarly, genetic deletion of the H1 but not the H2 receptor resulted in a 60% reduction of lesions compared with ApoE(-/-) controls. The H1 receptor enhanced LDL permeability and lipid accumulation in the aorta, whereas plasma lipoprotein levels remained unaltered. In contrast, the H1 receptor did not affect proliferation and migration of vascular smooth muscle cells. Bone marrow transplantation confirmed that the formation of atherosclerotic lesions depended on the H1 receptor in vascular cells, whereas its presence in bone marrow-derived cells was irrelevant for plaque development. Mice expressing the H1 receptor exhibited higher levels of the chemokine (C-C motif) ligand 5 and higher numbers of macrophages and T-helper lymphocytes in plaques, higher numbers of circulating lymphocytes, and larger spleens. CONCLUSION: These data indicate that H1 but not H2 receptor activation drives the formation of atherosclerotic lesions through an increased vascular permeability for LDL, which is associated with an enhanced secondary aortic and systemic inflammation. These data open novel perspectives for the prevention and treatment of atherosclerotic vascular disease.

Consumo de Alcohol durante el Embarazo: Múltiples Efectos Negativos en el Feto / Alcohol Consumption during Pregnancy: Many Adverse Effects on the Fetus

Los efectos de la exposición prenatal al alcohol pueden ser identificados prácticamente en todo el cuerpo, produciendo entre otros: graves anomalías neurológicas y del crecimiento, déficit cognitivo y académico, trastornos psicológicos, problemas de comportamiento y dificultades para una vida independiente, además de aumentar el riesgo de aborto espontáneo, el nacimiento prematuro y la mortinatalidad. El término trastorno del espectro alcohólico fetal es asignado a un gran conjunto de presentaciones clínicas presentes en el feto que son producidas por el consumo de alcohol en la madre durante el embarazo. El Síndrome Alcohólico fetal representa el tipo más grave de estas presentaciones, y es una afección que incapacita tanto mental como físicamente de por vida, debido a que, a pesar de la investigación sobre tratamientos actualmente no existe cura. Por último es importante saber que todos los defectos causados por la exposición prenatal al alcohol son totalmente prevenibles.

The effects of prenatal exposure to alcohol can be identified virtually the entire body, producing among other things: serious neurological abnormalities and growth, cognitive and academic deficits, psychological disorders, behavioral problems and difficulties for independent living, in addition to increasing the risk of miscarriage, premature birth and stillbirth. The term fetal alcohol spectrum disorder is assigned to a wide range of clinical presentations in the fetus are caused by alcohol consumption during pregnancy. Fetal alcohol syndrome is the most serious of these presentations, and a condition that is both mentally and physically disabled for life because even though the research on treatments currently no cure. Finally it is important to know that all the defects caused by prenatal exposure to alcohol is totally preventable.

Brain-derived erythropoietin protects from focal cerebral ischemia by dual activation of ERK-1/-2 and Akt pathways.

Apart from its hematopoietic function, erythropoietin (Epo) exerts neuroprotective functions in brain hypoxia and ischemia. To examine the mechanisms mediating Epo's neuroprotective activity in vivo, we made use of our transgenic mouse line tg21 that constitutively expresses human Epo in brain without inducing excessive erythrocytosis. We show that human Epo is expressed in tg21 brains and that cortical and striatal neurons carry the Epo receptor. After middle cerebral artery occlusion, human Epo potently protected brains of tg21 mice against ischemic injury, both when severe (90 min) and mild (30 min) ischemia was imposed. Histochemical studies revealed that Epo induced an activation of JAK-2, ERK-1/-2, and Akt pathways in the ischemic brain. This activation was associated with elevated Bcl-XL and decreased NO synthase-1 and -2 levels in neurons. Intracerebroventricular injections of selective inhibitors of ERK-1/-2 (PD98059) or Akt (wortmannin) pathways revealed that both ERK-1/-2 and Akt were required for Epo's neuroprotective function, antagonization of either pathway completely abolishing tissue protection. On the other hand, ERK-1/-2 and Akt blockade did not reverse the neuronal NO synthase-1/-2 inhibition, indicating that Epo down-regulates these NO synthases in an ERK-1/-2 and Akt independent manner. On the basis of our data, the dual activation of ERK-1/-2 and Akt is crucial for Epo's neuroprotective activity.

Erythropoietin protects from axotomy-induced degeneration of retinal ganglion cells by activating ERK-1/-2.

Apart from its hematopoietic function, erythropoietin (Epo) exerts neuroprotective activity upon reduced oxygenation or ischemia of brain, retina, and spinal cord. To examine whether Epo has an impact on the retrograde degeneration of retinal ganglion cells (RGCs) following optic nerve transection in vivo, we made use of our transgenic mouse line tg21 that constitutively expresses human Epo preferentially in neuronal cells without inducing polycythemia. We show that the tg21 retina expresses human Epo and that RGCs in this mouse line carry the Epo receptor. Upon axotomy, the RGCs of Epo transgenic tg21 mice were protected against degeneration, as compared with wild-type control animals. Western blot analysis revealed decreased phosphorylation levels of STAT-5 and reduced expression of Bcl-XL in RGCs of axotomized tg21 animals, suggesting that the corresponding pathways are not crucial for Epo's neuroprotective activity. Increased phosphorylation levels of ERK-1/-2 and Akt, as well as decreased caspase-3 activity, however, were observed in injured tg21 retinae. Injection of selective inhibitors of ERK-1/-2 (PD98059) or Akt (Wortmannin) pathways into the vitreous space revealed that transgenic Epo protected the RGCs by a pathway involving ERK-1/-2 but not Akt. In view that axotomy-induced degeneration of RGC occurs slowly, and considering the earlier data on the safety and efficacy of Epo in human stroke patients, we predict the clinical implementation of recombinant human Epo not only in patients with acute ischemic stroke, but also with more delayed degenerative neurological diseases.

Dopaminergic metabolism in carotid bodies and high-altitude acclimatization in female rats.

We tested the hypothesis that ovarian steroids stimulate breathing through a dopaminergic mechanism in the carotid bodies. In ovariectomized female rats raised at sea level, domperidone, a peripheral D2-receptor antagonist, increased ventilation in normoxia (minute ventilation = +55%) and acute hypoxia (+32%). This effect disappeared after 10 daily injections of ovarian steroids (progesterone + estradiol). At high altitude (3,600 m, Bolivian Institute for High-Altitude Biology-IBBA, La Paz, Bolivia), neutered females had higher carotid body tyrosine hydroxylase activity (the rate-limiting enzyme for catecholamine synthesis: +129%) and dopamine utilization (+150%), lower minute ventilation (-30%) and hypoxic ventilatory response (-57%), and higher hematocrit (+18%) and Hb concentration (+21%) than intact female rats. Consistent signs of arterial pulmonary hypertension (right ventricular hypertrophy) also appeared in ovariectomized females. None of these parameters was affected by gonadectomy in males. Our results show that ovarian steroids stimulate breathing by lowering a peripheral dopaminergic inhibitory drive. This process may partially explain the deacclimatization of postmenopausal women at high altitude.