Midbrain Cavernous Malformation: Microsurgical Nuances and an Anatomoclinical Review 2-Dimensional Video.

Midbrain cavernous malformations (MCMs) are rare and dangerous taken the important structures and tracts located in this segment of the brainstem. MCM treatment is still controversial, and surgical resection is basically indicated in cases of recurrent hemorrhage and progressive neurologic deterioration. The optimal moment to operate ruptured MCM is in the subacute stage. Once indicated for surgical resection, preoperative planning needs to be individualized. There are various ways to access midbrain lesions, depending on the extension and predominant location: lateral subtemporal, posterior transtentorial, interhemispheric transcallosal, and anterior temporopolar approaches, or some of the alternatives. The aim of this Video 1 case is to review the surrounding anatomic structures and demonstrate the advantages of the semisitting position and the viability of the supracerebellar infratentorial approach for a tegmental midbrain lesion.1-10 In this 2-dimensional video, we present an 18-year-old man with a 4-year history of diplopia and third nerve palsy, which worsened 10 days before admission. He underwent microsurgical total resection of this MCM via extreme lateral supracerebellar infratentorial approach in a semisitting position. At the end, the surgical site and surrounding structures were reviewed microscopically and endoscopically. The patient tolerated the surgery well, and the perioperative course was uneventful. His recovery was smooth but he maintained the previous oculomotor nerve palsy. We discuss important steps of the surgical approach, local neuroanatomy, and the microsurgical techniques for the resection of these challenging MCM. The goal is total resection of the MCM with the preservation of the developmental venous anomaly and the surrounding white fiber tracts.

New insights on neurodegeneration triggered by iron accumulation: Intersections with neutral lipid metabolism, ferroptosis, and motor impairment.

Brain iron accumulation constitutes a pathognomonic indicator in several neurodegenerative disorders. Metal accumulation associated with dopaminergic neuronal death has been documented in Parkinson's disease. Through the use of in vivo and in vitro models, we demonstrated that lipid dysregulation manifests as a neuronal and glial response during iron overload. In this study, we show that cholesterol content and triacylglycerol (TAG) hydrolysis were strongly elevated in mice midbrain. Lipid cacostasis was concomitant with the loss of dopaminergic neurons, astrogliosis and elevated expression of α-synuclein. Exacerbated lipid peroxidation and markers of ferroptosis were evident in the midbrain from mice challenged with iron overload. An imbalance in the activity of lipolytic and acylation enzymes was identified, favoring neutral lipid hydrolysis, and consequently reducing TAG and cholesteryl ester levels. Notably, these observed alterations were accompanied by motor impairment in iron-treated mice. In addition, neuronal and glial cultures along with their secretomes were used to gain further insight into the mechanism underlying TAG hydrolysis and cholesterol accumulation as cellular responses to iron accumulation. We demonstrated that TAG hydrolysis in neurons is triggered by astrocyte secretomes. Moreover, we found that the ferroptosis inhibitor, ferrostatin-1, effectively prevents cholesterol accumulation both in neurons and astrocytes. Taken together, these results indicate that lipid disturbances occur in iron-overloaded mice as a consequence of iron-induced oxidative stress and depend on neuron-glia crosstalk. Our findings suggest that developing therapies aimed at restoring lipid homeostasis may lead to specific treatment for neurodegeneration associated with ferroptosis and brain iron accumulation.

On the Cut-Off Value of the Anteroposterior Diameter of the Midbrain Atrophy in Spinocerebellar Ataxia Type 2 Patients.

(1) Background: Spinocerebellar ataxias (SCA) is a term that refers to a group of hereditary ataxias, which are neurological diseases characterized by degeneration of the cells that constitute the cerebellum. Studies suggest that magnetic resonance imaging (MRI) supports diagnoses of ataxias, and linear measurements of the aneteroposterior diameter of the midbrain (ADM) have been investigated using MRI. These measurements correspond to studies in spinocerebellar ataxia type 2 (SCA2) patients and in healthy subjects. Our goal was to obtain the cut-off value for ADM atrophy in SCA2 patients. (2) Methods: This study evaluated 99 participants (66 SCA2 patients and 33 healthy controls). The sample was divided into estimations (80%) and validation (20%) samples. Using the estimation sample, we fitted a logistic model using the ADM and obtained the cut-off value through the inverse of regression. (3) Results: The optimal cut-off value of ADM was found to be 18.21 mm. The area under the curve (AUC) of the atrophy risk score was 0.957 (95% CI: 0.895-0.991). Using this cut-off on the validation sample, we found a sensitivity of 100.00% (95% CI: 76.84%-100.00%) and a specificity of 85.71% (95% CI: 42.13%-99.64%). (4) Conclusions: We obtained a cut-off value that has an excellent discriminatory capacity to identify SCA2 patients.

Developmental toxicity of pyriproxyfen induces changes in the ultrastructure of neural cells and in the process of skull ossification.

Some studies relate the use of pyriproxyfen (PPF) in drinking water with damage to embryonic neurodevelopment, including a supposed association with cases of microcephaly. However, the effects on neural cells and skull ossification in embryos remain unclear. This study aims to investigate the effects of PPF on the structure and ultrastructure of brain cells and its influence on the skull ossification process during embryonic development. Chicken embryos, used as an experimental model, were exposed to concentrations of 0.01 and 10 mg/l PPF at E1. The findings demonstrated that PPF led to notable ultrastructural alterations such as reduced cilia and microvilli of ependymal cells and damage to mitochondria, endoplasmic reticulum, Golgi bodies, and cell membranes in neural cells. The frequency of changes and the degree of these cell damage between the forebrain and midbrain were similar. PPF induced a reduction in fox3 transcript levels, specific for differentiation of neurons, and a reduction in the NeuN protein content related to mature neurons and dendritic branches. PPF impacted the ossification process of the skull, as evidenced by the increase in the ossified area and the decrease in inter-bone spacing. In conclusion, this study highlights the ability of PPF to affect neurodevelopmental processes by inducing ultrastructural damage to neural cells, concomitant with a reduction in NeuN and fox3 expression. This detrimental impact coupled with deficiencies in skull ossification can prevent the proper growth and development of the brain.

Supracerebellar-Infratrochlear Approach for Midbrain Cavernoma: 3-Dimensional Operative Video.

Gravity retraction is an underutilized adjunct in neurosurgery. Gravity is gentler than retractor blades; it does not cause brain edema or injury, and it tends to open natural subarachnoidal plans to deep lesions.1-3 A good example of this is the supracerebellar infratrochlear approach4-7 in semisitting position for resection to a midbrain cavernous malformation. This approach was selected because the cavernous malformation was 1 mm under the lateral mesencephalic sulcus. The procedure was developed with the use of transesophageal ultrasound and physiological neuromonitoring. We present a 3-dimensional video of this surgery with all the tricks and details used in the procedure. The patient consented to the procedure and to publication of the photos and surgical video.

Histamine Modulates Midbrain Dopamine Neuron Differentiation Through the Regulation of Epigenetic Marks.

During midbrain development, dopamine neuron differentiation occurs before birth. Epigenetic processes such as DNA methylation and demethylation as well as post-translational modification of histones occur during neurogenesis. Here, we administered histamine (HA) into the brain of E12 embryos in vivo and observed significant lower immunoreactivity of Lmx1a+ and Tyrosine Hydroxylase (TH)+ cells, with parallel decreases in the expression of early (Lmx1a, Msx1) and late (Th) midbrain dopaminergic (mDA) genes. With MeDIP assays we found that HA decreases the percentage of 5-methylcytosine of Pitx3 and Th, without changes in 5-hydroxymethylcytosine. Additionally, HA treatment caused a significant increase in the repressive epigenetic modifications H3K9me3 in Pitx3 and Th, and also more H3K27me3 marks in Th. Furthermore, HA has a long-term effect on the formation of the nigrostriatal and mesolimbic/mesocortical pathways, since it causes a significant decrease in midbrain TH immunoreactivity, as well as alterations in dopaminergic neuronal fibers, and significant lower TH-positive area in the forebrain in whole-mount stainings. These findings suggest that HA diminishes dopaminergic gene transcription by altering several epigenetic components related to DNA and histone modifications, which affects mDA neuron progression during development.

Understanding the role of dopamine in conditioned and unconditioned fear.

Pharmacological and molecular imaging studies in anxiety disorders have primarily focused on the serotonin system. In the meantime, dopamine has been known as the neurotransmitter of reward for 60 years, particularly for its action in the nervous terminals of the mesocorticolimbic system. Interest in the mediation by dopamine of the well-known brain aversion system has grown recently, particularly given recent evidence obtained on the role of D2 dopamine receptors in unconditioned fear. However, it has been established that excitation of the mesocorticolimbic pathway, originating from dopaminergic (DA) neurons from the ventral tegmental area (VTA), is relevant for the development of anxiety. Among the forebrain regions innervated by this pathway, the amygdala is an essential component of the neural circuitry of conditioned fear. Current findings indicate that the dopamine D2 receptor-signaling pathway connecting the VTA to the basolateral amygdala modulates fear and anxiety, whereas neural circuits in the midbrain tectum underlie the expression of innate fear. The A13 nucleus of the zona incerta is proposed as the origin of these DA neurons projecting to caudal structures of the brain aversion system. In this article we review data obtained in studies showing that DA receptor-mediated mechanisms on ascending or descending DA pathways play opposing roles in fear/anxiety processes. Dopamine appears to mediate conditioned fear by acting at rostral levels of the brain and regulate unconditioned fear at the midbrain level.

Subtemporal approach for the resection of a midbrain cavernous malformation: evaluation of safe surgical corridors.

Brainstem cavernous malformation management is complex due to its critical location and deleterious effect when bleeding. Therefore, every case should be thoroughly analyzed preoperatively. We present the case of a female patient with a midbrain cavernous malformation. A comprehensive anatomical and clinical analysis of the surgical corridors is done to decide the safest route. A subtemporal approach was done and the lateral mesencephalic sulcus and vein were important anatomical landmarks to guide the safe entry zone. Nuances of technique and surgical pearls related to the safe entry zones of the midbrain are discussed and illustrated in this operative video. The video can be found here: https://youtu.be/vYA-IgiT2lU.

Descripción de cambios en la difusibilidad media en resonancia magnética por lesiones del sistema reticular activador ascendente en pacientes adultos con trauma craneoencefálico y alteración del estado de conciencia / Description of changes in mean diffusivity in magnetic resonance of injuries of the ascending reticular system in patients with traumatic brain injury and impaired consciousness

RESUMEN INTRODUCCIÓN: Los pacientes con trauma craneoencefálico severo pueden tener secuelas neurológicas graves que generan discapacidad de rangos diferentes según la escala de Barthel. La alteración del estado de consciencia es la secuela más grave y es causa de dependencia completa de estos pacientes por la pérdida del autocuidado. La relación entre los hallazgos anormales en las neuroimágenes y los diferentes estados de conciencia ha sido objeto de investigación en los últimos años, con la posibilidad de que existan nuevas opciones con el posproceso de imágenes obtenidas por resonancia magnética nuclear. Este estudio pretende describir las alteraciones en la difusibilidad media haciendo posproceso en la secuencia de DWI en 4 pacientes con trauma craneoencefálico severo y alteración del estado de consciencia, quienes en la fase aguda del trauma fueron estudiados con imágenes convencionales de tomografía y resonancia. MATERIALES Y MÉTODOS: Se describe una serie de 4 casos de pacientes con trauma craneoencefálico severo y alteración del estado de consciencia a quienes se realizó resonancia cerebral simple. Las imágenes fueron sometidas a un posproceso de la secuencia de DWI analizando diferentes regiones por donde transcurren las fibras del sistema reticular activador ascendente (SRAA) (cuerpos restiformes, rafe medio del mesencéfalo, tálamo, regiones subinsulares y lóbulos frontales basales). Igualmente se tomaron valores de difusibilidad en regiones similares, en 5 sujetos sin alteración estructural cerebral tomados como controles. RESULTADOS: Se encontró disminución en la difusibilidad media en las diferentes regiones establecidas en el estudio, que tuvieron diferente localización en cada paciente. Los valores disminuyeron aproximadamente en un 50 % respecto a los del grupo control, observando lesiones en áreas que no fueron identificadas en la interpretación de la imagen cuando fue adquirida durante el trauma. CONCLUSIONES: El posproceso de la secuencia DWI muestra disminución en los valores de difusibilidad media en regiones por donde transcurren las vías del sistema reticular activado ascendente, estos cambios que explican las diferentes alteraciones en el estado de conciencia, no fueron visualizados en las imágenes interpretadas bajo las técnicas convencionales. Se requiere nuevos estudios para establecer las características operativas de la prueba que permitan definir su potencial utilidad dentro de los algoritmos de clasificación inicial de los pacientes con trauma craneoencefálico severo.

SUMMARY INTRODUCTION: Patients with severe traumatic brain injury may have severe neurological sequelae that generate disability of different ranges, according to the Barthel scale. The consciousness impairment is the most serious sequela and is a cause of complete dependence of these patients, due to the loss of self-care. The relationship between abnormal findings in neuroimaging and different states of consciousness has been the subject of research in recent years, with the possibility of new options with the post-processing of magnetic resonance imaging (MRI). This study aims to describe the alterations in the mean diffusivity by post-processing of the diffusion weighted imaging (DWI) sequence in 4 patients with severe traumatic brain injury and impairment of consciousness, who were studied with computed tomography (CT) and MRI in the acute phase of the trauma. MATERIALS AND METHODS: We describe a series of 4 cases of patients with severe traumatic brain injury and impaired consciousness in whom a non-enhanced brain MRI was performed. The DWI sequence images were post-processed, analyzing different regions through which the fibers of the Ascending Reticular Activating System (ARAS) (including restiform bodies, midbrain, thalamus, sub-insular regions and basal frontal lobes) pass. Likewise, diffusivity values were taken in similar regions, in 5 subjects without any structural brain abnormality, who were taken as controls. RESULTS: There was a decrease in mean diffusivity in the different regions established in the study, which had different locations in each patient. Values decreased approximately 50 percent from values in normal patients. After post-processing, some lesions were observed in areas that were not identified in the initial MRI interpretation during the trauma. CONCLUSIONS: The post-processing of the DWI sequence shows a decrease in the mean diffusivity values in regions where the ARAS pathways pass through. These changes explaining the different alterations in consciousness were not visualized in the images interpreted under conventional MRI techniques. New studies are required to establish the operative characteristics of this test, that allow to define its potential utility within the algorithms of initial classification of patients with severe traumatic brain injury.

Holmes Tremor Secondary to a Stabbing Lesion in the Midbrain.

Background: The development of Holmes tremor (HT) after a direct lesion of the midbrain has rarely been reported in the literature, although several etiologies have been linked with HT, such as stroke, brainstem tumors, multiple sclerosis, head trauma, or infections. Phenomenology Shown: A 31-year-old male, having been stabbed in the right eye, presented with a rest and action tremor in the left upper limb associated with left hemiparesis with corresponding post-contrast volumetric magnetic resonance imaging T1 with sagittal oblique reformation showing the knife trajectory reaching the right midbrain. Educational Value: Despite the rarity of the etiology of HT in the present case, clinicians working with persons with brain injuries should be aware of this type of situation.

Dopamine D2 receptors regulate unconditioned fear in deep layers of the superior colliculus and dorsal periaqueductal gray.

RATIONALE: Electrical and chemical stimulation of the dorsal periaqueductal gray (dPAG), deep layers of the superior colliculus (dlSC), and inferior colliculus (IC) causes freezing and escape behavior in rodents. Systemic injections of the selective dopamine D2 receptor antagonist sulpiride increased the number of switch-off responses (SORs) to light and auditory evoked potentials in response to loud sounds. Dopamine D2 receptor inhibition in the IC was shown to enhance unconditioned fear. Nevertheless, the role of dopamine receptors in the dlSC and dPAG in the mediation of unconditioned fear has not yet been demonstrated. OBJECTIVES: The purpose of the present study was to characterize the effects of sulpiride injections (4 and 8 µg/0.2 µl) in the dlSC and dPAG in rats that were subjected to unconditioned fear paradigms. METHODS: Switch-off responses to light and exploratory behavior in the elevated plus maze were used to evaluate unconditioned fear in rats. RESULTS: Intra-dlSC microinjections of sulpiride increased the number of SORs to light. Intra-dlSC and intra-dPAG injections of sulpiride reduced the number of entries into and time spent on the open arms and decreased end-arm exploration and head dipping in the elevated plus maze. CONCLUSION: These findings suggest that dopamine, through D2 receptors in the dlSC and dPAG, is involved in defense reactions that are organized in the midbrain tectum.

Participation of the dorsal periaqueductal grey matter in the hypoxic ventilatory response in unanaesthetized rats.

AIM: Although periaqueductal grey matter activation is known to elicit respiratory and cardiovascular responses, the role of this midbrain area in the compensatory responses to hypoxia is still unknown. To test the participation of the periaqueductal grey matter in cardiorespiratory and thermal responses to hypoxia in adult male Wistar rats, we performed a chemical lesion of the dorsolateral/dorsomedial or the ventrolateral/lateral periaqueductal grey matter using ibotenic acid. METHODS: Pulmonary ventilation, mean arterial pressure, heart rate and body temperature were measured in unanaesthetized rats during normoxic and hypoxic exposure (5, 15, 30 min, 7% O2). RESULTS: An ibotenic acid lesion of the dorsolateral/dorsomedial periaqueductal grey matter caused a higher increase in pulmonary ventilation (67.1%, 1730±282.5 mL kg(-1) min(-1)) compared to the Sham group (991.4±194 mL kg(-1) min(-1)) after 15 min in hypoxia, whereas for the ventrolateral/Lateral periaqueductal grey matter lesion, no differences were observed between groups. Mean arterial pressure, heart rate and body temperature were not affected by a dorsolateral/dorsomedial or ventrolateral/lateral periaqueductal grey matter lesion. CONCLUSION: Middle to caudal portions of the dorsolateral/dorsomedial periaqueductal grey matter neurones modulate the hypoxic ventilatory response, exerting an inhibitory modulation during low O2 situations. In addition, the middle to caudal portions of the dorsolateral/dorsomedial or ventrolateral/lateral periaqueductal grey matter do not appear to exert a tonic role on cardiovascular or thermal parameters during normoxic and hypoxic conditions.

Morphometry MRI in the differential diagnosis of parkinsonian syndromes / Morfometria por ressonância magnética no diagnóstico diferencial das síndromes parkinsonianas

This study evaluates the diagnostic value of morphometric magnetic resonance imaging (MRI) in the differential diagnosis among Parkinson's disease (PD), progressive supranuclear palsy (PSP) and multiple system atrophy (MSA). We studied 21 PD cases, 11 MSA-c, 8 MSA-p and 20 PSP cases. Midbrain area (Ams), pons area (Apn), middle cerebellar peduncle (MCP) and superior cerebellar peduncle (SCP) were measured using MRI. Comparisons were made between PD, MSA-p, MSA-c and PSP. Apn, MCP and SCP morphometry dimensions presented differences among groups. Ams below 105 mm² and SCP smaller than 3 mmwere the most predictive measures of PSP (sensitivity 95.0 and 80.0 percent, respectively). For the group of MSA-c patients, Apn area below 315 mm² showed good specificity and positive predictive value (93.8 percent and 72.7 percent, respectively). In conclusion, dimensions and cut off values obtained from routine MRI can differentiate between PD, PSP and MSA-c with good sensitivity, specificity and accuracy.

Morfometria pela ressonância magnética (RM) no diagnóstico diferencial entre doença de Parkinson (DP), paralisia supranuclear progressiva (PSP) e atrofia de múltiplos sistemas (AMS). Este estudo avaliou a RM no diagnóstico diferencial de 21 casos com DP, 11 AMS-c, 8 AMS-p e 20 com PSP. A área sagital do mesencéfalo (Ams), área sagital da ponte (Apn), largura do pedúnculo cerebelar médio (PCM) e pedúnculo cerebelar superior (PCS) foram medidas pela RM e realizadas comparações entre destes pacientes. A Ams <105 mm² e a largura média do PCS <3 mm foram preditivas para PSP (sensibilidade de 95,0 e 80,0 por cento, respectivamente). Nos casos de AMS-c a área pontina <315 mm² apresentou boa especificidade e valor preditivo positivo para o diagnóstico (93,8 por cento e 72,7 por cento). Em conclusão, as dimensões e valores de cortes obtidos a partir da RM podem diferenciar PD, PSP e AMS-c, com sensibilidade, especificidade e precisão.

Analysis of the brainstem internal morphology of the capuchin monkey (Cebus apella) / Análise da morfologia interna do tronco encefálico de macaco-prego (Cebus apella)

The gross anatomy and the internal morphology of the brainstem of the monkey Cebus apella were described based on the observations made on adult brainstens. Six adult Cebus apella monkeys were used for anatomical observations and for the study of the internal morphology they were cut into serial sections at six different levels (pyramidal decussation; superior portion of the olive; inferior portion of the olive; pons; superior colliculus and inferior colliculus) and properly stained for studies of the internal structure. Our results show that the Cebus apella brainstem is characterized by the presence of a bulbpontine sulcus; an enlarged brainstem, particularly of the medulla oblongata, with a consequent laterization of the trapezoid body, the presence of inferior olivary complex, the apparent origin of cranial nerves distant from the pyramids and of its decussation; presence of the antero-lateral sulcus separating the pyramids of the olives; expressive development of the trapezoid body, of the pons, nuclei of the pons and of the cerebral peduncle. These results are consistent with previous descriptions for other primates and suggest that the organization and development of the Brainstem structures share similarities with superior primates including humans which reflect the motor abilities of the studied species.

A anatomia e a morfologia interna do tronco encefálico (TE) do macaco-prego (Cebus apella) foram descritas com base nas observações feitas em troncos encefálicos de macacos adultos. Seis macacos Cebus apella adultos foram utilizados para as observações anatômicas. Para os estudos da morfologia interna os TE foram cortados seriadamente em seis níveis diferentes: decussação piramidal, porção superior da oliva, porção inferior da oliva, ponte, colículo superior e colículo inferior. Após esse procedimento eles foram corados com a técnica de Mulligan modificada por nós. Nossos resultados mostram que o TE de Cebus apella é caracterizado pela presença do sulco bulbo-pontino, aumento do tamanho do TE, especialmente da medula oblonga, com consequente lateralização do corpo trapezoide, presença do sulco ântero-lateral separando as pirâmides das olivas; desenvolvimento expressivo do corpo trapezoide, da ponte, dos núcleos da ponte e do pedúnculo cerebral. Estes resultados são consistentes com descrições prévias para outros primatas na literatura e sugerem que a organização e desenvolvimento do TE exibe semelhanças com primatas superiores, incluindo o homem, o que reflete as habilidades motoras da espécie estudada.

Analysis of the brainstem internal morphology of the capuchin monkey (Cebus apella) / Análise da morfologia interna do tronco encefálico de macaco-prego (Cebus apella)

The gross anatomy and the internal morphology of the brainstem of the monkey Cebus apella were described based on the observations made on adult brainstens. Six adult Cebus apella monkeys were used for anatomical observations and for the study of the internal morphology they were cut into serial sections at six different levels (pyramidal decussation; superior portion of the olive; inferior portion of the olive; pons; superior colliculus and inferior colliculus) and properly stained for studies of the internal structure. Our results show that the Cebus apella brainstem is characterized by the presence of a bulbpontine sulcus; an enlarged brainstem, particularly of the medulla oblongata, with a consequent laterization of the trapezoid body, the presence of inferior olivary complex, the apparent origin of cranial nerves distant from the pyramids and of its decussation; presence of the antero-lateral sulcus separating the pyramids of the olives; expressive development of the trapezoid body, of the pons, nuclei of the pons and of the cerebral peduncle. These results are consistent with previous descriptions for other primates and suggest that the organization and development of the Brainstem structures share similarities with superior primates including humans which reflect the motor abilities of the studied species.(AU)

A anatomia e a morfologia interna do tronco encefálico (TE) do macaco-prego (Cebus apella) foram descritas com base nas observações feitas em troncos encefálicos de macacos adultos. Seis macacos Cebus apella adultos foram utilizados para as observações anatômicas. Para os estudos da morfologia interna os TE foram cortados seriadamente em seis níveis diferentes: decussação piramidal, porção superior da oliva, porção inferior da oliva, ponte, colículo superior e colículo inferior. Após esse procedimento eles foram corados com a técnica de Mulligan modificada por nós. Nossos resultados mostram que o TE de Cebus apella é caracterizado pela presença do sulco bulbo-pontino, aumento do tamanho do TE, especialmente da medula oblonga, com consequente lateralização do corpo trapezoide, presença do sulco ântero-lateral separando as pirâmides das olivas; desenvolvimento expressivo do corpo trapezoide, da ponte, dos núcleos da ponte e do pedúnculo cerebral. Estes resultados são consistentes com descrições prévias para outros primatas na literatura e sugerem que a organização e desenvolvimento do TE exibe semelhanças com primatas superiores, incluindo o homem, o que reflete as habilidades motoras da espécie estudada.(AU)

Immunohistochemical study of acute effects of ethanol on midbrain of wistar rats associated with the date of birth of neurons in encephalon / Estudio inmunohistoquímico de los efectos agudos del etanol sobre el mesencéfalo de ratas wistar asociado con la fecha de formación de neuronas en el cerebro

The verification of the acute effects of ethanol on the midbrain, which neurons are mainly formed in E14, will ratify if the acute effects of ethanol are associated, in terms of prevalence, to the date of birth of neurons in certain regions of the brain. The aim of this study was to determine the effects of acute exposure to ethanol on the neuronal density of the midbrain and to associate these results with acute effects of ethanol in other regions of the brain under the same conditions. The rats were treated with intraperitoneal ethanol during one day (E12) and 1h after the last ethanol injection was applied to BrdU. The animals were sacrificed; the brains were removed and sectioned. The sections were treated with DAB for the BrdU revelation, the slides were stained with safranin for one group and another group was stained with H & E. The effects of acute injection of ethanol in E12 on the midbrain were not detected in this study. Data from literature suggest that the deleterious action of acute ethanol consumption only occur if the drug is injected at times near the beginning of the migration of neurons in that particular region of the brain.

La verificación de los efectos agudos del etanol sobre el mesencéfalo, cuyas neuronas se forman principalmente en la E14, puede ratificar si los efectos agudos del etanol están asociados, en términos de prevalencia, a la fecha de nacimiento de neuronas en ciertas regiones del cerebro. El objetivo de este estudio fue determinar los efectos de la exposición aguda al etanol sobre la densidad neuronal del mesencéfalo y asociar estos resultados con los efectos agudos de etanol en otras regiones del cerebro bajo las mismas condiciones. Las ratas fueron tratadas con etanol intraperitoneal durante un día (E12) y 1h después de la última inyección de etanol fue aplicado BrdU. Los animales fueron sacrificados, los cerebros fueron removidos y seccionados. Las secciones fueron tratados con DAB para la revelación de BrdU, las secciones fueron teñidas con safranina para un grupo y otro grupo se tiñeron con H&E. Los efectos agudos de la inyección de etanol en E12 sobre el mesencéfalo no fueron detectados en este estudio. Los datos de la literatura sugieren que los efectos deletéreos del consumo agudo de etanol sólo se producen si la droga se inyecta en etapas cercanas al comienzo de la migración de las neuronas en esa región particular del cerebro.

Bilateral ptosis and supranuclear downgaze paralysis

The purpose of this article is to highlight an uncommon combination of supranuclear downward gaze paralysis with bilateral eyelid ptosis in a 53-years-old man with a radiation induced midbrain tumor and to discuss the aspects regarding the centers and pathways that mediate supranuclear vertical gaze movements.

O objetivo deste artigo é ressaltar uma rara condição caracterizada por paralisia supranuclear do olhar conjugado para baixo associada a ptose palpebral bilateral em um homem de 53 anos, causada por tumor mesencefálico radio-induzido, e discutir os aspectos relacionados ao controle supranuclear dos movimentos oculares verticais.

Expression of D-type cyclins in differentiating cells of the mouse spinal cord

The D-type cyclins form complexes with the cyclin dependent (CD) kinases CDK4 and CDK6 and promote the G1-S phase transition of the cell cycle by antagonizing the retinoblastoma suppresser protein pRB. In the developing nervous system D-type cyclins show spatially and temporally dynamic patterns of expression. We demonstrated that cyclin D1 was transiently expressed in differentiating spinal cord ventral interneurons while cyclin D3 protein was expressed in differentiating motor neurons and dorsal interneurons. This expression of cyclin D3 in neurons of the mantle zone was extended to all regions of the spinal cord at E15.5. The results suggest that cyclin D1 and D3 have specific functions in differentiating neurons. Similarly, in the developing midbrain-hindbrain region the D-type cyclins were expressed in different subsets of cells. Our results argue in favor of different functions for D-type cyclins during proliferation and differentiation of neural progenitors.