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ABSTRACT: Autopsy followed by histopathological examination is foundational in clinical and forensic medicine for discovering and understanding pathological changes in disease, their underlying processes, and cause of death. Imaging technology has become increasingly important for advancing clinical research and practice, given its noninvasive, in vivo and ex vivo applicability. Medical and forensic autopsy can benefit greatly from advances in imaging technology that lead toward minimally invasive, whole-brain virtual autopsy. Brain autopsy followed by histopathological examination is still the hallmark for understanding disease and a fundamental modus operandi in forensic pathology and forensic medicine, despite the fact that its practice has become progressively less frequent in medical settings. This situation is especially relevant with respect to new diseases such as COVID-19 caused by the SARS-CoV-2 virus, for which our neuroanatomical knowledge is sparse. In this narrative review, we show that ad hoc clinical autopsies and histopathological analyses combined with neuroimaging of the principal circumventricular organs are critical to gaining insight into the reconstruction of the pathophysiological mechanisms and the explanation of cause of death (ie, atrium mortis) related to the cardiovascular effects of SARS-CoV-2 infection in forensic and clinical medicine.
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COVID-19 , Humanos , COVID-19/patología , COVID-19/diagnóstico por imagen , Neuroimagen/métodos , Autopsia/métodos , Encéfalo/patología , Encéfalo/diagnóstico por imagen , SARS-CoV-2 , Patologia Forense/métodos , Relevancia ClínicaRESUMEN
Current views on immunity support the idea that immunity extends beyond defense functions and is tightly intertwined with several other fields of biology such as virology, microbiology, physiology and ecology. It is also critical for our understanding of autoimmunity and cancer, two topics of great biological relevance and for critical public health considerations such as disease prevention and treatment. Central to this review, the immune system is known to interact intimately with the nervous system and has been recently hypothesized to be involved not only in autonomic and limbic bio-behaviors but also in cognitive function. Herein we review the structural architecture of the brain network involved in immune response. Furthermore, we elaborate upon the implications of inflammatory processes affecting brain-immune interactions as reported recently in pathological conditions due to SARS-Cov-2 virus infection, namely in acute and post-acute COVID-19. Moreover, we discuss how current neuroimaging techniques combined with ad hoc clinical autopsies and histopathological analyses could critically affect the validity of clinical translation in studies of human brain-immune interactions using neuroimaging. Advances in our understanding of brain-immune interactions are expected to translate into novel therapeutic avenues in a vast array of domains including cancer, autoimmune diseases or viral infections such as in acute and post-acute or Long COVID-19.
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Hydrocephalus is a central nervous system condition characterized by CSF buildup and ventricular hypertrophy. It is divided into two types: communicative and non-communicating hydrocephalus. Congenital hydrocephalus has been linked to several changes in the subcommissural organ (SCO). However, it is unclear whether these changes occur before or as a result of the hydrocephalic illness. This report presents three cases of human fetuses with hydrocephalus: one non-communicating case, two communicating cases, and two controls. Hematoxylin-Eosin (H&E) or cresyl violet and immunohistochemistry with anti-transthyretin were used to analyze SCO morphological and secretory changes. We conclude that in the cases presented here, there could be an early regression in the SCO of the communicating cases that is not present in the non-communicating case.
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Hypertension is the leading cause of cardiovascular affection and premature death worldwide. The spontaneously hypertensive rat (SHR) is the most common animal model of hypertension, which is characterized by secondary ventricular dilation and hydrocephalus. Aquaporin (AQP) 1 and 4 are the main water channels responsible for the brain's water balance. The present study focuses on defining the expression of AQPs through the time course of the development of spontaneous chronic hypertension. We performed immunofluorescence and ELISA to examine brain AQPs from 10 SHR, and 10 Wistar−Kyoto (WKY) rats studied at 6 and 12 months old. There was a significant decrease in AQP1 in the choroid plexus of the SHR-12-months group compared with the age-matched control (p < 0.05). In the ependyma, AQP4 was significantly decreased only in the SHR-12-months group compared with the control or SHR-6-months groups (p < 0.05). Per contra, AQP4 increased in astrocytes end-feet of 6 months and 12 months SHR rats (p < 0.05). CSF AQP detection was higher in the SHR-12-months group than in the age-matched control group. CSF findings were confirmed by Western blot. In SHR, ependymal and choroidal AQPs decreased over time, while CSF AQPs levels increased. In turn, astrocytes AQP4 increased in SHR rats. These AQP alterations may underlie hypertensive-dependent ventriculomegaly.
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Acuaporinas , Hidrocefalia , Hipertensión , Animales , Ratas , Ratas Endogámicas SHR , Ratas Endogámicas WKY , Acuaporina 1/metabolismo , Encéfalo/metabolismo , Hidrocefalia/metabolismo , Hipertensión/metabolismo , Agua/metabolismo , Acuaporina 4/metabolismo , Acuaporinas/metabolismoRESUMEN
Aquaporin 4 (AQP4) is a cerebral glial marker that labels ependymal cells and astrocytes' endfeet and is the main water channel responsible for the parenchymal fluid balance. However, in brain development, AQP4 is a marker of glial stem cells and plays a crucial role in the pathophysiology of pediatric hydrocephalus. Gliogenesis characterization has been hampered by a lack of biomarkers for precursor and intermediate stages and a deeper understanding of hydrocephalus etiology is needed. This manuscript is a focused review of the current research landscape on AQP4 as a possible biomarker for gliogenesis and its influence in pediatric hydrocephalus, emphasizing reactive astrogliosis. The goal is to understand brain development under hydrocephalic and normal physiologic conditions.
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Acuaporina 4 , Hidrocefalia , Astrocitos/metabolismo , Niño , Gliosis , Humanos , Neuroglía/metabolismo , Agua/metabolismoRESUMEN
Hydrocephalus is a distension of the ventricular system associated with ventricular zone disruption, reactive astrogliosis, periventricular white matter ischemia, axonal impairment, and corpus callosum alterations. The condition's etiology is typically attributed to a malfunction in classical cerebrospinal fluid (CSF) bulk flow; however, this approach does not consider the unique physiology of CSF in fetal and perinatal patients. The parenchymal fluid contributes to the glymphatic system, and plays a fundamental role in pediatric hydrocephalus, with aquaporin 4 (AQP4) as the primary facilitator of these fluid movements. Despite the importance of AQP4 in the pathophysiology of hydrocephalus, it's expression in human fetal life is not well-studied. This manuscript systematically defines the brain expression of AQP4 in human brain development under control (n = 13) and hydrocephalic conditions (n = 3). Brains from 8 postconceptional weeks (PCW) onward and perinatal CSF from control (n = 2), obstructive (n = 6) and communicating (n = 6) hydrocephalic samples were analyzed through immunohistochemistry, immunofluorescence, western blot, and flow cytometry. Our results indicate that AQP4 expression is observed first in the archicortex, followed by the ganglionic eminences and then the neocortex. In the neocortex, it is initially at the perisylvian regions, and lastly at the occipital and prefrontal zones. Characteristic astrocyte end-feet labeling surrounding the vascular system was not established until 25 PCW. We also found AQP4 expression in a subpopulation of glial radial cells with processes that do not progress radially but, rather, curve following white matter tracts (corpus callosum and fornix), which were considered as glial stem cells (GSC). Under hydrocephalic conditions, GSC adjacent to characteristic ventricular zone disruption showed signs of early differentiation into astrocytes which may affect normal gliogenesis and contribute to the white matter dysgenesis. Finally, we found that AQP4 is expressed in the microvesicle fraction (p < 0.01) of CSF from patients with obstructive hydrocephalus. These findings suggest the potential use of AQP4 as a diagnostic and prognostic marker of pediatric hydrocephalus and as gliogenesis biomarker.
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Hidrocefalia , Sustancia Blanca , Acuaporina 4/metabolismo , Astrocitos/metabolismo , Encéfalo/patología , Líquido Cefalorraquídeo , Niño , Humanos , Hidrocefalia/patología , Sustancia Blanca/patologíaRESUMEN
The choroid plexus (ChP) is involved in the production of cerebrospinal fluid (CSF) and is intimately related to CSF physiopathology. Aquaporin-1 (AQP1) is the water channel directly implicated in CSF production and a potential therapeutic target in the management of CSF circulation disorders. Pathologies that present ventriculomegaly are associated with defective CSF turnover and AQPs are involved in both the production and reabsorption of CSF. This work examines the levels of AQP1 and its dynamics in ventriculomegaly conditions such as congenital hydrocephalus (communicating and obstructive) or type II lissencephaly versus control. We specifically address the expression of AQP1 in the CSF of 16 term-pregnancy infants where it was found to be significantly increased in obstructive cases when compared with communicating hydrocephalus or control patients. We also defined histologically the expression of AQP1 in the ChP from 6 nonsurvival preterm-pregnancy infants ranging ages between 20 and 25 gestational weeks in which AQP1 was mainly expressed at the apical pole of the ChP epithelium (ChPE) in control and lissencephalic patients. AQP1 expression from the Chiari malformation case showed an inverted polarity being expressed in the basal pole of the ChPE colocalizing with the glucose transporter 1 where this transporter is naturally located.
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Acuaporina 1/biosíntesis , Acuaporina 1/líquido cefalorraquídeo , Malformación de Arnold-Chiari/metabolismo , Malformación de Arnold-Chiari/patología , Plexo Coroideo/metabolismo , Hidrocefalia/metabolismo , Hidrocefalia/patología , Adulto , Biomarcadores/líquido cefalorraquídeo , Ventrículos Cerebrales/patología , Femenino , Humanos , Recién Nacido , Recien Nacido Prematuro , Lisencefalia/patología , EmbarazoRESUMEN
Aquaporin 1 (AQP1) and aquaporin 4 (AQP4) have been identified in the eye as playing an essential role in the formation of the aqueous humor along with the Naâº/K⺠ATPase pump. Different authors have described the relationship between blood pressure, aqueous humor production, and intraocular pressure with different conclusions, with some authors supporting a positive correlation between blood pressure and intraocular pressure while others disagree. The aim of this work was to study the effect of high blood pressure on the proteins involved in the production of aqueous humor in the ciliary body (CB) and iris. For this purpose, we used the eyes of spontaneously hypertensive rats (SHR) and their control Wistar-Kyoto rats (WKY). Immunofluorescence was performed in different eye structures to analyze the effects of hypertension in the expression of AQP1, AQP4, and the Naâº/K⺠ATPase α1 and α2 subunits. The results showed an increase in AQP1 and Naâº/K⺠ATPase α1 and a decrease in AQP4 and Naâº/K⺠ATPase α2 in the CB of SHR, while an increase in AQP4 and no significant differences in AQP1 were found in the iris. Therefore, systemic hypertension produced changes in the proteins implicated in the movement of water in the CB and iris that could influence the production rate of aqueous humor, which would be affected depending on the duration of systemic hypertension.
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The choroid plexuses (ChP) are highly vascularized tissues suspended from each of the cerebral ventricles. Their main function is to secret cerebrospinal fluid (CSF) that fills the ventricles and the subarachnoid spaces, forming a crucial system for the development and maintenance of the CNS. However, despite the essential role of the ChP-CSF system to regulate the CNS in a global manner, it still remains one of the most understudied areas in neurobiology. Here we define by immunohistochemistry the expression of different proteins involved in the maturation and functionality of the ChP from the late embryological period to maturity. We found an opposite gradient of expression between aquaporin 1 (AQP1) and glucose transporter 1 (Glut 1) that define functional maturation in the ChP periphery, and proliferating cell nuclear antigen (PCNA) and calbindin (CB), present in the ChP root zone with proliferative activity. We conclude that the maturation of the ChP matures from distal to proximal, starting in the areas nearest to the cortex, expressing in the distal, mature areas AQP1 and Glut1 (related to ChP functionality to support cortex development), and in the proximal immature areas (ChP root) CB and PCNA related to progenitor activity and proliferation.
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OBJECTIVE: The aim of the present work was to make a comparative analysis of the cerebrospinal fluid levels of Tumor necrosis factor (TNFα) and aquaporin 1 (AQP1) in (i) healthy elder control, (ii) patients with mild cognitive impairment and, (iii) patients with idiopathic normal pressure hydrocephalus. PATIENTS AND METHODS: Samples of CSF were taken from seven patients with MCI, 77 years average age; six patients with iNPH, 75 years average age; eleven healthy subjects, 60year average age, were used as controls. The cerebrospinal fluid levels of AQP1 and TNFα were studied by enzyme immunoassay (ELISA). RESULTS: In mild cognitive impairment the total protein content of the CSF and the relative CSF levels of AQP1 and TNFα were similar to those of control subjects and different from those of iNPH patients. On the other hand, in iNPH patients the CSF content of proteins was low and the levels of TNFα were significantly high while those of AQP1 were insignificantly high. CONCLUSION: These finding may help the differential diagnosis and prognosis of mild cognitive impairment and normal pressure hydrocephalus patients.
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Acuaporina 1/líquido cefalorraquídeo , Disfunción Cognitiva/líquido cefalorraquídeo , Hidrocéfalo Normotenso/líquido cefalorraquídeo , Factor de Necrosis Tumoral alfa/líquido cefalorraquídeo , Anciano , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Compromised secretory function of choroid plexus (CP) and defective cerebrospinal fluid (CSF) production, along with accumulation of beta-amyloid (Aß) peptides at the blood-CSF barrier (BCSFB), contribute to complications of Alzheimer's disease (AD). The AD triple transgenic mouse model (3xTg-AD) at 16 month-old mimics critical hallmarks of the human disease: ß-amyloid (Aß) plaques and neurofibrillary tangles (NFT) with a temporal- and regional- specific profile. Currently, little is known about transport and metabolic responses by CP to the disrupted homeostasis of CNS Aß in AD. This study analyzed the effects of highly-expressed AD-linked human transgenes (APP, PS1 and tau) on lateral ventricle CP function. Confocal imaging and immunohistochemistry revealed an increase only of Aß42 isoform in epithelial cytosol and in stroma surrounding choroidal capillaries; this buildup may reflect insufficient clearance transport from CSF to blood. Still, there was increased expression, presumably compensatory, of the choroidal Aß transporters: the low density lipoprotein receptor-related protein 1 (LRP1) and the receptor for advanced glycation end product (RAGE). A thickening of the epithelial basal membrane and greater collagen-IV deposition occurred around capillaries in CP, probably curtailing solute exchanges. Moreover, there was attenuated expression of epithelial aquaporin-1 and transthyretin (TTR) protein compared to Non-Tg mice. Collectively these findings indicate CP dysfunction hypothetically linked to increasing Aß burden resulting in less efficient ion transport, concurrently with reduced production of CSF (less sink action on brain Aß) and diminished secretion of TTR (less neuroprotection against cortical Aß toxicity). The putative effects of a disabled CP-CSF system on CNS functions are discussed in the context of AD.
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Kallmann syndrome (KS) is a genetic disorder which combines hypogonadotropic hypogonadism and anosmia. Hypogonadism is characterized by the absence or reduced levels of gonadotropin-releasing hormone and anosmia due to olfactory bulb aplasia. KS treatment usually begins just before puberty, but brain sexual maturation occurs long before puberty normally at perinatal age. As brain cells implicated in the development of the olfactory and reproductive system have a rostral and a caudal origin, and the rostral origin is affected by aplasia in KS and the caudal origin does not seem to be affected, the early treatment of KS, as proposed in this paper, is to attain brain sexual maturation at the most appropriate age possible to prevent the eunuchoid behavior and appearance observed in KS.
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Síntomas Conductuales/prevención & control , Encéfalo/crecimiento & desarrollo , Síndrome de Kallmann/tratamiento farmacológico , Síndrome de Kallmann/patología , Modelos Biológicos , Maduración Sexual/fisiología , Factores de Edad , Encéfalo/fisiopatología , HumanosRESUMEN
Neuromyelitis optica is an inflammatory disease characterized by neuritis and myelitis of the optic nerve. Its physiopathology is connected with the aquaporin-4 water channel, since antibodies against aquaporin-4 have been found in the cerebrospinal fluid and blood of neuromyelitis optica patients. The seropositivity for aquaporin-4 antibodies is used for the diagnosis of neuromyelitis optica or neuromyelitis optica spectrum disease. On the other hand, aquaporin-4 is expressed in astrocyte feet in the brain-blood barrier and subventricular zones of the brain ventricles. Aquaporin-4 expression is high in cerebrospinal fluid in hydrocephalus. Furthermore, neuroepithelial denudation precedes noncommunicating hydrocephalus and this neuroepithelial disruption could allow aquaporin-4 to reach anomalous brain areas where it is unrecognized and induce the generation of aquaporin-4 antibodies which could cause the neuromyelitis optica and certain types of hydrocephalus.
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The medial preoptic area is a structure located in the hypothalamic anteroventral third ventricle region, and is closely related to the olfactory brain development and sexual differentiation of the brain. The medial preoptic area surrounds the organum vasculosum of the lamina terminalis, and both structures are the main areas where synthesis of gonadotropin-releasing hormone occurs in the brain. Neurons synthesizing gonadotropin-releasing hormone migrate from the medial nasal epithelium to the rostral brain and reach the organum vasculosum of the lamina terminalis and the medial preoptic area. Kallmann syndrome is a genetic disorder which combines hypogonadotropic hypogonadism and anosmia. Hypogonadism is characterized by the absence or reduced levels of gonadotropin-releasing hormone and anosmia due to olfactory bulb aplasia. This paper speculates on the connection between the development of the medial preoptic area, the organum vasculosum of the lamina terminalis and olfactory bulbs with Kallmann syndrome, since the anteroventral third ventricle region is crucial for the normal development of these structures and its connection with the olfactory nerves and sexual maturation.
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Hipotálamo/fisiología , Síndrome de Kallmann/fisiopatología , Área Preóptica/fisiología , AnimalesRESUMEN
BACKGROUND: Aquaporin-4 (AQP4) is a water channel mainly located in the ventricular ependymal cells (brain-CSF barrier), the sub-ependymal glia, glia limitans and in end-feet of astrocytes in at the blood-brain barrier (BBB). METHODS: In the present work, the expression of AQP4 in the cerebrospinal fluid (CSF) in control and congenital human hydrocephalus infants (obstructive and communicating), was analysed by Western-blot and enzyme immunoassay (ELISA). RESULTS: AQP4 was found to be high compared to the control in the CSF in congenital hydrocephalus patients. Western-blot showed higher values for AQP4 than controls in communicating hydrocephalus (communicating: 38.3%, control: 6.9% p < 0.05) although the increase was not significant in obstructive hydrocephalus (obstructive: 14.7%). The AQP4 quantification by ELISA also showed that, the mean concentration of AQP4 in CSF was significantly higher in communicating hydrocephalus (communicating: 11.32 ± 0.69 ng/ml, control: 8.61 ± 0.31 ng/ml; p < 0.05). However, there was no increase over control in obstructive hydrocephalus (obstructive: 8.65 ± 0.80 ng/ml). CONCLUSIONS: AQP4 has a modulatory effect on ependyma stability and acts in CSF production and reabsorption. Therefore, the increase of AQP4 in the CSF in congenital hydrocephalus could be due to the fact that AQP4 passes from the parenchyma to the CSF and this AQP4 movement may be a consequence of ependyma denudation.
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The aim of the present work is to analyze the cerebrospinal fluid proteomic profile, trying to find possible biomarkers of the effects of hypertension of the blood to CSF barrier disruption in the brain and their participation in the cholesterol and ß-amyloid metabolism and inflammatory processes. Cerebrospinal fluid (CSF) is a system linked to the brain and its composition can be altered not only by encephalic disorder, but also by systemic diseases such as arterial hypertension, which produces alterations in the choroid plexus and cerebrospinal fluid protein composition. 2D gel electrophoresis in cerebrospinal fluid extracted from the cistern magna before sacrifice of hypertensive and control rats was performed. The results showed different proteomic profiles between SHR and WKY, that α-1-antitrypsin, apolipoprotein A1, albumin, immunoglobulin G, vitamin D binding protein, haptoglobin and α-1-macroglobulin were found to be up-regulated in SHR, and apolipoprotein E, transthyretin, α-2-HS-glycoprotein, transferrin, α-1ß-glycoprotein, kininogen and carbonic anhidrase II were down-regulated in SHR. The conclusion made here is that hypertension in SHR produces important variations in cerebrospinal fluid proteins that could be due to a choroid plexus dysfunction and this fact supports the close connection between hypertension and blood to cerebrospinal fluid barrier disruption.
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Luteinizing hormone-releasing hormone (LHRH) neurons and fibers are located in the anteroventral hypothalamus, specifically in the preoptic medial area and the organum vasculosum of the lamina terminalis. Most luteinizing hormone-releasing hormone neurons project to the median eminence where they are secreted in the pituitary portal system in order to control the release of gonadotropin. The aim of this study is to provide, using immunohistochemistry and female brain rats, a new description of the luteinizing hormone-releasing hormone fibers and neuron localization in the anterior hypothalamus. The greatest amount of the LHRH immunoreactive material was found in the organum vasculosum of the lamina terminalis that is located around the anterior region of the third ventricle. The intensity of the reaction of LHRH immunoreactive material decreases from cephalic to caudal localization; therefore, the greatest immunoreaction is in the organum vasculosum of the lamina terminalis, followed by the dorsomedial preoptic area, the ventromedial preoptic area, and finally the ventrolateral medial preoptic area, and in fibers surrounding the suprachiasmatic nucleus and subependymal layer on the floor of the third ventricle where the least amount immunoreactive material is found.
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In human spina bifida aperta (SBA), cerebral pathogenesis [hydrocephalus, Sylvius aqueduct (SA) stenosis and heterotopias] is poorly understood. In animal models, loss of ventricular lining (ependymal denudation) causes SA stenosis and hydrocephalus. We aimed to investigate whether ependymal denudation also takes place in human foetal SBA. Considering that ependymal denudation would be related to alterations in junction proteins, sections through SA of five SBA and six control foetuses (gestational ages ranged between 37 and 40 weeks) were immunostained for markers of ependyma (caveolin 1, ßIV-tubulin, S100), junction proteins (N-cadherin, connexin-43, neural cell adhesion molecule (NCAM), blood vessels (Glut-1) and astrocytes [glial fibrillary acidic protein (GFAP)]. In control foetuses, ependymal denudation was absent. In SBA foetuses different stages of ependymal denudation were observed: (i) intact ependyma/neuroepithelium; (ii) imminent ependymal denudation (with abnormal subcellular location of junction proteins); (iii) ependymal denudation (with protrusion of neuropile into SA, formation of rosettes and macrophage invasion); (iv) astroglial reaction. It is suggested that abnormalities in the formation of gap and adherent junctions result in defective ependymal coupling, desynchronized ciliary beating and ependymal denudation, leading to hydrocephalus. The presence of various stages of ependymal denudation within the same full-term SBA foetuses suggests continuation of the process after birth.
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Acueducto del Mesencéfalo/patología , Epéndimo/patología , Espina Bífida Quística/patología , Feto , Técnica del Anticuerpo Fluorescente , Humanos , Hidrocefalia/etiología , Hidrocefalia/patología , Microscopía Confocal , Espina Bífida Quística/complicacionesRESUMEN
Synaptosomes and plasma membranes obtained from rat brain display ectoenzymatic hydrolytic activity responsible for hydrolysis of the neurotransmitter/neuroregulatory nucleotides diadenosine polyphosphates. Intact synaptosomes and plasma and synaptic membranes isolated by sucrose-gradient ultracentrifugation from several brain regions (hypothalamus, hippocampus, temporal cortex, frontal cortex striatum and cerebellum) degraded the fluorogenic substrates diethenoadenosine polyphosphates up to ethenoadenosine as by-product. Purified ectoenzyme cleaved substrates always releasing the mononucleotide moieties ethenoadenosine 5'-monophosphate and the corresponding ethenoadenosine (n-1) 5'-phosphate. Ectoenzymatic hydrolysis reached maximal activity at pH 9.0 (pH range 6.5-9.0) and was activated by Ca(2+) and Mg(2+) ions, with maximal effects around 2.0 mM cation. EDTA drastically reduced activity and Zn(2+) was required for enzyme reactivation. Hydrolysis of substrates followed hyperbolic kinetics with K(m) values in the 3-10 microM range. Diadenosine polyphosphates and heparin behaved as competitive inhibitors in the enzymatic hydrolysis of diethenoadenosine polyphosphates and AMP, ATP, alpha,beta-methyleneADP, ADPbetaS ATPgammaS, beta,gamma-methyleneATP, suramin and diethyl pyrocarbonate were also inhibitors. Ectoenzymatic activity shared the typical characteristics of members of the ecto-nucleotide pyrophosphatase/phosphodiesterase (E-NPP) family and inhibition data suggest that NPP1 ectoenzyme is involved in the cleavage of extracellular diadenosine polyphosphates in brain. Synaptic membranes from cerebellum, hypothalamus and hippocampus presented the highest activities and no activity differences were observed between young and aged animals. However, plasma membranes showed a more homogeneous distribution of ectoenzymatic activity but a general increase was detected in aged animals. Enhancement of ectoenzymatic diadenosine polyphosphate cleaving activity found in plasma membranes from old animals could play a deleterious role in aged brain by limiting neuroprotective effects reported for extracellular diadenosine tetraphosphate.
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Membrana Celular/enzimología , Sistema Nervioso Central/enzimología , Fosfatos de Dinucleósidos/metabolismo , Líquido Extracelular/enzimología , Neuronas/enzimología , Hidrolasas Diéster Fosfóricas/metabolismo , Pirofosfatasas/metabolismo , Factores de Edad , Envejecimiento/metabolismo , Animales , Membrana Celular/ultraestructura , Sistema Nervioso Central/ultraestructura , Activación Enzimática/fisiología , Hidrólisis , Cinética , Masculino , Neuronas/ultraestructura , Fármacos Neuroprotectores/metabolismo , Ratas , Ratas Wistar , Membranas Sinápticas/enzimología , Membranas Sinápticas/ultraestructura , Sinaptosomas/enzimología , Sinaptosomas/ultraestructuraRESUMEN
p73, a homolog of the p53 tumor suppressor, codes for full-length transactivating (TA) and N-terminally truncated (DeltaN) isoforms, with pro- and anti-apoptotic activities, respectively. We examined the expression of the main p73 isoforms in adult human and mouse telencephalon and choroid plexus by immunohistochemistry on paraffin sections, and immunoblotting (IB) of tissue extracts and cerebrospinal fluid (CSF), using antibodies against different protein domains. Cortical neurons expressed TAp73 predominantly in the cytoplasm and DeltaNp73 mainly in the nucleus, with partial overlap in the cytoplasm. Highest expression was found in the hippocampus. IB showed an array of TAp73 variants in adult human cortex and hippocampus. IB of human choroid plexus and CSF using TAp73-specific antibodies revealed the presence of a approximately 90-kDa protein whose molecular weight was reduced after N-deglycosylation, suggesting that glycosylated TAp73 is exported into the CSF. In the mouse, high expression of TAp73 was also detected in the subcommissural organ (SCO), an ependymal gland absent in adult humans. TAp73 colocalized with anti-fibra-Reissner-antibody (AFRU), which is a marker of Reissner's fiber, the secreted SCO product. p73-deficient mice had generalized cortical hypoplasia and hydrocephalus; in addition, we observed a dramatic size reduction of the choroid plexus. However, the SCOs were apparently unaltered and continued to secrete Reissner's fiber. Our findings point to complex and widespread p73 activities in the maintenance of adult cortical neurons and in brain homeostasis. TAp73 in the CSF may play important roles in the maintenance of the adult ventricular wall as well as in the development of the proliferating neuroepithelium.