RESUMO
The aggregation of amyloid-ß (Aß) peptides into senile plaques is a hallmark of Alzheimer's disease (AD) and is hypothesized to be the primary cause of AD related neurodegeneration. Previous studies have shown the ability of curcumin to both inhibit the aggregation of Aß peptides into oligomers or fibrils and reduce amyloids in vivo. Despite the promise of curcumin and its derivatives to serve as diagnostic, preventative, and potentially therapeutic AD molecules, the mechanism by which curcumin and its derivatives bind to and inhibit Aß fibrils' formation remains elusive. Here, we investigated curcumin and a set of curcumin derivatives in complex with a hexamer peptide model of the Aß1-42 fibril using nearly exhaustive docking, followed by multi-ns molecular dynamics simulations, to provide atomistic-detail insights into the molecules' binding and inhibitory properties. In the vast majority of the simulations, curcumin and its derivatives remain firmly bound in complex with the fibril through primarily three different principle binding modes, in which the molecules interact with residue domain 17LVFFA21, in line with previous experiments. In a small subset of these simulations, the molecules partly dissociate the outermost peptide of the Aß1-42 fibril by disrupting ß-sheets within the residue domain 12VHHQKLVFF20. A comparison between binding modes leading or not leading to partial dissociation of the outermost peptide suggests that the latter is attributed to a few subtle key structural and energetic interaction-based differences. Interestingly, partial dissociation appears to be either an outcome of high affinity interactions or a cause leading to high affinity interactions between the molecules and the fibril, which could partly serve as a compensation for the energy loss in the fibril due to partial dissociation. In conjunction with this, we suggest a potential inhibition mechanism of Αß1-42 aggregation by the molecules, where the partially dissociated 16KLVFF20 domain of the outermost peptide could either remain unstructured or wrap around to form intramolecular interactions with the same peptide's 29GAIIG33 domain, while the molecules could additionally act as a patch against the external edge of the second outermost peptide's 16KLVFF20 domain. Thereby, individually or concurrently, these could prohibit fibril elongation.
Assuntos
Peptídeos beta-Amiloides/química , Curcumina/química , Sequência de Aminoácidos , Simulação de Dinâmica MolecularRESUMO
Prostate cancer is biologically and clinically a heterogeneous disease which makes imaging evaluation challenging. Magnetic resonance imaging (MRI) has considerable potential to improve prostate cancer detection and characterization. Until recently morphologic MRI has not been routinely incorporated into clinical care because of its limitation to detect, localize and characterize prostate cancer. Performing prostate gland MRI using functional techniques has the potential to provide unique information regarding tumor behavior, including treatment response. In order for multiparametric MRI data to have an impact on patient management, the collected data need to be relayed to clinicians in a standardized way for image construction, analysis and interpretation. This will ensure that patients are treated effectively and in the most appropriate way. Scoring systems similar to those employed successfully for breast imaging need to be developed.
Assuntos
Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Próstata/patologia , Neoplasias da Próstata/patologia , Humanos , MasculinoRESUMO
In recent years magnetic resonance imaging (MRI) has been increasingly established in the diagnosis of prostate cancer in addition to transrectal ultrasonography (TRUS). The use of T2-weighted imaging allows an exact delineation of the zonal anatomy of the prostate and its surrounding structures. Other MR imaging tools, such as dynamic contrast-enhanced T1-weighted imaging or diffusion-weighted imaging allow an inference of the biochemical characteristics (multiparametric MRI). Prostate cancer, which could only be diagnosed using MR imaging or lesions suspected as being prostate cancer, which are localized in the anterior aspect of the prostate and were missed with repetitive TRUS biopsy, need to undergo MR guided biopsy. Recent studies have shown a good correlation between MR imaging and histopathology of specimens collected by MR-guided biopsy. Improved lesion targeting is therefore possible with MR-guided biopsy. So far data suggest that MR-guided biopsy of the prostate is a promising alternative diagnostic tool to TRUS-guided biopsy.
Assuntos
Biópsia/métodos , Imageamento por Ressonância Magnética/métodos , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/patologia , Ultrassonografia/métodos , Humanos , MasculinoRESUMO
Organizing centers in the developing brain provide an assortment of instructive patterning cues, including Sonic hedgehog (Shh). Here we characterize the forebrain phenotype caused by loss of Ttc21b, a gene we identified in an ENU mutagenesis screen as a novel ciliary gene required for retrograde intraflagellar transport. The Ttc21b mutant has defects in limb, eye and, most dramatically, brain development. We show that Shh signaling is elevated in the rostral portion of the mutant embryo, including in a domain in or near the zona limitans intrathalamica. We demonstrate here that ciliary defects seen in the Ttc21b mutant extend to the embryonic brain, adding forebrain development to the spectrum of tissues affected by defects in ciliary physiology. We show that development of the Ttc21b brain phenotype is modified by lowering levels of the Shh ligand, supporting our hypothesis that the abnormal patterning is a consequence of elevated Shh signaling. Finally, we evaluate Wnt signaling but do not find evidence that this plays a role in causing the perturbed neurodevelopmental phenotype we describe.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Embrião de Mamíferos , Proteínas Hedgehog/metabolismo , Morfogênese/fisiologia , Mutação , Prosencéfalo , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Padronização Corporal/fisiologia , Embrião de Mamíferos/anormalidades , Embrião de Mamíferos/anatomia & histologia , Embrião de Mamíferos/fisiologia , Fator 8 de Crescimento de Fibroblasto/genética , Fator 8 de Crescimento de Fibroblasto/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Proteínas Hedgehog/genética , Fatores de Transcrição Kruppel-Like/genética , Fatores de Transcrição Kruppel-Like/metabolismo , Camundongos , Proteínas do Tecido Nervoso/genética , Proteínas do Tecido Nervoso/metabolismo , Fenótipo , Prosencéfalo/anatomia & histologia , Prosencéfalo/embriologia , Prosencéfalo/metabolismo , Transdução de Sinais/fisiologia , Proteínas Wnt/genética , Proteínas Wnt/metabolismo , Proteína Gli3 com Dedos de ZincoRESUMO
OBJECTIVES: (1) To investigate the reproducibility of computer-assisted measurements of knee alignment angle (KA) from digitized radiographs of osteoarthritis (OA) participants requiring total knee arthroplasty (TKA) and (2) to determine whether landmark choice affects the precision of KA measurements on radiographs. METHODS: Using a custom algorithm, femoral, central, and tibial measurement-guiding rules were interactively placed on digitized posteroanterior fixed-flexion knee radiographs by mouse control and positioned according to different anatomic landmarks. The angle subtended by lines connecting these guiding rules was measured by three readers to assess interobserver, intraobserver and experience-inexperience reproducibility. Test-retest reproducibility was evaluated with duplicate radiographs from a healthy cohort. Reproducibility was assessed using root-mean square coefficients of variation (RMSCV%). The Bland-Altman method was performed on data obtained from varying anatomic landmarks (confidence interval, CI= 95%). RESULTS: From 16 healthy and 30 TKA participants, reproducibility analyses revealed a high degree of intraobserver (n=38, RMSCV=0.56%), interobserver (n=38, RMSCV=0.72%), test-retest (n=16, RMSCV=0.87%) and experience-inexperience (n=38, RMSCV=0.73%) reproducibility with variances below 1%. Varying the orientation of tibial and femoral rules according to anatomic landmarks produced a difference that exceeded an a priori limit of agreement of -1.11 degrees to +1.67 degrees. CONCLUSION: Our custom-designed software provides a robust method for measuring KAs within digitized knee radiographs. Although test-retest analyses were only performed in a healthy cohort, we anticipate a similar degree of reproducibility in an OA sample. A standardized set of anatomic landmarks employed for KA measurement is recommended since arbitrary selection of landmarks resulted in imprecise KA measurement even with a computer-assisted technique.
Assuntos
Articulação do Joelho/diagnóstico por imagem , Osteoartrite do Joelho/diagnóstico por imagem , Amplitude de Movimento Articular/fisiologia , Adulto , Artroplastia do Joelho , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Articulação do Joelho/anatomia & histologia , Masculino , Osteoartrite do Joelho/fisiopatologia , Radiografia , Reprodutibilidade dos TestesRESUMO
OBJECTIVES: To determine the ability of radiographic bone texture (BTX) parameters to quantify subchondral tibia sclerosis and to examine clinical relevance for assessing osteoarthritis (OA) progression. We examined the relationship between BTX parameters and each of (1) location-specific joint space width (JSW) [JSW(x)] and minimum JSW (mJSW) of the affected compartment, and (2) knee alignment (KA) angle in knee radiographs of participants undergoing total knee arthroplasty (TKA). DESIGN: Digitized fixed-flexion knee radiographs were analyzed for run-length and topological BTX parameters in a subchondral region using an algorithm. Medial JSW(x) was computed at x=0.200, 0.225, 0.250 and 0.275 according to a coordinate system defined by anatomic landmarks. mJSW was determined for medial and lateral compartment lesions. KA angles were determined from radiographs using an anatomic landmark-guided algorithm. JSW measures and the magnitude of knee malalignment were each correlated with BTX parameters. Reproducibility of BTX parameters was measured by root-mean square coefficients of variation (RMSCV%). RESULTS: Run-length BTX parameters were highly reproducible (RMSCV%<1%) while topological parameters showed poorer reproducibility (>5%). In TKA participants (17 women, 13 men; age: 66+/-9 years; body mass index (BMI): 31+/-6 kg m(-2); WOMAC: 41.5+/-16.1; Kellgren-Lawrence score mode: 4), reduced trabecular spacing (Tb.Sp) and increased free ends (FE) were correlated with decreased JSW after accounting for BMI, gender and knee malalignment. These relationships were dependent on site of JSW measurement. CONCLUSION: High reproducibility in quantifying bone sclerosis using Tb.Sp and its significant relationship with JSW demonstrated potential for assessing OA progression. Increased trabecular FE and reduced porosity observed with smaller JSW suggest collapsing subchondral bone or trabecular plate perforation in advanced knee OA.
Assuntos
Densidade Óssea/fisiologia , Cartilagem Articular/patologia , Articulação do Joelho/patologia , Osteoartrite do Joelho/patologia , Tíbia/patologia , Idoso , Progressão da Doença , Feminino , Humanos , Articulação do Joelho/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Osteoartrite do Joelho/diagnóstico por imagem , Radiografia , Reprodutibilidade dos Testes , Esclerose/diagnóstico por imagem , Esclerose/patologia , Tíbia/diagnóstico por imagemRESUMO
Aggregation of neurotransmitter receptors at pre- and postsynaptic structures is crucial for efficient neuronal communication. In contrast to the wealth of information about postsynaptic specializations, little is known about the molecular organization of presynaptic membrane proteins. We show here that the metabotropic glutamate receptor mGluR7a, which localizes specifically to presynaptic active zones, interacts in vitro and in vivo with PICK1. Coexpression in heterologous systems induces coclustering dependent upon the extreme C terminus of mGluR7a and the PDZ domain of PICK1. mGluR7a and PICK1 localize to excitatory synapses in hippocampal neurons. Furthermore, whereas transfected mGluR7a clusters at presynaptic sites, mGluR7adelta3 lacking the PICK1 binding site targets to axons but does not cluster. These results suggest that PICK1 is a component of the presynaptic machinery involved in mGluR7a aggregation and in modulation of glutamate neurotransmission.
Assuntos
Proteínas de Transporte/metabolismo , Proteínas Nucleares/metabolismo , Terminações Pré-Sinápticas/metabolismo , Agregação de Receptores/genética , Receptores de Glutamato Metabotrópico/genética , Receptores de Glutamato Metabotrópico/metabolismo , Animais , Sítios de Ligação/genética , Proteínas de Transporte/genética , Células Cultivadas , Proteínas do Citoesqueleto , Fibroblastos/citologia , Fibroblastos/metabolismo , Imunofluorescência , Genes Reporter , Proteínas de Fluorescência Verde , Hipocampo/citologia , Hipocampo/metabolismo , Imuno-Histoquímica , Proteínas Luminescentes/genética , Neurônios/citologia , Neurônios/metabolismo , Proteínas Nucleares/genética , Ligação Proteica/genética , Isoformas de Proteínas/química , Estrutura Terciária de Proteína/genética , Ratos , Receptores de Glutamato Metabotrópico/química , Transfecção , Técnicas do Sistema de Duplo-HíbridoRESUMO
Homer is a neuronal immediate early gene (IEG) that is enriched at excitatory synapses and binds group 1 metabotropic glutamate receptors (mGluRs). Here, we characterize a family of Homer-related proteins derived from three distinct genes. Like Homer IEG (now termed Homer 1a), all new members bind group 1 mGluRs. In contrast to Homer 1a, new members are constitutively expressed and encode a C-terminal coiled-coil (CC) domain that mediates self-multimerization. CC-Homers form natural complexes that cross-link mGluRs and are enriched at the postsynaptic density. Homer 1a does not multimerize and blocks the association of mGluRs with CC-Homer complexes. These observations support a model in which the dynamic expression of Homer 1a competes with constitutively expressed CC-Homers to modify synaptic mGluR properties.
Assuntos
Proteínas de Transporte/fisiologia , Proteínas do Tecido Nervoso/metabolismo , Neuropeptídeos/fisiologia , Receptores de Glutamato Metabotrópico/metabolismo , Sinapses/metabolismo , Sequência de Aminoácidos , Animais , Encéfalo/metabolismo , Proteínas de Transporte/antagonistas & inibidores , Proteínas de Transporte/química , Proteínas de Transporte/genética , Proteínas de Arcabouço Homer , Camundongos , Dados de Sequência Molecular , Família Multigênica/genética , Neuropeptídeos/antagonistas & inibidores , Neuropeptídeos/química , Neuropeptídeos/genética , Ratos , Distribuição TecidualRESUMO
Shank is a recently described family of postsynaptic proteins that function as part of the NMDA receptor-associated PSD-95 complex (Naisbitt et al., 1999 [this issue of Neuron]). Here, we report that Shank proteins also bind to Homer. Homer proteins form multivalent complexes that bind proline-rich motifs in group 1 metabotropic glutamate receptors and inositol trisphosphate receptors, thereby coupling these receptors in a signaling complex. A single Homer-binding site is identified in Shank, and Shank and Homer coimmunoprecipitate from brain and colocalize at postsynaptic densities. Moreover, Shank clusters mGluR5 in heterologous cells in the presence of Homer and mediates the coclustering of Homer with PSD-95/GKAP. Thus, Shank may cross-link Homer and PSD-95 complexes in the PSD and play a role in the signaling mechanisms of both mGluRs and NMDA receptors.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Proteínas de Transporte/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neurônios/química , Neuropeptídeos/metabolismo , Receptores de Glutamato Metabotrópico/metabolismo , Animais , Sítios de Ligação/fisiologia , Células COS , Cálcio/metabolismo , Canais de Cálcio/metabolismo , Proteínas de Transporte/química , Proteínas de Transporte/genética , Proteína 4 Homóloga a Disks-Large , Proteínas de Arcabouço Homer , Humanos , Receptores de Inositol 1,4,5-Trifosfato , Peptídeos e Proteínas de Sinalização Intracelular , Rim/citologia , Proteínas de Membrana , Microscopia Imunoeletrônica , Mutagênese Sítio-Dirigida/fisiologia , Neurônios/metabolismo , Neuropeptídeos/química , Prolina/metabolismo , Estrutura Terciária de Proteína , Coelhos , Ratos , Receptores Citoplasmáticos e Nucleares/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Proteínas Associadas SAP90-PSD95 , Sinapses/química , Sinapses/metabolismo , Sinapses/ultraestrutura , TransfecçãoRESUMO
Mutations in a gene encoding a multitransmembrane protein, termed presenilin 1 (PS1), are causative in the majority of early-onset cases of AD. To determine the topology of PS1, we utilized two strategies: first, we tested whether putative transmembranes are sufficient to export a protease-sensitive substrate across a lipid bilayer; and second, we examined the binding of antibodies to specific PS1 epitopes in cultured cells selectively permeabilized with the pore-forming toxin, streptolysin-O. We document that the "loop," N-terminal, and C-terminal domains of PS1 are oriented toward the cytoplasm.
Assuntos
Proteínas de Membrana/química , Precursor de Proteína beta-Amiloide/química , Precursor de Proteína beta-Amiloide/genética , Animais , Células CHO/química , Células CHO/fisiologia , Células COS/química , Células COS/fisiologia , Cricetinae , Citoplasma/química , Éxons/genética , Humanos , Proteínas de Membrana/genética , Mutação/fisiologia , Presenilina-1 , Conformação Proteica , Estrutura Terciária de Proteína , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genéticaRESUMO
The present experiment examined oral ethanol self-administration in 5-HT1b knockout (KO) mice and 5-HT1b wide-type (WT) control mice using a continuous access operant procedure. After lever press training, adult 5-HT1b KO and 5-HT1b WT mice were placed in operant chambers on a 23 h per day basis with access to food (FR1), 10% v/v ethanol (FR4), and water from a sipper tube. KO mice displayed higher rates of responding on the ethanol-associated lever compared to WT mice. KO mice also consumed greater amounts of water. Food responding was the same in both genotypes. Following 30 sessions, ethanol concentration was altered every 5 days. Response patterns were determined using 0, 5, and 20% v/v ethanol concentrations. Ethanol responding (0, 5, 10, and 20% v/v) was also examined after the addition of 0.15% saccharin. KO mice and WT mice showed similar response rates for all ethanol concentrations. Since KO mice showed greater levels of ethanol responding only for unsweetened 10% v/v ethanol, and showed modest ethanol self-administration overall, the present results are not consistent with the notion that 5-HT1b KO have a generally greater preference for ethanol than 5-HT1b WT mice.
Assuntos
Consumo de Bebidas Alcoólicas/genética , Condicionamento Operante/fisiologia , Receptores de Serotonina/genética , Animais , Relação Dose-Resposta a Droga , Etanol/administração & dosagem , Feminino , Masculino , Camundongos , Camundongos Knockout , Motivação , Receptor 5-HT1B de Serotonina , Receptores de Serotonina/fisiologia , AutoadministraçãoRESUMO
Decision-theoretic refinement planning is a new technique for finding optimal courses of action. The authors sought to determine whether this technique could identify optimal strategies for medical diagnosis and therapy. An existing model of acute deep venous thrombosis of the lower extremities was encoded for analysis by the decision-theoretic refinement planning system (DRIPS). The encoding represented 6,206 possible plans. The DRIPS planner used artificial intelligence techniques to eliminate 5,150 plans (83%) from consideration without examining them explicitly. The DRIPS system identified the five strategies that minimized cost and mortality. The authors conclude that decision-theoretic planning is useful for examining large medical-decision problems.
Assuntos
Inteligência Artificial , Tomada de Decisões Assistida por Computador , Teoria da Decisão , Algoritmos , Análise Custo-Benefício , Árvores de Decisões , Humanos , Modelos Biológicos , Design de Software , Tromboflebite/diagnóstico , Tromboflebite/terapia , Fatores de TempoRESUMO
Mutations in two related genes, PS1 (1) and PS2 (2,3) located on chromosomes 14 and 1, respectively, account for the majority of early onset cases of familial Alzheimer's disease (FAD). PS1 and PS2 are predominantly localized in the endoplasmic reticulum and Golgi (4-7). PS1 is a 467 amino acid peptide predicted to contain between seven and nine transmembrane helices based on hydrophobicity profiles (1,8). The protein topology of PS1 and its C. elegans homologues, SEL-12 and HOP-1, have been examined by several investigators (7,9-13). This chapter describes two approaches we utilized to determine the topological orientation of the PS1 N-terminal, and C-terminal domains, and a hydrophilic "loop" region encompassing amino acids 263-407. The first approach is based on the proteolytic sensitivity of amyloid precursor protein (APP) protein chimeras to endoproteolytic cleavage by ß-secretase in the lumen of the Golgi. The second approach is based on selective permeabilization of the plasma membrane using a bacterial pore-forming toxin, streptolysin-O (SLO), and subsequent immunocytochemical probing for cytosolic epitopes using specific antibodies. Both of these methods can be easily adapted to determine the topology of other membrane proteins.
RESUMO
The human neurodegenerative diseases, including motor neuron disease and Alzheimer's disease (AD), are characterized by a selective involvement of certain regions of the brain/spinal cord and selected populations of neurons. Sporadic amyotrophic lateral sclerosis (ALS) is an age-associated disease with cytoskeletal abnormalities and death of motor neurons; familial ALS (FALS), an autosomal dominant disease linked to mutations in superoxide dismutase 1 (SOD1), is manifested by inclusions and degeneration of motor neurons. Autosomal dominant familial AD (FAD), linked to mutations in presenilin (PS1 and PS2) genes or the amyloid precursor protein (APP) gene, shows brain abnormalities (e.g., neurofibrillary tangles, deposits of .-amyloid A., and death of subsets of neurons) similar to those that occur in sporadic AD, the risk of which is enhanced by the presence of one or two copies of apolipoprotein E4 (apoE4) alleles. To examine the mechanisms of these diseases, investigators have used a variety of animal models, including experimentally produced, spontaneously occurring, or genetically engineered models of disease. Studies of models of degeneration of motor neurons (axotomy) and cytoskeletal abnormalities seen in motor neuron disease (i.e., axonopathy induced by .,.'-iminodipropionitrile (IDPN), hereditary canine spinal muscular atrophy (HCSMA), and neurofilament NF transgenic Tg mice) have demonstrated that NF-filled swellings of axons are related to alterations in the biology of NF transport. Tg mice with SOD1 mutations, which develop the clinical features of FALS, show selective degeneration of motor neurons, which is attributed to the acquisition of toxic properties by mutant SOD1. Models of AD include: aged monkeys that show both cognitive/memory deficits and cellular abnormalities (amyloid deposition/cytoskeletal abnormalities of neurons) in cortex and hippocampus; and Tg mice that express mutant human FAD-linked genes (i.e., APP and PS1) and show increased levels of A.42, amyloid deposits, dystrophic neurites, and local responses of astrocytes and microglia. This review discusses the behavioral/neuropathological features of AD, the results of investigations of mechanisms of disease in model systems, and potential utility of some of these models for testing new therapies.
Assuntos
Doença de Alzheimer , Doença de Alzheimer/genética , Doença de Alzheimer/patologia , Doença de Alzheimer/fisiopatologia , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/patologia , Esclerose Lateral Amiotrófica/fisiopatologia , Animais , Modelos Animais de Doenças , Cães , Humanos , Camundongos , Camundongos TransgênicosRESUMO
The control of growth, patterning, and differentiation of the mammalian forebrain has a large genetic component, and many human disease loci associated with cortical malformations have been identified. To further understand the genes involved in controlling neural development, we have performed a forward genetic screen in the mouse (Mus musculus) using ENU mutagenesis. We report the results from our ENU screen in which we biased our ascertainment toward mutations affecting neurodevelopment. Our screen had three components: a careful morphological and histological examination of forebrain structure, the inclusion of a retinoic acid response element-lacZ reporter transgene to highlight patterning of the brain, and the use of a genetically sensitizing locus, Lis1/Pafah1b1, to predispose animals to neurodevelopmental defects. We recovered and mapped eight monogenic mutations, seven of which affect neurodevelopment. We have evidence for a causal gene in four of the eight mutations. We describe in detail two of these: a mutation in the planar cell polarity gene scribbled homolog (Drosophila) (Scrib) and a mutation in caspase-3 (Casp3). We find that refining ENU mutagenesis in these ways is an efficient experimental approach and that investigation of the developing mammalian nervous system using forward genetic experiments is highly productive.
Assuntos
Etilnitrosoureia/efeitos adversos , Regulação da Expressão Gênica no Desenvolvimento , Estudos de Associação Genética , Ensaios de Triagem em Larga Escala , Mutagênicos/efeitos adversos , Doenças do Sistema Nervoso/genética , Prosencéfalo/metabolismo , 1-Alquil-2-acetilglicerofosfocolina Esterase/genética , 1-Alquil-2-acetilglicerofosfocolina Esterase/metabolismo , Animais , Caspase 3/genética , Caspase 3/metabolismo , Mapeamento Cromossômico , Cruzamentos Genéticos , Impressões Digitais de DNA , Etilnitrosoureia/administração & dosagem , Feminino , Genes Reporter , Heterozigoto , Homozigoto , Humanos , Imuno-Histoquímica , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Masculino , Camundongos , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/metabolismo , Mutagênicos/administração & dosagem , Mutação , Doenças do Sistema Nervoso/embriologia , Doenças do Sistema Nervoso/metabolismo , Doenças do Sistema Nervoso/patologia , Fenótipo , Polimorfismo de Nucleotídeo Único , Prosencéfalo/citologia , Prosencéfalo/efeitos dos fármacos , Prosencéfalo/embriologia , TransgenesAssuntos
Doença das Coronárias , Vasos Coronários/fisiologia , Esforço Físico , Adulto , Eletrocardiografia , Humanos , Isquemia , Masculino , Pessoa de Meia-IdadeRESUMO
The aim of the present study was two-fold: first, to examine the temporal relationship between increased expression of Fos in LHRH neurons of proestrous hamsters and increased plasma levels of LH, FSH, estradiol-17 beta (E2), and progesterone (P4); and second, to establish whether male hamsters, like females, also show diurnal variations in the number of LHRH neurons expressing Fos. Blood samples were collected from proestrous females at 0900 n, 1200 h, 1500 h, and 1800 h and also from males at 0300 h, 0900 h, 1500 h, and 2100 h. RIA of the plasma revealed significant peaks of LH, FSH, and E2 at 1500 h, and of P4 at 1800 h in the females; a significant but smaller peak of LH also occurred at 1500 h in the males. Double-label immunocytochemistry, using antibodies directed against amino acids 127-152 of the human Fos protein and against LHRH, showed that female hamsters expressed Fos in fewer than 10% of their LHRH neurons during the morning and at noon of proestrus but in approximately 41% of these neurons during the late afternoon (1800 h). In contrast, no expression of Fos occurred in LHRH neurons of male hamsters at any time of the day. The finding that the females showed an increase in the number of LHRH neurons expressing Fos after, and not before, the initiation of the preovulatory gonadotropin surge is significant because it does not readily support the hypothesis that this expression of immediate-early genes is in some way associated with the induction of the surge. Instead, the results are consistent with the view that expression of Fos in LHRH neurons reflects either the activation of a mechanism responsible for terminating the surge or, alternatively, the activation of a compensatory mechanism responsible for replenishing depleted neuropeptide stocks.
Assuntos
Ritmo Circadiano , Expressão Gênica , Genes fos , Hormônio Liberador de Gonadotropina/fisiologia , Neurônios/metabolismo , Animais , Cricetinae , Estradiol/sangue , Feminino , Hormônio Foliculoestimulante/sangue , Hormônio Luteinizante/sangue , Masculino , Mesocricetus , Proestro/fisiologia , Progesterona/sangue , Caracteres SexuaisRESUMO
Light-microscope immunocytochemistry was used to investigate the LHRH system of adult male Syrian hamsters. Half of the animals were transferred from long to short photoperiods (14L:10D to 6L:18D) for 10 wk, causing plasma gonadotropin levels and the testes to revert to a prepubertal condition. In spite of the marked differences in the reproductive axis between the two groups of hamsters, the number of immunopositive LHRH neurons observed in the preoptic-medial septal area and diagonal band of Broca was approximately 400 in both cases; of these, 87-91% were monopolar and 9-13% were bipolar, regardless of whether the brains were sectioned in a coronal or sagittal plane. These results, therefore, fail to support the hypothesis that photoperiodic changes in the number of LHRH neurons play a major role in controlling the seasonal regression and recrudescence of the reproductive system in the hamster. However, morphometric analysis of the perikarya using an IBAS 2000 automatic image analyzer revealed a photoperiod-related difference. Surprisingly, the perikarya of both monopolar and bipolar LHRH neurons were significantly larger in hamsters that had been maintained on short days, as opposed to long days. These findings, therefore, are in harmony with the view that the inhibitory effect of short days on the reproductive axis is mediated through a suppression of LHRH secretion, which in turn is reflected as an increase in the net content of LHRH within the brain.