RESUMO
Human embryonic stem cells (hESCs) differentiate into specialized cells, including midbrain dopaminergic neurons (DANs), and Non-human primates (NHPs) injected with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine develop some alterations observed in Parkinson's disease (PD) patients. Here, we obtained well-characterized DANs from hESCs and transplanted them into two parkinsonian monkeys to assess their behavioral and imaging changes. DANs from hESCs expressed dopaminergic markers, generated action potentials, and released dopamine (DA) in vitro. These neurons were transplanted bilaterally into the putamen of parkinsonian NHPs, and using magnetic resonance imaging techniques, we calculated the fractional anisotropy (FA) and mean diffusivity (MD), both employed for the first time for these purposes, to detect in vivo axonal and cellular density changes in the brain. Likewise, positron-emission tomography scans were performed to evaluate grafted DANs. Histological analyses identified grafted DANs, which were quantified stereologically. After grafting, animals showed signs of partially improved motor behavior in some of the HALLWAY motor tasks. Improvement in motor evaluations was inversely correlated with increases in bilateral FA. MD did not correlate with behavior but presented a negative correlation with FA. We also found higher 11C-DTBZ binding in positron-emission tomography scans associated with grafts. Higher DA levels measured by microdialysis after stimulation with a high-potassium solution or amphetamine were present in grafted animals after ten months, which has not been previously reported. Postmortem analysis of NHP brains showed that transplanted DANs survived in the putamen long-term, without developing tumors, in immunosuppressed animals. Although these results need to be confirmed with larger groups of NHPs, our molecular, behavioral, biochemical, and imaging findings support the integration and survival of human DANs in this pre-clinical PD model.
Assuntos
Células-Tronco Embrionárias Humanas , Doença de Parkinson , Animais , Humanos , Neurônios Dopaminérgicos/metabolismo , Células-Tronco Embrionárias Humanas/metabolismo , Haplorrinos/metabolismo , Mesencéfalo/metabolismo , Dopamina/metabolismo , Doença de Parkinson/terapia , Doença de Parkinson/metabolismoRESUMO
We studied changes in the expression of growth-associated protein 43 (GAP43), glial fibrillary acidic protein (GFAP), and calcium-binding proteins (calbindin [Cb] and parvalbumin [Pv]) in the dorsal lateral geniculate nucleus (dLGN) of four capuchin monkeys with laser-induced retinal lesions. The lesions were generated with the aid of a neodymium-YAG dual-frequency laser with shots of different intensity and at different survival time in each animal. The expression of these proteins in the layers of the dLGN was evaluated by performing histodensitometry of coronal sections throughout the nucleus. High-power laser shots administered at the border of the optic disc (OD)-injured fibers resulted in large scotomas. These lesions produced a devastating effect on fibers in this passage, resulting in large deafferentation of the dLGN. The time course of plasticity expressed in this nucleus varied with the degree of the retinal lesion. Topographically, corresponding portions of the dLGN were inferred by the extent of the ocular dominance column revealed by cytochrome oxidase histochemistry in flattened preparations of V1. In the region representing the retinal lesion, the expression of GFAP, GAP43, Pv, and Cb increased and decreased in the corresponding dLGN layers shortly after lesion induction and returned to their original values with different time courses. Synaptogenesis (indicated by GAP43 expression) appeared to be increased in all layers, while "cleansing" of the glial-damaged region (indicated by GFAP expression) was markedly greater in the parvocellular layers, followed by the magnocellular layers. Schematic drawings of optic discs laser lesions and of series of coronal sections of the dLGN, in three monkeys, depicting the areas of the nucleus deafferented by the lesions.
Assuntos
Corpos Geniculados , Parvalbuminas , Animais , Calbindinas/metabolismo , Haplorrinos/metabolismo , Lasers , Parvalbuminas/metabolismo , Vias Visuais/metabolismoRESUMO
The spontaneous object recognition (SOR) task is one of the most widely used behavioral protocols to assess visual memory in animals. However, only recently was it shown that nonhuman primates also perform well on this task. Here we further characterized this new monkey recognition memory test by assessing the performance of adult marmosets after an acute systemic administration of two putative amnesic agents: the competitive muscarinic acetylcholine receptor antagonist scopolamine (SCP; 0.05 mg/kg) and the noncompetitive N-methyl-d-aspartate glutamate receptor antagonist MK-801 (0.015 mg/kg). We also determined whether the acetylcholinesterase inhibitor donepezil (DNP; 0.50 mg/kg), a clinically-used cognitive enhancer, reverses memory deficits caused by either drug. The subjects had an initial 10 min sample trial where two identical neutral objects could be explored. After a 6 h retention interval, recognition was based on an exploratory preference for a new rather than familiar object during a 10 min test trial. Both SCP and MK-801 impaired the marmosets' performance on the SOR task, as both objects were explored equivalently. Co-administration of 0.50 mg/kg of DNP reversed the SCP- but not the MK-801-induced memory deficit. These results indicate that cholinergic and glutamatergic pathways mediate object recognition memory in the monkey SOR task.
Assuntos
Maleato de Dizocilpina/farmacologia , Teste de Campo Aberto/efeitos dos fármacos , Reconhecimento Psicológico/efeitos dos fármacos , Escopolamina/farmacologia , Acetilcolinesterase/metabolismo , Animais , Callithrix/metabolismo , Donepezila/farmacologia , Antagonistas de Aminoácidos Excitatórios/farmacologia , Feminino , Haplorrinos/metabolismo , Masculino , Memória/efeitos dos fármacos , Transtornos da Memória/tratamento farmacológico , Transtornos da Memória/metabolismo , Antagonistas Muscarínicos/farmacologia , Nootrópicos/farmacologia , Receptores Muscarínicos/metabolismoRESUMO
Alzheimer's disease (AD) and type 2 diabetes appear to share similar pathogenic mechanisms. dsRNA-dependent protein kinase (PKR) underlies peripheral insulin resistance in metabolic disorders. PKR phosphorylates eukaryotic translation initiation factor 2α (eIF2α-P), and AD brains exhibit elevated phospho-PKR and eIF2α-P levels. Whether and how PKR and eIF2α-P participate in defective brain insulin signaling and cognitive impairment in AD are unknown. We report that ß-amyloid oligomers, AD-associated toxins, activate PKR in a tumor necrosis factor α (TNF-α)-dependent manner, resulting in eIF2α-P, neuronal insulin receptor substrate (IRS-1) inhibition, synapse loss, and memory impairment. Brain phospho-PKR and eIF2α-P were elevated in AD animal models, including monkeys given intracerebroventricular oligomer infusions. Oligomers failed to trigger eIF2α-P and cognitive impairment in PKR(-/-) and TNFR1(-/-) mice. Bolstering insulin signaling rescued phospho-PKR and eIF2α-P. Results reveal pathogenic mechanisms shared by AD and diabetes and establish that proinflammatory signaling mediates oligomer-induced IRS-1 inhibition and PKR-dependent synapse and memory loss.
Assuntos
Peptídeos beta-Amiloides/toxicidade , Encéfalo/efeitos dos fármacos , Proteínas Substratos do Receptor de Insulina/metabolismo , Polímeros/toxicidade , Fator de Necrose Tumoral alfa/metabolismo , eIF-2 Quinase/metabolismo , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/química , Animais , Encéfalo/metabolismo , Modelos Animais de Doenças , Haplorrinos/metabolismo , Hipoglicemiantes/farmacologia , Proteínas Substratos do Receptor de Insulina/antagonistas & inibidores , Transtornos da Memória/metabolismo , Transtornos da Memória/patologia , Camundongos , Camundongos Knockout , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Fosforilação/efeitos dos fármacos , Polímeros/química , Receptores Tipo I de Fatores de Necrose Tumoral/deficiência , Receptores Tipo I de Fatores de Necrose Tumoral/genética , Receptores Tipo I de Fatores de Necrose Tumoral/metabolismo , Transdução de Sinais/efeitos dos fármacos , Sinapses/efeitos dos fármacos , Sinapses/metabolismo , Fator de Necrose Tumoral alfa/antagonistas & inibidores , eIF-2 Quinase/deficiência , eIF-2 Quinase/genéticaRESUMO
This study describes the identification of the Plasmodium vivax rhoptry antigen Pv34 whose sequence was obtained based on homology comparison with the Plasmodium falciparum Pf34. The pv34 gene product was characterized by molecular biology and immunological techniques. Additionally, association of Pv34 to detergent-resistant microdomains (DRMs), expression in late blood-stage parasites and recognition of recombinant Pv34 (rPv34) by sera from P. vivax-infected Aotus monkeys and patients was assessed. Lymphoproliferation and cytokine secretion was also evaluated in individuals living in malaria endemic areas. Altogether, the data support carrying out further studies to assess the immunogenicity and protection-inducing ability of rPv34 as component of a multi-antigenic, multi-stage vaccine against vivax malaria.
Assuntos
Vacinas Antimaláricas/imunologia , Plasmodium vivax/imunologia , Proteínas de Protozoários/imunologia , Adulto , Idoso , Animais , Western Blotting , Citocinas/metabolismo , Eletroforese em Gel de Poliacrilamida , Técnica Indireta de Fluorescência para Anticorpo , Haplorrinos/imunologia , Haplorrinos/metabolismo , Haplorrinos/parasitologia , Humanos , Pessoa de Meia-Idade , CoelhosRESUMO
En condiciones fisiológicas las células aeróbicas producen cantidades de Especies Reactivas de Oxígeno. La supervivencia celular depende del balance entre los procesos oxidativos y las defensas antioxidantes. Esta interacción determina si la célula se encuentra en estrés oxidativo o no. Recientes estudios sugieren que una reducida capacidad en el metabolismo oxidativo así como estados proinflamatorios contribuyen a cambios neurodegenerativos relacionados con la edad en los humanos. Por tal motivo en el presente estudio nosotros comparamos los niveles séricos de la actividad de la superóxido dismutasa (SOD), Catalasa (CAT) y también los niveles de malonildialdehido (MDA) y el factor de necrosis tumoral a (TNFa) en primates no humanos jóvenes y viejos. Nuestros resultados sugieren relación entre las alteraciones del metabolismo oxidativo con los cambios neurodegenerativos que ocurren en los monos.