RESUMEN
The protein α-synuclein, a major component of Lewy bodies in nigral neurons of aged and Parkinson's disease (PD) patients, normally co-localizes with synaptophysin and regulates the pool of synaptic vesicles. Our earlier study on substantia nigra pars compacta (SNpc) in an Asian-Indian population, demonstrated an age-associated linear but non-logarithmic increase in soluble α-synuclein without any loss of nigral neurons. Another distinctive finding was the presence of activated microglia in the ventrolateral region of the aged nigra, suggesting sub-threshold neurodegeneration. Since microglia prune dendrites, we evaluated the alterations in dendritic arborisation in the SNpc from autopsied midbrains of Asian-Indians through aging, using Golgi-Kopsch protocol. Further, we evaluated the expression of synaptic proteins, synaptophysin and synaptotagmin-11 as parallel markers of synaptic transmission anomalies. The dendritic arborization pattern was typical of large multipolar neurons. A subtle but non-significant decline in parameters like dendritic length and number of intersections was noted. Thus, the alterations were milder than those reported in PD. In the neurons of the young (till 10 years), faint cytoplasmic immunoreactivity of synaptic proteins was noted. In the adults and elderly, it was membrane-bound or appeared as punctae within neuropil. Both proteins showed a slight age-related decline, suggesting a mild decrease in the synaptic vesicular traffic, affecting the dopamine transmission with age that may manifest as minor motor disabilities in the elderly. Mapping the differences in synaptic profiles in differentially susceptible ethnic populations, could reveal interesting insights. Thus, nigra of aged individuals and PD patients share pathogenic features that differ in magnitude.
Asunto(s)
Envejecimiento/metabolismo , Envejecimiento/patología , Enfermedad de Parkinson/metabolismo , Enfermedad de Parkinson/patología , Porción Compacta de la Sustancia Negra/metabolismo , Porción Compacta de la Sustancia Negra/patología , Adulto , Anciano , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , Plasticidad Neuronal/fisiología , Neuronas/metabolismo , Neuronas/patología , Sinaptofisina/metabolismo , Sinaptotagminas/metabolismoRESUMEN
The amygdala is a medial temporal lobe structure implicated in social and emotional regulation. In typical development (TD), the amygdala continues to increase volumetrically throughout childhood and into adulthood, while other brain structures are stable or decreasing in volume. In autism spectrum disorder (ASD), the amygdala undergoes rapid early growth, making it volumetrically larger in children with ASD compared to TD children. Here we explore: (a) if dendritic arborization in the amygdala follows the pattern of protracted growth in TD and early overgrowth in ASD and (b), if spine density in the amygdala in ASD cases differs from TD from youth to adulthood. The amygdala from 32 postmortem human brains (7-46 years of age) were stained using a Golgi-Kopsch impregnation. Ten principal neurons per case were selected in the lateral nucleus and traced using Neurolucida software in their entirety. We found that both ASD and TD individuals show a similar pattern of increasing dendritic length with age well into adulthood. However, spine density is (a) greater in young ASD cases compared to age-matched TD controls (<18 years old) and (b) decreases in the amygdala as people with ASD age into adulthood, a phenomenon not found in TD. Therefore, by adulthood, there is no observable difference in spine density in the amygdala between ASD and TD age-matched adults (≥18 years old). Our findings highlight the unique growth trajectory of the amygdala and suggest that spine density may contribute to aberrant development and function of the amygdala in children with ASD.
Asunto(s)
Amígdala del Cerebelo/crecimiento & desarrollo , Amígdala del Cerebelo/patología , Trastorno del Espectro Autista/patología , Espinas Dendríticas/ultraestructura , Neuronas/citología , Adolescente , Adulto , Factores de Edad , Niño , Femenino , Humanos , Masculino , Persona de Mediana Edad , Tinción con Nitrato de Plata , Adulto JovenRESUMEN
BACKGROUND: Golgi stains are notoriously capricious, particularly when applied to human brain. The well-known difficulties, which include complete failure of impregnation, patchy staining, unstable staining, and extensive crystalline deposits in superficial sections, have discouraged many from attempting to use these techniques. A reliable method that produces uniform impregnation in tissue from human autopsies and experimental animals is needed. NEW METHOD: The method described, "NeoGolgi", modifies previous Golgi-Cox protocols (Glaser and Van der Loos, 1981). Changes include: much longer time (>10 weeks) in Golgi solution, agitation on a slowly rocking platform, more gradual infiltration with Parlodion, more thorough removal of excess staining solution during embedding, and shorter exposure to ammonia after infiltration. RESULTS: The procedure has successfully stained over 220 consecutive frontal or hippocampal blocks from more than 175 consecutive human autopsy cases. Dendritic spines are easily recognized, and background is clear, allowing examination of very thick (200 µm) sections. Stained neurons are evenly distributed within cortical regions. The stain is stable for at least eight years. Most importantly, all stained neurons are apparently well-impregnated, eliminating ambiguity between pathology and poor impregnation that is inherent to other methods. COMPARISON WITH EXISTING METHODS: Most methods of Golgi staining are poorly predictable. They often fail completely, staining is patchy, and abnormal morphology is often indistinguishable from poor impregnation. "NeoGolgi" overcomes these problems. CONCLUSION: Starting with unfixed tissue, it is possible to obtain Golgi staining of predictably high quality in brains from human autopsies and experimental animals.