Division of Marine Biology and Fisheries, Rosenstiel School of Marine and Atmospheric Science, University of Miami Miami, FL, USA.
Front Aging Neurosci. 2014 May 9;6:84. doi: 10.3389/fnagi.2014.00084. eCollection 2014.
Invertebrate models have advantages for understanding the basis of behavioral aging due to their simple nervous systems and short lifespans. The potential usefulness of Aplysia californica in aging research is apparent from its long history of neurobiological research, but it has been underexploited in this model use. Aging of simple reflexes at both single sensory neuron and neural circuit levels was studied to connect behavioral aging to neurophysiological aging. The tail withdrawal reflex (TWR), righting reflex, and biting response were measured throughout sexual maturity in 3 cohorts of hatchery-reared animals of known age. Reflex times increased and reflex amplitudes decreased significantly during aging. Aging in sensory neurons of animals with deficits in measures of the TWR and biting response resulted in significantly reduced excitability in old animals compared to their younger siblings. The threshold for firing increased while the number of action potentials in response to depolarizing current injection decreased during aging in sensory neurons, but not in tail motoneurons. Glutamate receptor-activated responses in sensory neurons also decreased with aging. In old tail motoneurons, the amplitude of evoked EPSPs following tail shock decreased, presumably due to reduced sensory neuron excitability during aging. The results were used to develop stages of aging relevant to both hatchery-reared and wild-caught Aplysia. Aplysia is a viable aging model in which the contributions of differential aging of components of neural circuits may be assessed.
无脊椎动物模型因其简单的神经系统和较短的寿命，在理解行为衰老的基础方面具有优势。加利福尼亚海兔在神经生物学研究方面有着悠久的历史，因此在衰老研究中具有潜在的应用价值，但在这种模型的应用中却没有得到充分利用。研究了单感觉神经元和神经回路水平上简单反射的衰老，以将行为衰老与神经生理衰老联系起来。在已知年龄的 3 组孵化场饲养的动物的整个性成熟过程中，测量了尾部退缩反射（TWR）、翻身反射和咬反应。随着年龄的增长，反射时间显著增加，反射幅度显著降低。在 TWR 和咬反应测量值存在缺陷的动物的感觉神经元中，衰老导致与年轻兄弟姐妹相比，老年动物的兴奋性显著降低。感觉神经元的放电阈值随着年龄的增长而增加，而响应去极化电流注入的动作电位数量减少，但在尾部运动神经元中则没有。谷氨酸受体激活的反应也随年龄的增长而减少。在老年尾部运动神经元中，尾部电击后诱发 EPSP 的幅度减小，这可能是由于衰老过程中感觉神经元兴奋性降低所致。这些结果用于开发与孵化场饲养和野生捕获的加利福尼亚海兔相关的衰老阶段。加利福尼亚海兔是一种可行的衰老模型，可以评估神经回路组成部分的差异衰老的贡献。
