Kraft Nadine, Rössler Wolfgang, Groh Claudia
Biocenter, Behavioral Physiology and Sociobiology, University of Würzburg, Würzburg, Germany.
Dev Neurobiol. 2025 Oct;85(4):e23006. doi: 10.1002/dneu.23006.
Honeybee (Apis mellifera) workers exhibit remarkable behavioral plasticity throughout adult life. In spring and summer, they transition through diverse tasks over a short lifespan of 4-6 weeks. This involves dramatic changes in sensory environment and cognitive demands associated with pronounced structural neuronal plasticity in the mushroom bodies (MBs), high-order brain centers for sensory integration, learning, and memory. This plasticity manifests as age- and experience-related volume increase in sensory input regions of the MB calyces, accompanied by pruning of projection neuron (PN) boutons in synaptic microcircuits within visual and olfactory compartments. As winter approaches, honeybees suspend brood rearing and foraging activities to survive the cold months by forming a tight, thermoregulated cluster. Unique physiological adaptations enable winter bees to live up to 8 months until a new generation emerges in spring. This extended lifespan occurs during a period of reduced sensory input and high metabolic costs raising the question of how such conditions affect structural neuronal plasticity. Using synapsin immunolabeling and 3D confocal-microscopy image analyses of MB synaptic neuropils in whole-mount brains of age-controlled worker bees, we found that winter bees retain a high degree of neuronal plasticity throughout their lifespan. MB calyces exhibit an initial volume increase followed by a period of stagnation to then undergo another expansion at the onset of spring foraging. While olfactory PN boutons exhibit continuous pruning, visual bouton numbers remain stable during winter. We conclude that winter bees retain comparable neuronal capacities to summer bees, despite strong differences in lifespan, physiological, and environmental conditions.
蜜蜂（西方蜜蜂）工蜂在成年后的整个生命过程中表现出显著的行为可塑性。在春季和夏季，它们在短短4 - 6周的寿命中经历各种不同的任务。这涉及到感觉环境和认知需求的巨大变化，这些变化与蘑菇体（MBs）中明显的结构神经元可塑性相关，蘑菇体是用于感觉整合、学习和记忆的高级脑中心。这种可塑性表现为MB萼片感觉输入区域与年龄和经验相关的体积增加，同时伴随着视觉和嗅觉区室突触微回路中投射神经元（PN）轴突终扣的修剪。随着冬季临近，蜜蜂暂停育雏和觅食活动，通过形成紧密的、温度调节的蜂群来度过寒冷的月份。独特的生理适应使越冬蜂能够活到8个月，直到春天新一代蜜蜂出现。这种延长的寿命发生在感觉输入减少和代谢成本高昂的时期，这就引发了这样的条件如何影响结构神经元可塑性的问题。通过对年龄可控的工蜂全脑MB突触神经纤维网进行突触素免疫标记和三维共聚焦显微镜图像分析，我们发现越冬蜂在其整个寿命过程中都保持着高度的神经元可塑性。MB萼片最初体积增加，随后有一段停滞期，然后在春季觅食开始时再次扩张。虽然嗅觉PN轴突终扣持续修剪，但视觉轴突终扣数量在冬季保持稳定。我们得出结论，尽管越冬蜂在寿命、生理和环境条件上有很大差异，但它们保留了与夏季蜜蜂相当的神经元能力。
