Vázquez Araceli, Hernández-Oliveras Andrés, Santiago-García Juan, Caba Mario, Gonzalez-Lima Francisco, Olivo Diana, Corona-Morales Aleph A
Doctorado en Ciencias Biomédicas, Universidad Veracruzana, Xalapa, Veracruz, México.
Doctorado en Ciencias de la Salud, Universidad Veracruzana, Xalapa, Veracruz, México.
Physiol Behav. 2020 Apr 1;217:112824. doi: 10.1016/j.physbeh.2020.112824. Epub 2020 Jan 25.
When food is restricted daily to a fixed time, animals show uncoupled molecular, physiological and behavioral circadian rhythms from those entrained by light and controlled by the suprachiasmatic nucleus. The loci of the food-entrainable oscillator and the mechanisms by which rhythms emerge are unclear. Using animals entrained to the light-dark cycle, recent studies indicate that astrocytes in the suprachiasmatic nucleus play a key role in the regulation of circadian rhythms. However, it is unknown whether astrocytic cells can be synchronized by circadian restricted feeding. Studying the olfactory bulb (OB) of rabbit pups entrained to daily feeding, we hypothesized that the expression of glial fibrillary acidic protein (GFAP) and the morphology of GFAP-immunopositive cells change in synchrony with timing of feeding. By using pups fed at 1000 h or 2200 h, we found that GFAP protein expression in the OB changes with a nadir at feeding time and a peak 16 h after feeding. We also found that length of radial glia processes, the most abundant GFAP cell in the rabbit pup OB, shows a daily change also coupled to feeding time. These temporal changes of GFAP were expressed in anti-phase to the rhythms of locomotor activity and c-Fos immunoreactivity. The results indicate that GFAP expression and elongation-retraction of radial glia processes are coupled by feeding time and suggest that glia cells may play an important functional role in food entraining of the OB circadian oscillator.
当每天将食物限制在固定时间时，动物会表现出与由光诱导并由视交叉上核控制的分子、生理和行为昼夜节律脱耦联的昼夜节律。食物可诱导振荡器的位点以及节律产生的机制尚不清楚。利用适应明暗周期的动物，最近的研究表明视交叉上核中的星形胶质细胞在昼夜节律调节中起关键作用。然而，尚不清楚星形胶质细胞是否能通过昼夜限时进食实现同步化。通过研究适应每日定时喂食的兔幼崽的嗅球（OB），我们推测胶质纤维酸性蛋白（GFAP）的表达以及GFAP免疫阳性细胞的形态会随喂食时间同步变化。通过使用在1000时或2200时喂食的幼崽，我们发现嗅球中GFAP蛋白表达在喂食时最低，在喂食后16小时达到峰值。我们还发现，兔幼崽嗅球中最丰富的GFAP细胞——放射状胶质细胞突起的长度也呈现出与喂食时间相关的每日变化。GFAP的这些时间变化与运动活动和c-Fos免疫反应性的节律呈反相表达。结果表明，GFAP表达和放射状胶质细胞突起的伸长-收缩与喂食时间相关联，提示胶质细胞可能在嗅球昼夜振荡器的食物诱导中发挥重要功能作用。
