Vestibular-mediated increase in central serotonin plays an important role in hypergravity-induced hypophagia in rats
Vestibular-mediated increase in central serotonin plays an important role in hypergravity-induced hypophagia in rats
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DOI：
10.1152/japplphysiol.00515.2010
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发表时间：
2010-12-01
影响因子：
3.3
通讯作者：
Morita, Hironobu
中科院分区：
文献类型：
--
作者：
Abe, Chikara;Tanaka, Kunihiko;Morita, Hironobu
暴露于超重力环境下可诱发急性短暂性吞咽障碍，并通过前庭损伤（VL）部分恢复，提示前庭系统参与了超重力诱导的吞咽障碍的传入通路。将大鼠置于3-G环境14天后，脑室旁下丘脑核、杏仁核中央核、前庭内侧核、中缝核、孤立束核和后脑区含fos细胞增多。VL完全消除或显著抑制Fos表达的增加。因此，这些区域可能对下咽的开始和整合至关重要。由于前庭核含有5-羟色胺能神经元，并且5-羟色胺（5-HT）是食下咽的关键神经递质，可能与晕动病有关，我们假设中央5-HT在超重力状态下增加并诱发食下咽。为了验证这一观点，我们测量了大鼠在3g环境中饲养14天后脑脊液中5-羟色胺的浓度。5-羟色胺浓度在超重力环境下升高，而在VL大鼠中这种升高完全消失。此外，5-HT2A拮抗剂（酮色林）显著降低了3-G（120分钟）负荷诱导的前庭内侧核Fos表达，长期服用酮色林可改善超重诱导的吞咽功能减退。这些结果表明，超重通过前庭输入诱导中央5-HT的增加，这种增加在超重诱导的吞咽中起重要作用。5-HT2A受体参与前庭核超重力应激的信号转导。
Exposure to a hypergravity environment induces acute transient hypophagia, which is partially restored by a vestibular lesion (VL), suggesting that the vestibular system is involved in the afferent pathway of hypergravity-induced hypophagia. When rats were placed in a 3-G environment for 14 days, Fos-containing cells increased in the paraventricular hypothalamic nucleus, the central nucleus of the amygdala, the medial vestibular nucleus, the raphe nucleus, the nucleus of the solitary tract, and the area postrema. The increase in Fos expression was completely abolished or significantly suppressed by VL. Therefore, these regions may be critical for the initiation and integration of hypophagia. Because the vestibular nucleus contains serotonergic neurons and because serotonin (5-HT) is a key neurotransmitter in hypophagia, with possible involvement in motion sickness, we hypothesized that central 5-HT increases during hypergravity and induces hypophagia. To examine this proposition, the 5-HT concentrations in the cerebrospinal fluid were measured when rats were reared in a 3-G environment for 14 days. The 5-HT concentrations increased in the hypergravity environment, and these increases were completely abolished in rats with VL. Furthermore, a 5-HT2A antagonist (ketanserin) significantly reduced 3-G (120 min) load-induced Fos expression in the medial vestibular nucleus, and chronically administered ketanserin ameliorated hypergravity-induced hypophagia. These results indicate that hypergravity induces an increase in central 5-HT via the vestibular input and that this increase plays a significant role in hypergravity-induced hypophagia. The 5-HT2A receptor is involved in the signal transduction of hypergravity stress in the vestibular nucleus.