Dietary therapy restores glutamatergic input to orexin/hypocretin neurons after traumatic brain injury in mice
Dietary therapy restores glutamatergic input to orexin/hypocretin neurons after traumatic brain injury in mice
复制标题
DOI：
10.1093/sleep/zsx212
复制
发表时间：
2018-03-01
期刊：
影响因子：
5.6
通讯作者：
Lim, Miranda M.
中科院分区：
文献类型：
--
作者：
Elliott, Jonathan E.;De Luche, Samuel E.;Lim, Miranda M.
研究目标：在之前的工作中，膳食支链氨基酸（BCAA）补充剂（谷氨酸和γ-氨基丁酸（GABA）从头合成的前体）可以恢复小鼠创伤性脑损伤（TBI）后受损的睡眠-觉醒调节和食欲素神经元活动。据推测，TBI 通过减少区域兴奋性（谷氨酸）和/或增加抑制性（GABA）输入来减少食欲素神经元活动。因此，我们假设 TBI 会减少接触食欲素神经元的神经末梢中的突触谷氨酸和/或增加突触 GABA，而补充 BCAA 会恢复 TBI 诱导的突触谷氨酸和/或 GABA 变化。 方法：对脑组织进行处理，进行食欲素预嵌入二氨基联苯胺标记和谷氨酸或 GABA 后嵌入免疫金标记。使用电子显微镜对三组小鼠（每组 n = 8）中接触食欲素阳性外侧下丘脑神经元的突触前神经末梢内谷氨酸和 GABA 免疫金的密度进行定量：假手术/未受伤对照、不补充 BCAA 的 TBI 和补充 BCAA 的 TBI（TBI 后 48 小时给予 5 天）。与 TBI 病变相邻的皮质半影区（VIb 层）内的谷氨酸和 GABA 也进行了定量。结果：在下丘脑和皮质中，TBI 降低了突触前末端形成轴突接触的相对谷氨酸密度。然而，补充支链氨基酸仅恢复接触食欲素阳性下丘脑神经元的突触前末梢内的相对谷氨酸密度。补充 BCAA 不会改变下丘脑或皮质内形成轴体接触的突触前末梢的相对谷氨酸密度，或形成轴体或轴突接触的突触前末梢的相对 GABA 密度。结论：这些结果表明 TBI 通过降低谷氨酸密度来损害食欲素神经元功能，并强调补充 BCAA 作为恢复食欲素神经元谷氨酸密度的潜在疗法。
Study Objectives: In previous work, dietary branched-chain amino acid (BCAA) supplementation, precursors to de novo glutamate and gamma-aminobutyric acid (GABA) synthesis, restored impaired sleep-wake regulation and orexin neuronal activity following traumatic brain injury (TBI) in mice. TBI was speculated to reduce orexin neuronal activity through decreased regional excitatory (glutamate) and/or increased inhibitory (GABA) input. Therefore, we hypothesized that TBI would decrease synaptic glutamate and/or increase synaptic GABA in nerve terminals contacting orexin neurons, and BCAA supplementation would restore TBI-induced changes in synaptic glutamate and/or GABA.Methods: Brain tissue was processed for orexin pre-embed diaminobenzidine labeling and glutamate or GABA postembed immunogold labeling. The density of glutamate and GABA immunogold within presynaptic nerve terminals contacting orexin-positive lateral hypothalamic neurons was quantified using electron microscopy in three groups of mice (n = 8 per group): Sham/noninjured controls, TBI without BCAA supplementation, and TBI with BCAA supplementation (given for 5 days, 48 hr post-TBI). Glutamate and GABA were also quantified within the cortical penumbral region (layer VIb) adjacent to the TBI lesion.Results: In the hypothalamus and cortex, TBI decreased relative glutamate density in presynaptic terminals making axodendritic contacts. However, BCAA supplementation only restored relative glutamate density within presynaptic terminals contacting orexin-positive hypothalamic neurons. BCAA supplementation did not change relative glutamate density in presynaptic terminals making axosomatic contacts, or relative GABA density in presynaptic terminals making axosomatic or axodendritic contacts, within either the hypothalamus or cortex.Conclusions: These results suggest TBI compromises orexin neuron function via decreased glutamate density and highlight BCAA supplementation as a potential therapy to restore glutamate density to orexin neurons.