Hypocretin/orexin peptide release occurs mostly extrasynaptically, is self-controlled, and specifically enhanced in female rats

IF 4.2 2区医学 Q1 NEUROSCIENCES

Experimental Neurology Pub Date : 2025-08-20 DOI:10.1016/j.expneurol.2025.115438

Carlos Carrera-Cañas, Isabel de Andrés, Marta Callejo, Miguel Garzón

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引用次数: 0

Abstract

The hypothalamic hypocretinergic/orexinergic (Hcrt/Ox) system comprises two neuropeptides -Hcrt1/OxA and Hcrt2/OxB- and two receptors -Hcrt/OxR1 and Hcrt/OxR2- which perform multiple modulatory actions. Its neurotransmission mechanism remains poorly understood despite its malfunction entails narcolepsy and low cerebrospinal fluid (CSF)-Hcrt1/OxA levels is the most specific biomarker of the disease. This work examines: (1) synaptic and volume Hcrt/Ox transmission types; (2) Hcrt/Ox receptors involvement in Hcrt/Ox-peptide release/synthesis; and (3) Hcrt/Ox system sexual dimorphism.

Axonal central/peripheral distribution of dense-core vesicles (dcv) containing Hcrt1/OxA and small synaptic vesicles (ssv) loaded with glutamate was analyzed by electron microscopy in naïve rats immunolabeled for Hcrt1/OxA at the locus coeruleus area. In addition, two sets of mixed male and female rats receiving intraperitoneal (i.p.) injections of either DMSO (vehicle) or 30 mg/kg suvorexant (a dual Hcrt/Ox receptor antagonist) for 7 days were used. Hcrt1/OxA was measured in CSF and in synaptic terminals (synaptosome preparations) from the oral pontine tegmentum (OPT) of these rats using ELISA.

Hcrt1/OxA-loaded dcv were more clustered in the axonal periphery than ssv, and Hcrt1/OxA enrichment was higher in CSF than in OPT-synaptosome preparations. Hcrt/Ox transmission blockade with suvorexant produced intracellular accumulation of Hcrt1/OxA, in parallel to its previously reported decrease in CSF. Female rats showed higher Hcrt1/OxA basal levels than males in CSF but not in OPT-Syn samples.

Our results support the notion that: (1) volume/extrasynaptic Hcrt/Ox-peptide release is greater than synaptic/perisynaptic release, (2) Hcrt/OxR1 controls Hcrt/Ox-peptide release rather than synthesis in Hcrt/Ox neurons, and (3) Hcrt/Ox volume neurotransmission is enhanced in females.

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下丘脑分泌素/食欲素肽的释放主要发生在突触外，是自我控制的，并在雌性大鼠中特异性增强

下丘脑下丘脑分泌能/食欲能（Hcrt/Ox）系统包括两个神经肽- hcrt1 /OxA和Hcrt2/OxB-和两个受体-Hcrt/OxR1和Hcrt/OxR2-执行多种调节作用。其神经传递机制尚不清楚，尽管其功能障碍导致嗜睡症和低脑脊液(CSF)-Hcrt1/OxA水平是该疾病最特异性的生物标志物。这项工作检查：(1)突触和体积Hcrt/Ox传递类型；(2) Hcrt/Ox受体参与Hcrt/Ox肽的释放/合成；(3) Hcrt/Ox系两性异形。在免疫标记Hcrt1/OxA的naïve大鼠的蓝斑区，用电镜分析了含有Hcrt1/OxA的致密核囊泡（dcv）和装载谷氨酸的小突触囊泡（ssv）在轴突中央/外周的分布。此外，两组雌雄混合大鼠分别腹腔注射DMSO（对照物）或30 mg/kg suvorexant （Hcrt/Ox受体双拮抗剂）7天。采用酶联免疫吸附法（ELISA）测定大鼠脑脊液和口桥脑被（OPT）突触末端（突触体制剂）中的Hcrt1/OxA水平。装载Hcrt1/OxA的dcv比ssv更聚集在轴突外周，脑脊液中Hcrt1/OxA的富集程度高于opt突触体。过量阻断Hcrt/Ox传递可产生细胞内Hcrt1/OxA积累，与先前报道的脑脊液中Hcrt1/OxA减少平行。雌性大鼠脑脊液中Hcrt1/OxA的基础水平高于雄性，而OPT-Syn样品中没有。我们的研究结果支持以下观点：(1)体积/突触外Hcrt/Ox-肽释放大于突触/突触周围释放；(2)Hcrt/OxR1控制Hcrt/Ox-肽释放而不是Hcrt/Ox神经元的合成；(3)雌性Hcrt/Ox体积神经传递增强。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Experimental Neurology 医学-神经科学

CiteScore

10.10

自引率

3.80%

发文量

258

审稿时长

42 days

期刊介绍： Experimental Neurology, a Journal of Neuroscience Research, publishes original research in neuroscience with a particular emphasis on novel findings in neural development, regeneration, plasticity and transplantation. The journal has focused on research concerning basic mechanisms underlying neurological disorders.