Freundt-Revilla Jessica, Kegler Kristel, Baumgärtner Wolfgang, Tipold Andrea
Department of Small Animal Medicine and Surgery, University of Veterinary Medicine Hannover Foundation, Hannover, Germany.
Center for Systems Neuroscience, Hannover, Germany.
PLoS One. 2017 Jul 10;12(7):e0181064. doi: 10.1371/journal.pone.0181064. eCollection 2017.
The endocannabinoid system is a regulatory pathway consisting of two main types of cannabinoid receptors (CB1 and CB2) and their endogenous ligands, the endocannabinoids. The CB1 receptor is highly expressed in the central and peripheral nervous systems (PNS) in mammalians and is involved in neuromodulatory functions. Since endocannabinoids were shown to be elevated in cerebrospinal fluid of epileptic dogs, knowledge about the species specific CB receptor expression in the nervous system is required. Therefore, we assessed the spatial distribution of CB1 receptors in the normal canine CNS and PNS. Immunohistochemistry of several regions of the brain, spinal cord and peripheral nerves from a healthy four-week-old puppy, three six-month-old dogs, and one ten-year-old dog revealed strong dot-like immunoreactivity in the neuropil of the cerebral cortex, Cornu Ammonis (CA) and dentate gyrus of the hippocampus, midbrain, cerebellum, medulla oblongata and grey matter of the spinal cord. Dense CB1 expression was found in fibres of the globus pallidus and substantia nigra surrounding immunonegative neurons. Astrocytes were constantly positive in all examined regions. CB1 labelled neurons and satellite cells of the dorsal root ganglia, and myelinating Schwann cells in the PNS. These results demonstrate for the first time the spatial distribution of CB1 receptors in the healthy canine CNS and PNS. These results can be used as a basis for further studies aiming to elucidate the physiological consequences of this particular anatomical and cellular distribution.
内源性大麻素系统是一种调节途径，由两种主要类型的大麻素受体（CB1和CB2）及其内源性配体——内源性大麻素组成。CB1受体在哺乳动物的中枢和外周神经系统（PNS）中高度表达，并参与神经调节功能。由于已证明内源性大麻素在癫痫犬的脑脊液中升高，因此需要了解神经系统中物种特异性CB受体的表达情况。因此，我们评估了正常犬中枢神经系统和外周神经系统中CB1受体的空间分布。对一只健康的四周龄幼犬、三只六个月龄犬和一只十岁犬的大脑、脊髓和外周神经的几个区域进行免疫组织化学分析，结果显示在大脑皮质、海马的海马角（CA）和齿状回、中脑、小脑、延髓和脊髓灰质的神经毡中有强烈的点状免疫反应性。在苍白球和黑质围绕免疫阴性神经元的纤维中发现密集的CB1表达。在所有检查区域，星形胶质细胞始终呈阳性。CB1标记背根神经节的神经元和卫星细胞，以及外周神经系统中的髓鞘形成雪旺细胞。这些结果首次证明了健康犬中枢神经系统和外周神经系统中CB1受体的空间分布。这些结果可作为进一步研究的基础，旨在阐明这种特定解剖和细胞分布的生理后果。
