Department of Anatomy, College of Medicine, Konkuk University, Hwayang-dong, Gwangjin-gu, 143-701 Seoul, South Korea.
Brain Res. 2011 Apr 6;1383:169-78. doi: 10.1016/j.brainres.2011.01.077. Epub 2011 Jan 31.
The mesopontine cholinergic complex comprising the pedunculopontine (PPTg) and laterodorsal (LDTg) tegmental nuclei is a key component of ascending reticular activating system. The brainstem cholinergic nuclei are yet under the control of descending projections from hypothalamic arousal centers such as the hypocretinergic, lateral hypothalamus (LH), and the histaminergic, tuberomammillary nucleus (TMN). The present study was designed to determine the differential projection pattern as well as the laterality of descending TMN projections to the PPTg and LDTg. Our results showed that each TMN subdivision provided differential projections to the mesopontine complex. The majority of PPTg-projecting neurons were located in ventrolateral TMN mainly at its subpial border, whereas LDTg-projecting cells were in dorsomedial TMN with a few in the medial border of the ventrolateral subdivision. For both PPTg and LDTg cases, retrogradely labeled neurons were more pronounced in each TMN subdivision ipsilateral to the injection site. The light microscopic observation also indicated that hypocretinergic, terminal-like boutons formed close appositions to somata as well as proximal dendrites of PPTg- or LDTg-projecting TMN neurons. Taken together, the present observations suggested that each TMN subdivision provide differential projections to the mesopontine cholinergic complex and that the LH, via the TMN, provides indirect, descending projections to the complex as well.
中脑胆碱能复合体包括脚桥核（PPTg）和外侧背核（LDTg）脑桥被盖核，是上行网状激活系统的关键组成部分。脑干胆碱能核受下丘脑唤醒中心（如食欲肽能、外侧下丘脑（LH）和组胺能、结节乳头核（TMN））的下行投射的控制。本研究旨在确定 TMN 向 PPTg 和 LDTg 的投射模式的差异以及偏侧性。我们的结果表明，每个 TMN 细分都对中脑复合体提供了不同的投射。大多数投射到 PPTg 的神经元位于 TMN 的腹外侧，主要位于其软脑膜边界，而投射到 LDTg 的细胞位于 TMN 的背内侧，少数位于腹外侧细分的内侧边界。对于 PPTg 和 LDTg 病例，逆行标记的神经元在注射部位对侧的每个 TMN 细分中更为明显。光镜观察还表明，食欲肽能、终末样终末与 PPTg 或 LDTg 投射 TMN 神经元的胞体和近端树突形成紧密贴合。总之，目前的观察结果表明，每个 TMN 细分都对中脑胆碱能复合体提供了不同的投射，LH 通过 TMN 也对复合体提供了间接的下行投射。
