Garcia N, Santafé M M, Salon I, Lanuza M A, Tomàs J
Histology and Neurobiology Unit, Faculty of Medicine and Health Sciences, Rovira i Virgili University, carrer St Llorenç num. 21, 43201 Reus, Spain.
Histol Histopathol. 2005 Jul;20(3):733-43. doi: 10.14670/HH-20.733.
Using intracellular recording and immunohistochemistry, we studied the presynaptic muscarinic autoreceptor subtypes controlling ACh release in the neuromuscular junctions of the newborn (3-6 days postnatal) and adult (30-40 days) rat. In the Levator auris longus muscles of both newborn and adult rats, acetylcholine release was modified by the M1-receptor selective antagonists pirenzepine (10 microM) and MT-7 (100 nM) and by the M2-receptor selective antagonists methoctramine (1 microM) and AF-DX 116 (10 microM). The M4-receptor selective antagonists tropicamide (1 microM) and MT-3 (100 nM) can also modify the neurotransmitter release in certain synapses of the newborn muscles. The neurotransmitter release was not altered by the M3-receptor selective antagonist 4-DAMP (1 microM) in the adult or newborn rats. However, we directly demonstrate by immunocytochemistry the presence of these receptors in the motor endplates and conclude that M1-, M2-, M3- and M4-type muscarinic receptors are present in all the neuromuscular junctions of the rat muscle both in newborn and adult animals. These receptors may be located in the perisynaptic glial cell as well as at the nerve terminals.
利用细胞内记录和免疫组织化学技术，我们研究了控制新生（出生后3 - 6天）和成年（30 - 40天）大鼠神经肌肉接头处乙酰胆碱（ACh）释放的突触前毒蕈碱自身受体亚型。在新生和成年大鼠的耳长肌中，乙酰胆碱的释放受到M1受体选择性拮抗剂哌仑西平（10微摩尔）和MT - 7（100纳摩尔）以及M2受体选择性拮抗剂甲溴东莨菪碱（1微摩尔）和AF - DX 116（10微摩尔）的影响。M4受体选择性拮抗剂托吡卡胺（1微摩尔）和MT - 3（100纳摩尔）也能改变新生肌肉某些突触处的神经递质释放。在成年或新生大鼠中，M3受体选择性拮抗剂4 - DAMP（1微摩尔）未改变神经递质的释放。然而，我们通过免疫细胞化学直接证明了这些受体在运动终板中的存在，并得出结论，M1、M2、M3和M4型毒蕈碱受体在新生和成年动物的大鼠肌肉所有神经肌肉接头中均有存在。这些受体可能位于突触周围的神经胶质细胞以及神经末梢。
