Dopamine receptor 2 (DRD2) and ghrelin receptor (GHSR1a) agonists both stimulate defecation by actions at the lumbosacral defecation center. Dopamine is in nerve terminals surrounding autonomic neurons of the defecation center, whereas ghrelin is not present in the spinal cord. Dopamine at D2 receptors generally inhibits neurons, but at the defecation center, its effect is excitatory.

中文翻译：

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脊髓排便中心的多巴胺和生长素释放肽受体共表达和相互作用

多巴胺受体 2 (DRD2) 和生长素释放肽受体 (GHSR1a) 激动剂都通过在腰骶排便中心的作用刺激排便。多巴胺位于排便中心自主神经元周围的神经末梢，而脊髓中不存在生长素释放肽。D2 受体的多巴胺通常会抑制神经元，但在排便中心，其作用是兴奋的。