It is common opinion that maximal activation of luteinizing hormone (LH)-dependent steroidogenic signal occurs at <1% of human LH/choriogonadotropin (hCG) receptor (LHCGR) occupancy. This effect would be a consequence of an excess of receptors expressed on the surface of theca cells, resulting in a pool of LHCGRs remaining unbound (spare). This concept was borrowed from historical pharmacological studies, when discrepancies between ligand-receptor binding and dose-response curves of cAMP were evaluated by treating mouse or rat Leydig cells with hCG in vitro. Recent findings demonstrated the specificity of LH- and hCG-dependent effects, receptor heterodimerization, and differing behaviors of rodent versus human gonadotropin-responsive cells, which may help to revise the 'spare' LHCGRs concept applied to human ovarian physiology and assisted reproduction.

中文翻译：

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“备用”促黄体激素受体：事实与虚构

人们普遍认为，黄体生成素 (LH) 依赖性类固醇生成信号的最大激活发生在 <1% 的人 LH/绒毛膜促性腺激素 (hCG) 受体 (LHCGR) 占用率。这种效应可能是由于在膜细胞表面表达的受体过多，导致 LHCGR 池保持未结合（备用）。这个概念是从历史药理学研究中借用的，当时通过在体外用 hCG 处理小鼠或大鼠 Leydig 细胞来评估 cAMP 的配体-受体结合和剂量-反应曲线之间的差异。最近的研究结果证明了 LH 和 hCG 依赖性效应、受体异二聚化以及啮齿动物与人类促性腺激素反应细胞的不同行为的特异性，这可能有助于修改“备用”