Dorsa D M, Smith E R, Davidson J M
Endocrinology. 1981 Sep;109(3):729-35. doi: 10.1210/endo-109-3-729.
Continuous exposure of intact male rats to [6-D-(2-naphthyl)-alanine]LHRH, a highly potent LHRH agonist, diminished testis and pituitary weights and decreased basal plasma levels of testosterone and LH. In addition, treatment with this analog abolished the pituitary hypertrophy and LH hypersecretion normally associated with castration. Alterations of male sex behavior were also noted in these animals. Analog-treated intact rats showed longer intromission latencies and mount latencies in early tests and ceased to show sexual behavior 6-8 weeks after initiation of treatment. In addition, the gradual decline in behavior normally observed after castration was markedly accelerated by analog administration. Castrates bearing 5-mm Silastic testosterone-containing capsules which maintained copulatory performance displayed behavioral deficiencies when given the peptide. No significant effect of analog was noted in rats with 30-mm Silastic implants, which provide a higher level of testosterone replacement. Continuous analog treatment promotes endocrine effects consistent with complete antagonism of the effects of endogenous LHRH. The behavioral disruption associated with this manipulation suggests a role for endogenous LHRH in maintaining sex behavior in a low testosterone environment.
将完整雄性大鼠持续暴露于一种高效促性腺激素释放激素（LHRH）激动剂[6-D-(2-萘基)-丙氨酸]LHRH，会使睾丸和垂体重量减轻，并降低睾酮和促黄体生成素（LH）的基础血浆水平。此外，用这种类似物治疗可消除通常与去势相关的垂体肥大和LH分泌过多现象。在这些动物中还观察到了雄性性行为的改变。经类似物处理的完整大鼠在早期试验中表现出更长的插入潜伏期和爬跨潜伏期，并且在开始治疗6 - 8周后停止表现出性行为。此外，去势后通常观察到的行为逐渐衰退在给予类似物后明显加速。植入含5毫米硅橡胶睾酮胶囊以维持交配能力的去势大鼠在给予该肽后表现出行为缺陷。在植入30毫米硅橡胶且能提供更高水平睾酮替代的大鼠中未观察到类似物的显著影响。持续的类似物治疗会产生与内源性LHRH作用完全拮抗相一致的内分泌效应。与这种操作相关的行为破坏表明内源性LHRH在低睾酮环境中维持性行为方面发挥作用。
