Bitran D, Thompson J T, Hull E M, Sachs B D
Department of Psychology, University of Connecticut, Storrs 06269-1020.
Pharmacol Biochem Behav. 1989 Nov;34(3):453-8. doi: 10.1016/0091-3057(89)90540-6.
Dopaminergic compounds have been shown to facilitate male sexual responses in various contexts. We investigated the effects of a specific D2 dopamine receptor agonist, quinelorane (LY163502), on sexual responses elicited in the restrained supine male rat (i.e., ex copula reflex tests). Penile erections, evoked by retraction of the penile sheath, were inhibited by systemic administration of 10 micrograms/kg quinelorane; however, the occurrence of seminal emission was dramatically increased. A smaller dose of 0.25 ng/kg was without effect. In a second experiment, intracranial microinjection of quinelorane was followed by ex copula reflex tests. The medial preoptic area (MPOA) has been previously implicated in the dopaminergic regulation of male copulatory behavior. The effects of an intra-MPOA injection of quinelorane on seminal emission and erectile responses were similar to those observed following systemic administration. These results are consistent with the hypothesis that DA receptors in the MPOA are important in the regulation of male sexual behavior and suggest that D2 receptors in the MPOA may decrease ejaculatory threshold while inhibiting erectile mechanisms.
多巴胺能化合物已被证明在各种情况下都能促进雄性性行为反应。我们研究了一种特定的D2多巴胺受体激动剂喹那罗林（LY163502）对束缚仰卧雄性大鼠诱发的性行为反应的影响（即交配后反射试验）。阴茎鞘回缩诱发的阴茎勃起，在全身给予10微克/千克喹那罗林后受到抑制；然而，射精的发生率却显著增加。0.25纳克/千克的较小剂量则没有效果。在第二个实验中，颅内微量注射喹那罗林后进行交配后反射试验。内侧视前区（MPOA）先前已被认为与雄性交配行为的多巴胺能调节有关。内侧视前区内注射喹那罗林对射精和勃起反应的影响与全身给药后观察到的结果相似。这些结果与内侧视前区的多巴胺受体在雄性性行为调节中起重要作用的假设一致，并表明内侧视前区的D2受体可能会降低射精阈值，同时抑制勃起机制。
