MacDonald A, McGrath J C
Br J Pharmacol. 1984 May;82(1):25-34. doi: 10.1111/j.1476-5381.1984.tb16438.x.
Responses of the rat vas deferens to drugs and to field stimulation were examined in sexually immature rats. The vasa from immature rats often exhibited spontaneous contractions and displayed greater sensitivity to the contractile effects of alpha-adrenoceptor agonists. The responses of the vasa from immature rats to single pulse field stimulation lacked the adrenergic component of the response although the non-adrenergic component was present. The responses were antagonized by alpha 2-adrenoceptor agonists. In the presence of cocaine, an adrenergic component of the response did appear. During trains of pulses the pre- and postjunctional effects of adrenergic transmission which are found in adult rats were absent in vasa from immature rats. Electron microscopic studies showed no qualitative differences in adrenergic innervation in vasa from immature and adult rats. It is concluded that a state of 'pre-innervation supersensitivity' associated with a lack of functional adrenergic transmission exists in the vas deferens of immature rats. The supersensitivity disappears and functional transmission develops during the period in which testosterone secretion increases in the rat. The reason for the lack of functional transmission at a time when the innervation appears to be morphologically mature is not clear but may be due to the noradrenaline release mechanism not being fully operative.
在性未成熟的大鼠中研究了大鼠输精管对药物和场刺激的反应。未成熟大鼠的输精管常表现出自发性收缩，并且对α-肾上腺素能受体激动剂的收缩作用表现出更高的敏感性。未成熟大鼠输精管对单脉冲场刺激的反应缺乏反应中的肾上腺素能成分，尽管存在非肾上腺素能成分。这些反应被α2-肾上腺素能受体激动剂拮抗。在可卡因存在的情况下，反应中确实出现了肾上腺素能成分。在脉冲串期间，未成熟大鼠输精管中不存在成年大鼠输精管中发现的肾上腺素能传递的节前和节后效应。电子显微镜研究表明，未成熟和成年大鼠输精管中的肾上腺素能神经支配在质量上没有差异。得出的结论是，未成熟大鼠的输精管中存在与缺乏功能性肾上腺素能传递相关的“神经支配前超敏状态”。在大鼠睾酮分泌增加的时期，超敏性消失且功能性传递发展。在神经支配在形态上似乎成熟时缺乏功能性传递的原因尚不清楚，但可能是由于去甲肾上腺素释放机制未完全起作用。
