Smith C M, Strand F L
Peptides. 1981 Summer;2(2):197-206. doi: 10.1016/s0196-9781(81)80034-4.
The adrenocorticotropin fragment ACTH/MSH 4--10 (0.1 ug/kg IP) effectively modulates the neuromuscular responses of 9 to 15 day old rats. Muscle (extensor digitorum longus) contraction amplitude is increased, fatigue is delayed and muscle half-relaxation time is shortened during 20 min of continuous in situ stimulation of a branch of the deep peroneal nerve (square wave shocks 10 Hz, duration 0.5 msec, strength supermaximal). No effect on contraction time is seen. There is no facilitation or change in any contraction parameter in rats older than two weeks (16 to 40 days) indicating that these older animals, like normal adult rats, are unaffected by the peptide. Immature rats, however, are even more sensitive than hypophysectomized adult rats [29] to the ameliorative action of ACTH/MSH 4-10. This early sensitivity to ACTH/MSH 4--10 corresponds to important developmental changes occurring in nerve and muscle during the most critical period in postnatal development, the first two weeks.
促肾上腺皮质激素片段促肾上腺皮质激素/促黑素4-10（0.1微克/千克，腹腔注射）可有效调节9至15日龄大鼠的神经肌肉反应。在原位持续刺激腓深神经分支20分钟（方波电击，10赫兹，持续时间0.5毫秒，强度为超最大强度）期间，肌肉（趾长伸肌）收缩幅度增加，疲劳延迟，肌肉半松弛时间缩短。未观察到对收缩时间的影响。两周以上（16至40日龄）的大鼠在任何收缩参数上均未出现易化或变化，这表明这些较大的动物与正常成年大鼠一样，不受该肽的影响。然而，未成熟大鼠对促肾上腺皮质激素/促黑素4-10的改善作用甚至比垂体切除的成年大鼠[29]更为敏感。对促肾上腺皮质激素/促黑素4-10的这种早期敏感性与出生后发育最关键时期（前两周）神经和肌肉中发生的重要发育变化相对应。
