Dib B, Falchi M
Laboratoire de Physiologie, de l'Environnement Faculté de Médecine Grange-Blanche, Université Claude Bernard Lyon I, France.
Int J Clin Pharmacol Res. 1997;17(1):37-46.
Rats were taught to self-administer beta-endorphin (0.1 microgram or 0.5 microgram/microliter) or NaCl 9% by pressing a lever that activated a pump connected with a cannula implanted in the lateral cerebral ventricle (icv). The pump delivered 1 microliter at each lever pressing. After a training period of 2 weeks, the self-injection behaviour was studied before, during and after nociceptive stimulation. In response to a nociceptive stimulation, 4 rats increased their self-injection of beta-endorphin at 0.5 microgram/microliter per injection. This effect is specific for beta-endorphin since under identical conditions 6 rats did not increase the injection of isotonic NaCl saline solution. Another 6 rats did not increase their self-injection during nociceptive electrical stimulation and the post-nociceptive period when the dose of beta-endorphin was 0.1 microgram/microliter per injection. However these animals self-administered significantly higher levels of beta-endorphin during the pre-control period. Also studied were the acute effects of 10 micrograms of icv beta-endorphin on tail-flick latency in sec. The acute administration of 10 micrograms of beta-endorphin induced a long-lasting analgesia. The results show that the rats increased beta-endorphin self-administration during the pre-control period when the dose was 0.1 microgram/microliter and during the nociceptive stimulation period when the dose was 0.5 microgram/microliter. In the former case the self-administration had the profile of a voluntary doping drug intake, in the latter case the profile was that of an antalgic self-medication.
通过按压一根与植入大脑侧脑室（icv）的套管相连的泵的杠杆，训练大鼠自行注射β-内啡肽（0.1微克或0.5微克/微升）或9%的氯化钠溶液。每次按压杠杆，泵会输送1微升溶液。经过2周的训练期后，在伤害性刺激前、刺激期间和刺激后研究大鼠的自我注射行为。在对伤害性刺激的反应中，4只大鼠将每次注射0.5微克/微升的β-内啡肽的自我注射量增加了。这种效应是β-内啡肽特有的，因为在相同条件下，6只大鼠并没有增加等渗氯化钠盐溶液的注射量。当每次注射β-内啡肽的剂量为0.1微克/微升时，另外6只大鼠在伤害性电刺激期间和伤害性刺激后并没有增加自我注射量。然而，这些动物在对照前期自行注射了显著更高水平的β-内啡肽。还研究了脑室内注射10微克β-内啡肽对甩尾潜伏期（以秒计）的急性影响。急性注射10微克β-内啡肽可诱导持久的镇痛作用。结果表明，当剂量为0.1微克/微升时，大鼠在对照前期增加了β-内啡肽的自我给药量；当剂量为0.5微克/微升时，大鼠在伤害性刺激期间增加了β-内啡肽的自我给药量。在前一种情况下，自我给药具有自愿服用兴奋剂药物的特征；在后一种情况下，自我给药具有止痛自我用药的特征。
