Ross E L, Komisaruk B R, O'Donnell D
J Comp Physiol Psychol. 1979 Apr;93(2):330-6. doi: 10.1037/h0077555.
Probing against the vaginal cervix (CP) suppresses responses to noxious stimulation in rats. The first experiment rules out the possibility that this effect is due to CP-induced immobilization. All rats first learned to press a panel, thus terminating noxious skin shock. Then they either received CP (experimentals) or did not (controls) when they pressed the panel during skin shock that was inescapable. The controls soon showed extinction of the panel-press response, whereas the experimentals continued pressing the panel and obtaining CP, for significantly more trials. The rats thus performed an operant response for CP at a time before CP could have blocked their movement. The second experiment argues against the possiblity that CP exerts its effect by "distracting" the rats from the skin shock. The rats received inescapable skin shock which continued for 7 sec after each panel-press response. During this shock one group received CP, and another received perineal probing ("distraction" control). The panel-press latency was significantly shorter in the CP group than in the perineal group. Latency in a control group, in which shock was terminated as soon as the rats pressed the panel, did not differ significantly from the CP group. Latency in another control group, in which the shock persisted for 7 sec after the rats pressed the panel with no probing being applied, was not significantly different from that of the perineal-probing group but was significantly longer than latency in the CP group. Thus the present studies suggest that CP is indeed analgesic and that this effect of CP is mediated by neither movement inhibition nor distraction.
对阴道宫颈（CP）进行探查可抑制大鼠对伤害性刺激的反应。第一个实验排除了这种效应是由CP诱导的固定不动所致的可能性。所有大鼠首先学会按压面板，从而终止伤害性皮肤电击。然后，当它们在无法逃避的皮肤电击期间按压面板时，实验组接受CP（实验组），而对照组不接受（对照组）。对照组很快就表现出按压面板反应的消退，而实验组则继续按压面板并获得CP，次数明显更多。因此，在CP可能阻止它们移动之前，大鼠就对CP做出了操作性反应。第二个实验反驳了CP通过将大鼠从皮肤电击上“分散注意力”来发挥其作用的可能性。大鼠接受无法逃避的皮肤电击，每次按压面板反应后持续7秒。在这种电击期间，一组接受CP，另一组接受会阴探查（“分散注意力”对照组）。CP组的按压面板潜伏期明显短于会阴组。在大鼠按压面板后电击立即终止的对照组中，潜伏期与CP组无显著差异。在大鼠按压面板后电击持续7秒且不进行探查的另一对照组中，潜伏期与会阴探查组无显著差异，但明显长于CP组。因此，目前的研究表明CP确实具有镇痛作用，并且CP的这种作用既不是由运动抑制介导的，也不是由分散注意力介导的。
