Thorn-Gray B E, Johnson M H, Ashbrook R M
Behav Neural Biol. 1982 Sep;36(1):69-76. doi: 10.1016/s0163-1047(82)90256-4.
Male albino Holtzman rats were stereotaxically implanted with two bipolar stimulating electrodes, aimed at the periaqueductal gray matter of the brainstem. Focal brain stimulation-produced analgesia was assessed by the tail-flick method. After establishing that focal brain stimulation elicited analgesia at both sites, behavioral tolerance (i.e., reduced analgesia) was induced at one site through repeated stimulation. Upon elicitation of tolerance at one site, stimulation was immediately switched to the other site (which had not been previously rendered tolerant) and analgesia was assessed. Tail-flick latencies revealed transfer of behavioral tolerance from the site given repeated stimulation to the site not given repeated stimulation. While the mechanism involved in this cross-tolerance is not known, a neurochemical substrate may be involved.
雄性白化霍尔兹曼大鼠通过立体定位植入两个双极刺激电极，目标是脑干的导水管周围灰质。通过甩尾法评估局灶性脑刺激产生的镇痛效果。在确定局灶性脑刺激在两个部位均能引起镇痛后，通过重复刺激在一个部位诱导行为耐受性（即镇痛作用减弱）。当在一个部位诱导出耐受性后，立即将刺激切换到另一个部位（该部位之前未产生耐受性）并评估镇痛效果。甩尾潜伏期显示行为耐受性从接受重复刺激的部位转移到未接受重复刺激的部位。虽然这种交叉耐受性所涉及的机制尚不清楚，但可能涉及一种神经化学底物。
