Austin J H, Nygren L G, Fuxe K
Med Biol. 1976 Dec;54(5):352-63.
A system is described for recording psoas muscle contractions in response to stimuli delivered to the sole of the foot of the acute spinalized unanaesthetized rat. Clonidine, an alpha adrenergic receptor agonist, caused a major increase in this flexor reflex amplitude. The increase was blocked by phenoxybenzamine at a dosage level of 20 mg/kg which did not, of itself, reduce flexor reflex amplitude. Older, larger rats responded significantly more forcefully to clonidine than did younger, smaller rats. However, these differences between rats of different size tended to disappear when the data were expressed in terms of 0/0 of original baseline amplitude. L-dopa, 75 mg/kg, increased the flexor reflex amplitude more so than did L(+)erythro dihydroxyphenylserine (DOPS) at twice the disage in rats pretreated with reserpine and nialamide. Other DOPS isomers were less effective, and L(-)threo DOPS was toxic. These results support the view that spinal noradrenaline receptors exist that increase the psoas flexor reflex. The advantages of the present system are twofold: first, the results may be quantitated; second, small amounts of potential central noradrenaline receptor agonists and antagonists may be tested for their effect on the flexor reflex using relatively few unanaesthetized rats.
描述了一种用于记录急性脊髓化未麻醉大鼠对足底刺激作出反应时腰大肌收缩的系统。α肾上腺素能受体激动剂可乐定可使这种屈肌反射幅度大幅增加。苯氧苄胺以20mg/kg的剂量可阻断这种增加，而该剂量本身并不会降低屈肌反射幅度。年龄较大、体型较大的大鼠对可乐定的反应明显比年龄较小、体型较小的大鼠更强烈。然而，当数据以原始基线幅度的百分比表示时，不同大小大鼠之间的这些差异往往会消失。在经利血平和烟酰胺预处理的大鼠中，75mg/kg的左旋多巴比两倍剂量的L(+)赤型二羟基苯丝氨酸（DOPS）更能增加屈肌反射幅度。其他DOPS异构体效果较差，而L(-)苏型DOPS有毒。这些结果支持存在能增加腰大肌屈肌反射的脊髓去甲肾上腺素受体这一观点。本系统的优点有两方面：第一，结果可进行量化；第二，使用相对较少的未麻醉大鼠就可测试少量潜在的中枢去甲肾上腺素受体激动剂和拮抗剂对屈肌反射的影响。
