Tseng L L, Tang R
Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee.
Neuroscience. 1989;33(1):93-100. doi: 10.1016/0306-4522(89)90313-8.
Microinjection of morphine sulfate into dorsal raphe, ventrolateral central gray and dorsolateral central gray inhibits spinal nociceptive reflexes. The effects of the blockade of spinal opioid, adrenergic, and serotonergic receptors by intrathecal injection of naloxone, yohimbine and methysergide, respectively, on inhibition of the tail-flick response induced by morphine microinjected into dorsal raphe, ventrolateral central gray and dorsolateral central gray were studied. Naloxone (20 micrograms) given intrathecally effectively antagonized inhibition of the tail-flick response induced by morphine (4 micrograms) given into dorsal raphe and ventrolateral central gray, but not dorsolateral central gray. On the other hand, intrathecal injection of yohimbine (30 micrograms) antagonized inhibition of the tail-flick response induced by morphine given into ventrolateral central gray and dorsolateral central gray, but not dorsal raphe. Intrathecal injection of prazosin (30 micrograms) did not antagonize inhibition of the tail-flick response induced by morphine given into dorsal raphe or lateral central gray. Intrathecal injection of methysergide (30 micrograms) only partially antagonized inhibition of the tail-flick response induced by morphine given into dorsal raphe, but not ventrolateral central gray and dorsolateral central gray. It is concluded that the analgesia induced by morphine injected into dorsal raphe is mediated by spinal opioid receptors but not by spinal alpha 2-adrenergic receptors while the analgesia produced by morphine given into dorsolateral central gray is mediated by spinal alpha 2-adrenergic receptors. The analgesia induced by morphine given into ventrolateral central gray is mediated in part by both spinal alpha 2-adrenergic and opioid receptors.(ABSTRACT TRUNCATED AT 250 WORDS)
向中缝背核、腹外侧中央灰质和背外侧中央灰质微量注射硫酸吗啡可抑制脊髓伤害性反射。分别通过鞘内注射纳洛酮、育亨宾和麦角新碱阻断脊髓阿片类、肾上腺素能和5-羟色胺能受体，研究其对向中缝背核、腹外侧中央灰质和背外侧中央灰质微量注射吗啡所诱导的甩尾反应抑制作用的影响。鞘内注射20微克纳洛酮可有效拮抗向中缝背核和腹外侧中央灰质注射4微克吗啡所诱导的甩尾反应抑制作用，但对背外侧中央灰质无效。另一方面，鞘内注射30微克育亨宾可拮抗向腹外侧中央灰质和背外侧中央灰质注射吗啡所诱导的甩尾反应抑制作用，但对中缝背核无效。鞘内注射30微克哌唑嗪不能拮抗向中缝背核或外侧中央灰质注射吗啡所诱导的甩尾反应抑制作用。鞘内注射30微克麦角新碱仅部分拮抗向中缝背核注射吗啡所诱导的甩尾反应抑制作用，对腹外侧中央灰质和背外侧中央灰质无效。结论是，向中缝背核注射吗啡所诱导的镇痛作用由脊髓阿片类受体介导，而非脊髓α2-肾上腺素能受体介导；而向背外侧中央灰质注射吗啡所产生的镇痛作用由脊髓α2-肾上腺素能受体介导。向腹外侧中央灰质注射吗啡所诱导的镇痛作用部分由脊髓α2-肾上腺素能受体和阿片类受体共同介导。（摘要截短于250字）
