The mu opiate receptor is responsible for descending pain inhibition originating in the periaqueductal gray region of the rat brain.
The mu opiate receptor is responsible for descending pain inhibition originating in the periaqueductal gray region of the rat brain.
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DOI：
10.1016/0014-2999(88)90145-8
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发表时间：
1988-10
影响因子：
5
通讯作者：
D. J. Smith;J. M. Perrotti;T. Crisp;M. Cabral;J. Long;J. Scalzitti
中科院分区：
文献类型：
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作者：
D. J. Smith;J. M. Perrotti;T. Crisp;M. Cabral;J. Long;J. Scalzitti
将对 μ、κ、σ 和 δ 阿片受体表现出选择性的阿片激动剂显微注射到大鼠大脑的导水管周围灰色区域 (PAG)，以确定与下行疼痛抑制启动相关的受体亚型。脊髓组织的热伤害性甩尾反射用于检测镇痛。仅吗啡 (μ) 和 [D-Ala2, D-Leu5] 脑啡肽 (DADLE) (δ>μ) 产生镇痛。然而，这两种药物似乎都是通过 μ（吗啡）受体发挥作用，因为：(1) DADLE 的作用不受 δ 受体拮抗剂抑制，(2) 选择性更高的 δ 激动剂 [D-Pen2、D-Pen5]脑啡肽无效，以及 (3) 对其他非 μ 受体位点具有选择性的激动剂（乙基酮环佐辛和 U50,488H 用于 κ；n-烯丙基正美他佐辛用于 κ） σ）也无效。看来 DADLE 可能充当 PAG 中吗啡受体的部分激动剂。该肽是一种效力低的激动剂，当最大有效剂量的肽与吗啡同时施用时观察到拮抗作用。乙基酮环佐辛和正美佐辛也被发现可以拮抗吗啡，这一观察结果与它们除了分别对 κ 和 σ 受体具有激动作用之外还可以充当 μ 受体拮抗剂的建议是一致的。因此，μ 受体似乎负责大鼠 PAG 的棘叶镇痛。
Opiate agonists exhibiting selectivity for μ, κ, σ and δ opiate receptors were microinjected into the periaqueductal gray region (PAG) of the brain of rats to determine the receptor subtype(s) associated with the initiation of descending pain inhibition. The spinally organized, heat nociceptive tail-flick reflex was used to detect analgesia. Only morphine (μ) and [D-Ala2, D-Leu5]enkephalin (DADLE) (δ>μ) produced analgesia. However, both drugs appeared to be acting through the μ (morphine) receptor, since: (1) the action of DADLE was not inhibited by δ receptor antagonists, (2) a more highly selective δ agonist [D-Pen2, D-Pen5]enkephalin was ineffective and (3) agonists selective at other non-μ receptor sites (ethylketocyclazocine and U50,488H for κ; n-allylnormetazocine for σ) were also ineffective. It appeared that DADLE might be acting as a partial agonist at the morphine receptor in the PAG. The peptide was an agonist with low efficacy, and when a maximally effective dose of the peptide was administered simultaneously with morphine antagonism was observed. Ethylketocyclazocine and n-allynormetazocine were also found to antagonize morphine, an observation that is consistent with the suggestion that they may act as μ receptor antagonists in addition to their agonistic action at κ and σ receptors, respectively. Thus, μ receptors appear to be responsible for the spinopetal analgesia from the PAG of the rat.