Magnan J, Tiberi M
Département de Pharmacologie, Université de Montréal, Que., Canada.
Brain Res Dev Brain Res. 1989 Feb 1;45(2):275-81. doi: 10.1016/0165-3806(89)90045-x.
The presence of multiple opioid binding sites in human fetal brain at 20 weeks gestational age was determined using the following selective tritiated ligands: D-Ala2, N-MePhe4, Gly-ol5-enkephalin (DAGO) for the mu-type, D-Pen2, D-Pen5-enkephalin (DPDP) for the delta-type and U-69,593 for the kappa-type. [3H]DAGO and [3H]U-69,593 each bind to a single class of high-affinity sites in membrane preparations with respective Kd values of 0.96 +/- 0.33 nM and 0.57 +/- 0.20 nM. The binding capacity for [3H]DAGO is 1.38 +/- 0.21 pmol/g tissue whereas [3H]U-69,593 has a binding capacity of 1.04 +/- 0.22 pmol/g tissue. Using DPDP we did not detect any specific high-affinity binding sites in human fetal brain. The non-selective tritiated opioid ethylketazocine (EKC) labels a homogenous class of sites with a Kd of 0.17 +/- 0.01 nM and a binding capacity of 2.15 +/- 0.15 pmol/g tissue, a value that is not statistically different from the total capacity obtained with [3H]DAGO and [3H]U-69,593. Competition studies using selective unlabeled opioids against the binding of [3H]-DAGO, [3H]U-69,593 or [3H]EKC indicate that opioid sites present in human fetal brain possess similar pharmacological characteristics to those found in human and mammalian adult brain. The results of this study present the first evidence for the presence of mu- and kappa-type opioid sites in human fetal brain and this may support the postulated role of the opioid system in the neurobiological development.
使用以下选择性氚标记配体测定了孕20周时人类胎儿大脑中多个阿片类结合位点的存在情况：用于μ型的D-Ala2、N-MePhe4、Gly-ol5-脑啡肽（DAGO），用于δ型的D-Pen2、D-Pen5-脑啡肽（DPDP）以及用于κ型的U-69,593。[3H]DAGO和[3H]U-69,593各自在膜制剂中与一类单一的高亲和力位点结合，其各自的解离常数（Kd）值分别为0.96±0.33 nM和0.57±0.20 nM。[3H]DAGO的结合容量为1.38±0.21 pmol/g组织，而[3H]U-69,593的结合容量为1.04±0.22 pmol/g组织。使用DPDP时，我们在人类胎儿大脑中未检测到任何特异性高亲和力结合位点。非选择性氚标记阿片类药物乙基酮佐辛（EKC）标记一类均一的位点，其Kd为0.17±0.01 nM，结合容量为2.15±0.15 pmol/g组织，该值与用[3H]DAGO和[3H]U-69,593获得的总容量无统计学差异。使用选择性未标记阿片类药物针对[3H]-DAGO、[3H]U-69,593或[3H]EKC的结合进行的竞争研究表明，人类胎儿大脑中存在的阿片类位点具有与人类和哺乳动物成体大脑中发现的位点相似的药理学特征。本研究结果首次证明了人类胎儿大脑中存在μ型和κ型阿片类位点，这可能支持了阿片类系统在神经生物学发育中假定的作用。
