Simmons K, Jones D J
Brain Res. 1985 Feb;350(1-2):306-10. doi: 10.1016/0165-3806(85)90275-5.
Norepinephrine (NE) stimulated cyclic adenosine 3',5'-monophosphate (cyclic AMP) accumulation in regional spinal cord and cortical tissue slices from postnatal rats demonstrated distinct developmental patterns. NE-concentration-response studies using a 10-min incubation period demonstrated minimal NE-stimulated cyclic AMP accumulation in whole spinal cord at PD 1-5 with maximal sensitivity on PD 12. Thereafter, sensitivity decreased to adult values at PD 30. Sensitivity changes were reflected in alterations in maximal response only since NE EC50s all averaged 10(-6) M. This agrees with no change in calculated Kd for NE with increased Vmax to PD 12 and a reduction thereafter. Studies on regional spinal cord and cerebral cortical cyclic AMP accumulation indicated peak NE sensitivity in cervical and thoracic cord occurred at PD 10, in lumbar cord at PD 15, and in cerebral cortex at PD 20. The fact that inhibition of phosphodiesterase (PPDE) produced the same percentage alteration in peak accumulation in spinal cord slices regardless of postnatal age suggests that PPDE is not the primary determinant of the ontogenic changes. The results indicate that the postnatal development of spinal NE receptors may be reflected in an increase in the responsiveness of the cyclic AMP system to NE.
去甲肾上腺素（NE）刺激新生大鼠脊髓和皮质组织切片中3',5'-环磷酸腺苷（环磷腺苷）的积累呈现出不同的发育模式。使用10分钟孵育期的NE浓度-反应研究表明，在出生后第1-5天，整个脊髓中NE刺激的环磷腺苷积累极少，在出生后第12天敏感性最高。此后，敏感性在出生后第30天降至成年水平。敏感性变化仅反映在最大反应的改变上，因为NE的半数有效浓度（EC50）平均均为10^(-6) M。这与NE的解离常数（Kd）在出生后第12天Vmax增加之前没有变化，之后降低的情况一致。对脊髓区域和大脑皮质环磷腺苷积累的研究表明，颈髓和胸髓中NE敏感性峰值出现在出生后第10天，腰髓中出现在出生后第15天，大脑皮质中出现在出生后第20天。无论出生后年龄如何，磷酸二酯酶（PPDE）的抑制在脊髓切片中峰值积累产生相同百分比的变化，这一事实表明PPDE不是个体发育变化的主要决定因素。结果表明，脊髓NE受体的出生后发育可能反映在环磷腺苷系统对NE反应性的增加上。
