Department of Pharmacology and Experimental Neuroscience, 985800 Nebraska Medical Center, Omaha, NE 68198-5800, USA.
Neuroscience. 2011 Sep 29;192:761-72. doi: 10.1016/j.neuroscience.2011.06.045. Epub 2011 Jun 22.
Alpha-2 adrenergic receptors (A2AR) regulate multiple brain functions and are enriched in developing brain. Studies demonstrate norepinephrine (NE) plays a role in regulating brain maturation, suggesting it is important in A2AR development. To investigate this we employed models of NE absence and excess during brain development. For decreases in NE we used N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride (DSP4), a specific noradrenergic neurotoxin. Increased noradrenergic terminal density was produced by methylazoxymethanol acetate (MAM) treatment. A2AR density was assayed with [(3)H]RX821002 autoradiography. DSP4 lesions on postnatal day (PND) 3 produce A2AR decreases in many regions by PND 5. A2AR recover to control levels by PND 15 and 25 and there is no further change in total receptor density. We also assayed A2AR in brains lesioned with DSP4 on PND 13, 23, 33 and 43 and harvested 22 days post-lesion. A2AR levels remain similar to control at each of these time points. We examined A2AR functionality and high affinity state with epinephrine-stimulated [(35)S]GTPγS and [(125)I]p-iodoclonidine autoradiography, respectively. On PND 25, control animals and animals lesioned with DSP4 on PND 3 have similar levels of [(35)S]GTPγS incorporation and no change in high affinity state. This is in contrast to increases in A2AR high affinity state produced by DSP4 lesions of mature brain. We next investigated A2AR response to increases in norepinephrine levels produced by MAM. In contrast to DSP4 lesions, increasing NE results in a large increase in A2AR. Animals treated with MAM on gestational day 14 had cortical [(3)H]RX821002 binding 100-200% greater than controls on PND 25, 35, 45, 55 and 65. These data indicate that NE regulation of A2AR differs in developing and mature brain and support the idea that NE regulates A2AR development and this has long term effects on A2AR function.
阿尔法-2 肾上腺素能受体（A2AR）调节多种大脑功能，并且在发育中的大脑中丰富存在。研究表明去甲肾上腺素（NE）在调节大脑成熟中起作用，这表明它在 A2AR 发育中很重要。为了研究这一点，我们在大脑发育过程中使用了 NE 缺乏和过量的模型。对于 NE 的减少，我们使用了 N-（2-氯乙基）-N-乙基-2-溴苯甲胺盐酸盐（DSP4），这是一种特定的去甲肾上腺素神经毒素。甲基偶氮甲醇乙酸盐（MAM）处理会增加去甲肾上腺素末梢密度。A2AR 密度通过 [(3)H]RX821002 放射自显影进行测定。DSP4 损伤在出生后第 3 天（PND3）导致许多区域的 A2AR 在 PND5 时减少。A2AR 在 PND15 和 PND25 时恢复到对照水平，并且总受体密度没有进一步变化。我们还在 PND13、23、33 和 43 时用 DSP4 损伤大脑，并在损伤后 22 天收获。在这些时间点，A2AR 水平仍与对照相似。我们分别用肾上腺素刺激的 [(35)S]GTPγS 和 [(125)I]p-碘氯定 autoradiography 研究了 A2AR 的功能和高亲和力状态。在 PND25 时，对照动物和 PND3 时用 DSP4 损伤的动物具有相似水平的 [(35)S]GTPγS 掺入，并且高亲和力状态没有变化。这与成熟大脑中 DSP4 损伤产生的 A2AR 高亲和力状态的增加形成对比。接下来，我们研究了 MAM 引起的 NE 水平增加对 A2AR 的反应。与 DSP4 损伤相反，增加 NE 会导致 A2AR 大量增加。在妊娠第 14 天用 MAM 治疗的动物在 PND25、35、45、55 和 65 时皮质 [(3)H]RX821002 结合比对照高 100-200%。这些数据表明，NE 对 A2AR 的调节在发育中和成熟的大脑中是不同的，并支持 NE 调节 A2AR 发育的观点，这对 A2AR 的功能有长期影响。
