Dunn-Meynell A A, Levin B E
Department of Veterans Affairs Medical Center, East Orange, NJ 07018.
Brain Res. 1993 Sep 24;623(1):25-32. doi: 10.1016/0006-8993(93)90005-8.
Norepinephrine (NE), acting on brain adrenoceptors, plays an important role in barrel field neuronal activity and plasticity. For this reason, the distribution of alpha 1- and alpha 2-adrenoceptors in the somatosensory cortex barrel field was studied by autoradiographic techniques in rats undergoing plastic change or NE depletion. In layers IV and V of the cortex, the pattern of alpha 1-adrenoceptors (assessed by [3H]prazosin binding) varied across the barrel field. There was relatively low binding within the barrels themselves, with 21% higher binding in the surrounding septa. alpha 2-Adrenoceptor binding (assessed with [3H]paraminoclonidine) was almost homogeneous across the entire barrel field. Two weeks after noradrenergic deafferentation by unilateral lesioning of the locus coeruleus, there was a 16% upregulation of [3H]prazosin binding. This then returned to control levels of by 8 weeks. Peripheral deafferentation of sensory input to the barrel field produced the opposite effect on alpha 1-adrenoceptors. Unilateral removal of all but the central (C3) vibrissa (which induces plastic changes in the cortical representation of the spared virbrissa) caused a 12% decrease in [3H]prazosin binding in the whole barrel field at 2 weeks after surgery which returned to normal by 8 weeks. Therefore, alpha 1-adrenoceptors in the barrel field of the rat are affected in opposite ways by changes in NE content and afferent sensory input. We hypothesize that alpha 1-adrenoceptor levels are modulated after vibrissectomy through either an indirect reaction to reduced cortical gamma-aminobutyric acid levels, or by a reordering of metabolic priorities during plastic change of the cortical neuronal network.
去甲肾上腺素（NE）作用于脑内肾上腺素能受体，在桶状区神经元活动和可塑性方面发挥重要作用。因此，利用放射自显影技术，对经历可塑性变化或NE耗竭的大鼠体感皮层桶状区α1和α2肾上腺素能受体的分布进行了研究。在皮层的IV层和V层，α1肾上腺素能受体的模式（通过[3H]哌唑嗪结合评估）在整个桶状区有所不同。桶状区内的结合相对较低，周围间隔区的结合高21%。α2肾上腺素能受体结合（用[3H]对氨基可乐定评估）在整个桶状区几乎是均匀的。通过单侧损毁蓝斑进行去甲肾上腺素能传入纤维切断术后两周，[3H]哌唑嗪结合上调了16%。然后在8周时恢复到对照水平。对桶状区感觉输入进行外周传入纤维切断对α1肾上腺素能受体产生相反的影响。单侧切除除中央（C3）触须外的所有触须（这会在保留触须的皮层表征中诱导可塑性变化），术后2周整个桶状区[3H]哌唑嗪结合减少12%，8周时恢复正常。因此，大鼠桶状区的α1肾上腺素能受体受NE含量变化和传入感觉输入的相反影响。我们假设，在切除触须后，α1肾上腺素能受体水平通过对皮层γ-氨基丁酸水平降低的间接反应或在皮层神经元网络可塑性变化期间代谢优先级的重新排序而受到调节。
