Mantz J, Milla C, Glowinski J, Thierry A M
Chaire de Neuropharmacologie, INSERM U.114, Collège de France, Paris.
Neuroscience. 1988 Nov;27(2):517-26. doi: 10.1016/0306-4522(88)90285-0.
The medial prefrontal cortex receives converging projections from the mediodorsal thalamic nucleus, dopaminergic cells from the ventral tegmental area dn noradrenergic cells from the locus coeruleus. Stimulation of the ventral tegmental area inhibits the spontaneous activity of prefrontal cortical neurons and blocks the excitatory response evoked by stimulation of the mediodorsal thalamic nucleus (10 Hz). The aim of the present study was to compare the influence of dopaminergic and noradrenergic afferents on the spontaneous and evoked activity of medial prefrontal cortical neurons. In ketamine-anaesthetized rats, repetitive stimulation (20 Hz, 10 s) of the locus coeruleus produced a long-lasting post-stimulus inhibition (mean duration: 45 s) of the spontaneous activity of 56% of the tested cells. This effect was decreased markedly following selective destruction of the ascending noradrenergic pathways (local 6-hydroxy-dopamine injection) or depletion of cortical catecholamines by alpha-methyl-para-tyrosine pretreatment, suggesting that these inhibitory responses are mediated by noradrenergic neurons. The excitatory response to mediodorsal thalamus nucleus stimulation (10 Hz) could still be evoked during the post-stimulus inhibitory period induced by locus coeruleus stimulation (20 Hz, 10 s) resulting in the enhancement of signal-to-noise ratio. On the other hand, a population of prefrontal cortex neurons (26%) was found to be reproducibly activated by noxious tail pinch. This evoked response was still present during the post-stimulus inhibitory period induced by locus coeruleus stimulation but was completely suppressed during stimulation of the ventral tegmental area (10 Hz). In conclusion, these results indicate that the dopaminergic and noradrenergic systems exert a completely distinct control of information transfer in the medial prefrontal cortex.
内侧前额叶皮质接收来自背内侧丘脑核、腹侧被盖区多巴胺能细胞以及蓝斑去甲肾上腺素能细胞的汇聚投射。刺激腹侧被盖区可抑制前额叶皮质神经元的自发活动，并阻断由背内侧丘脑核刺激（10赫兹）诱发的兴奋性反应。本研究的目的是比较多巴胺能和去甲肾上腺素能传入对内侧前额叶皮质神经元自发和诱发活动的影响。在氯胺酮麻醉的大鼠中，对蓝斑进行重复刺激（20赫兹，10秒）可对56%的受试细胞的自发活动产生持久的刺激后抑制（平均持续时间：45秒）。在选择性破坏上行去甲肾上腺素能通路（局部注射6-羟基多巴胺）或通过α-甲基-对酪氨酸预处理耗尽皮质儿茶酚胺后，这种效应明显减弱，表明这些抑制性反应是由去甲肾上腺素能神经元介导的。在蓝斑刺激（20赫兹，10秒）诱发的刺激后抑制期内，仍可诱发对背内侧丘脑核刺激（10赫兹）的兴奋性反应，从而提高信噪比。另一方面，发现一群前额叶皮质神经元（26%）可被有害的尾部夹捏反复激活。这种诱发反应在蓝斑刺激诱发的刺激后抑制期内仍然存在，但在腹侧被盖区刺激（10赫兹）期间被完全抑制。总之，这些结果表明多巴胺能和去甲肾上腺素能系统对内侧前额叶皮质的信息传递施加了完全不同的控制。
