García-Medina Nadia Edith, Vera Gabriela, Miranda María Isabel
Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla No. 3001, Juriquilla, Querétaro, Qro. 76230, Mexico.
Departamento de Neurobiología Conductual y Cognitiva, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla No. 3001, Juriquilla, Querétaro, Qro. 76230, Mexico.
Behav Brain Res. 2015 Feb 1;278:202-9. doi: 10.1016/j.bbr.2014.09.023. Epub 2014 Sep 22.
Taste memory depends on motivational and post-ingestional consequences after a single taste-illness pairing. During conditioned taste aversion (CTA), the taste and visceral pathways reach the nucleus of the solitary tract (NTS), which is the first relay in the CNS and has a vital function in receiving vagal chemical stimuli and humoral signals from the area postrema that receives peripheral inputs also via vagal afferent fibers. The specific aim of the present set of experiments was to determine if the NTS is involved in the noradrenergic and glutamatergic activation of the basolateral amygdala (BLA) during CTA. Using in vivo microdialysis, we examined whether chemical NTS stimulation induces norepinephrine (NE) and/or glutamate changes in the BLA during visceral stimulation with intraperitoneal (i.p.) injections of low (0.08 M) and high (0.3 M) concentrations of lithium chloride (LiCl) during CTA training. The results showed that strength of CTA can be elicited by chemical NTS stimulation (Ringer's high potassium solution; 110 mM KCl) and by intra-NTS microinjections of glutamate, immediately after, but not before, low LiCl i.p. injections that only induce a week aversive memory. However visceral stimulation (with low or high i.p. LiCl) did not induce significantly more NE release in the amygdala compared with the NE increment induced by NTS potassium depolarization. In contrast, high i.p. concentrations of LiCl and chemical NTS stimulation induced a modest glutamate sustained release, that it is not observed with low LiCl i.p. injections. These results indicate that the NTS mainly mediates the visceral stimulus processing by sustained releasing glutamate in the BLA, but not by directly modulating NE release in the BLA during CTA acquisition, providing new evidence that the NTS has an important function in the transmission of signals from the periphery to brain systems that process aversive memory formation.
味觉记忆取决于单次味觉与疾病配对后的动机和摄食后结果。在条件性味觉厌恶（CTA）过程中，味觉和内脏通路到达孤束核（NTS），孤束核是中枢神经系统中的第一个中继站，在接收来自最后区的迷走神经化学刺激和体液信号方面具有重要功能，最后区也通过迷走神经传入纤维接收外周输入。本系列实验的具体目的是确定在CTA过程中，NTS是否参与基底外侧杏仁核（BLA）的去甲肾上腺素能和谷氨酸能激活。我们使用体内微透析技术，研究在CTA训练期间，通过腹腔注射低浓度（0.08 M）和高浓度（0.3 M）的氯化锂（LiCl）进行内脏刺激时，化学性NTS刺激是否会诱导BLA中去甲肾上腺素（NE）和/或谷氨酸的变化。结果表明，化学性NTS刺激（林格氏高钾溶液；110 mM KCl）和NTS内微量注射谷氨酸可以引发CTA的强度，且是在低剂量LiCl腹腔注射仅诱导一周厌恶记忆之后立即引发，而非之前。然而，与NTS钾去极化诱导的NE增加相比，内脏刺激（低剂量或高剂量腹腔注射LiCl）并未在杏仁核中诱导出显著更多的NE释放。相反，高剂量腹腔注射LiCl和化学性NTS刺激诱导了适度的谷氨酸持续释放，而低剂量腹腔注射LiCl则未观察到这种情况。这些结果表明，在CTA获得过程中，NTS主要通过在BLA中持续释放谷氨酸来介导内脏刺激处理，而不是直接调节BLA中的NE释放，这为NTS在将外周信号传递到处理厌恶记忆形成的脑系统中具有重要功能提供了新证据。
