Kosten T, Contreras R J
Department of Psychiatry, Yale University, New Haven, CT 06519.
Behav Brain Res. 1989 Oct 1;35(1):9-21. doi: 10.1016/s0166-4328(89)80003-8.
Previous studies have shown that area postrema (AP) lesions cause deficits in conditioned taste aversion in the rat. They also lead to chronically lowered heart rate which can be reversed by the animals' increased appetite for and ingestion of hypertonic saline. Although not previously examined in conditioned taste aversion, changes in autonomic nervous system activity as reflected in heart rate may be an important aspect of conditioning. The present study investigated the effects of AP lesions on heart rate conditioned responses (CRs) and unconditioned responses (UCRs). Two groups of AP lesioned and sham-operated rats, one that did and one that did not drink saline solution to raise heart rate, were studied. Both LiCl and scopolamine, which have opposite effects on heart rate, were the unconditioned stimulus (UCS) agents in two separate studies. In intact rats, LiCl-mediated conditioned taste aversion was associated with decreased conditioned stimulus (CS) intake and decreased heart rate Both effects were blunted by AP lesions, although all rats displayed heart rate UCRs to LiCl. The AP rats that drank saline behaved like intact rats exhibiting both a conditioned taste aversion and conditioned heart rate responses to the CS. Although CS intake decreased, no heart rate CRs developed with scopolamine. Scopolamine-mediated conditioned taste aversion was attenuated in both saline and non-saline drinking AP-lesioned groups. Thus, when conditioned taste aversion was associated with heart rate CRs, the AP lesion-induced deficit was counteracted by saline ingestion. Conversely, when there were no heart rate CRs, conditioned taste aversion was disrupted by the lesion regardless of saline ingestion.
先前的研究表明，最后区（AP）损伤会导致大鼠条件性味觉厌恶出现缺陷。这些损伤还会导致心率长期降低，而动物对高渗盐水食欲增加并摄入高渗盐水后，心率降低的情况可以得到逆转。尽管先前未在条件性味觉厌恶中进行研究，但心率所反映的自主神经系统活动变化可能是条件作用的一个重要方面。本研究调查了AP损伤对心率条件反应（CRs）和非条件反应（UCRs）的影响。研究了两组AP损伤大鼠和假手术大鼠，一组饮用盐溶液以提高心率，另一组不饮用。在两项单独的研究中，对心率有相反作用的氯化锂（LiCl）和东莨菪碱均作为非条件刺激（UCS）剂。在完整大鼠中，LiCl介导的条件性味觉厌恶与条件刺激（CS）摄入量减少和心率降低有关。AP损伤使这两种效应减弱，尽管所有大鼠对LiCl均表现出心率非条件反应。饮用盐水的AP大鼠表现得像完整大鼠，对CS既表现出条件性味觉厌恶又表现出条件性心率反应。尽管CS摄入量减少，但东莨菪碱并未引发心率条件反应。在饮用盐水和不饮用盐水的AP损伤组中，东莨菪碱介导的条件性味觉厌恶均减弱。因此，当条件性味觉厌恶与心率条件反应相关时，摄入盐水可抵消AP损伤引起的缺陷。相反，当不存在心率条件反应时，无论是否摄入盐水，损伤都会破坏条件性味觉厌恶。
