Edmonds B K, Edwards G L
Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
Brain Res. 1996 Mar 11;712(1):127-33. doi: 10.1016/0006-8993(95)01419-5.
Paraquat is a herbicide capable of eliciting conditioned taste aversion (CTA), a behavioral response characteristic of toxicosis. The area postrema (AP) is a hindbrain circumventricular organ previously shown to be important in mediating signs of paraquat-induced toxicity, namely CTA and weight loss. The relationship between neural substrates for paraquat-induced CTA and activation of the hypothalamic-pituitary-adrenal (HPA) axis was investigated in Sprague-Dawley rats with lesions centered on the AP (APX) and sham-operated (SHM) rats administered paraquat (25 mumol/kg) or saline (1 ml/kg). Injection of paraquat at a dose sufficient to condition taste aversion, but produce no other signs of overt toxicity, significantly increased plasma corticosterone concentrations in SHM rats up to 4 h after administration. Paraquat-induced activation of the HPA axis was significantly attenuated in AP-lesioned rats as compared to sham-operated controls. These findings suggest the area postrema is a common neural substrate for the behavioral and neuroendocrine responses to paraquat.
百草枯是一种能够引发条件性味觉厌恶（CTA）的除草剂，CTA是中毒的一种行为反应特征。最后区（AP）是后脑室周器官，先前已证明其在介导百草枯诱导的毒性迹象（即CTA和体重减轻）方面很重要。在以AP为中心进行损伤的Sprague-Dawley大鼠（APX）和假手术（SHM）大鼠中，研究了百草枯诱导的CTA的神经基质与下丘脑-垂体-肾上腺（HPA）轴激活之间的关系，这些大鼠分别给予百草枯（25 μmol/kg）或生理盐水（1 ml/kg）。注射足以引发味觉厌恶但不产生其他明显毒性迹象的剂量的百草枯后，SHM大鼠给药后长达4小时血浆皮质酮浓度显著升高。与假手术对照组相比，AP损伤大鼠中百草枯诱导的HPA轴激活明显减弱。这些发现表明，最后区是对百草枯的行为和神经内分泌反应的共同神经基质。
