The area postrema is involved in paraquat-induced conditioned aversion behavior and neuroendocrine activation of the hypothalamic-pituitary-adrenal axis.
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.
Edmonds
B K
BK
Department of Physiology and Pharmacology, College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
Edwards
G L
GL
D000704:Analysis of Variance; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D003216:Conditioning, Operant / Q000187:drug effects*; D003345:Corticosterone / Q000097:blood; D004305:Dose-Response Relationship, Drug; D006540:Herbicides / Q000494:pharmacology*; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects; D008297:Male; D009490:Neurosecretory Systems / Q000187:drug effects*; D010269:Paraquat / Q000494:pharmacology*; D010913:Pituitary-Adrenal System / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012249:Rhombencephalon / Q000502:physiology*; D013649:Taste / Q000187:drug effects
D006540:Herbicides; D010269:Paraquat; D003345:Corticosterone