Dopamine susceptibility of APO-SUS rats is not per se coupled to HPA-axis activity

• Published in: Physiology & behavior 2011-02, Vol.102 (2), p.121-125
• Main Authors: van Schijndel, Jessica E, van Zweeden, Martine, van Loo, Karen M.J, Lubbers, Luuk J, Pesman, Gerard J, Sweep, Fred C.G.J, Martens, Gerard J.M
• Format: Article
• Language: English
• Subjects: ACTH, free corticosterone; Adrenocorticotropic Hormone - metabolism; agonists; Analysis of Variance; animal models; Animals; Apomorphine; Apomorphine - pharmacology; Behavior, Animal - drug effects; Behavioral psychophysiology; Biological and medical sciences; Corticosteroid-binding globulin; Corticosterone - metabolism; corticotropin; dopamine; Dopamine - metabolism; Dopamine Agonists - pharmacology; dopamine receptors; Exploratory Behavior - drug effects; Fundamental and applied biological sciences. Psychology; Hypothalamo-Hypophyseal System - physiology; Male; Pituitary-Adrenal System - physiology; Polymorphism, Single Nucleotide - genetics; Psychiatry; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Rat model; Rats; Rats, Wistar; Transcortin - genetics
• ISSN: 0031-9384; 1873-507X
• DOI: 10.1016/j.physbeh.2010.10.013

Abstract A synergistic relationship is thought to exist between hypothalamic–pituitary–adrenal (HPA) axis activity and dopamine neurotransmission. To test whether a high response to dopamine indeed implies a hyperactive HPA-axis, we here used Wistar rats that were selected twice independently (original and replicate lines) for a high or low susceptibility to the dopamine receptor agonist apomorphine (so-called APO-SUS and APO-UNSUS rats, respectively). The APO-SUS rats from the original line displayed a hyperactive HPA-axis in that higher basal and stress-induced adrenocorticotropic hormone (ACTH) levels, and lower basal free-corticosterone levels were observed than those found in the original APO-UNSUS rats. In contrast, the activity of the HPA-axis in the APO-SUS rats from the replicate line did not differ from that in the replicate APO-UNSUS rats. Thus, in the APO-SUS/APO-UNSUS rat model the level of HPA-axis activity is not necessarily causally linked to dopamine responsiveness, implying that a hyperactive HPA-axis is not a prerequisite for a high dopaminergic response.