Behavioral and endocrine adaptation, and up-regulation of NPY expression in rat amygdala following repeated restraint stress.
A single 1 h restraint increases experimental anxiety in the elevated plus-maze through actions within the amygdala, while intra-amygdala administration of neuropeptide Y (NPY) has the opposite effect. Endogenous amygdala NPY expression is suppressed by single restraint, providing a possible mechanism for the anxiety-promoting action of this stressor. Here, we examined whether repeated stressor exposure might lead to an adaptation (habituation or sensitization) with regard to plus-maze behavior and glucocorticoid response, and whether this might be accompanied by altered effects of the stressor on NPY expression. Following repeated restraint (1 h/day, 9-10 days), neither an anxiogenic-like effect of the stressor nor a glucocorticoid response were present. This behavioral and endocrine adaptation was accompanied by an up-regulation of prepro-NPY mRNA and NPY peptide in amygdala but not in hypothalamic or cortical extracts, an effect opposite to that previously seen after a single restraint session. Thus, an up-regulation of NPY expression in the amygdala complex may be an adaptive mechanism recruited to cope with a repeated stressor.
Thorsell
A
A
Addiction Center South, Karolinska Institute, Huddinge University Hospital, Sweden.
Carlsson
K
K
Ekman
R
R
Heilig
M
M
D000222:Adaptation, Physiological / Q000502:physiology; D000223:Adaptation, Psychological / Q000502:physiology; D000679:Amygdala / Q000378:metabolism*; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D003345:Corticosterone / Q000096:biosynthesis; D004703:Endocrine System / Q000502:physiology*; D008297:Male; D009478:Neuropeptide Y / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D011863:Radioimmunoassay; D051381:Rats; D017207:Rats, Sprague-Dawley; D012149:Restraint, Physical; D012260:Ribonucleases / Q000378:metabolism; D013315:Stress, Psychological / Q000378:metabolism*; D015854:Up-Regulation / Q000502:physiology*; D015430:Weight Gain / Q000502:physiology
D009478:Neuropeptide Y; D012333:RNA, Messenger; D012260:Ribonucleases; D003345:Corticosterone