Restraint-induced corticosterone secretion and hypothalamic CRH mRNA expression are augmented during acute withdrawal from chronic cocaine administration.
Stress responses during cocaine withdrawal likely contribute to drug relapse and may be intensified as a consequence of prior cocaine use. The present study examined changes in stressor-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis during acute withdrawal from chronic cocaine administration. Adult male Sprague-Dawley rats received daily administration of cocaine (30 mg/kg, i.p.) or saline for 14 days. Twenty-four hours after the last injection, rats in each group were sacrificed under stress-free conditions or following 30 min of immobilization. Plasma corticosterone (CORT) was measured in trunk-blood using radioimmunoassay, corticotropin-releasing hormone (CRH) mRNA levels in the paraventricular nucleus (PVN) of the hypothalamus were measured using in situ hybridization and glucocorticoid receptor (GR) protein expression in the pituitary gland and dissected brain regions was measured using Western blot analysis. Basal CRH mRNA in the PVN was unaltered as a result of prior cocaine administration. However, a significant increase in CRH mRNA was observed 90 min following the termination of restraint in cocaine withdrawn, but not saline-treated, rats. Basal CORT was also unaffected by prior cocaine administration, but the CORT response measured immediately after restraint was significantly augmented in cocaine-withdrawn rats. Differences in GR protein expression in number of regions implicated in negative feedback regulation of HPA function, including the hypothalamus, were not observed. These findings indicate that the HPA response to stressors is intensified during early withdrawal from cocaine administration and may be independent of changes in GR-mediated negative feedback.
Mantsch
John R
JR
Department of Biomedical Sciences, Marquette University, Milwaukee, WI 53201, USA.
Taves
Sarah
S
Khan
Tayyiba
T
Katz
Eric S
ES
Sajan
Tanveer
T
Tang
Lee C
LC
Cullinan
William E
WE
Ziegler
Dana R
DR
D000818:Animals; D003042:Cocaine / Q000009:adverse effects; D019970:Cocaine-Related Disorders / Q000378:metabolism* / Q000503:physiopathology; D003345:Corticosterone / Q000097:blood / Q000378:metabolism*; D003346:Corticotropin-Releasing Hormone / Q000235:genetics*; D018765:Dopamine Uptake Inhibitors / Q000009:adverse effects; D005246:Feedback / Q000187:drug effects / Q000502:physiology; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects / Q000378:metabolism; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism; D010913:Pituitary-Adrenal System / Q000187:drug effects / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011965:Receptors, Glucocorticoid / Q000378:metabolism; D012149:Restraint, Physical; D013315:Stress, Psychological / Q000378:metabolism* / Q000503:physiopathology; D013375:Substance Withdrawal Syndrome / Q000378:metabolism* / Q000503:physiopathology; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
D018765:Dopamine Uptake Inhibitors; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D003346:Corticotropin-Releasing Hormone; D003042:Cocaine; D003345:Corticosterone