Abstract
Rationale Rats raised in isolation self-administer more amphetamine than rats raised in enrichment. Objective This study examined whether differential rearing alters basal and amphetamine-stimulated corticosterone and whether blocking glucocorticoid receptors alters amphetamine self-administration in differentially reared rats. Methods The rats were raised from 21 to 51 days of age in either an enriched condition (EC), social condition (SC), or isolated condition (IC). Following the repeated collection of basal blood samples, the rats were administered amphetamine (0.5 or 2.0 mg/kg, i.p.) or saline, and blood samples were collected again. In another experiment, EC and IC rats were trained to i.v. self-administer amphetamine (0.003 or 0.03 mg/kg/infusion) and then were pretreated with the glucocorticoid receptor antagonist RU-486 (5, 10, or 20 mg/kg; i.p.) or vehicle prior to the session. Results Basal-free corticosterone levels were ~4 times higher in IC rats than in either EC or SC rats with the first blood collection, but not with repeated collections. IC rats showed a more rapid amphetamine-induced increase in corticosterone levels than EC and SC rats. RU-486 pretreatment decreased amphetamine self-administration dose-dependently in both EC and IC rats; however, using an amphetamine unit dose of 0.03 mg/kg/infusion, the effect of RU-486 was blunted in IC rats (maximal decrease of ~40% in IC and ~90% in EC), suggesting an environment-induced difference in the role of glucocorticoid receptors in stimulant reinforcement. Conclusion The increase in stimulant self-administration produced by social isolation may involve enhanced reactivity of the hypothalamo-pituitary-adrenal stress axis.
| Original language | English |
|---|---|
| Pages (from-to) | 293-301 |
| Number of pages | 9 |
| Journal | Psychopharmacology |
| Volume | 218 |
| Issue number | 1 |
| DOIs | |
| State | Published - Nov 2011 |
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All Science Journal Classification (ASJC) codes
- Pharmacology
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Environmental-induced differences in corticosterone and glucocorticoid receptor blockade of amphetamine self-administration in rats. / Stairs, Dustin; Prendergast, Mark A.; Bardo, Michael T.
In: Psychopharmacology, Vol. 218, No. 1, 11.2011, p. 293-301.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Environmental-induced differences in corticosterone and glucocorticoid receptor blockade of amphetamine self-administration in rats
AU - Stairs, Dustin
AU - Prendergast, Mark A.
AU - Bardo, Michael T.
PY - 2011/11
Y1 - 2011/11
N2 - Rationale Rats raised in isolation self-administer more amphetamine than rats raised in enrichment. Objective This study examined whether differential rearing alters basal and amphetamine-stimulated corticosterone and whether blocking glucocorticoid receptors alters amphetamine self-administration in differentially reared rats. Methods The rats were raised from 21 to 51 days of age in either an enriched condition (EC), social condition (SC), or isolated condition (IC). Following the repeated collection of basal blood samples, the rats were administered amphetamine (0.5 or 2.0 mg/kg, i.p.) or saline, and blood samples were collected again. In another experiment, EC and IC rats were trained to i.v. self-administer amphetamine (0.003 or 0.03 mg/kg/infusion) and then were pretreated with the glucocorticoid receptor antagonist RU-486 (5, 10, or 20 mg/kg; i.p.) or vehicle prior to the session. Results Basal-free corticosterone levels were ~4 times higher in IC rats than in either EC or SC rats with the first blood collection, but not with repeated collections. IC rats showed a more rapid amphetamine-induced increase in corticosterone levels than EC and SC rats. RU-486 pretreatment decreased amphetamine self-administration dose-dependently in both EC and IC rats; however, using an amphetamine unit dose of 0.03 mg/kg/infusion, the effect of RU-486 was blunted in IC rats (maximal decrease of ~40% in IC and ~90% in EC), suggesting an environment-induced difference in the role of glucocorticoid receptors in stimulant reinforcement. Conclusion The increase in stimulant self-administration produced by social isolation may involve enhanced reactivity of the hypothalamo-pituitary-adrenal stress axis.
AB - Rationale Rats raised in isolation self-administer more amphetamine than rats raised in enrichment. Objective This study examined whether differential rearing alters basal and amphetamine-stimulated corticosterone and whether blocking glucocorticoid receptors alters amphetamine self-administration in differentially reared rats. Methods The rats were raised from 21 to 51 days of age in either an enriched condition (EC), social condition (SC), or isolated condition (IC). Following the repeated collection of basal blood samples, the rats were administered amphetamine (0.5 or 2.0 mg/kg, i.p.) or saline, and blood samples were collected again. In another experiment, EC and IC rats were trained to i.v. self-administer amphetamine (0.003 or 0.03 mg/kg/infusion) and then were pretreated with the glucocorticoid receptor antagonist RU-486 (5, 10, or 20 mg/kg; i.p.) or vehicle prior to the session. Results Basal-free corticosterone levels were ~4 times higher in IC rats than in either EC or SC rats with the first blood collection, but not with repeated collections. IC rats showed a more rapid amphetamine-induced increase in corticosterone levels than EC and SC rats. RU-486 pretreatment decreased amphetamine self-administration dose-dependently in both EC and IC rats; however, using an amphetamine unit dose of 0.03 mg/kg/infusion, the effect of RU-486 was blunted in IC rats (maximal decrease of ~40% in IC and ~90% in EC), suggesting an environment-induced difference in the role of glucocorticoid receptors in stimulant reinforcement. Conclusion The increase in stimulant self-administration produced by social isolation may involve enhanced reactivity of the hypothalamo-pituitary-adrenal stress axis.
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U2 - 10.1007/s00213-011-2448-4
DO - 10.1007/s00213-011-2448-4
M3 - Article
C2 - 21887496
AN - SCOPUS:82955187314
VL - 218
SP - 293
EP - 301
JO - Psychopharmacology
JF - Psychopharmacology
SN - 0033-3158
IS - 1
ER -