Effects of Clonidine on Pituitary- Adrenocortical Axis in Morphine-Tolerant Rats and after Naloxone-lnduced Withdrawal
- 1 January 1992
- journal article
- research article
- Published by S. Karger AG in Pharmacology
- Vol. 44 (3) , 158-164
- https://doi.org/10.1159/000138908
Abstract
The effects of systemically administered clonidine on pituitary-adrenocortical axis in morphine-tolerant rats and after naloxone-induced withdrawal were examined. In naive animals, clonidine (0.5 and 1 mg/kg s.c.) significantly increased plasma β-endorphin-like immunoreactivity (β-END-LI) and cortisol levels. This effect was significantly reduced in morphine-tolerant animals. Naloxone treatment induced an increase of plasma β-END-LI and cortisol levels in morphine-tolerant animals. The increase in cortisol level after withdrawal was significantly reduced by clonidine. These results are consistent with an interaction between α2-adrenoceptors and opioid systems in the control of pituitary-adrenocortical axis during morphine tolerance and withdrawal.Keywords
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