Effects of self-administered cocaine on plasma adrenocorticotropic hormone and cortisol in male rhesus monkeys

Jillian H. Broadbear, Gail Winger, Theodore J. Cicero, James H. Woods

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

This study was designed to examine the effects of self-administered cocaine on hypothalamic-pituitary-adrenal (HPA) axis activity in rhesus monkeys. Initially, basal release of cortisol and adrenocorticotropic hormone (ACTH) was measured in singly housed male and female monkeys (n = 9) over a 24-h period using plasma samples obtained from indwelling venous catheters. Basal cortisol and ACTH levels in both male and female rhesus monkeys demonstrated a circadian pattern of release, with peak levels for cortisol (19.60 ± 2.16 μg/dl) and ACTH (19.63 ± 2.56 pg/ml) measured at 6:00 AM. The nadir for ACTH (6.27 ± 0.62 pg/ml) occurred at 6:00 PM, preceding the cortisol nadir (5.55 ± 1.21 μg/dl) at 9:00 PM. The reinforcing effects of saline, 0.01, 0.03, 0.1, and 0.3 mg/kg/injection cocaine were then evaluated using a fixed-ratio 30, time-out 10-min schedule of reinforcement in seven male monkeys. Blood was sampled before, during, and after self-administration sessions. Self-administration of cocaine produced dose-dependent increases in cortisol and ACTH. One dose of cocaine (0.03 mg/kg/injection), although reliably self-administered, did not produce a significant increase in HPA axis activity. These results indicate that although cocaine dose-dependently increases HPA axis activity, the HPA effect is more likely a consequence of overall cocaine intake than it is an indicator of cocaine doses that are sufficient to maintain self-administration behavior.

Original languageEnglish (US)
Pages (from-to)1641-1647
Number of pages7
JournalJournal of Pharmacology and Experimental Therapeutics
Volume289
Issue number3
StatePublished - Jun 1999
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Medicine
  • Pharmacology

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