Psychopharmacology

, Volume 224, Issue 1, pp 133–143

Social rank, chronic ethanol self-administration, and diurnal pituitary–adrenal activity in cynomolgus monkeys

Authors

    • Oregon National Primate Research CenterOregon Health and Science University
  • Megan N. McClintick
    • Oregon National Primate Research CenterOregon Health and Science University
  • Kathleen A. Grant
    • Oregon National Primate Research CenterOregon Health and Science University
    • Department of Behavioral NeuroscienceOregon Health and Science University
Original Investigation

DOI: 10.1007/s00213-012-2707-z

Cite this article as:
Helms, C.M., McClintick, M.N. & Grant, K.A. Psychopharmacology (2012) 224: 133. doi:10.1007/s00213-012-2707-z

Abstract

Rationale

Dominance hierarchies affect ethanol self-administration, with greater intake among subordinate animals compared to dominant animals. Excessive ethanol intake disrupts circadian rhythms. Diurnal rhythms of the hypothalamic–pituitary–adrenal axis have not been characterized in the context of ethanol self-administration with regard to social rank.

Objective

This study aimed to determine whether diurnal pituitary–adrenal hormonal rhythms account for differences between social ranks in ethanol self-administration or are differentially affected by ethanol self-administration between social ranks.

Methods

During alternating individual (n = 11–12) and social (n = 3 groups) housing of male cynomolgus monkeys (Macaca fascicularis), diurnal measures of cortisol and adrenocorticotropic hormone (ACTH) were obtained from plasma samples three times per week. Social rank was determined, ethanol (4 %, w/v) self-administration was induced, and then the monkeys were allowed a choice of water or ethanol for 22 h/day for 49 weeks.

Results

For all social ranks, plasma ACTH was elevated during social housing, but cortisol was stable, although greater among dominant monkeys. Ethanol self-administration blunted the effect of social housing, cortisol, and the diurnal rhythm for both hormones, regardless of daily ethanol intake (1.2–4.2 g/kg/day). Peak ACTH and cortisol were more likely to be observed in the morning during ethanol access. Ethanol, not vehicle, intake was lower during social housing across social ranks. Only dominant monkeys showed significantly lower blood–ethanol concentration during social housing.

Conclusions

There was a low threshold for disruption of diurnal pituitary rhythms by ethanol drinking, but sustained adrenal corticosteroid rhythms. Protection against heavy drinking among dominant monkeys may have constrained ethanol intoxication, possibly to preserve dominance rank.

Keywords

EthanolHPA axisStressMonkeyCortisolACTH

Supplementary material

213_2012_2707_Fig5_ESM.jpg (85 kb)
Supplemental Fig. 1

Plasma ACTH and cortisol across the experiment among individual monkeys housed together in rack 1 (JPEG 85.0 kb)

213_2012_2707_MOESM1_ESM.tif (644 kb)
High resolution image (TIFF 644 kb)
213_2012_2707_Fig6_ESM.jpg (112 kb)
Supplemental Fig. 1

Plasma ACTH and cortisol across the experiment among individual monkeys housed together in rack 1 (JPEG 85.0 kb)

213_2012_2707_MOESM2_ESM.tif (756 kb)
High resolution image (TIFF 756 kb)
213_2012_2707_Fig7_ESM.jpg (68 kb)
Supplemental Fig. 1

Plasma ACTH and cortisol across the experiment among individual monkeys housed together in rack 1 (JPEG 85.0 kb)

213_2012_2707_MOESM3_ESM.tif (486 kb)
High resolution image (TIFF 486 kb)
213_2012_2707_Fig8_ESM.jpg (36 kb)
Supplemental Fig. 1

Plasma ACTH and cortisol across the experiment among individual monkeys housed together in rack 1 (JPEG 85.0 kb)

213_2012_2707_MOESM4_ESM.tif (213 kb)
High resolution image (TIFF 213 kb)
213_2012_2707_Fig9_ESM.jpg (85 kb)
Supplemental Fig. 1

Plasma ACTH and cortisol across the experiment among individual monkeys housed together in rack 1 (JPEG 85.0 kb)

213_2012_2707_MOESM5_ESM.tif (515 kb)
High resolution image (TIFF 515 kb)
213_2012_2707_Fig10_ESM.jpg (79 kb)
Supplemental Fig. 1

Plasma ACTH and cortisol across the experiment among individual monkeys housed together in rack 1 (JPEG 85.0 kb)

213_2012_2707_MOESM6_ESM.tif (513 kb)
High resolution image (TIFF 512 kb)

Copyright information

© Springer-Verlag 2012