AJP - Regulatory, Integrative and Comparative Physiology, Vol 252, Issue 3 548-R553, Copyright © 1987 by American Physiological Society
Prolonged alterations in plasma cortisol circadian rhythms following trauma in baboons
T. K. McIntosh
Few studies have been performed concerning alterations in the circadian
rhythmicity of adrenocortical function following trauma. The present study
examined the effects of surgical trauma of varying severity on the
secretory pattern of adrenocorticosteroids in the female baboon (Papio
anubus). In 30 baboons, blood samples were obtained every hour for three
96-h periods: 1 wk prior to surgery; beginning 30 min following incision
closure; and beginning 7 days following surgery. Animals were divided into
three groups: anesthesia/surgical controls, low-trauma group [(LT),
laparotomy plus 5-min bowel traction], or high-trauma group [(HT),
laparotomy plus 20-min bowel traction]. A postoperative rise in plasma
cortisol was observed that persisted up to 10 days postsurgery and could be
significantly correlated with severity of trauma. The episodic nature of
cortisol secretion was unaffected by surgery. The circadian rhythm of
cortisol was phase shifted in the LT group and abolished up to 8 days
postsurgery in the HT group. We conclude that the magnitude of posttrauma
rise and circadian disruption of plasma cortisol is correlated with
magnitude of surgical trauma. However, contrary to previous reports,
elevated levels of cortisol may persist for an extended time (10 days)
following the primary insult.
