Adrenocortical and nociceptive responses to opioid blockade in hypertension-prone men and women.
OBJECTIVE
Attenuated pain sensitivity and exaggerated adrenocortical stress reactivity have been documented in individuals at high risk for hypertension. The endogenous opioid system may play a role in these response alterations. We compared adrenocortical and nociceptive responses to opioid blockade using naltrexone in hypertension-prone men and women.


METHODS
Ninety-nine participants completed two sessions during which a placebo or 50 mg naltrexone was administered using a double-blind, counterbalanced design. Participants rated their pain and completed the McGill Pain Questionnaire (MPQ) after three assessments of the nociceptive flexion reflex and after assessment of nociceptive pain threshold and tolerance. Saliva samples were obtained throughout the sessions.


RESULTS
Salivary cortisol levels increased after pain assessment after the ingestion of naltrexone, but not after placebo, with the low-risk group exhibiting an earlier peak of cortisol response. Participants reported greater pain ratings and higher MPQ scores in the naltrexone versus placebo condition, and these effects were more pronounced in women. Pain threshold and tolerance were higher among high-risk men relative to low-risk men.


CONCLUSIONS
The results are consistent with the inhibitory effects of the endogenous opioids on cortisol response and suggest an altered response timeline among hypertension-prone individuals. The results demonstrate that hypoalgesia may be a marker of hypertension risk in men but not in women.
Department of Behavioral Sciences, University of Minnesota Medical School, Duluth, MN 55812, USA. malabsi@umn.edu
Mustafa
M
al'Absi
Christopher
C
France
Angie
A
Harju
Janis
J
France
Lorentz
L
Wittmers
D000293:Adolescent; D000302:Adrenal Cortex / Q000187:drug effects*; D000328:Adult; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis; D006973:Hypertension / Q000150:complications / Q000503:physiopathology*; D006987:Hypesthesia / Q000503:physiopathology; D008297:Male; D009271:Naltrexone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D009619:Nociceptors / Q000187:drug effects*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D012737:Sex Factors
D009292:Narcotic Antagonists; D009271:Naltrexone; D006854:Hydrocortisone