Title

Beta-Endorphin Immunoreactivity During High-Intensity Exercise With And Without Opiate Blockade

Keywords

Exercise; Man; Naloxone; Placebo; β-endorphin

Abstract

Nine highly fit men [mean (SE) maximum oxygen uptake, V̇O2max: 63.9 (1.7) ml·kg 1·min 1; age 27.6 (1.6) years] were studied during two treadmill exercise trials to determine plasma β-endorphin immunoreactivity during intense exercise (80% V̇O2max). A double-blind experimental design was used, and subjects performed the two exercise trials in counterbalanced order. Exercise trials were 30 min in duration and were conducted 7 days apart. One exercise trial was undertaken following administration of naloxone (1.2 mg; 3 cm3) and the other after receiving a placebo (0.9% NaCl saline; 3 cm3). Prior to each experimental trial, a flexible catheter was placed into an antecubital vein and baseline blood samples were collected. Thereafter, each subject received either a naloxone or placebo bolus injection. Blood samples were also collected after 10, 20 and 30 min of continuous exercise. β-Endorphin was higher (P < 0.05) during exercise when compared to preexercise in both trials. However, no statistically significant difference was found (P > 0.05) between exercise time points within either experimental trial, β-endorphin immunoreactivity was greater (P < 0.05) in the naloxone than in the placebo trial during each exercise sampling time point [10 min: 63.7 (3.9) pg·ml 1 vs 78.7 (3.8) pg·ml 1; 20 min: 68.7 (4.1) pg·ml 1 vs 83.8 (4.3) pg·ml 1; 30 min: 71.0 (4.3) pg·ml 1 vs 82.5 (3.2) pg·ml 1]. These data suggest that intense exercise induces significant increases in β-endorphin that are maintained over time during steady-rate exercise. Exercise and naloxone had an interactive effect on β-endorphin release that warrants further investigation. © Springer-Verlag 2001.

Publication Date

1-1-2001

Publication Title

European Journal of Applied Physiology

Volume

86

Issue

1

Number of Pages

92-96

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1007/s004210100501

Socpus ID

85047685045 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/85047685045

This document is currently not available here.

Share

COinS