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Circulating opioid peptides during water immersion in normal man.
P Coruzzi1, C Ravanetti, L Musiari
1Istituto di Semeiotica Medica, University of Parma, Italy.
Clinical Science (London, England : 1979)
|February 1, 1988
Summary
Head-out water immersion altered key hormone levels in healthy volunteers. Methionine-enkephalin increased, while beta-endorphin, adrenocorticotropic hormone, and prolactin decreased, suggesting hormonal regulation during fluid shifts.
Area of Science:
- Endocrinology
- Physiology
Background:
- Hormonal responses to physiological stressors are crucial for homeostasis.
- Water immersion is a unique model for inducing extracellular fluid volume expansion.
Purpose of the Study:
- To investigate the dynamic changes in specific pituitary hormones and neuropeptides during head-out water immersion.
- To explore potential regulatory mechanisms underlying these hormonal variations.
Main Methods:
- Healthy volunteers underwent head-out water immersion.
- Plasma levels of beta-endorphin, methionine-enkephalin, adrenocorticotropic hormone, and serum prolactin were measured.
- Hemodynamic parameters including mean arterial pressure and heart rate were monitored.
Main Results:
- Water immersion led to a significant increase in plasma methionine-enkephalin.
- Concurrently, plasma beta-endorphin, adrenocorticotropic hormone, and serum prolactin levels were suppressed.
- These hormonal changes were associated with a decrease in mean arterial pressure and heart rate.
Conclusions:
- Head-out water immersion significantly modulates circulating pituitary hormones and neuropeptides.
- A dopaminergic inhibitory mechanism is proposed to regulate beta-endorphin, adrenocorticotropic hormone, and prolactin during fluid volume expansion.
- These findings provide insights into neuroendocrine adaptations to simulated changes in body fluid distribution.